1

AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON DECEMBER 29, 2000

REGISTRATION NO. 333-69649
================================================================================
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

------------------------

AMENDMENT NO. 3
TO

FORM S-1
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933

------------------------

HYBRIDON, INC.
(EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)

DELAWARE                             2836                            04-3072298
(STATE OR OTHER JURISDICTION OF      (PRIMARY STANDARD INDUSTRIAL             (I.R.S. EMPLOYER
INCORPORATION OR ORGANIZATION)      CLASSIFICATION CODE NUMBER)           IDENTIFICATION NUMBER)

345 VASSAR STREET
CAMBRIDGE, MA 02139
(617) 679-5517

(ADDRESS, INCLUDING ZIP CODE, AND TELEPHONE NUMBER,
INCLUDING AREA CODE, OF REGISTRANT'S PRINCIPAL EXECUTIVE OFFICES)

SUDHIR AGRAWAL
PRESIDENT AND ACTING CHIEF EXECUTIVE OFFICER
HYBRIDON, INC.

345 VASSAR STREET
CAMBRIDGE, MA 02139
(617) 679-5517

(NAME, ADDRESS INCLUDING ZIP CODE, AND TELEPHONE NUMBER,
INCLUDING AREA CODE, OF AGENT FOR SERVICE)

------------------------

COPY TO:

JAMES POLLOCK, ESQ.
HOLLAND & KNIGHT LLP
ONE BEACON STREET
BOSTON, MA 02108
(617) 523-2700

------------------------

APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC: From time
to time after this registration statement becomes effective.

If any of the securities being registered on this Form are to be offered on
a delayed or continuous basis pursuant to Rule 415 under the Securities Act of
1933, check the following box.  [X]

If this Form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list the Securities Act registration statement number of the earlier
effective registration statement for the same offering.  [ ] ------------------

If this Form is a post-effective amendment filed pursuant to Rule 462(c)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering.  [ ] ------------------

If this form is a post-effective amendment filed pursuant to Rule 462(d)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering.  [ ] ------------------

If delivery of the prospectus is expected to be made pursuant to Rule 434,
please check the following box.  [ ]

(Calculation of Registration Fees Table on next page)

------------------------

THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL
FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION
STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(a) OF
THE SECURITIES ACT OF 1933 OR UNTIL THE REGISTRATION STATEMENT SHALL BECOME
EFFECTIVE, ON SUCH DATE AS THE COMMISSION, ACTING PURSUANT TO SAID SECTION 8(a),
MAY DETERMINE.
================================================================================

2

(Continued from previous page)

CALCULATION OF REGISTRATION FEE

---------------------------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------------------------
PROPOSED         PROPOSED
MAXIMUM         MAXIMUM
TITLE OF EACH CLASS OF          AMOUNT TO BE    OFFERING PRICE     AGGREGATE         AMOUNT OF           AMOUNT
SECURITIES TO BE REGISTERED    REGISTERED(10)      PER SHARE     OFFERING PRICE   REGISTRATION FEE   PREVIOUSLY PAID   AMOUNT DUE
---------------------------------------------------------------------------------------------------------------------------------

Series A convertible
preferred stock, $.01 par
value......................       724,295     $ 100.00 (2)     $  72,429,500       $21,728.85        $20,063.59      $ 1553.20
---------------------------------------------------------------------------------------------------------------------------------
Common stock, $.001 par
value......................     7,178,706     $1.15625 (3)     $   8,300,379       $ 2,490.11        $ 3,571.82      $       0
---------------------------------------------------------------------------------------------------------------------------------
Common stock, $.001 par
value......................       460,000     $0.54687 (4)     $     251,560       $    76.23        $    76.23      $       0
---------------------------------------------------------------------------------------------------------------------------------
Common stock, $.001 par
value......................       384,240     $   1.00 (8)     $     348,240       $   101.44        $     0.00      $   96.06
---------------------------------------------------------------------------------------------------------------------------------
Common stock, $.001 par
value, issuable upon
exercise of Founders
warrants...................       173,333     $   3.00 (1)(6)  $     519,999       $   157.58        $   157.58      $       0
---------------------------------------------------------------------------------------------------------------------------------
Common stock, $.001 par
value, issuable upon
conversion of Series A
convertible preferred
stock......................    19,071,741           -- (1)(5)             --               --                --             --
---------------------------------------------------------------------------------------------------------------------------------
Common stock, $.001 par
value, issuable upon
exercise of Class A
warrants...................     3,002,956     $   4.25 (1)(6)  $  12,762,563       $ 3,867.05        $ 3,867.05      $       0
---------------------------------------------------------------------------------------------------------------------------------
Common stock, $.001 par
value, issuable upon
exercise of Class B
warrants...................     1,752,945     $   2.40 (1)(6)  $   4,207,068       $ 1,274.74        $ 1,274.74      $       0
---------------------------------------------------------------------------------------------------------------------------------
Common stock, $.001 par
value, issuable upon
exercise of Class C
warrants...................       841,774     $   2.40 (1)(6)  $   2,020,258       $   657.88        $   657.88      $       0
---------------------------------------------------------------------------------------------------------------------------------
Common stock, $.001 par
value, issuable upon
exercise of Class D
warrants...................       672,267     $   2.40 (1)(6)  $   1,613,441       $   488.87        $   488.87      $       0
---------------------------------------------------------------------------------------------------------------------------------
Common stock, $.001 par
value, issuable upon
exercise of Founders
warrants...................       609,194     $   2.40 (1)(6)  $   1,462,066       $   443.01        $   443.01      $       0
---------------------------------------------------------------------------------------------------------------------------------
Common stock, $.001 par
value, issuable upon
exercise of Founders
warrants...................       588,235     $   4.25 (1)(6)  $   2,499,999       $   757.50        $   757.50      $       0
---------------------------------------------------------------------------------------------------------------------------------
Common stock, $.001 par
value, issuable upon
exercise of warrants.......     1,111,630     $   2.40 (1)(6)  $   2,667,912       $   808.38        $   808.38      $       0
---------------------------------------------------------------------------------------------------------------------------------
Common stock, $.001 par
value, issuable upon
conversion of
Pecks/Founders convertible
debt.......................     2,500,000     $   2.40 (1)(9)  $   6,000,000       $    15.00        $     0.00      $   15.00
---------------------------------------------------------------------------------------------------------------------------------
Common stock, $.001 par
value, issuable upon
conversion of December 1999
convertible debt...........    15,897,808     $   0.60 (1)(9)  $   9,538,685       $ 2,384.68        $     0.00      $2,384.68
---------------------------------------------------------------------------------------------------------------------------------
Common stock, $.001 par
value, issuable upon
conversion of convertible
debt that may be acquired
upon the exercise of
December 1999 warrants.....       679,046     $   0.66 (1)(7)  $     448,170       $   112.05        $     0.00      $  112.05
---------------------------------------------------------------------------------------------------------------------------------
Common stock, $.001 par
value, issuable upon
exercise of Pecks/Founders
subordination fee
warrants...................     2,750,000     $   0.60 (1)(6)  $   1,650,000       $   412.50        $     0.00      $  412.50
---------------------------------------------------------------------------------------------------------------------------------
Common stock, $.001 par
value, issuable upon
conversion of May 2000
convertible debt...........       214,043     $   1.08 (1)(9)  $     231,166       $    57.80        $     0.00      $   57.80
---------------------------------------------------------------------------------------------------------------------------------
Common stock, $.001 par
value, issuable upon
exercise of May 2000
placement agent warrants...       500,000     $   1.08 (1)(6)  $     540,000       $     135.        $     0.00      $    135.
---------------------------------------------------------------------------------------------------------------------------------
Common stock, $.001 par
value, issuable upon
exercise of May 2000
lenders warrants...........     1,000,000     $   1.08 (1)(6)  $   1,080,000       $     270.        $     0.00      $    270.
---------------------------------------------------------------------------------------------------------------------------------
Total Common Registered Per
Calculation of Fee table...    59,387,918                                                                             6,521.29
---------------------------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------------------------

(1) Pursuant to Rule 416, Hybridon is also registering that number of
additional shares of capital stock that may become issuable pursuant to
applicable anti-dilution provisions or pursuant to a stock dividend.

(2) Estimated solely for purposes of calculating the registration fee using the
proposed offering price of the Series A preferred stock, as required by
Rule 457(i). Does not include any shares of Series A preferred stock that
may be issued in the future as a dividend, which shares are expressly
excluded from this registration statement pursuant to Rule 416(b) under the
Securities Act.

(3) Estimated solely for purposes of calculating the registration fee using the
average of the bid and ask price for the common stock on December 17, 1998,
as required by Rule 457(c).

(4) Estimated solely for purposes of calculating the registration fee using the
average of the bid and ask price for the common stock on June 29, 1999, as
required by Rule 457(c).

(5) Pursuant to Rule 457(i) no additional registration fee is required.

(6) Estimated solely for purposes of calculating the Registration Fee using the
exercise price of the warrants, as required by Rule 457(g)(1).

3

(7)Estimated solely for purposes of calculating the registration fee using the
exercise price of warrants to purchase convertible debt at a 10% premium and
a $0.60 per share price to convert the debt into common stock, as required
by Rule 457(g)(1).

(8)Estimated solely for purposes of calculating the registration fee using
$1.00 per share, which was above the average of the bid and ask price for
the common stock on December 22, 2000, which exceeds the price required by
Rule 457(c).

(9)Estimated solely for purposes of calculating the registration fee using the
conversion price of the convertible notes, as required by Rule 457(g)(1).

(10)The following is a reconciliation of the shares being registered on this
Form S-1, as listed above in the "Calculation of Registration Fee" table to
the "Common Stock Included in Offering" column of the "Stockholders Selling
Common Stock" table that begins on page 48 and the "Convertible Preferred
Stock Included in Offering" column of the "Stockholders Selling Preferred
Stock" table that begins on page 53.

------------------------

RECONCILIATION OF SHARES BEING REGISTERED

----------------------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------------------
COMMON            COMMON            COMMON
STOCK             STOCK              STOCK
ISSUABLE UPON     ISSUABLE UPON      ISSUABLE UPON
SERIES A        THE CONVERSION    THE CONVERSION    THE EXERCISE OF    OTHER COMMON
CONVERTIBLE       OF SERIES A       OF DECEMBER       SUBORDINATION     STOCK BEING
PREFERRED STOCK      PREFERRED         1999 DEBT        FEE WARRANTS       REGISTERED
----------------------------------------------------------------------------------------------------------------------------

Composition of Shares:
----------------------------------------------------------------------------------------------------------------------------
Original Issuance...................      624,790          14,700,941        11,978,805         2,750,000
----------------------------------------------------------------------------------------------------------------------------
Accumulated dividends...............       99,505           2,341,294
----------------------------------------------------------------------------------------------------------------------------
Future dividends....................                        2,029,506
----------------------------------------------------------------------------------------------------------------------------
Commissions.........................                                            611,142
----------------------------------------------------------------------------------------------------------------------------
Accumulated interest................                                            820,756
----------------------------------------------------------------------------------------------------------------------------
Future interest.....................                                          2,487,105
----------------------------------------------------------------------------------------------------------------------------
Shares registered per Fee Table.....      724,295          19,071,741        15,897,808         2,750,000        21,668,369
----------------------------------------------------------------------------------------------------------------------------
Conversions to common...............      (92,285)         (2,171,442)
----------------------------------------------------------------------------------------------------------------------------
Future dividends....................                       (2,029,506)
----------------------------------------------------------------------------------------------------------------------------
Future interest.....................                                         (2,487,105)
----------------------------------------------------------------------------------------------------------------------------
Warrants not exercisable until
12/31/00..........................                                                           (2,750,000)
----------------------------------------------------------------------------------------------------------------------------
Registered-Selling Shareholder
Table.............................      632,010          14,870,793        13,410,703                 0        21,668,369
----------------------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------------------

------------------------------------  ------------
------------------------------------  ------------

TOTAL COMMON
STOCK BEING
REGISTERED
------------------------------------  ------------

Composition of Shares:
---------------------------------------------------------------
Original Issuance...................
----------------------------------------------------------------------------
Accumulated dividends...............
-----------------------------------------------------------------------------------------
Future dividends....................
------------------------------------------------------------------------------------------------------
Commissions.........................
-------------------------------------------------------------------------------------------------------------------
Accumulated interest................
----------------------------------------------------------------------------------------------------------------------------
Future interest.....................
----------------------------------------------------------------------------------------------------------------------------
Shares registered per Fee Table.....   59,387,918
----------------------------------------------------------------------------------------------------------------------------
Conversions to common...............   (2,171,442)
----------------------------------------------------------------------------------------------------------------------------
Future dividends....................   (2,029,506)
----------------------------------------------------------------------------------------------------------------------------
Future interest.....................   (2,487,105)
----------------------------------------------------------------------------------------------------------------------------
Warrants not exercisable until
12/31/00..........................   (2,750,000)
----------------------------------------------------------------------------------------------------------------------------
Registered-Selling Shareholder
Table.............................   49,949,865
----------------------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------------------

4

THE INFORMATION IN THIS PROSPECTUS IS NOT COMPLETE AND MAY BE CHANGED.
WE MAY NOT SELL THESE SECURITIES UNTIL THE REGISTRATION STATEMENT FILED
WITH THE SECURITIES AND EXCHANGE COMMISSION IS EFFECTIVE. THIS
PROSPECTUS IS NOT AN OFFER TO SELL THESE SECURITIES AND IS NOT
SOLICITING AN OFFER TO BUY THESE SECURITIES IN ANY STATE WHERE THE OFFER
OR SALE IS NOT PERMITTED.

SUBJECT TO COMPLETION DECEMBER 29, 2000

HYBRIDON, INC.

345 VASSAR STREET

CAMBRIDGE, MASSACHUSETTS 02139

SECONDARY OFFERING PROSPECTUS

724,295 SHARES OF SERIES A CONVERTIBLE PREFERRED STOCK

AND

59,387,918 SHARES OF COMMON STOCK

The shareholders named on pages 48-54 are offering to sell up to 724,295
shares of our series A preferred stock and up to 59,387,918 shares of our common
stock.

The common stock is quoted on the NASD Over-the-Counter or "OTC," Bulletin
Board under the symbol "HYBN." The reported closing bid price of the common
stock on the NASD OTC Bulletin Board on December 28, 2000, was $.42 per share.
Prior to this offering there has been no public market for the convertible
preferred stock.

SEE "RISK FACTORS" BEGINNING ON PAGE 3 OF THIS PROSPECTUS FOR A DISCUSSION
OF CERTAIN FACTORS THAT YOU SHOULD CONSIDER IN EVALUATING AN INVESTMENT IN THE
HYBRIDON'S COMMON STOCK OR SERIES A PREFERRED STOCK.

Neither the Securities and Exchange Commission nor any state securities
commission has approved or disapproved of these securities or determined if this
prospectus is truthful or complete. Any representation to the contrary is a
criminal offense.

The date of this prospectus is           , 2001.

5

TABLE OF CONTENTS

PAGE
----

Summary Financial Data......................................    1
Risk Factors................................................    3
Forward-Looking Statements..................................    5
Business....................................................    6
Properties..................................................   17
Legal Proceedings...........................................   17
Market for Registrant's Common Equity and Related
Stockholder Matters.......................................   17
Dividend Policy.............................................   18
Use of Proceeds.............................................   18
Selected Financial Data.....................................   19

Management's Discussion and Analysis of Financial Condition
and Results of Operations.................................   21
Directors and Executive Officers of Hybridon................   29
Executive Compensation......................................   31
Security Ownership of Certain Beneficial Owners and
Management................................................   37
Certain Relationships and Related Transactions..............   42
Selling Stockholders........................................   48
Description of Capital Stock................................   54
Transfer Agent and Registrar................................   57
Delaware Law and Certain Provisions of Hybridon's Restated
Certificate of Incorporation, Bylaws and Indebtedness.....   57
Plan of Distribution........................................   58
Legal Matters...............................................   59
Experts.....................................................   59
Additional Information......................................   59
Index to Consolidated Financial Statements..................  F-1

6

SUMMARY FINANCIAL DATA

YEARS ENDED                   NINE MONTHS ENDED
DECEMBER 31,                    SEPTEMBER 30,
--------------------------------------    -------------------
1997          1998          1999         1999       2000
----------    ----------    ----------    --------    -------
(IN THOUSANDS, EXCEPT PER SHARE DATA)         (UNAUDITED)

Statement of Operations Data:
Revenues:
Service revenue....................   $     --      $    375      $    365     $    295    $    70
Research and development...........        945         1,100           600          450         --
Royalty and other income...........         --            --           123          107         77
Interest income....................      1,079           148            92           82         66
--------      --------      --------     --------    -------
Total revenues.............      2,024         1,623         1,180          934        213
--------      --------      --------     --------    -------
Operating Expenses:
Research and development...........     35,326        14,183         5,783        4,525      2,794
General and administrative.........     11,027         6,573         3,664        2,947      2,340
Interest...........................      4,278         2,820           683          511      1,857
Restructuring......................     10,345            --            --           --         --
--------      --------      --------     --------    -------
Total operating expenses...     60,976        23,576        10,130        7,983      6,991
--------      --------      --------     --------    -------
Loss from continuing
operations...............    (58,952)      (21,953)       (8,950)      (7,049)    (6,778)
Income (loss) from
discontinued
operations...............    (10,509)       (4,028)       (1,553)      (1,283)     5,292
--------      --------      --------     --------    -------
Loss before extraordinary gain.......    (69,461)      (25,981)      (10,503)      (8,332)    (1,486)
--------      --------      --------     --------    -------
Extraordinary item:
Gain on conversion of 9%
convertible Subordinated notes
payable.........................         --         8,877            --           --         --
--------      --------      --------     --------    -------
Net loss.............................    (69,461)      (17,104)      (10,503)      (8,332)    (1,486)
Accretion of preferred stock
dividend...........................         --        (2,689)       (4,232)      (3,194)    (3,112)
--------      --------      --------     --------    -------
Net loss applicable to common
stockholders.......................   $(69,461)     $(19,793)     $(14,735)    $(11,526)   $(4,598)
========      ========      ========     ========    =======
Basic and diluted net loss per common
share from:
Continuing operations..............   $ (11.67)     $  (1.85)     $  (0.57)    $  (0.45)   $ (0.40)
Discontinued operations............      (2.08)        (0.34)        (0.10)       (0.08)      0.31
Extraordinary gain.................         --          0.75            --           --         --
--------      --------      --------     --------    -------
Net loss per share.................     (13.76)        (1.44)        (0.66)       (0.53)     (0.09)
Accretion of preferred stock
dividends.......................         --         (0.23)        (0.27)       (0.20)     (0.18)
--------      --------      --------     --------    -------
Net loss per share applicable to
common stockholders.............   $ (13.76)     $  (1.67)     $  (0.93)    $  (0.74)   $ (0.27)
========      ========      ========     ========    =======
Shares used in computing basic and
Diluted net loss per common
share(1)...........................      5,050        11,859        15,811       15,654     17,130

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DECEMBER 31,
----------------------    SEPTEMBER 30,
1998         1999           2000
---------    ---------    -------------

Balance Sheet Data:
Cash, cash equivalents and short-term Investments(2)...  $   5,608    $   2,552      $   5,236
Working capital deficit................................     (5,306)      (6,534)        (3,253)
Total assets...........................................     15,092       10,717         11,430
Line of credit.........................................         --           --            231
9% convertible subordinated notes payable..............      1,306        1,306          1,306
8% convertible subordinated notes payable..............         --        6,100          7,737
Accumulated deficit....................................   (238,448)    (253,183)      (257,781)
Total stockholders' equity (deficit)...................      2,249       (6,072)        (6,378)

---------------

(1) Computed on the basis described in Note 2(l) of Notes to Consolidated
Financial Statements appearing elsewhere in this Prospectus.

(2) Short-term investments consisted of U.S. government securities with
maturities greater than ninety days but less than one year from the purchase
date.

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8

RISK FACTORS

Investing in our common stock is very risky. You should be able to bear the
complete loss of your investment. You should carefully consider the risks
presented by the following factors, in addition to the other information in this
prospectus.

OUR FINANCIAL CONDITION AND NEED FOR SUBSTANTIAL ADDITIONAL FUNDING

YOUR INVESTMENT COULD BE SUBSTANTIALLY DILUTED IF WE ISSUE SHARES TO OBTAIN
FINANCING WE NEED.

Our business is the discovery and development of drugs which act on genes
either to increase the production of proteins that combat disease or suppress
the production of proteins which cause or support diseases. In addition, we are
focusing on the design of immunostimulatory oligonucleotide compounds. Since our
founding in 1989, we have not produced any commercially viable drugs and we have
operated at a loss. In the past, we have financed our operations largely from
the sale of shares of common or preferred stock and the sale of debt or other
securities convertible into common stock.

In order to obtain the funds we needed to continue our operations, we will
need to issue shares of common stock or debt or securities convertible into
shares of common stock. We will probably need to issue a significant number of
shares in order to raise sufficient funds to pay our creditors, meet covenants
of our credit facility and continue our operations. This will result in
substantial dilution to your investment.

WE ARE NOT IN COMPLIANCE WITH ONE OF THE COVENANTS IN OUR LOAN AGREEMENT. IF OUR
LENDERS FORECLOSE, WE WILL HAVE FEW, OR NO, ASSETS TO DISTRIBUTE TO OUR
SHAREHOLDERS.

We have taken out a $6 million loan and have completed a $7.1 million 8%
note offering, both of which are secured by substantially all of our assets. The
loan and the 8% notes are owned in part by our affiliates. The loan agreement
for the $6 million loan requires us to maintain liquidity of $2,000,000 and a
net worth of $6,000,000. The 8% notes require us to maintain liquidity of
$1,500,000. On certain occasions in the past, our lenders have waived our
compliance with these requirements, but they may not be willing to do so in the
future. If our lenders and noteholders ever decline to give us waivers, we will
be in default and they will have the right to accelerate the repayment date on
the loan and the 8% notes and foreclose on our assets. Foreclosure will likely
force us to cease doing business or file for bankruptcy. If this should happen,
and we are liquidated, there will be few or no assets available for distribution
to our shareholders. Since the debt is owned in part by our affiliates, the
court may treat the loan as a capital contribution in which case there may be
assets available for distribution to our shareholders, along with the lenders.

WE EXPECT OUR OPERATING LOSSES TO CONTINUE INTO THE FUTURE.

As of September 30, 2000, we have incurred operating losses of
approximately $258 million. We expect to continue incurring operating losses
until revenues from the sale of any drugs that we succeed in developing exceed
our research and development and administrative costs. We will need to spend
substantial additional amounts on research and development, including
preclinical studies and clinical trials, in order to obtain the necessary
regulatory approvals. If we obtain regulatory approval, we will then need to
spend substantial amounts on sales and marketing efforts. See "Business --
Anticipated and Potential Costs."

OUR OPERATIONS

WE MAY NOT SUCCEED IN DEVELOPING A COMMERCIALLY VIABLE DRUG.

We do not currently have any drugs on the market and the drug candidates we
are working on are still in development. Before commercialization, a drug
candidate which has undergone pre-clinical trials with animals to test activity
and safety, must then pass several clinical trials with humans. Phase I testing
is conducted on a small group of healthy individuals for safety and dosage.
Phase I/II testing is on patients with targeted diseases to test safety and, to
a degree, effectiveness. Phase II is conducted on a large group of patients to

3

9

evaluate safety and effectiveness at different doses and Phase III is on a large
patient group to confirm effectiveness. Our drug closest to commercialization,
GEM(R) 231, is still in Phase II clinical trials. All of our other drug
candidates are in pre-clinical trials and have not been tested on humans.

Drug candidates, in general, have a low overall probability of being
commercialized, but that probability increases as the drug advances through the
various development stages. A drug may, for instance, be ineffective, have
undesirable side effects, or demonstrate other therapeutic characteristics that
prevent or limit its commercial use, or may prove too costly to produce in
commercial quantities. If our drug candidates cannot be successfully developed,
or if we are unable to obtain the necessary regulatory approval, we will not be
able to generate the revenues from the sale of drugs that we would need in order
to be profitable.

WE SOLD SUBSTANTIALLY ALL OF OUR REVENUE-GENERATING OPERATIONS.

Throughout our history we have engaged primarily in the research and
development of genetic drugs, however, in 1996 we formed Hybridon Speciality
Products to manufacture certain compounds for Hybridon's internal use, for use
by our collaborators and for sale to third parties. We sold the business and
assets of Hybridon Speciality Products on September 21, 2000, for approximately
$15,000,000. We are now even more dependent upon ultimate success of our drug
research and development activities for our long-term viability.

WE HAVE MANY COMPETITORS, AND MAY NOT BE ABLE TO COMPETE SUCCESSFULLY AGAINST
THEM.

Several companies, in particular Isis Pharmaceuticals, Inc. and Genta
Incorporated, are also in the business of developing antisense drugs. Isis has
received the approval of the U.S. Food and Drug Administration, or "FDA," for
Vitravene, is currently marketing this drug for the treatment of CMV retinitis,
and has several other drugs in clinical testing for the possible treatment of
cancer, including ISIS 3521 and 2503. Genta is testing G3139 in humans, also for
the treatment of cancer. These drugs candidates are further along in clinical
testing than Hybridon's cancer drug GEM(R) 231. Other companies have antisense
drugs in preclinical and clinical development, including Inex and AVI Biopharma.

In general, the human health care products industry is extremely
competitive. Many drugs are currently marketed for the treatment of cancer, such
as Taxol, Carboplatin, Taxotere and Camptosar. While it is unlikely that GEM(R)
231 will compete against these drugs, it may be used in combination with them.
GEM(R) 231 and other Hybridon antisense drugs may not, however, be able to
capture sufficient market share to be profitable.

To our knowledge two privately held companies are developing
immunostimulatory oligonucleotide drugs. These drug candidates are in clinical
trials for various indications, either alone or in combination with vaccines.

Furthermore, biotechnology and related pharmaceutical technologies have
undergone rapid and significant change and we expect that the technologies
associated with biotechnology research and development will continue to develop
rapidly. Our prospects depend in large part on our ability to compete with these
technologies. Any compounds, drugs or processes that we develop may become
obsolete before we recover the expenses incurred in developing them.

OUR ABILITY TO COMPETE WILL SUFFER IF WE ARE UNABLE TO PROTECT OUR PATENT RIGHTS
AND TRADE SECRETS OR IF WE INFRINGE THE PROPRIETARY RIGHTS OF THIRD PARTIES.

Our success will depend to a large extent on our ability to obtain U.S. and
foreign patent protection for drug candidates and processes, preserve trade
secrets and operate without infringing the proprietary rights of third parties.

To obtain a patent on an invention, the inventor must be the first to
invent it or the first to file a patent application for it. We cannot be sure
that the inventors of subject matter covered by patents and patent applications
that we own or license were the first to invent, or the first to file patent
applications for, those inventions. Furthermore, patents we own or license may
be challenged, infringed upon, invalidated, found to be unenforceable, or
circumvented by others, and our rights under any issued patents may not provide

4

10

sufficient protection against competing drugs or otherwise cover commercially
valuable drugs or processes. See "Business -- Patents, Trade Secrets, and
Licenses."

We seek to protect trade secrets and other unpatented proprietary
information, in part by means of confidentiality agreements with our
collaborators, employees, and consultants. If any of these agreements is
breached, we may be without adequate remedies. Also, our trade secrets may
become known or be independently developed by competitors.

OUR SECURITIES

BECAUSE "PENNY STOCK" RULES APPLY TO TRADING IN OUR COMMON STOCK, YOU MAY FIND
IT DIFFICULT TO SELL THE SHARES YOU PURCHASE IN THIS OFFERING.

Our common stock is a "penny stock," as it is not listed on an exchange and
trades at less than $5.00 a share. Broker-dealers who sell penny stocks must
provide purchasers of these stocks with a standardized risk-disclosure document.
It provides information about penny stocks and the nature and level of risks
involved in investing in the penny-stock market. A broker must also give a
purchaser, orally or in writing, bid and offer quotations and information
regarding broker and salesperson compensation, make a written determination that
the penny stock is a suitable investment for the purchaser, and obtain the
purchaser's written agreement to the purchase. The penny stock rules may make it
difficult for you to sell your shares of our stock. Because of the rules, there
is less trading in penny stocks. Also, many brokers choose not to participate in
penny stock transactions.

CERTAIN EXISTING STOCKHOLDERS HOLD A SUBSTANTIAL PORTION OF OUR STOCK, AND
CONSEQUENTLY COULD CONTROL MOST MATTERS REQUIRING APPROVAL BY STOCKHOLDERS.

Our officers, directors and principal stockholders own or control more than
60% of our common stock on a fully-diluted basis. As a result, these
stockholders, acting together, have the ability to control most matters
requiring approval by the stockholders. This concentration of ownership may have
the effect of delaying or preventing a change in control of Hybridon.

FORWARD-LOOKING STATEMENTS

This prospectus contains forward-looking statements that do not reflect
historical facts, but instead reflect Hybridon's current expectations, estimates
and projections regarding its business. Forward-looking statements can be found
in the material set forth under "Risk Factors," "Business," and "Management's
Discussion and Analysis of Financial Condition and Results of Operations," and
are characterized by use of words such as "believes," "plans," "expects," and
"anticipates." Forward-looking statements are not guarantees of future
performance, and necessarily involve risks and uncertainties, and Hybridon's
results could differ materially from those anticipated in the forward-looking
statements contained in this prospectus.

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BUSINESS

HYBRIDON

Hybridon, established in 1989, engages in the discovery and development of
genetic drugs which treat diseases by acting on a particular gene or protein.
The genetic drugs being developed by Hybridon are based on "antisense"
technology, in that they use synthetic genetic material, also called
oligonucleotides, with the aim of inhibiting or reducing the body's production
of proteins that directly or indirectly cause or support a given disease.

Hybridon has developed and owns certain innovations in antisense
technology. These include important innovations in areas of medicinal chemistry,
which concern the design of new antisense oligonucleotide compounds. Hybridon
also has rights to technology allowing the chemical modifications of
oligonucleotides.

Hybridon has also developed a portfolio of chemically modified
immunostimulatory oligonucleotide compounds.

Lastly, until September 21, 2000, the day Hybridon sold its Hybridon
Speciality Products ("HSP") business, Hybridon manufactured and sold
oligonucleotide compounds. Hybridon sold the business and assets of HSP in order
to focus on its drug research and development activities and to provide working
capital to fund its activities.

These aspects of Hybridon's business are discussed below.

TECHNOLOGY OVERVIEW

INTRODUCTION

The heart, brain, liver and other organs in the human body function
together to support life. Each microscopic cell within these organs produces
proteins that affect how that cell functions within its organ, and ultimately
how efficiently each organ functions within the body. Most human diseases are
caused by abnormal production or performance of proteins within individual
cells. In some instances, cell proteins act directly to cause or support a
disease. In other instances, cell proteins interfere with other proteins that
prevent or combat disease. Traditional drugs are designed to interact with
protein molecules that cause or support diseases. Antisense drugs are designed
to work at an earlier stage to stop the production of disease-causing or
disease-supporting proteins.

The information that controls a cell's production of a specific protein is
contained in the gene relating to that protein. Each gene is made up of two
intertwined strands of DNA that form a structure called a "double helix." Each
strand of DNA consists of a string of individual DNA building blocks, called
nucleotides, arranged in a specific sequence. Each strand is made of linked
molecules, known as the "backbone," and attached to the backbone are molecules
known as "bases." It is the sequence of bases that contains genetic information.
One of the paired strands contains the information that directs the composition
of a specific protein, and is called the "coding" strand. The other strand, the
"non-coding" strand, contains a different but complementary sequence of
nucleotides.

The full complement of human genes, known as the human "genome," consists
of over 100,000 genes and contains the information required to produce all human
proteins. A copy of the complete human genome is present in each cell, and each
cell makes proteins based on its copy of the genome. Cells make proteins in a
two-stage process. First, the cell creates a molecule of messenger RNA
consisting of a string of nucleotides in a sequence complementary to the
sequence of the coding strand of DNA. This is called the "sense" sequence. A
sequence that is complementary to the sense sequence is called the "antisense"
sequence. Then, the cell then produces proteins based on the information
contained in the messenger RNA. The number of copies of messenger RNA the cell
produces will affect how many copies of a given protein it produces.

A normal cell produces a given set of normal proteins in the right amount
for the body to function properly. A diseased cell produces inappropriate or
mutant proteins, or produces the wrong amount of normal

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proteins. A cell produces mutant proteins when its DNA changes, either through
mutation, as in many types of cancer cells, or by infection with a virus.

CONVENTIONAL DRUGS

Most drugs are chemicals that stimulate or suppress the function of a
particular molecule, usually a protein, with tolerable side effects. Most drug
side effects arise when a drug interacts with proteins in addition to the target
protein. Generally, the fewer other proteins a drug interacts with, the fewer
the side effects.

Conventional drugs generally aim to bind only two or three points of the
target molecule. Frequently, however, sites on other non-target molecules
resemble the target binding site enough to permit the conventional drug to bind
to some degree to those non-target molecules. This lack of selectivity can
result in unwanted side effects, potentially leading to decreased effectiveness.

A further characteristic of conventional drugs is that developing them is a
time-consuming and expensive process. For every compound that is found to be
effective and have tolerable side effects, thousands may be investigated and
rejected.

ANTISENSE DRUGS

An oligonucleotide with a sequence exactly complementary to that of the
messenger RNA of a specific gene can bind to and inhibit the expression of the
messenger RNA, thereby decreasing or eliminating the production of
disease-causing or disease-supporting proteins. Antisense technology involves
the design and synthesis of such oligonucleotides. Hybridon believes that drugs
based on antisense technology may be more effective, cause fewer side effects,
and have a greater range of applications than conventional drugs because
antisense drugs are designed to intervene in the production of proteins, rather
than after the proteins are made, and in a highly specific fashion.

Advances in mapping the human genome, including work conducted by academic
institutions, biotechnology companies and pharmaceutical companies, have allowed
many targets for antisense drugs to be identified. Once a gene associated with a
disease-associated protein is identified, an antisense oligonucleotide can be
designed, and the pharmaceutical effects of that oligonucleotide can be improved
by chemical modification. Chemically-modified oligonucleotides can be composed
of DNA, RNA, or a combination of the two.

Because the nucleotide sequence of a chemically-modified antisense
oligonucleotide is complementary to its target sequence on the messenger RNA of
a given gene, the antisense oligonucleotide forms a large number of bonds at the
target site, typically between 40 and 60. This allows it to form a strong bond
with the messenger RNA. A few identical messenger RNA molecules can cause the
cell to produce many copies of a protein; similarly, a few identical
chemically-modified antisense oligonucleotides can stop this process. This is
due in part to an enzyme called RNase H that can destroy messenger RNA bound to
an oligonucleotide without destroying the oligonucleotide itself, thus freeing
the oligonucleotide to bind with, and cause the destruction of, other messenger
RNA molecules. This process is generally known as catalytic activity. All of
Hybridon's drugs are designed to take advantage of this catalytic activity so
that a relatively small number of antisense molecules can effectively inhibit
production of disease-associated proteins.

HYBRIDON ANTISENSE TECHNOLOGY

Hybridon's antisense chemistry builds on the pioneering work in the
antisense field begun in the 1970s by Dr. Paul C. Zamecnik, a founder,
consultant and director of Hybridon. Development of Hybridon's antisense
chemistry has been directed by Dr. Sudhir Agrawal, Hybridon's Chief Scientific
Officer and now also President and Acting Chief Executive Officer. It has been
based on what is referred to in this prospectus as "advanced chemistries,"
namely Hybridon's ability to alter the chemical makeup of the oligonucleotide
backbone in a manner that makes oligonucleotides safer and more stable without
adversely affecting their ability to promote the destruction of messenger RNA.

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MEDICINAL CHEMISTRIES.  Hybridon's first antisense drug, GEM(R) 91, targets
the messenger RNA that codes for an essential protein in Type 1 Human
Immunodeficiency Virus, or "HIV-1." GEM(R) 91 is based on first-generation
phosphorothioate chemistry, which altered the naturally-occurring, or native,
form of oligonucleotides by replacing certain oxygen atoms in the backbone with
sulfur atoms. GEM(R) 91 was more stable than native DNA, but was still able to
trigger the action of RNaseH, leading to catalytic activity. However, there were
side effects caused by the administration of this modified DNA into the body. In
particular, in the last clinical trial of GEM(R) 91 treatment of three of the
nine patients with advanced HIV disease was interrupted due to unacceptable
decreases in platelet counts. As a result, Hybridon discontinued the GEM(R) 91
program. Hybridon has, however, used the information gained from the human
clinical trials of GEM(R) 91 to design its advanced oligonucleotide chemistries.

Hybridon's scientists have designed and made over twenty families of
advanced oligonucleotide chemistries, including DNA/RNA combinations, also
called hybrid or mixed backbone chemistries. Hybridon believes that antisense
compounds based on these advanced chemistries will show favorable pharmaceutical
characteristics and significantly improve therapeutic value compared to earlier
antisense drug candidates. These compounds are likely to have the following
desirable characteristics:

- fewer side effects

- greater stability in the body, thereby permitting a patient to take doses
less frequently

- greater potency, thereby permitting a patient to take lower doses

- potential for multiple routes of administration, including by injection,
orally, or topically

DRUG POTENTIATION TECHNOLOGY.  Hybridon has discovered that certain
oligonucleotides are able to enhance the activity of irinotecan, a marketed
anti-cancer drug, when the two are used together in animal models of cancer. The
observed increase in activity is not solely due to an antisense mechanism. This
discovery is being further studied to determine the mechanism of the effect and
to possibly prepare for human clinical trials.

FUNCTIONAL GENOMIC TECHNOLOGY.  With the advent of human genome project,
there have been hundreds of newly discovered genes whose functions have not yet
been established. A reliable, fast and economic way to study the function of any
gene is through the use of antisense oligonucleotides specifically designed for
a specific messinger RNA. It is important to understand the role of each gene in
normal and disease conditions before designing drugs for that specific target.

Hybridon has an established program for the use of antisense
oligonucleotides for the study of the function of any newly discovered gene
(functional genomics). Hybridon's antisense obligonucleotides are especially
useful in these studies because of their increased specificity. The target
validation protocols used for the design of antisense oligonucleotides for
functional genomics studies use stringent principles developed at Hybridon
through its extensive experience in the antisense field to increase specificity
and reduce non-antisense effects.

REGULATORY KNOW-HOW.  Hybridon drug development personnel have extensive
experience in working with the FDA and other drug regulatory agencies in an
efficient and cost-effective manner. Hybridon has assisted its spinoff companies
in preparing essential components of their submissions to the FDA.

IMMUNOSTIMULATORY OLIGONUCLEOTIDE TECHNOLOGY

Oligonucleotides containing cytosine-guanosine dinucleotides (CpG-motif)
are known to mobilize the body's immune defense system. This effect is called
immunostimulation. Independently published reports have shown that
CpG-motif-containing oligonucleotide compounds have therapeutic potential as a
vaccine adjuvant and as immunotherapy treatment for cancer, infectious and
allergic diseases.

Hybridon has found that by introducing modifications in sugar, heterocyclic
ring and internucleotide linkages at specific points relative to CpG-motif in
the oligonucleotide compounds causes significant increase in immunostimulatory
activity. These discoveries are being used to synthesize proprietary
immunostimulatory

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oligonucleotide compounds that are potent immunostimulatory agents. These potent
proprietary immunostimulatory oligonucleotide compounds could be used as
immunotherapy treatment of cancer, infectious or allergic diseases, or used
together with various vaccines.

Hybridon has entered into materials transfer agreements with several
biotech and pharmaceutical companies whereby Hybridon supplies modified
oligonucleotides to these companies which will evaluate their potential for
immunostimulatory effects.

DRUG DEVELOPMENT AND DISCOVERY

DRUG DEVELOPMENT AND APPROVAL PROCESS

The process of taking a compound from the laboratory to human patients
generally takes 10 to 15 years. This process is extremely expensive and is
rigorously regulated by governmental agencies, including, in the U.S., the Food
and Drug Administration, or the "FDA." Each drug must undergo a series of
trials, both preclinical and clinical, before the FDA will consider approving it
for commercial sale. The FDA or any company conducting drug trials can
discontinue those trials at any time if it feels that patients are being exposed
to an unacceptable health risk or if there is not enough evidence that the drug
is effective. The FDA may also require a company to provide additional
information or conduct additional tests before it will permit a drug to proceed
from one phase of trials to the next.

The phases of preclinical and clinical trials are described below:

- Preclinical Studies.  Preclinical trials involve the testing of a given
compound in animals to provide data on the activity and safety of the
compound before the compound is administered to humans.

- Investigational New Drug Application.  If the data from research and
preclinical trials are promising, Hybridon may file an Investigational
New Drug Application, or "IND," with the FDA. The IND contains the
results of the preclinical trials and the protocol for the first clinical
trial. The IND becomes active in 30 days unless the FDA disapproves it or
requires additional information. Once the IND becomes active, Hybridon
can begin clinical trials in the U.S.

- Phase I Clinical Trials.  In Phase I trials, the drug is given to a small
group of healthy individuals or patients with the disease. These trials
are designed to produce data on the drug's safety, the maximum safe dose,
and how the drug is absorbed, distributed, metabolized and excreted over
time. In some cases, Phase I trials can give an early indication of a
drug's effectiveness. A limited Phase I trial is sometimes called a Pilot
Phase I trial.

- Phase I/II Clinical Trials.  In Phase I/II trials, the drug is given to
patients with the diseases to evaluate safety and to get an early
indication of a drug's effectiveness. This type of trial is commonly used
in the evaluation of oncology drugs.

- Phase II Clinical Trials.  In Phase II trials, the drug is given to a
larger group of patients with the disease for purposes of evaluating the
drug's effectiveness and side effects at varying doses and schedules of
administration and thereby determining the optimal dose and schedule for
the larger Phase III trials that follow.

- Phase III Clinical Trials.  These trials generally have a large number of
patients. The primary purpose of a Phase III trial is to confirm the
drug's effectiveness and produce additional information on side effects.

- New Drug Application.  Once Phase III trials are complete, Hybridon will
file a New Drug Application, or "NDA," with the FDA. The NDA contains all
of the information gathered from the Phase I, I/II, II and III trials.
Based on the FDA's review of the NDA, the FDA may approve the drug for
commercial sale. The FDA may deny an NDA if the applicable regulatory
requirements are not met. The FDA may also require additional tests
before approving an NDA. Even after approval by the FDA, Hybridon must
file additional reports about the drug with the FDA from time to time.
The

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FDA may withdraw product approvals if a company fails to comply with
ongoing regulatory standards or if problems occur after a company starts
marketing a drug.

- Accelerated Approval.  The FDA is authorized to grant accelerated review
to NDAs for drugs that are intended to treat persons with debilitating
and life-threatening illnesses, especially if no satisfactory
alternatives are available. The more severe the disease, the more likely
it is that the drug will qualify for accelerated review. If a new drug is
approved after accelerated review, the FDA may require Hybridon to
conduct specific post-marketing studies regarding the drug's safety,
benefits and optimal use.

The regulatory process in other countries is generally similar to the U.S.
regulatory process.

DRUG DEVELOPMENT AND DISCOVERY PROGRAMS

Hybridon is focusing its drug development and discovery efforts on
developing antisense compounds for the treatment of diseases in three major
therapeutic areas: cancer, viral infections and diseases of the eye.

Hybridon believes there are significant additional opportunities for the
use of antisense. For example, in the treatment of cancer, compared to
conventional anti-cancer drugs, antisense may provide:

- more specific therapy

- more rapid development of drugs targeting newly-discovered cancer-related
proteins

- fewer toxic side effects, thereby allowing repeat and long-term therapy,
either alone or in combination with other cancer therapies, such as
radiation or chemotherapy

- when used in combination therapy, therapeutic effects that complement the
benefits of conventional drugs

For these reasons, Hybridon is exploring new antisense targets relevant to
the treatment of cancer.

CLINICAL PROGRAMS

Hybridon has conducted clinical trials with antisense drugs targeting
cancer and HIV-1 AIDS. Hybridon is seeking partners for each of its compounds in
clinical development.

CANCER

Unlike normal human cells, cancer cells grow in an uncontrolled and harmful
manner. The protein molecule protein kinase A, or "PKA," has been implicated in
the formation and growth of various solid tumors, including colon, ovarian,
breast, and lung tumors. There are two kinds of PKA. It is normal to find type I
in developing fetuses, but abnormal to find it in adults. By contrast, PKA type
II is found in, and is necessary to the health of, normal adults. Certain cancer
cells produce PKA type I in adults. Hybridon is developing a cancer drug, GEM(R)
231, that is designed to reduce the production of the harmful PKA type I without
interfering with the production of PKA type II. Most current drug candidates
based on conventional mechanisms have unacceptable side effects.

Hybridon has conducted a Phase I clinical trial to evaluate the safety of
GEM(R) 231 at multiple doses, and has found that patients tolerate it well. This
trial explored the maximum tolerated dose of GEM(R) 231 for both single doses
and multiple doses, and even high doses of GEM(R) 231 did not show the side
effects normally seen with current cancer treatments. This trial was not
conducted for the purpose of evaluating the efficiency of GEM(R) 231.

Hybridon is currently conducting additional studies with GEM(R) 231 in
patients with solid tumors that had not been cured by prior therapy. These
studies include a pilot Phase II trial and a Phase I/II trial. In addition,
Hybridon has begun the first in a series of Phase I/II trials treating patients
with solid tumors with GEM(R) 231 in combination with the anti-cancer therapies
Taxol(R) and Taxotere(R).

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HIV-1 AND AIDS

Acquired Immune Deficiency Syndrome, "AIDS," is caused by infection with
HIV-1 and leads to severe, life-threatening impairment of the immune system.
AIDS therapy using a combination of drugs has resulted in decreased rates of
death and improvement in the quality of life for patients who are HIV-positive
or have AIDS. There are, however, reports that this therapy may be failing to
give sustained clinical benefit. Hybridon believes this underscores the need for
new AIDS therapies.

Hybridon has completed a Pilot Phase I clinical study in Europe of GEM(R)
92, Hybridon's advanced chemistry compound for the treatment of HIV-1 infection
and AIDS. This study was designed to explore the safety of GEM(R) 92 and to
provide information on its absorption after oral dosing and injection. The
patients tolerated well all doses that they were given in the pilot study.
Further, GEM(R) 92 was detected in the blood after both oral dosing and
injection, suggesting that it may be possible to develop GEM(R) 92 as an oral
drug. Hybridon believes this was the first study of the oral administration of
an antisense molecule to humans. In in-vitro studies, beneficial effects were
observed when GEM(R) 92 was used in combination with several marketed AIDS
drugs. Importantly, both its medicinal approach and genetic target are unique,
in that no antisense drug has been approved for the treatment of AIDS, and no
other drug has the same target on the HIV-1 genome.

PRECLINICAL PROGRAMS

Hybridon has also conducted preclinical studies in the following areas:

TARGET                                PRIMARY THERAPEUTIC INDICATION(S)          STATUS
------                                ---------------------------------          ------

MDM2 (a protein involved in          Cancer                                 Seeking marketing
programmed cell death)                                                    partner
Vascular Endothelial Growth Factor   Cancer                                 Seeking marketing
(a protein that can cause                                                 partner
abnormal formation of new blood
vessels)
Retinopathies (e.g. macular            Seeking marketing
degeneration and diabetic              partner
retinopathy)
Hepatitis C Virus                    Hepatitis C (which can lead to         Seeking marketing
liver cancer)                          partner

HYBRIDON SPINOUTS

Hybridon has used multiple strategies to fund applications of its antisense
technology that it cannot develop at present without external funding. Hybridon
has used one such strategy, formation of spinout companies, to form MethylGene,
Inc. and OriGenix Technologies Inc. for the continued development of certain
product candidates.

METHYLGENE, INC.

In 1996, Hybridon and three Canadian institutional investors formed
MethylGene. Hybridon owns approximately 22% of MethylGene. Hybridon has granted
exclusive worldwide licenses and sublicenses to MethylGene to develop and market
the following:

- antisense compounds to inhibit the protein DNA methyltransferase for the
treatment of any disease

- other methods of inhibiting DNA methyltransferase for the treatment of
any disease

- antisense compounds to inhibit up to two additional targets for the
treatment of cancers

Research has shown that DNA methyltransferase, a protein, is overproduced
in some tumors, such as non-small-cell lung cancer, colon cancer, and breast
cancer tumors.

The Canadian investors who invested in MethylGene have the right to
exchange all of the shares of stock in MethylGene that they initially purchased
for shares of Hybridon common stock on the basis of 37.5 MethylGene shares, for
which they paid approximately U.S. $56.25, for one share of Hybridon common
stock, subject to adjustments.

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On September 21, 2000, Hybridon sold its HSP business. Prior to such sale,
Hybridon supplied MethylGene with its oligonucleotide supply needs. In
connection with the Asset Sale, the purchaser now supplies MethylGene with
oligonucleotides.

MethylGene commenced Phase I clinical trials of its first compound, MG98,
for the treatment of cancer in May 1999. Hybridon is also performing drug
development and other services for MethylGene. The continuation of these
services is currently being reviewed by both parties.

ORIGENIX TECHNOLOGIES INC.

In January 1999, Hybridon and three Canadian institutional investors formed
OriGenix to develop and market drugs for the treatment of infectious diseases,
with an initial focus on viral diseases. Hybridon owns approximately 28% of
OriGenix.

Hybridon has granted to OriGenix exclusive worldwide licenses and
sublicenses to antisense technology developed by Hybridon for the treatment of
human papillomavirus, or "HPV," and hepatitis B virus infections. HPV infection
can cause a variety of warts, including benign genital warts. HPV infection can
also lead to cervical cancer. Hepatitis B infections can lead to liver cirrhosis
and cancer of the liver. OriGenix may in the future negotiate with Hybridon for
licenses or sublicenses relating to additional targets. Hybridon may also
perform drug development and other services for OriGenix.

On September 21, 2000, Hybridon sold certain of its assets relating to the
manufacture of oligonucleotides ("Asset Sale"). Prior to such sale, Hybridon
supplied OriGenix with its oligonucleotide supply needs. In connection with the
Asset Sale, the purchaser now supplies OriGenix with oligonucleotides.
Otherwise, the relationship between Hybridon and OriGenix is substantially
unchanged.

CORPORATE COLLABORATION

An important part of Hybridon's business strategy is to enter into research
and development collaborations, licensing agreements, or other strategic
alliances, primarily with biotechnology and pharmaceutical corporations, to
develop certain products. Subject to sufficient funds being available, Hybridon
intends to proceed with Phase II clinical trials of its cancer drug GEM(R) 231.
For drugs other than drug GEM(R) 231, Hybridon does not anticipate proceeding
with any of its other clinical programs beyond their current stages of
development without a collaborative arrangement with a corporate partner.
Hybridon expects to retain the rights to manufacture many of the products it may
license pursuant to its existing and any future collaborations.

G.D. SEARLE & CO.

From January 1996 to March 2000 Hybridon and Searle engaged in a research
and development collaboration for the development of antisense compounds. Most
recently, Searle and Hybridon were investigating antisense inhibitors of MDM2, a
protein involved in programmed cell death, or apoptosis. It is believed that
MDM2 may play an important role in many types of cancer.

Through January 2000, Searle made annual research payments to Hybridon of
$600,000. In March 2000, however, Searle elected not to extend this research and
development collaboration. Hybridon may seek a new development partner for this
program.

Consistent with its January 1996 agreement with Hybridon, Searle is
required to return to Hybridon all licenses granted to Searle, including the
recently issued U.S. patent 6,013,786, which covers specific antisense
inhibitors of human MDM2. Hybridon has the right to use any of Searle's patent
rights relating to the work performed under the collaboration, including all
antisense rights relating to MDM2.

Hybridon will pay Searle a royalty if it successfully commercializes any
antisense compounds discovered as a result of their collaboration.

Pursuant to their collaboration, Searle also purchased 200,000 shares of
common stock in Hybridon's 1996 initial public offering.

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HYBRIDON SPECIALTY PRODUCTS

In 1996, Hybridon formed HSP to manufacture oligonucleotide compounds both
for Hybridon's internal use, for use by its collaborators and for sale to third
parties. On September 21, 2000, the Company sold the business and the assets of
its Hybridon Specialty Products business ("HSP") for $15,000,000 to Boston
Biosystems, Inc., a Delaware corporation (the "Purchaser") and wholly owned
subsidiary of Avecia, Inc. In addition, the Purchaser assumed approximately
$414,000 of liabilities related to the assets to be sold. The Company received
$11,550,000 of the purchase price at closing prior to any transaction costs,
$450,000 was retained for thirty (30) days by the Purchaser to cover potential
indemnification claims and raw materials inventory requirements. To date,
Hybridon has received approximately $176,000 of the amount owed. Lastly,
$3,000,000 will be payable as contingent consideration one year from the date of
Closing upon the satisfaction of certain conditions.

The purpose of the transaction was to allow the Company's management to
concentrate attention and resources on and provide working capital for the
Company's highest value-added core drug discovery and development business. The
Company believes that this portion of its business offers more promise for the
future and greater opportunities for growth.

The Company will retain all liabilities arising out of or relating to HSP
prior to the Closing, other than those specifically assumed by the Purchaser.
The Company does not expect any of the retained liabilities to have a material
adverse effect on its future results of operations. The agreement governing the
sale of HSP to the Purchaser contains representations, warranties and covenants
of the parties customary in such transactions.

MARKETING STRATEGY

When and if any drugs Hybridon is developing are ready for market, Hybridon
plans to market the drugs either directly, using its own sales force, or through
co-marketing, licensing, distribution or similar arrangements with other
pharmaceutical and biotechnology companies, particularly if the products are
intended to serve a large, geographically-diverse patient population. On the
other hand, direct marketing of any of its proposed drugs would require a
substantial marketing staff and sales force supported by a distribution system.
By contrast, co-marketing or other arrangements with other pharmaceutical or
biotechnology companies would allow Hybridon to avoid the significant cost
involved in direct marketing, but would make Hybridon reliant on the efforts of
others. While Hybridon has developed general marketing strategies, it has not
reached this stage in development with respect to any drugs, and thus
necessitating the implementation of any of these strategies.

ACADEMIC AND RESEARCH COLLABORATIONS

Hybridon has entered into a number of collaborative research relationships
with independent researchers and leading academic and research institutions and
U.S. government agencies, including the National Institutes of Health, or "NIH."
Such research relationships allow Hybridon to augment its internal research
capabilities and obtain access to specialized knowledge or expertise.

In general, Hybridon's collaborative research agreements require Hybridon
to pay various amounts to support the research. Hybridon usually procures the
oligonucleotides, which the collaborator then tests. If in the course of
conducting research under its agreement with Hybridon a collaborator, solely or
jointly with Hybridon, creates any invention, Hybridon generally has an option
to negotiate an exclusive, worldwide, royalty-bearing license to the invention.
Inventions developed solely by Hybridon's scientists in connection with a
collaborative relationship generally are owned exclusively by Hybridon. Most of
these collaborative agreements are nonexclusive and can be cancelled on short
notice.

Since July 1997, as part of its restructuring, Hybridon has allowed a
number of its collaborative research agreements to expire and has terminated
certain others, but has maintained those that it believes support its current
drug discovery and development programs.

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DRUG DEVELOPMENT SERVICES

Hybridon's Drug Development Department has experience in the design and
conduct of preclinical and clinical trials and has prepared and submitted
reports and other regulatory documents in connection with the three Hybridon
advanced chemistry antisense compounds that have entered clinical studies.
Pursuant to a contract with MethylGene, Hybridon's Drug Development Department
has also used its expertise to help design and monitor the preclinical trials of
MethylGene's antisense compound, MG98, that led to MethylGene's submission of
IND applications in Canada and the U.S. MethylGene compensated Hybridon for
these services. Hybridon may perform similar services for OriGenix.

PATENTS, TRADE SECRETS, AND LICENSES

Hybridon's success will largely depend on its ability to:

- obtain U.S. and foreign patent protection for drug candidates and
processes

- preserve trade secrets

- operate without infringing the proprietary rights of third parties

Hybridon's policy is to file patent applications to protect technology,
inventions and improvements that it considers important to the development of
its business, and to obtain licenses to other patents that could help Hybridon
maintain or enhance its competitive position. As of December 15, 2000, Hybridon
owned or exclusively licensed in excess of 89 U.S. and foreign issued and
allowed patents, of which 71 are U.S. patents. Hybridon also has 45 U.S. and 84
foreign patent applications. The foreign patent and patent application counts
include Japan, Canada and Europe as a whole, as well as other non-European
individual countries. These patents and applications cover various chemically
advanced oligonucleotides, target sequences, oligonucleotide products,
analytical methods, and methods for antisense treatment of various diseases. The
patents expire on dates ranging from 2006 to 2015.

Hybridon is the worldwide exclusive licensee under several U.S. issued
patents or allowed patent applications owned by University of Massachusetts
Medical Center, or "UMMC," relating to oligonucleotides and hybrid or mixed
backbone chemistries. Many of these patents and patent applications have
corresponding patents issued by, or corresponding patent applications on file
in, other major industrial countries. One of the issued U.S. patents and one of
the issued European patents cover antisense oligonucleotides as new compositions
of matter for stopping the replication of HIV. Coverage of the other issued U.S.
patents includes composition and use of oligonucleotides based on advanced
chemistries, composition of certain modified oligonucleotides that are useful
for diagnostic tests or assays, and methods of purifying oligonucleotides. The
UMMC patents licensed to Hybridon expire at various dates starting in 2006.

Hybridon is the exclusive licensee under various other U.S. and foreign
patents and patent applications, including two U.S. patent applications owned by
McGill University relating to oligonucleotides and DNA methyltransferase.
Hybridon and Massachusetts General Hospital jointly own one issued U.S. patent
applicable to Alzheimer's disease. Hybridon holds an exclusive license to
Massachusetts General Hospital's interests under this patent.

The field of each of these licenses extends to a wide variety of genetic
targets. Hybridon is also a nonexclusive licensee of certain patents exclusively
licensed to Genzyme covering certain technology relating to MDM2.

The U.S. Patent and Trademark Office, or "PTO," has informed Hybridon that
certain patent applications exclusively licensed by Hybridon from UMMC will be
submitted to the Board of Patent Appeals and Interferences of the PTO to
determine whether an interference should be declared with issued U.S. patents
held by the NIH relating to oligonucleotide phosphorothioates. An interference
proceeding is a proceeding to determine who was the first to invent, and thus
who is entitled to a patent for, a claimed invention. While Hybridon is of the
opinion that the UMMC patent application has a prima-facie case for priority
against the NIH for an invention that includes phosphorothioate-modified
oligonucleotides, there can be no assurance, however, that the PTO will declare
an interference, or if it does, what the outcome will be. If

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20

Hybridon were to win the interference, others making, using or selling certain
phosphothioate-modified oligonucleotides would be required to obtain a license
from Hybridon. As part of the HSP sale, the Company granted the Purchaser an
option to a license to use the patent applications that are the subject of the
potential interference.

The PTO declared a four-way interference involving two UMMC U.S. patents,
for which Hybridon is the exclusive licensee, relating to a particular type of
modified oligonucleotides. The other parties to this interference were
Integrated DNA Technologies, Isis Pharmaceuticals, Inc. and Gilead Sciences,
Inc. This interference was settled in early 1999. In connection with the
settlement, Hybridon has obtained a nonexclusive license to certain patents and
patent applications owned by IDT that broadly claim chemical modifications to
oligonucleotides. Hybridon has also granted a nonexclusive license to IDT to
make, use, and sell limited quantities of oligonucleotides incorporating certain
of Hybridon's advanced chemistries.

Under its licenses, Hybridon is obligated to pay royalties on its net sales
of products or processes covered by the licensed technology and, in some cases,
to pay a percentage of sublicense income that it receives. These licenses impose
various commercialization, sublicensing, insurance and other obligations on
Hybridon. If Hybridon fails to comply with these requirements, the license could
be terminated.

Legal standards relating to the validity of patents covering pharmaceutical
and biotechnological inventions and the scope of claims made under such patents
are still developing. As a result, Hybridon's ability to obtain and enforce
patents that protect its drugs is uncertain and involves complex legal and
factual questions.

That Hybridon owns or licenses pending or future patent applications does
not mean that patents based on those applications will ultimately be issued.
First, to obtain a patent on an invention, one must be the first to invent it or
the first to file a patent application for it. Patent applications in the U.S.
are maintained in secrecy until patents are issued, and publication of any given
discovery in the scientific or patent literature tends to lag behind the actual
date of that discovery by several months. Consequently, Hybridon cannot be
certain that the inventors of subject matter covered by patents and patent
applications that it owns or licenses were the first to invent, or the first to
file patent applications for, those inventions.

Others, including Hybridon's competitors, also hold issued patents and
patent applications relating to antisense technology or particular genetic
targets. Holders of any of these patents or patent applications may be able to
require Hybridon to change or cease making or using certain products or
processes, or obtain an exclusive or nonexclusive license in return for
licensing fees, which may be substantial. Hybridon may not be able to obtain any
such licenses at a reasonable cost. Furthermore, such licenses may be made
available to competitors of Hybridon on an exclusive or nonexclusive basis.
Failure to obtain such licenses could have a material adverse effect on
Hybridon.

Hybridon requires its employees, consultants, outside scientific
collaborators, sponsored researchers and other advisors to execute
confidentiality agreements. These agreements provide that all confidential
information developed or made known by Hybridon to the individual is to be kept
confidential, subject to specific exceptions. In the case of employees, the
agreements provide that all inventions conceived by the individual are the
exclusive property of Hybridon. These agreements may not, however, provide
meaningful protection for Hybridon's trade secrets or adequate remedies in the
event of breach.

Consistent with pharmaceutical industry and academic standards, Hybridon's
agreements with academic and research institutions and U.S. government agencies
may provide that the results of a given collaboration, or any developments that
derive from the collaboration, will be freely published, that information or
materials supplied by Hybridon will not be treated as confidential, and that
Hybridon must negotiate a license to developments and results in order to
commercialize products incorporating them. There can be no assurance that
Hybridon will be able successfully to obtain any such license at a reasonable
cost or that such developments and results will not be made available to
competitors of Hybridon on an exclusive or nonexclusive basis. See
"Business -- Academic and Research Collaborations."

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21

GOVERNMENT REGULATION

Hybridon's research and clinical development activities are regulated for
safety, effectiveness and quality by numerous governmental authorities in the
U.S. and other countries. Hybridon believes that it is in material compliance
with all applicable federal, state and foreign legal and regulatory
requirements.

In addition to regulations enforced by the FDA in connection with product
approvals, Hybridon also is subject to regulation under the Occupational Safety
and Health Act and other present and potential future federal, state or local
regulations. Furthermore, because Hybridon uses hazardous materials, chemicals,
viruses, and various radioactive compounds, it must comply with U.S. Department
of Transportation and Environmental Protection Agency regulations and other
federal, state, and foreign laws and regulations regarding hazardous waste
disposal, air emissions, and waste-water discharge. Although Hybridon believes
that it complies with these laws and regulations, it cannot completely eliminate
the risk of accidental contamination or injury from these materials.

COMPETITION

There are a number of companies, both privately and publicly held, that are
conducting research and development activities on technologies and products
aimed at therapeutic regulation of gene expression, including antisense drugs.
One competitor of Hybridon has recently received FDA approval to market an
antisense therapeutic product for the treatment of CMV retinitis. To our
knowledge two privately held companies are developing immunostimulatory
oligonucleotide drugs. These drug candidates are in clinical trials for various
indications, either alone or in combination with vaccines. Hybridon believes
that the interest in these technologies and products will increase. It is
possible that Hybridon's competitors will succeed in developing products that
are more effective than Hybridon's. Furthermore, Hybridon's proposed drugs will
be competing with other kinds of drugs. Given the fundamental differences
between antisense technology and other drug technologies, antisense drugs may be
less effective at treating some diseases than other kinds of drugs.

Biotechnology and related pharmaceutical technologies have undergone and
continue to be subject to rapid and significant change. Hybridon expects that
the technologies associated with biotechnology research and development will
continue to develop rapidly. Hybridon's future will depend in large part on its
ability to compete with these technologies.

Hybridon has many competitors, including major pharmaceutical and chemical
companies, biotechnology firms, and universities and other research
institutions. Many of these competitors have substantially greater financial,
technical, and human resources than Hybridon, and many have significantly
greater experience than Hybridon in undertaking preclinical studies and clinical
trials of new pharmaceutical products and obtaining FDA and other regulatory
approvals. Accordingly, Hybridon's competitors may succeed in obtaining
regulatory approvals for products more rapidly than Hybridon. Furthermore, if
Hybridon receives approval to commence commercial sales of products, it will
also be competing with respect to marketing capabilities, an area in which it
has limited experience.

EMPLOYEES

As of December 21, 2000, Hybridon employed 14 individuals full-time, of
whom 10 held advanced degrees. 10 of these employees are engaged in research and
development activities and 4 are employed in finance, corporate development, and
legal and general administrative activities. Many of Hybridon's management and
professional employees have had prior experience with pharmaceutical,
biotechnology, or medical products companies. None of Hybridon's employees is
covered by a collective bargaining agreement, and management considers relations
with its employees to be good.

On February 15, 2000, Hybridon announced that E. Andrews Grinstead, III,
Hybridon's former Chief Executive Officer, had taken an unexpected medical leave
of absence of indefinite duration due to a serious illness and that Mr.
Grinstead had been replaced as President. Dr. Sudhir Agrawal, formerly Senior
Vice

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President of Discovery, has assumed the position of President and Acting Chief
Executive Officer during Mr. Grinstead's absence and subsequent termination of
employment.

PROPERTIES

Hybridon leases approximately 26,000 square feet of laboratory space in
Cambridge, Massachusetts under a lease that expires April 30, 2007. The annual
rent for this space is approximately $650,000. Hybridon intends to sublease
approximately 7,500 square feet of this to a third party under a sublease that
would expire in mid-2002.

LEGAL PROCEEDINGS

Hybridon is not a party to any litigation that it believes could damage
Hybridon or its business.

MARKET FOR REGISTRANT'S COMMON EQUITY AND
RELATED STOCKHOLDER MATTERS

From January 24, 1996 until December 2, 1997, Hybridon's common stock was
traded on the Nasdaq National Market under the symbol "HYBN." Prior to January
24, 1996, there was no established public trading market for Hybridon's common
stock.

On December 2, 1997, Hybridon's common stock was removed from the Nasdaq
National Market and began being quoted on the NASD OTC Bulletin Board. Quotes on
the NASD OTC Bulletin Board may reflect inter-dealer prices, without retail
markups, markdowns or commissions and do not necessarily represent actual
transactions.

On December 10, 1997, Hybridon effected a one-for-five reverse stock split
of its common stock. As a result of the reverse stock split, each five shares of
common stock was automatically converted into one share of common stock, with
cash payments for any fractional shares.

The following table sets forth for the periods indicate the high and low
sales prices per share of the common stock during each of the quarters set forth
below as reported on the Nasdaq National Market and the NASD OTC Bulletin Board
since January 1, 1998:

HIGH      LOW
------    ------

1998
First Quarter..............................................  $3.359    $1.000
Second Quarter.............................................    2.75     1.609
Third Quarter..............................................   2.516     1.125
Fourth Quarter.............................................    3.25     1.125

1999
First Quarter..............................................  $1.875    $1.000
Second Quarter.............................................    1.50     0.250
Third Quarter..............................................    1.50     0.350
Fourth Quarter.............................................    1.75     0.406

2000
First Quarter..............................................  $6.875    $0.844
Second Quarter.............................................   3.436     0.750
Third Quarter..............................................   1.313     0.500

The reported closing bid price of the common stock on the NASD OTC Bulletin
Board on December 28, 2000 was $.42 per share.

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DIVIDEND POLICY

The convertible preferred stock pays dividends at 6.5% per year, payable
semi-annually in arrears. These dividends may be paid either in cash or in
additional shares of convertible preferred stock, at the discretion of Hybridon.

Hybridon has never declared or paid cash dividends on its capital stock,
and Hybridon does not expect to pay any dividends on its common stock or any
cash dividends on the convertible preferred stock in the foreseeable future. The
indenture under which Hybridon issued 9% convertible subordinated notes on April
2, 1997, limits Hybridon's ability to pay dividends or make other distributions
on its common stock or to pay cash dividends on the convertible preferred stock.
As of November 3, 2000, $1.3 million in total principal amount of the 9% notes
remained outstanding.

In addition, Hybridon is currently prohibited from paying cash dividends
under the loan held by the Lender. See "Management's Discussion and Analysis of
Financial Condition and Results of Operation -- 1998 Financing
Activities -- $6.0 Million Loan."

USE OF PROCEEDS

Hybridon will not receive any proceeds from the sale of the securities by
selling stockholders other than proceeds upon exercise of certain Hybridon
warrants. Those proceeds will be added to Hybridon's general working capital.

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24

SELECTED FINANCIAL DATA

The selected balance sheet data set forth below, as of December 31, 1998
and 1999, and the statements of operations data for each of the three years in
the period ending December 31, 1999, come from Hybridon's consolidated financial
statements which have been audited by Arthur Andersen LLP, independent public
accountants, and which are included elsewhere in this prospectus. The selected
financial data as of December 31, 1995, 1996 and 1997 and for the years ended
December 31, 1995 and 1996 have been derived from Hybridon's consolidated
financial statements, as adjusted to reflect the disposition of Hybridon's
Hybridon Specialty Products business as discontinued operations, not included in
this prospectus, all of which have been audited by Arthur Andersen LLP,
independent public accountants. The selected financial data as of September 30,
2000 and for the nine months ended September 30, 1999 and 2000 are derived from
Hybridon's unaudited consolidated financial statements which are included
elsewhere in this Prospectus and which include, in the opinion of Hybridon, all
adjustments (consisting only of normal recurring adjustments) that are necessary
for a fair presentation of its financial position and the results of its
operations for those periods. Operating results for the nine months ended
September 30, 2000 are not necessarily indicative of the results that may be
expected for the fiscal year ending December 31, 2000. The selected consolidated
financial data should be read along with, and are qualified by reference to,
"Management's Discussion and Analysis of Financial Condition and Results of
Operations," Hybridon's consolidated financial statements and notes thereto and
the Report of Independent Public Accountants included elsewhere in this
prospectus.

NINE MONTHS
YEAR ENDED DECEMBER 31,                  ENDED DECEMBER 31,
----------------------------------------------------   ------------------
1995       1996       1997       1998       1999       1999      2000
--------   --------   --------   --------   --------   --------   -------
(IN THOUSANDS, EXCEPT PER SHARE DATA)              (UNAUDITED)

Statement of Operations Data:
Revenues:
Service revenue.....................................  $     --   $     --   $     --   $    375   $    365   $    295   $    70
Research and development............................     1,186      1,419        945      1,100        600        450        --
Royalty and other income............................        --         62         --         --        123        107        77
Interest income.....................................       219      1,447      1,079        148         92         82        66
--------   --------   --------   --------   --------   --------   -------
Total revenues................................     1,405      2,928      2,024      1,623      1,180        934       213
--------   --------   --------   --------   --------   --------   -------
Operating Expenses:
Research and development............................    28,531     33,150     35,326     14,183      5,783      4,525     2,794
General and administrative..........................     6,094     11,347     11,027      6,573      3,664      2,947     2,340
Interest............................................        81         34      4,278      2,820        683        511     1,857
Restructuring.......................................        --         --     10,345         --         --         --        --
--------   --------   --------   --------   --------   --------   -------
Total operating expenses............................    34,706     44,531     60,976     23,576     10,130      7,983     6,991
--------   --------   --------   --------   --------   --------   -------
Loss from continuing operations.....................   (33,301)   (41,603)   (58,952)   (21,953)    (8,950)    (7,049)   (6,778)
Income (loss) from discontinued operations..........    (1,246)    (5,250)   (10,509)    (4,028)    (1,553)    (1,283)    5,292
--------   --------   --------   --------   --------   --------   -------
Loss before extraordinary gain........................        --    (46,853)   (69,461)   (25,981)   (10,503)    (8,332)   (1,486)
Extraordinary item:
Gain on conversion of 9% convertible Subordinated
notes payable.....................................        --         --         --      8,877         --         --        --
--------   --------   --------   --------   --------   --------   -------
Net loss..............................................   (34,547)   (46,853)   (69,461)   (17,104)   (10,503)    (8,332)   (1,486)
Accretion of preferred stock dividend.................        --         --         --     (2,689)    (4,232)    (3,194)   (3,112)
--------   --------   --------   --------   --------   --------   -------
Net loss applicable to common stockholders............  $(34,547)  $(46,853)  $(69,461)  $(19,793)  $(14,735)  $(11,526)  $(4,598)
========   ========   ========   ========   ========   ========   =======
Basic and diluted net loss per common share from:
Continuing operations...............................  $ (91.28)  $  (9.09)  $ (11.67)  $  (1.85)  $  (0.57)  $  (0.45)  $ (0.40)
Discontinued operations.............................     (3.41)     (1.15)     (2.08)     (0.34)     (0.10)     (0.08)     0.31
Extraordinary gain..................................        --         --         --       0.75         --         --        --
--------   --------   --------   --------   --------   --------   -------
Net loss per share..................................    (94.70)    (10.24)    (13.76)     (1.44)     (0.66)     (0.53)    (0.09)
Accretion of preferred stock dividends..............        --         --         --      (0.23)     (0.27)     (0.20)    (0.18)
--------   --------   --------   --------   --------   --------   -------
Net loss per share applicable to common
stockholders......................................  $ (94.70)  $ (10.24)  $ (13.76)  $  (1.67)  $  (0.93)  $  (0.74)  $ (0.27)
========   ========   ========   ========   ========   ========   =======
Shares Used in Computing Basic and diluted Net Loss
per common share(1)...............................       365      4,576      5,050     11,859     15,811     15,654    17,130
========   ========   ========   ========   ========   ========   =======

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DECEMBER 31,                             SEPTEMBER 30,
-------------------------------------------------------------    -------------
1995         1996         1997         1998         1999           2000
---------    ---------    ---------    ---------    ---------    -------------
(UNAUDITED)

Balance Sheet Data:
Cash, cash equivalents and short-term
investments(2)..............................  $   5,284    $  16,419    $   2,202    $   5,608    $   2,552      $   5,236
Working capital (deficit).....................        258        9,483      (21,992)      (5,306)      (6,534)        (3,253)
Total assets..................................     18,908       38,295       30,480       15,092       10,717         11,430
Long-term debt and capital lease obligations,
net of current portion......................        484        6,959        1,328           --           --             --
Line of credit................................         --           --           --           --           --            231
9% convertible subordinated notes payable.....         --           --       50,000        1,306        1,306          1,306
8% convertible subordinated notes payable.....         --           --           --           --        6,100          7,737
Accumulated deficit...........................   (102,341)    (149,194)    (218,655)    (238,448)    (253,183)      (257,781)
Total stockholders' equity (deficit)..........     12,447       22,855      (46,048)       2,249       (6,072)        (6,378)
---------    ---------    ---------    ---------    ---------      ---------

---------------

(1) Computed on the basis described in Note 2(l) of Notes to consolidated
financial statements appearing elsewhere in this prospectus.

(2) Short-term investments consisted of U.S. government securities with
maturities greater than ninety days but less than one year from the purchase
date.

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26

MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION
AND RESULTS OF OPERATIONS

GENERAL

Hybridon is involved in the discovery and development of genetic medicines
based on antisense technology and the design of immunostimulatory
oligonucleotide compounds. Hybridon began operations in February 1990 and since
that time has been involved primarily in research and development efforts,
developing its manufacturing capabilities, and raising capital. In order to
commercialize its therapeutic products, Hybridon will need to address a number
of technological challenges and comply with comprehensive regulatory
requirements. All revenues received by Hybridon to date have been from
collaborative agreements, interest on invested funds and revenues from the
custom contract manufacturing of synthetic DNA and reagent products by its
manufacturing business, Hybridon Specialty Products ("HSP") prior to the
disposal thereof in September 2000.

Hybridon has incurred total losses of approximately $257.8 million through
September 30, 2000. Hybridon expects that its research and development and
general and administrative expenses will be significant in 2000 and future years
as it pursues its core drug development programs and expects to continue to
incur operating losses and significant capital needs.

Hybridon has completed the sale of its Hybridon Specialty Products business
to Avecia Limited ("Avecia"); one of Europe's leading specialty chemicals
companies, through its subsidiary, Boston Biosystems, Inc. Avecia acquired the
oligonucleotide manufacturing business and certain related intellectual property
of Hybridon Specialty Products business for US$15.0 million, of which $12.0
million, less $0.5 million for certain indemnity purposes, is payable at closing
and $3.0 million is payable after one year, subject to offset rights under the
contract (this sale, the "Asset Sale"). Avecia and Hybridon have also agreed
that through 2002 Avecia will supply oligonucleotides for Hybridon and its
associated operations. Hybridon will be required to purchase certain amounts of
oligonucleotides from Avecia until approximately the end of 2001.

On May 30, 2000, Hybridon entered into a Line of Credit Agreement pursuant
to which certain lenders (the "LOC Lenders") agreed to provide Hybridon with an
8%, $2.0 million credit facility (the "Line of Credit" or "LOC"). The Line of
Credit was intended to provide Hybridon with working capital any time prior to
the earlier of September 30, 2000, and the date the Asset Sale was consummated.
On July 10, 2000 and August 10, 2000, Hybridon drew down approximately $0.5
million on each of these dates under the Line of Credit, representing a total
draw down of $1.0 million. On September 28, 2000 Hybridon paid back
approximately $0.8 million and converted the remaining, approximately $0.2
million to common stock in October 2000. Hybridon has no additional borrowing
capacity under this Line of Credit.

Hybridon's existing cash resources are expected to be sufficient to operate
into the third quarter of 2001, at which time it expects to collect the second
installment of the proceeds from the Asset Sale in the amount of $3.0 million,
which should enable it to sustain its operations through the year 2001. Hybridon
will be required to raise substantial additional funds from external sources to
support its operations in 2002 and beyond.

As of December 21, 2000, Hybridon had 14 full-time employees.

The financial statements of Hybridon have been restated to reflect the
financial results of the Hybridon Specialty Products business as a discontinued
operation for the periods ended September 30, 2000 and 1999, and the years ended
December 31, 1999, 1998 and 1997.

RESULTS OF OPERATIONS

NINE MONTHS ENDED SEPTEMBER 30, 2000 AND 1999

REVENUES

Hybridon had total revenues of $0.2 million and $0.9 million for the nine
months ended September 30, 2000 and 1999, respectively.

Receipt of service revenues from MethylGene, Inc. and OriGenix
Technologies, Inc., entities in which Hybridon has an equity interest, were $0.1
million and $0.3 million for the nine months ended September 30,

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27

2000 and 1999, respectively. This decrease represents a decrease in support
services provided to these entities by Hybridon.

Revenues from research and development collaborations were zero and $0.5
million for the nine months ended September 30, 2000 and 1999, respectively.
This decrease is primarily due to the termination by Searle of its collaboration
agreement with Hybridon.

RESEARCH AND DEVELOPMENT EXPENSES

Hybridon's research and development expenses were $2.8 million and $4.5
million for the nine months ended September 30, 2000 and 1999, respectively.
This decrease reflects Hybridon's lower levels of cash available for
expenditures in 2000. Research and development salaries and related costs
remained at approximately the same level in 2000 as 1999. Hybridon's patent
expenses remained at approximately the same level in 2000 as 1999.

GENERAL AND ADMINISTRATIVE EXPENSES

Hybridon's general and administrative expenses were $2.3 million and $2.9
million for the nine months ended September 30, 2000 and 1999, respectively. The
decrease reflects Hybridon's lower levels of cash available for expenditures in
2000. General and administrative expenses related to business development and
public relations remained at approximately the same level in 2000 as 1999, as
did legal and accounting expenses.

INTEREST EXPENSE

Hybridon's interest expense was $1.9 million and $0.5 million for the nine
months ended September 30, 2000 and 1999, respectively. This increase is
attributable to the issuance of the 8% convertible subordinated notes in
December 1999 and the draw down on the Line of Credit.

LOSS FROM CONTINUING OPERATIONS

As a result of the above factors, Hybridon incurred losses from continuing
operations of $6.8 million and $7.0 million for the nine months ended September
30, 2000 and 1999, respectively.

LOSS FROM DISCONTINUING OPERATIONS

Hybridon incurred income from discontinued operations of $5.3 million and a
loss of $1.3 million for the nine months ended September 30, 2000 and 1999,
respectively. The net income from discontinued operations, as presented on the
consolidated statement of operations for the nine months ended September 30,
2000, includes the gain on sale of its Hybridon Specialty Products Business of
$6.1 million as well as the operating loss from discontinued operations for the
nine months ended September 30, 2000, totaling $0.8 million. For all other
periods presented, the net loss relates solely to the operating results of the
Hybridon Specialty Products business.

NET LOSS

Hybridon recorded preferred stock dividends on the Series A convertible
preferred stock of $3.1 million and $3.2 million for the nine months ended
September 30, 2000 and 1999, respectively, resulting in a net loss applicable to
common stockholders of $4.6 million and $11.5 million for the nine months ended
September 30, 2000 and 1999, respectively.

YEARS ENDED DECEMBER 31, 1997, 1998 AND 1999

REVENUES

Hybridon had total revenues from continuing operations of $2.0 million in
1997, $1.6 million in 1998, and $1.2 million in 1999. During 1997, 1998 and
1999, Hybridon received revenues from research and development collaborations of
$0.9 million, $1.1 million and $0.6 million, respectively. Research and
development collaboration revenues increased in 1998 from 1997, primarily due to
Hybridon receiving certain payments under its license agreement with MethylGene,
Inc. Research and development collaboration revenues decreased in 1999 from
1998, primarily due to a reduction in revenues recorded under this license

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28

agreement. Also, in March 2000, Hybridon announced that Searle, a collaborative
partner of Hybridon, was terminating its collaboration agreement with Hybridon.

Product and service revenues were zero in 1997, $0.4 million in 1998 and
$0.4 million in 1999. The increase in revenues in 1998 over those in 1997 was
primarily the result of service revenue from MethylGene, an entity in which
Hybridon has an approximately 30% equity interest. The revenues in 1999 were
primarily derived from MethylGene, Inc. and OriGenix Technologies, Inc.,
entities in which Hybridon has an equity interest. The service revenues received
from MethylGene decreased from $0.4 million to $0.3 million and increased for
OriGenix from zero to $0.1 million for 1998 and 1999, respectively.

Revenues from royalty and other income were zero in 1997, zero in 1998 and
$0.1 million in 1999. The 1999 revenue consisted primarily of a NIH grant and an
equipment lease between Hybridon and OriGenix Technologies, Inc.

Revenues from interest income were $1.1 million in 1997, $0.1 million in
1998 and $0.1 million in 1999. The decrease in interest income in 1998 from 1997
was the result of lower cash balances available for investment.

RESEARCH AND DEVELOPMENT EXPENSES

During 1997, 1998 and 1999, Hybridon expended $35.3 million, $14.2 million
and $5.8 million, respectively, on research and development activities.

The decreases in research and development expenses each year reflect
Hybridon's reduction of its operating expenses in 1997 and 1998 pursuant to the
restructuring that began in 1997 and was completed in 1998 and the lower levels
of cash available for expenditures in 1999. The restructuring included the
termination of operations at Hybridon's facilities in Europe, and also resulted
in significant reductions in employees and employee-related expenses, clinical
and outside testing, consulting, materials and lab expenses.

In addition, the facilities expense included in research and development
expenses decreased significantly in 1998 and 1999 as a result of moving
Hybridon's corporate offices and lab space in July 1998 from Cambridge to
Milford, Massachusetts and the sublease of its remaining unused Cambridge
facilities.

Research and development salaries and related costs decreased in 1998 from
1997 due to the substantial reduction in the number of employees involved in
research and development in 1998. Research and development salaries and related
costs remained at approximately the same level in 1999 as 1998.

Hybridon's patent expenses remained at approximately the same level in 1997
as 1998 and 1999.

GENERAL AND ADMINISTRATIVE EXPENSES

Hybridon incurred general and administrative expenses of $11.0 million in
1997, $6.6 million in 1998 and $3.7 million in 1999. The decreases reflect
Hybridon's reduction of its operating expenses in 1997 and 1998 pursuant to the
restructuring which began in 1997 and was completed in 1998, which resulted in
significant reduction in employees and employee-related expenses and consulting
expenses. General and administrative expenses related to business development,
public relations and legal and accounting expenses also decreased in 1999.

In addition, the facilities expense included in general and administrative
expenses also decreased significantly in 1999 as a result of moving Hybridon's
corporate offices to Milford, Massachusetts in 1998.

INTEREST EXPENSE

Interest expense was $4.3 million in 1997, $2.8 million in 1998 and $0.7
million in 1999. The decreases are attributable to the exchange of approximately
$48.7 million of the 9% convertible subordinated notes issued in the second
quarter of 1997 for Series A preferred stock on May 5, 1998. In addition, the
outstanding balance of loans needed to finance the purchase of property and
equipment was reduced in May 1998, resulting in a subsequent reduction in
interest expense. Due to the issuance of the 8% convertible subordinated notes
in December 1999, Hybridon's interest expense will increase beginning in 2000.

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RESTRUCTURING CHARGE

As a part of its restructuring plan, Hybridon recorded an $10.3 million
restructuring charge in 1997 to provide for the following:

- the termination costs of certain research programs and other contracts

- the loss of certain leased facilities, net of sublease income and other
contracts

- severance, benefits and related costs for terminated employees

- the write down of assets to net realizable value.

LOSS FROM CONTINUING OPERATIONS

As a result of the above factors, Hybridon incurred losses from continuing
operations of $59.0 million in 1997, $22.0 million in 1998 and $9.0 million in
1999.

LOSS FROM DISCONTINUING OPERATIONS

Hybridon incurred losses from discontinued operations of $10.5 million in
1997, $4.0 million in 1998 and $1.6 million in 1999.

NET LOSS

Hybridon incurred losses from operations before extraordinary items of
$69.5 million in 1997, $26.0 million in 1998 and $10.5 million in 1999. Hybridon
had extraordinary income of $8.9 million in 1998 resulting from the conversion
of $48.7 million principal amount of its 9% notes to Series A preferred stock in
the second quarter of 1998. In accordance with Statement of Financial Accounting
Standards No. 15, Accounting by Debtors and Creditors for Troubled Debt
Restructurings, Hybridon recorded an extraordinary gain of approximately $8.9
million related to the exchange. The extraordinary gain represents the
difference between the carrying value of the 9% notes offered for exchange and
the fair value of the Series A preferred stock issued upon the exchange, as
determined by the per share sales price of such stock sold in May 1998 in the
private offering described below. As a result of this extraordinary gain,
Hybridon's net loss was reduced to $17.1 million for 1998.

Hybridon had recorded preferred stock dividends on the Series A convertible
preferred stock of $2.7 million and $4.2 million in 1998 and 1999, respectively,
resulting in a net loss applicable to common stockholders of $19.8 million and
$14.7 million for 1998 and 1999, respectively. The net loss applicable to common
stockholders for 1997 was $69.5 million.

LIQUIDITY AND CAPITAL RESOURCES

GENERAL

Since inception, Hybridon has incurred significant losses, which it has
funded through the issuance of equity securities, debt issuances, sales by
Hybridon Specialty Products, which has been sold, and through research and
development collaborations and licensing arrangements.

During the nine months ended September 30, 2000, Hybridon utilized
approximately $5.4 million to fund continuing operating activities and did not
incur any capital expenditures. For the same period, net cash utilized by
discontinued operations was $0.2 million. The primary use of cash for operating
activities was to fund Hybridon's loss, before the gain from discontinued
operations, of $6.8 million. Hybridon expects to purchase a minimal amount of
capital equipment in 2000 as part of its effort to conserve cash resources.

During the year ended December 31, 1999, Hybridon utilized approximately
$8.6 million to fund continuing operating activities and approximately $8,000
for capital expenditures. The primary use of cash for operating activities was
to fund Hybridon's continuing loss of $9.0 million. Hybridon expects to purchase
a minimal amount of capital equipment in 2000 as part of its effort to conserve
cash resources.

CASH RESOURCES

Hybridon had cash and cash equivalents of $10.2 million at September 30,
2000, of which $5.0 million is classified as restricted cash. This restricted
cash is pledged the same as collateral, to secure Hybridon's

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obligation to, among others, the holders of the 8% Convertible Notes. The amount
of the pledge will be reduced as Hybridon's obligations are converted to equity
or repaid. On November 3, 2000, Hybridon's obligations included $1.3 million
principal amount of 9% notes, a $6.0 million loan from Founders Financial Group
LP (formerly Forum Capital Markets, LLC) (Founders) and others (collectively,
the "Lenders"), approximately $8.0 million in 8% Convertible Notes and accrued
interest as described below, and approximately $0.6 million of accounts payable.
The loan agreement covering the $6.0 million loan from the Lenders contains
certain financial covenants that require Hybridon to maintain minimum tangible
net worth and minimum liquidity requirements. The Lenders have granted Hybridon
a waiver of compliance with the minimum tangible net worth requirement at
September 30, 2000, and has agreed not to require that Hybridon comply with that
requirement for any periods commencing October 1, 2000 through December 31,
2000.

Hybridon received approximately $11.5 million of the $15.0 million from the
sale of its Hybridon Specialty Products business to Avecia. In October 2000,
Hybridon received approximately $0.2 million. Also, $0.3 million is currently
subject to negotiation. The remaining $3.0 million is payable after one year,
subject to offset rights under the contract, including Hybridon's performance
under a supply agreement that requires it to buy certain amounts of
oligonucleotides.

On May 30, 2000, Hybridon entered into a Line of Credit Agreement pursuant
to which the Line of Credit Lenders agreed to provide Hybridon with an 8%, $2.0
million Line of Credit. The Line of Credit was intended to provide Hybridon with
working capital until the Asset Sale was consummated. On July 10, 2000 and
August 10, 2000, Hybridon drew down approximately $0.5 million each under the
Line of Credit representing a total draw down of $1.0 million. On September 28,
2000, following the close of the Asset Sale, Hybridon repaid approximately $0.8
million of principal and interest in cash. In October 2000, Hybridon converted
the remaining $0.2 million of principal and interest into equivalent shares of
common stock at $1.08 per share (214,043 shares), pursuant to the terms of the
original agreement. Hybridon has no additional borrowing capacity under this
Line of Credit.

The Line of Credit Lenders have joined with the holders of Hybridon's 8%
Convertible Notes issued in 1999 and the Lender in a July 10, 2000 amendment
(the "Amendment") to the Subordination and Intercreditor Agreement.

In the Amendment all parties to the Subordination and Intercreditor
Agreement agree to release their lien on the portion of the collateral that
includes assets to be conveyed in the Asset Sale. In return for this partial
release, Hybridon set aside, from the proceeds of the Asset Sale, the sum of
$5.0 million which it classifies as restricted cash on its balance sheet and
pledged the same as collateral to secure its obligation to the 8% Convertible
Noteholders and the Lenders. The amount of the pledge will be reduced as the
debt is converted to equity or repaid. Hybridon can collect and keep the
interest on this $5.0 million. The parties to the Subordination and
Intercreditor Agreement, as amended, will continue to have a lien on
substantially all of the assets of Hybridon remaining after the Asset Sale.

In connection with the Line of Credit, Hybridon has (a) issued to the
representatives of the Line of Credit Lenders warrants to purchase up to 500,000
shares of Hybridon's common stock at an exercise price of $1.08 per share and
(b) issued to the Line of Credit Lenders, proportionate to their respective
interests in the Letter of Credit, warrants to purchase 1,000,000 shares of
Hybridon's common stock at an exercise price of $1.08 per share.

1999 FINANCING ACTIVITIES

Hybridon sold an aggregate of $1,500,000 principal amount of promissory
notes to E. Andrews Grinstead, III, Hybridon's Chief Executive Officer, at face
value during September and November of 1999. These notes accrued interest at 12%
per annum and in December 1999 were converted into 8% Convertible Notes due
2002. Hybridon also sold an aggregate of approximately $525,000 of debt to
purchasers in a private placement transaction in October and November 1999; as
of December 13, 1999, this debt automatically converted into 8% Convertible
Notes.

On December 13, 1999, Hybridon sold an aggregate of an additional $4.1
million principal amount of 8% Convertible Notes to purchasers in a private
placement transaction. At December 31, 1999, including the 8% Convertible Notes
issued upon conversion of the debt issued to Mr. Grinstead and other purchasers,
the

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principal amount of 8% notes outstanding was $6.1 million. After the financing
was completed in the first quarter of 2000, the principal amount of 8%
Convertible Notes outstanding, including financing costs and accrued interest,
was approximately $7.7 million.

Under the terms of the 8% Convertible Notes, Hybridon must make semiannual
interest payments on the outstanding principal balance through the maturity date
of November 30, 2002. The 8% Convertible Notes are convertible at any time prior
to the maturity date at a conversion price equal to $0.60 per share of common
stock (the Conversion Ratio), subject to adjustment under certain circumstances,
as defined. If the 8% Convertible Notes are prepaid before the maturity date,
all noteholders are entitled to receive warrants to purchase the number of
shares of common stock equal to the number of shares of common stock that would
be issued using the Conversion Ratio, with an exercise price of $0.60 per share
of common stock.

In connection with the 8% Convertible Notes, Hybridon must comply with
certain covenants. These covenants include, without limitation, the requirement
that Hybridon make all payments of interest when due and maintain consolidated
cash balances of at least $1.5 million as of the last day of any calendar month.
At September 30, 2000, Hybridon is in compliance with the covenant regarding
consolidated cash balances. If an event of default (as defined) occurs, the
noteholders may declare the unpaid principal and interest due and payable
immediately. If Hybridon defaults with respect to payment of interest, Hybridon
will be required to pay interest at a default rate equal to 12%.

In addition, in connection with the issuance of the 8% Convertible Notes,
the Lenders of the $6.0 Million Loan received a warrant to purchase 2,750,000
shares of common stock at $.60 per share. The warrant was granted as
consideration to the Lenders for relinquishing to holders of the 8% Convertible
Notes seniority upon liquidation of Hybridon. Hybridon computed the value of the
warrant to be $547,328, using the Black-Scholes option-pricing model. Hybridon
has recorded this amount as a deferred financing cost, which will be amortized
to interest expense over the term of the 8% Convertible Notes.

1998 FINANCING ACTIVITIES

On February 6, 1998, Hybridon commenced an offer to the holders of the 9%
notes to exchange the 9% notes for Series A preferred stock and certain warrants
of Hybridon. On May 5, 1998, noteholders holding $48.7 million of principal and
$2.4 million of interest tendered such principal and accrued interest to
Hybridon for 510,505 shares of Series A preferred stock and warrants to purchase
3,002,958 shares of common stock with an exercise price of $4.25 per share.

On May 5, 1998, Hybridon completed a private offering of equity securities
raising total gross proceeds of approximately $26.7 million from the issuance of
9,597,476 shares of common stock, 114,285 shares of Series A preferred stock and
warrants to purchase 3,329,486 shares of common stock at $2.40 per share. The
gross proceeds include the conversion of approximately $5.9 million of accounts
payable, capital lease obligations and other obligations into common stock.
Hybridon incurred approximately $1.6 million of cash expenses related to the
private offering and issued 597,699 shares of common stock and warrants to
purchase 1,720,825 shares of common stock at $2.40 per share to the placement
agents. In addition, Hybridon was obligated to issue an additional 300,000
shares in connection with this transaction. For more information about this
transaction, see note 10(b) of the notes to consolidated statements.

Beginning April 1, 2000, Hybridon may redeem the 9% notes at its option for
a 4.5% premium over the original issuance price, provided that from April 1,
2000 to March 31, 2001, the 9% notes may not be redeemed unless the closing
price of the common stock equals or exceeds 150% of the conversion price for a
period of at least 20 out of 30 consecutive trading days and the 9% Notes are
redeemed within 60 days after such trading period. The premium decreases by 1.5%
each year through March 31, 2003. Upon a change of control of Hybridon, as
defined, Hybridon will be required to offer to repurchase the 9% notes at 150%
of the original issuance price.

$6.0 MILLION LOAN

In December 1996, Hybridon entered into a five-year $7,500,000 note payable
with a bank. The note contained certain financial obligations that required
Hybridon to maintain a minimum worth and a minimum liquidity and prohibited the
payment of dividends. The note was payable in 59 equal installments of $62,500

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beginning on February 1, 1997, with a balloon payment of the then remaining
outstanding principal balance due on January 1, 2002. Because Hybridon was
required to make certain prepayments of principal during 1998, the outstanding
principal balance of the loan at November 16, 1998 was approximately $2.8
million. Effective November 20, 1998, the Lenders purchased the loan from the
bank. Founders and Pecks are affiliates of two members of Hybridon's board of
directors. In connection with this purchase, Founders and Pecks loaned an
additional $3.2 million to Hybridon so as to increase the outstanding principal
amount of the note to $6,000,000. In addition, the terms of the note payable
were amended as follows:

- the maturity was extended to November 30, 2003

- the interest rate was decreased to 8%

- interest is payable monthly in arrears, with the principal due in full at
maturity

- the note payable is convertible, at the option of Founders and Pecks, in
whole or in part, into shares of common stock of Hybridon at a conversion
price equal to $2.40 a share

- the threshold of the minimum liquidity obligation was reduced from
$4,000,000 to $2,000,000

- the note payable may not be prepaid, in whole or in part, at any time
prior to December 1, 2000

The other terms of the note payable were unchanged.

FACILITY LEASES

As of December 31, 1999, Hybridon had future operating lease commitments of
approximately $4.5 million through 2007 for its existing leases.

NET OPERATING LOSS CARRYFORWARDS

As of December 31, 1999, Hybridon had approximately $228.7 million and $4.2
million of net operating loss and tax credit carryforwards, respectively. The
Tax Reform Act of 1986 contains certain provisions that may limit Hybridon's
ability to utilize net operating loss and tax credit carryforwards in any given
year if certain events occur, including cumulative changes in ownership
interests in excess of 50% over a three-year period. Hybridon has completed
several financings since the effective date of the Tax Act, which, as of
December 31, 1999, have resulted in ownership changes in excess of 50%, as
defined under the Tax Act and which will limit Hybridon's ability to utilize its
net operating loss carryforwards.

HISTORY OF OPERATING LOSSES; UNCERTAINTY OF FUTURE PROFITABILITY

Since inception, Hybridon has incurred significant losses, which it has
funded through the issuance of equity securities, debt issuances, revenue from
the HSP business, and through research and development collaborations and
licensing arrangements.

FUTURE CAPITAL NEEDS

THE ASSET SALE

The purchase price in the Asset Sale was payable in two parts: $12.0
million at closing (of which the Purchaser has retained $273,856 and is in
negotiations with Hybridon over that amount, and $3.0 million, payable one year
from the date of closing. Receipt of the additional $3.0 million payment one
year from the date of closing is subject to additional conditions, notably
Hybridon's purchase of certain quantities of product from Boston Biosystems
under a supply agreement, and is also subject to offset rights granted to Boston
Biosystems.

Hybridon expects that the first installment of the proceeds from the Asset
Sale, in the amount of approximately $12 million, should enable it to operate
into the third quarter of 2001, at which time it expects to collect the second
installment of the proceeds from the Asset Sale in the amount of $3.0 million,
which should enable it to sustain its operations through the year 2001, assuming
that Avecia claims no offset pursuant to offset rights granted it. Even though
Hybridon expects to have sufficient cash to fund its operations through 2001, it
will be required to raise substantial additional funds from external sources to
support its operations in 2002 and beyond.

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UNCERTAINTY OF ADDITIONAL FUNDING

Hybridon's future capital needs will depend on many factors, including the
following:

- the amount received under the contingent portion of the Asset Sale
consideration

- continued scientific progress in its research

- whether or not its drug discovery and development programs succeed

- progress with preclinical and clinical trials

- the time and costs involved in obtaining regulatory approvals

- the costs involved in filing, prosecuting and enforcing patent claims

- competing technological and market developments

- establishing and maintaining collaborative academic and commercial
research, development and marketing relationships

- the costs of manufacturing scale-up and commercialization activities and
arrangements

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DIRECTORS AND EXECUTIVE OFFICERS OF HYBRIDON

The following table sets forth certain information regarding the executive
officers and directors of Hybridon as of November 3, 2000.

NAME                                       AGE                    POSITION
----                                       ---                    --------

Sudhir Agrawal, D.Phil...................  47     President and Acting Chief Executive
Officer, Senior Vice President of
Discovery, Chief Scientific Officer,
and Director (Class III)
James B. Wyngaarden, M.D. ...............  76     Chairman of the Board of Directors (Class
II)
Nasser Menhall...........................  45     Director (Class I)
Arthur W. Berry..........................  59     Director (Class I)
C. Keith Hartley.........................  58     Director (Class I)
Paul C. Zamecnik, M.D....................  88     Director (Class II)
Camille Chebeir..........................  62     Director (Class II)
Youssef El-Zein..........................  52     Director (Class III)

Sudhir Agrawal joined Hybridon in February 1990 and served as Principal
Research Scientist from February 1990 to January 1993 and as Vice President of
Discovery from December 1991 to January 1993 prior to being appointed Chief
Scientific Officer in January 1993, Senior Vice President of Discovery in March
1994, and President and Acting Chief Executive Officer in February 2000. He has
served on the board of directors since March 1993. Prior to joining Hybridon,
Dr. Agrawal served as a Foundation Scholar at the Worcester Foundation from 1987
through 1991. Dr. Agrawal served as a Research Associate at Research Council
Laboratory of Molecular Biology in Cambridge, England from 1985 to 1986,
studying synthetic oligonucleotides. Dr. Agrawal received a B.Sc. in chemistry,
botany and zoology in 1973, an M.Sc. in organic chemistry in 1975 and a D.Phil.
in chemistry in 1980 from Allahabad University in India.

James B. Wyngaarden was appointed member of the board of directors of
Hybridon in 1990, was Vice Chairman of the board of directors of Hybridon from
February 1997 to February 2000, and in February 2000 was appointed Chairman of
the board of directors of Hybridon. He was Foreign Secretary of the National
Academy of Sciences and the Institute of Medicine of the National Academy of
Sciences from 1990 to 1994; council member of the Human Genome Organization from
1990 to 1993 and Director from 1990 to 1991; and Director of the National
Institutes of Health from 1982 to 1989. He is a member of the board of directors
of Human Genome Sciences, Inc. and Magainin Pharmaceuticals, Inc.

Nasser Menhall was appointed member of the board of directors of Hybridon
in 1992. He has been a member of the board of directors and Chief Executive
Officer of the WorldCare Group, a teleradiology company, since 1993; President
of Pillar Limited, a private investment and management consulting firm, since
1990; and President of Biomedical Associates, a private investment firm, since
1990.

Arthur W. Berry was appointed member of the board of directors of Hybridon
in 1998. He has been Chairman and Managing Partner of Pecks Management Partners,
since 1990, and was Vice President and Co-Manager of the Alliance Convertible
Securities Group and President of the Alliance Convertible Fund from 1985 to
1990. Prior to joining Alliance, he was Vice President and Head of Special Funds
Section and Manager of the Harris Convertible Fund at Harris Bank and Senior
Portfolio Manager in the bank's Individual Investment Management Group. He is
also a member of the board of directors of Intellicorp, Inc.

Keith Hartley was appointed member of the board of directors of Hybridon in
2000. Mr. Hartley is Managing Partner of Hartley Capital Advisors, Merchant
Bankers. He was Managing Partner of Forum Capital Markets L.L.C. from August
1995 to August 2000. Prior to that Mr. Hartley was an independent financial
consultant from May 1991 to August 1995. He also serves as a Director of
Comdisco, Inc., Swisher International Group, Inc. and U.S. Diagnostics, Inc.

Paul C. Zamecnik was appointed member of the board of directors of Hybridon
in 1990. He was Principal Scientist at the Worcester Foundation for Biomedical
Research, Inc. from 1979 to 1996, and has been Collis P. Huntington Professor of
Oncologic Medicine Emeritus at the Harvard Medical School since 1979. He is also
currently Senior Scientist and Honorary Physician at Massachusetts General
Hospital in Boston.

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Youssef El-Zein was appointed member of the board of directors of Hybridon
in 1992, and has been Vice Chairman of the board of directors of Hybridon since
February 1997. He has been Executive Officer of Pillar S.A., a private
investment and management consulting firm, since 1991; Chairman of the WorldCare
Group since 1993; and member of the board of directors of Pillar Investment
Limited ("Pillar Investment"), a private investment and management consulting
firm, since 1991.

Camille Chebeir was appointed member of the board of directors of Hybridon
in 1999. Since 1995, he has been President of Sedco Services, Inc., a company
which manages investments of the bin Mafouz Saudi Arabian family. In that
capacity, he serves on the boards of various entities in which Sedco Services,
Inc. invests. Mr. Chebeir was previously the Executive Vice President/General
Manager of National Commercial Bank, New York branch. Mr. Chebeir is a former
President of the Arab Bankers Association of North America.

Hybridon's restated certificate of incorporation provides for a staggered
board of directors consisting of three classes, with each class being as nearly
equal in number as possible. At each annual meeting of Hybridon's stockholders,
the term of one class ends and the successors of the directors in that class are
elected for a term of three years. Hybridon has designated two Class III
directors, three Class I directors, and three Class II directors; they are
identified in the above table. They are to serve until the annual meeting of
stockholders to be held in 2001, 2002 and 2003, respectively, and until their
respective successors are elected and qualified, or until their earlier
resignation or removal. The restated certificate of incorporation provides that
directors may be removed only for cause by a majority of stockholders.

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EXECUTIVE COMPENSATION

COMPENSATION OF EXECUTIVE OFFICERS

SUMMARY COMPENSATION TABLE

The following table sets forth the compensation for the fiscal years ended
December 31, 1999 ("fiscal 1999"), December 31, 1998 and December 31, 1997 for
Hybridon's former Chief Executive Officer and Chief Scientific Officer, who were
serving as Executive Officers at December 31, 1999 and whose total annual salary
and bonus exceeded $100,000 in fiscal 1999:

SUMMARY COMPENSATION TABLE

LONG-TERM
ANNUAL COMPENSATION                COMPENSATION
--------------------------------------------      AWARDS
OTHER       SECURITIES   ------------
ANNUAL      UNDERLYING    ALL OTHER
NAME AND PRINCIPAL POSITION                   SALARY    BONUS   COMPENSATION    OPTIONS     COMPENSATION
---------------------------                  --------   -----   ------------   ----------   ------------

E. Andrews Grinstead, III...........  1999   $375,000     0       $93,750(1)   1,763,319(3)   $42,548(2)
former Chief Executive Officer and  1998   $375,000     0       $93,750(1)     500,000      $44,832(2)
former Director                     1997   $375,000     0       $93,750(1)      66,806      $53,784(2)
Sudhir Agrawal, D.Phil..............  1999   $250,000     0       $50,000(1)   1,618,263(3)   $25,962(2)
President and Acting Chief          1998   $250,000     0       $50,000(1)     500,000      $22,115(2)
Executive Officer, Senior           1997   $250,000     0       $50,000(1)      32,263      $13,462(2)
Vice President of Discovery,
and Chief Scientific Officer
and Director

---------------
(1) Other annual compensation paid, or to be paid, by Hybridon to, or for the
benefit of, the named executive officers is as follows:

1999       1998       1997
-------    -------    -------

E. Andrews Grinstead, III
Paid in lieu of employee benefits.....  $79,288    $79,903    $34,902
Purchase of life insurance and other
payments to third parties...........   14,462     13,487     58,848
-------    -------    -------
Total.................................  $93,750    $93,750    $93,750
=======    =======    =======

1999       1998       1997
-------    -------    -------

Sudhir Agrawal, D.Phil.
Paid in lieu of employee benefits.....  $36,789    $37,462    $38,132
Purchase of life insurance and other
payments to third parties...........   13,211     12,538     11,868
-------    -------    -------
Total.................................  $50,000    $50,000    $50,000
=======    =======    =======

(2) All other compensation paid, or to be paid, by Hybridon to, or for the
benefit of, the named executive officers is as follows:

1999       1998       1997
-------    -------    -------

E. Andrews Grinstead, III
Surrender of unused vacation days.....  $42,548    $28,832    $37,300
Additional payments...................        0     16,000     16,484
-------    -------    -------
Total.................................  $42,548    $44,832    $53,784
=======    =======    =======

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1999       1998       1997
-------    -------    -------

Sudhir Agrawal, D.Phil.
Surrender of unused vacation days.....  $25,962    $22,115    $13,462
-------    -------    -------
Total.................................  $25,962    $22,115    $13,462
=======    =======    =======

(3) During 1999 Hybridon reduced the exercise price of all employee stock
options to $.50 per share. The number of repriced stock options amounts to
1,263,319 and 1,118,263 for Mr. Grinstead and Dr. Agrawal, respectively.
These repriced stock options are included in the "Summary Compensation
Table."

OPTION GRANTS AND REPRICINGS TABLE

The following table sets forth certain information concerning grants and
repricings of stock options made during fiscal 1999 to each of the named
executive officers:

OPTION GRANTS AND REPRICINGS IN LAST FISCAL YEAR

INDIVIDUAL GRANTS
-----------------------                 POTENTIAL REALIZABLE
PERCENTAGE                               VALUE AT ASSUMED
NUMBER OF      OF TOTAL                              ANNUAL RATES OF STOCK
SECURITIES     OPTIONS      EXERCISE                PRICE APPRECIATION FOR
UNDERLYING    GRANTED TO     PRICE                      OPTIONS TERM(2)
OPTIONS     EMPLOYEES IN     PER      EXPIRATION   -----------------------
GRANTED     FISCAL YEAR     SHARE      DATE(1)        5%           10%
----------   ------------   --------   ----------   ---------   -----------

E. Andrews Grinstead, III
01/01/99 grant................    500,000         7.7%       $2.00      01/01/09    $323,477    $1,107,416
1999 repricings...............  1,263,319        19.4%       $0.50       Various    $ 79,821    $  423,299
---------
Total granted or repriced in
1999.......................  1,763,319
Less duplication for options
granted and repriced in
1999.......................   (500,000)
Total options outstanding at
12/31/99...................  1,263,319
=========
Sudhir Agrawal, D.Phil 01/01/99
grant.........................    500,000         7.7%       $2.00      01/01/09    $323,477    $1,107,416
1999 repricings...............  1,118,263        17.2%       $0.50       Various    $ 82,267    $  405,914
---------
Total granted or repriced in
1999.......................  1,618,263
Less duplication for options
granted and repriced in
1999.......................   (500,000)
---------
Total options outstanding at
12/31/99...................  1,118,263
=========

---------------
(1) The expiration date of each option is the tenth anniversary of the date on
which the option was originally granted.

(2) The amounts shown on this table represent hypothetical gains that could be
achieved for the respective options if exercised at the end of the option
term. These gains are based on assumed rates of stock increase of 5% and
10%, compounded annually from the date the respective options were repriced
or granted to their expiration date. The gains shown are net of the option
exercise price, but do not include deductions for taxes or other expenses
associated with the exercise. Actual gains, if any, on stock option
exercises will depend on the future performance of the common stock, the
optionholder's continued employment through the option period, and the date
on which the options are exercised. As of February 2, 2000, the last sale
price of common stock of Hybridon was $1.75.

(3) Mr. Grinstead and Dr. Agrawal had 680,596 and 551,356 exercisable options,
respectively, at 12/31/99. The remaining options become exercisable over
various periods through 9/30/03.

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STOCK OPTION REPRICING

The following table sets forth all repricings of stock options held by E.
Andrews Grinstead, III, Hybridon's former Chief Executive Officer, and Sudhir
Agrawal, Hybridon's President and Acting Chief Executive Officer, since
Hybridon's initial public offering on February 2, 1996.

10-YEAR OPTION/SAR REPRICINGS

NUMBER OF                                               LENGTH OF
SECURITIES     MARKET PRICE     EXERCISE                 ORIGINAL
UNDERLYING     OF STOCK AT      PRICE AT                OPTION TERM
OPTIONS/SARS'     TIME OF        TIME OF        NEW       REMAINING
REPRICED OR    REPRICING OR   REPRICING OR   EXERCISE   AT DATE OF
DATE        AMENDED       AMENDMENT      AMENDMENT      PRICE      AMENDMENT
--------   -------------   ------------   ------------   --------   -----------

E. Andrews Grinstead, III....  09/23/99      500,000         $0.38          $ 2.00       $0.50        9.28
09/23/99      500,000         $0.38          $ 2.00       $0.50        8.83
09/23/99       12,000         $0.38          $31.88       $0.50        7.66
09/23/99       38,000         $0.38          $30.00       $0.50        7.54
09/23/99       16,806         $0.38          $31.25       $0.50        7.41
09/23/99       50,000         $0.38          $57.85       $0.50        6.42
09/23/99       30,000         $0.38          $37.50       $0.50        5.48
09/23/99       19,600         $0.38          $37.50       $0.50        3.96
09/23/99       70,246         $0.38          $37.50       $0.50        3.62
09/23/99       26,667         $0.38          $25.00       $0.50        2.38

Sudhir Agrawal...............  09/23/99      500,000         $0.38          $ 2.00       $0.50        9.28
09/23/99      500,000         $0.38          $ 2.00       $0.50        8.83
09/23/99        6,000         $0.38          $31.88       $0.50        7.66
09/23/99       19,000         $0.38          $30.00       $0.50        7.54
09/23/99        7,263         $0.38          $31.25       $0.50        7.41
09/23/99       25,000         $0.38          $57.85       $0.50        6.42
09/23/99       20,000         $0.38          $37.50       $0.50        5.48
09/23/99       10,000         $0.38          $37.50       $0.50        3.29
09/23/99       21,000         $0.38          $17.50       $0.50        3.29
09/23/99       10,000         $0.38          $ 1.25       $0.50        2.38

The board of directors repriced all employee stock options effective
September 23, 1999. The options were repriced in order to provide additional
incentives to employees, since the previous option exercise prices were greater
than the market price of Hybridon's common stock.

AGGREGATED OPTION EXERCISES AND YEAR-END OPTION TABLE

The following table sets forth certain information concerning the number
and value of unexercised options held by each of the named executive officers on
December 31, 1999:

AGGREGATED OPTION EXERCISES IN LAST FISCAL YEAR AND FISCAL YEAR-END OPTION
VALUES

NUMBER OF           VALUE OF
SHARES            UNEXERCISED
UNDERLYING         IN THE MONEY
OPTIONS AT       OPTIONS AT FISCAL
FISCAL YEAR-END       YEAR-END(1)
---------------    -----------------
EXERCISABLE/        EXERCISABLE/
UNEXERCISABLE       UNEXERCISABLE
---------------    -----------------

E. Andrews Grinstead, III...............................  680,596/582,723    $347,104/$297,189
Sudhir Agrawal..........................................  551,356/566,907    $281,192/$289,123

---------------
(1) The closing price for the common stock as reported by The Nasdaq OTC
Bulletin Board on December 31, 1999 was $1.01. Value is calculated on the
basis of the difference between the option exercise price and $1.01,
multiplied by the number of shares of common stock underlying the option.

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39

DIRECTOR COMPENSATION

Each non-employee director is paid $1,500 for personal or telephonic
attendance at a board of directors or committee meeting. Other directors are not
entitled to compensation in their capacities as directors. All of the directors
are reimbursed for their expenses incurred in connection with their attendance
at board of directors and committee meetings. In addition, Dr. Zamecnik received
compensation in the amount of $83,995 in 1998 and $26,000 in 1999 in connection
with certain consulting services to Hybridon. Of this amount, Dr. Zamecnik
received 25,000 shares of common stock and warrants to purchase 6,250 shares of
common stock in lieu of $50,000 in cash, and $26,000 in convertible debt in lieu
of $26,000 in cash, which is convertible, at Dr. Zamecnik's option, into 43,333
shares of common stock. The remaining $33,995 was paid in cash. Hybridon also is
a party to consulting, advisory and other arrangements with various directors
and their affiliates. For a description of the foregoing arrangements with
Hybridon and certain other transactions between Hybridon and affiliates of
certain directors, see "Certain Transactions."

In October 1995, Hybridon adopted the 1995 director stock option plan.
Under the terms of the director plan, options to purchase 1,000 shares of common
stock were granted to each director of Hybridon, other than Mr. Grinstead and
Dr. Agrawal, on the following dates under the following terms:

- as of January 24, 1996 at an exercise price of $65.625 per share

- as of May 1, 1997, at an exercise price of $27.50 per share

- as of May 1, 1998 at an exercise price of $2.375 per share

- as of May 1, 1999 at an exercise price of $1.22 per share

The director plan also provides that options to purchase 5,000 shares of common
stock will be granted to each new director upon his or her initial election to
the board of directors. However, because of the one-for-five reverse stock split
described below, options to purchase 1,000 shares of common stock were granted
to Camille Chebeir and H.F. (Jake) Powell upon their appointment to the board of
directors in 1999. Mr. Powell has since resigned from Hybridon's board of
directors. In addition, on June 8, 1999, Hybridon's stockholders approved a
one-time grant of options to purchase 8,000 shares of Hybridon's common stock at
an exercise price of $0.47 per share to each director other than Mr. Grinstead
and Dr. Agrawal. Annual options to purchase 5,000 shares of common stock will be
granted to each eligible director on May 1 of each year. All options will vest
on the first anniversary of the date of grant or, in the case of options granted
automatically each year, on April 30 of the year following the date of the
grant; provided, that the exercisability of these options will be accelerated
upon the occurrence of a change in control, as defined in the director plan. A
total of 400,000 shares of common stock may be issued upon the exercise of stock
options granted under the director plan. The exercise price of options granted
under the director plan will equal the closing price of the common stock on the
date of grant. As of June 15, 1999, options to purchase an aggregate of 93,000
shares of common stock were outstanding under the director plan.

Non-employee directors also have received options to purchase common stock
of Hybridon under Hybridon's 1997 stock incentive plan and Hybridon's 1995 stock
option plan. In particular, in 1998, the board of directors voted to grant an
option to purchase 50,000 shares of common stock at $2.00 per share to Dr.
Wyngaarden and Mr. El-Zein, in recognition of their services as Vice Chairmen of
the board of directors during the previous twelve months. Mr. El-Zein declined
this grant. In addition, in 1998, the board of directors voted to grant 50,000
shares of common stock of Hybridon to Dr. Zamecnik in recognition of his
outstanding contributions to Hybridon.

EMPLOYMENT AGREEMENTS, TERMINATION OF EMPLOYMENT AND CHANGE IN CONTROL
ARRANGEMENTS

Hybridon was a party to an employment agreement with Mr. Grinstead for a
term commencing July 1, 1996 and ending June 30, 2001. On February 15, 2000,
Hybridon announced that Mr. Grinstead had taken an unexpected medical leave of
absence of indefinite duration due to a serious illness. Dr. Agrawal assumed the
position of President and Acting Chief Executive Officer. Mr. Grinstead's
agreement was terminated effective as of April 30, 2000. Ultimately, Hybridon
and Mr. Grinstead entered into a severance arrangement (the "Severance
Arrangement") on November 20, 2000, whereby Mr. Grinstead received his current
salary through May 1, 2000, health benefits, unused vacation allowance, payments
toward Cobra obligations, loan

34

40

forgiveness, acceleration of stock options and payment of legal fees associated
with his severance. Under this agreement, Mr. Grinstead had been entitled to
receive an annual base salary of $375,000. Mr. Grinstead also was eligible to
receive (a) a cash bonus each year related to the attainment of management
objectives specified by the board of directors and (b) additional payments of
$16,000 in years 1996 through 1999.

In accordance with the terms of Mr. Grinstead's previous employment
agreement, Hybridon loaned $190,000 to Mr. Grinstead in December 1992 pursuant
to the terms of a promissory note bearing simple interest at a rate of 6% per
year, which originally provided for the payment of principal and all interest on
the earlier of December 23, 1995 or the expiration or termination of Mr.
Grinstead's employment by Hybridon, but is currently payable on demand. This
loan remained outstanding as of December 31, 1999, at which date the total
unpaid balance of principal and interest was $270,050. Under the terms of the
Severance Arrangement Hybridon forgave, this loan obligation.

Hybridon was party to an employment agreement with Dr. Agrawal for the
period beginning July 1, 1996 and ending June 30, 2000. Although this agreement
has expired, Hybridon continues to honor the material components of this
Agreement until a new agreement is negotiated. Under this agreement, Dr. Agrawal
serves as Senior Vice President of Discovery and Chief Scientific Officer of
Hybridon and is currently entitled to receive an annual base salary of $250,000.
When Dr. Agrawal was appointed President and Acting Chief Executive Officer in
February 2000, he received an increase in salary to $300,000 per year. Other the
terms of his employment remained unchanged. Dr. Agrawal is eligible to receive a
cash bonus each year for achieving management objectives specified by the Chief
Executive Officer in and the board of directors. In the event Dr. Agrawal's
employment is terminated by Hybridon without cause or by him for good cause,
Hybridon will pay Dr. Agrawal during the 24-month period following his
termination a monthly amount equal to one-twelfth of the sum of Dr. Agrawal's
annual base salary as of the date of termination and the average bonus paid to
him during the three years preceding his termination. Hybridon will also
continue Dr. Agrawal's benefits for such period, subject to earlier termination
under certain circumstances. If his employment is terminated by Hybridon for
failure to perform his assigned duties, he will continue to receive his annual
base salary and benefits during the six-month period following such termination.
Notwithstanding the foregoing, in the event that Dr. Agrawal's employment is
terminated for any of the above reasons within 12 months following a change in
control of Hybridon, Dr. Agrawal will be entitled to receive, in lieu of the
payments described above, a lump sum payment equal to 300% of the sum of his
annual base salary and his average bonus amount.

The employment agreements entered into between Hybridon and each of Mr.
Grinstead and Dr. Agrawal provides that all stock options held by them,
including existing options and options to be granted in the future, shall
include the following terms:

- that in the event that either of them is terminated by Hybridon without
cause or by him for good cause the exercisability of such stock options
will be accelerated by two years and such stock options will be
exercisable for a two-year period following termination.

- that in the event of certain changes in control of Hybridon, its
liquidation or the sale of all or substantially all of its assets, all
such stock options not then exercisable will vest and become immediately
exercisable.

Hybridon is also a party to registration rights agreements with Mr.
Grinstead that provide that in the event Hybridon proposes to register any of
its securities under the Securities Act, at any time, with certain exceptions,
Mr. Grinstead shall be entitled to include the shares of common stock held by
him in such registration, subject to the right of the managing underwriter of
any underwritten offering to exclude from such registration for marketing
reasons some or all of such shares. Hybridon also is a party to indemnification
agreements with Mr. Grinstead pursuant to which Hybridon has agreed to indemnify
him for certain liabilities, including liabilities arising under the Securities
Act.

Stock options to purchase an aggregate of 207,513 shares of common stock
granted to the Named Executive Officers pursuant to the 1990 Plan provide that,
upon a change in control, all options granted thereunder will become fully
exercisable. In addition, pursuant to the terms of the employment agreements
entered into between Hybridon and each of them as described above, in April
1997, stock options to purchase an aggregate of 156,069 shares of common stock
granted to the Named Executive Officers under Hybridon's

35

41

1995 plan were amended to provide that such options will become fully
exercisable upon a change in control of Hybridon, and all stock options granted
to the Named Executive Officers after March 1, 1997 will provide that such
options will become fully exercisable upon a change of control of Hybridon.

COMPENSATION COMMITTEE INTERLOCKS AND INSIDER PARTICIPATION

On June 16, 1998 the board of directors re-established a Compensation
Committee consisting of Messrs. Berry and El-Zein and Dr. Wyngaarden. None of
the directors or executive officers of Hybridon had any "interlock"
relationships to report during Hybridon's fiscal year ended December 31, 1999.

Since January 1, 1999, Hybridon has entered into or is involved in certain
ongoing transactions with the following:

- Pillar S.A., Pillar Investment, Pillar Limited and Charles River Building
Limited Partnership, entities of which Messrs. El-Zein and Menhall are
affiliates

- entities advised by Pecks, an entity of which Mr. Berry is a principal

- Founders Financial Group, an entity of which Messrs. Purkey and Hartley
are affiliates

- each of Drs. Wyngaarden and Zamecnik and Mr. Powell

For further details of these transactions, see "Certain Transactions."

36

42

SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

The following table sets forth certain information as of October 2, 2000
with respect to the beneficial ownership of shares of common stock by each
person known to Hybridon to own beneficially more than 5% of the outstanding
shares of common stock, assuming conversion of all convertible debt or preferred
stock and exercise of all warrants and stock options by such person and only by
such person.

AMOUNT AND NATURE
OF BENEFICIAL OWNERSHIP(1)
--------------------------
NUMBER OF      PERCENT OF
NAME AND ADDRESS OF BENEFICIAL OWNER                            SHARES          CLASS
------------------------------------                          ----------     -----------

5% STOCKHOLDERS
Founders Financial Group, L.P. .............................  6,365,463(2)      27.03%
53 Forest Ave.
Old Greenwich, CT 06870
Michael A. Boyd.............................................  6,365,463(3)      27.03%
c/o Founders Financial Group, L.P.
53 Forest Ave.
Old Greenwich, CT 06870
Pecks Management Partners Ltd...............................  4,283,198(4)      19.27%
One Rockefeller Plaza
New York, New York 10022
General Motors Employees....................................  4,015,488(5)      18.29%
Domestic Group Trust
c/o General Motors Investment Management
767 Fifth Avenue
New York, New York 10153
E. Andrews Grinstead III....................................  3,791,502(6)      17.48%
c/o Hybridon, Inc.
345 Vassar St.
Cambridge, MA 02139
Guardian Life Insurance.....................................  3,535,469(7)      16.46%
Company of America
201 Park Avenue South, 7A
New York, New York 10003
Delaware State Employees Retirement Fund....................  2,667,952(8)      12.94%
c/o Pecks Management Partners Ltd.
One Rockefeller Plaza
New York, New York 10020
Yahia M. A. Bin Laden.......................................  2,439,169(9)      12.67%
2 rue Charles Bonnet
1206 Geneva, Switzerland
Nicris Limited..............................................  2,425,836(10)     12.61%
c/o Magnin Dunand & Associates
2 rue Charles Bonnet
1206 Geneva, Switzerland
Intercity Holdings Ltd......................................  2,216,666(11)     12.10%
c/o Cuson Milner House
18 Parliament Street
Hamilton, Bermuda
Abdelah Bin Mahfouz.........................................  2,216,666(12)     12.10%
c/o SEDCO
P.O. Box 4384
Jeddah 21491
Saudi Arabia
Lincoln National Life Insurance Co. ........................  1,871,819(13)      9.45%
c/o Lynch & Mayer
520 Madison Avenue
New York, New York 10022

37

43

AMOUNT AND NATURE
OF BENEFICIAL OWNERSHIP(1)
--------------------------
NUMBER OF      PERCENT OF
NAME AND ADDRESS OF BENEFICIAL OWNER                            SHARES          CLASS
------------------------------------                          ----------     -----------

Darrier Hentsch & Cie.......................................  1,361,215(14)      7.24%
4 rue de Saussure
1204 Geneva, Switzerland
Aegon USA...................................................  1,057,848(15)      5.57%
c/o Camden Asset Management, L.P.
Suite 330
Los Angeles, CA 90067
Ousamma Salem...............................................    995,601(16)      5.32%
28 Avenue de Messine
75008 Paris, France
Declaration of Trust for the Defined Benefit Plan of ICI....    967,064(17)      5.11%
American Holdings, Inc.
c/o Pecks Management Partners Ltd.
One Rockefeller Plaza
New York, New York 10022

---------------

(1) The number of shares beneficially owned is determined under rules
promulgated by the Securities and Exchange Commission, and the information
is not necessarily indicative of beneficial ownership for any other
purpose. Under these rules, beneficial ownership includes any shares as to
which the individual has sole or shared voting power or investment power
and also any shares which the individual has the right to acquire within 60
days after October 2, 2000, through the exercise of any stock option or
other right. The inclusion herein of such shares, however, does not
constitute an admission that the named stockholder is a direct or indirect
beneficial owner of such shares. Unless otherwise indicated, each person or
entity named in the table has sole voting power and investment power, or
shares such power with his or her spouse, with respect to all shares of
capital stock listed as owned by such person or entity.

(2) Founders Financial Group, L.P. holdings include:

- 468,859 shares issuable upon exercise of Class A warrants

- 328,677 shares issuable upon exercise of Class B warrants

- 280,517 shares issuable upon the exercise of Class C warrants

- 25,818 shares issuable upon the exercise of Class D warrants

- 761,568 shares issuable upon exercise of other warrants

- 1,250,000 shares issuable upon conversion of Founders' portion of the
$6,000,000 bank loan to Hybridon

- 1,870,963 shares issuable upon conversion of 79,516 shares of Series A
preferred stock owned by Founders

- 443,830 shares issuable upon conversion of $266,298 in convertible debt
and

- 177,532 shares issuable upon conversion of $106,519 in convertible debt
owned by Founders Defined Benefit Plan

(3)Includes the following owned by Founders Financial Group, L.P.:

- 757,699 shares of common stock

- 468,859 shares issuable upon exercise of Class A warrants

- 328,677 shares issuable upon exercise of Class B warrants

- 280,517 shares issuable upon the exercise of Class C warrants

- 25,818 shares issuable upon the exercise of Class D warrants

- 761,568 shares issuable upon exercise of other warrants

- 1,250,000 shares issuable upon conversion of Founders portion of the
$6,000,000 bank loan to Hybridon

38

44

- 1,870,963 shares issuable upon conversion of 79,516 shares of Series A
preferred stock owned by Founders

- 443,830 shares issuable upon conversion of $266,298 in convertible debt
and

- 177,532 shares issuable upon conversion of $106,519 in convertible debt
owned by Founders Defined Benefit Plan

Mr. Boyd is the sole director and shareholder of Michael A. Boyd, Inc. which
is the general partner of Founders Financial Group, L.P. Hence, Mr. Boyd
controls Founders Financial Group, L.P. and may be considered a beneficial
owner of the shares beneficially owned by such entity.

(4)Includes 129,735 shares of Series A preferred stock owned by investment
advisory clients of Pecks, which clients would receive dividends and the
proceeds from the sale of such shares. Two of these clients are Delaware
State Employees Retirement Fund and Declaration of Trust for the Defined
Benefit Plan of ICI American Holdings, Inc. These shares of Series A
preferred stock are convertible into 3,052,580 shares of common stock of
Hybridon. This amount also includes a total of 208,895 shares issuable upon
the exercise of Class A warrants and a total of 394,348 shares issuable upon
the exercise of Class D warrants held by the foregoing entities. This number
also includes 627,375 shares issuable upon conversion of a portion of the
$6,000,000 bank loan to Hybridon owned by the foregoing entities.

(5) Includes 125,676 shares of Series A preferred stock which are convertible
into 2,957,080 shares of Hybridon common stock. This amount also includes
492,783 shares issuable upon the exercise of Class A warrants and 565,625
shares issuable upon conversion of a portion of a $6,000,000 bank loan to
Hybridon owned by this entity.

(6) Includes 1,010,919 shares subject to outstanding stock options which are
exercisable within the 60-day period following October 2, 2000 as well as
2,733,990 shares issuable upon the conversion of $1,640,394 in convertible
debt owned by Mr. Grinstead.

(7) Includes 120,051 shares of Series A preferred stock which are convertible
into 2,824,726 shares of common stock of Hybridon. This amount also
includes 353,316 shares issuable upon the exercise of Class A warrants and
252,101 shares issuable upon the exercise of Class D warrants. This amount
also includes the following holdings of the Guardian Pension Trust Fund:

- 3,686 shares of Series A preferred stock which are convertible into
86,730 shares of Hybridon common stock and

- 18,596 shares issuable upon the exercise of class A warrants.

(8)Includes 80,942 shares of Series A preferred stock which are convertible
into 1,904,513 shares of common stock of Hybridon. This amount also includes
137,918 shares issuable upon the exercise of Class A warrants, 270,271
shares issuable upon the exercise of Class D warrants and 355,250 shares
issuable upon conversion of a portion of the $6,000,000 bank loan to
Hybridon owned by this entity.

(9) Includes 1,125,880 shares held by Nicris Limited and 234,764 shares
issuable upon the exercise of Class B warrants held by Nicris Limited and
1,065,192 shares issuable upon the conversion of $639,115 in convertible
debt owed to Nicris Limited. Mr. Bin Laden, a controlling stockholder of
Nicris, may be considered a beneficial owner of the shares beneficially
owned by such entity.

(10) Includes 234,764 shares issuable upon the exercise of Class B warrants held
by Nicris Limited and 1,065,192 shares issuable upon the conversion of
$639,115 in convertible debt owed to Nicris Limited.

(11)Includes 375,000 shares issuable upon the exercise of Class B warrants held
by Intercity Holdings Ltd.

(12)Includes 1,841,666 shares held by Intercity Holdings Ltd. and 375,000 shares
issuable upon exercise of Class B warrants held by Intercity Holdings. Mr.
Bin Mahfouz, a controlling stockholder of Intercity Holdings Ltd., may be
considered a beneficial owner of the shares beneficially owned by such
entity.

(13)Includes 47,197 shares of Series A preferred stock which are convertible
into 1,110,508 shares of common stock of Hybridon. This amount also includes
238,023 shares issuable upon the exercise of Class A warrants. This amount
also includes the following holdings of Lincoln National Convertible
Securities Fund:

- 18,314 shares of Series A preferred stock which are convertible into
430,929 shares of Hybridon common stock.

39

45

- 92,359 shares issuable upon the exercise of Class A warrants

(14)Includes 140,636 shares issuable upon the exercise of Class B warrants held
by Darrier Hentsch and 710,127 shares issuable upon the conversion of
$426,076 in convertible debt owned by Darrier Hentsch

(15) Includes the following owned by the listed companies:

PEOPLE'S BENEFIT
LIFE INSURANCE      MONUMENTAL LIFE     TRANSAMERICA
COMPANY         INSURANCE COMPANY    CORPORATION
----------------    -----------------    ------------

Shares issuable upon the conversion of
-10,313 shares of preferred stock owned by
People's Life.............................      242,650                   --                --
-18,052 shares of preferred stock owned by
Monumental Life...........................           --              424,758                --
Shares issuable upon the conversion of
Class A warrants.........................      148,345              148,345                --
Shares issuable upon the conversion of
Class C warrants.........................           --                   --            93,750

Aegon USA is a controlling stockholder of People's Benefit Life Insurance
Company, Monumental Life Insurance Company and Transamerica Corporation
and may be considered a beneficial owner of the shares beneficially owned
by such entities.

(16) Includes 443,894 shares issuable upon the exercise of warrants held by Mr.
Salem; 299,458 shares issuable upon the conversion of $179,675 in
convertible debt owned by Mr. Salem; and 148,882 shares issuable upon the
conversion of $89,329 in convertible debt that Mr. Salem has the right to
acquire upon exercise of warrants.

(17) Includes 29,223 shares of Series A preferred stock which are convertible
into 687,596 shares of common stock of Hybridon. This amount also includes
42,153 shares issuable upon the exercise of Class A warrants, 74,265 shares
issuable upon the exercise of Class D warrants and 163,050 shares issuable
upon conversion of a portion of the $6,000,000 bank loan to Hybridon owned
by this entity.

The following table sets forth certain information as of October 2, 2000,
with respect to the beneficial ownership of shares of common stock and Series A
preferred stock by each of Hybridon's directors and executive officers
individually, and the directors and executive officers of Hybridon as a group,
assuming conversion of all convertible debt or preferred stock and exercise of
all warrants and stock options by such person and only by such person.

SERIES A
COMMON STOCK           CONVERTIBLE PREFERRED STOCK
--------------------------    ----------------------------
AMOUNT AND                    AMOUNT AND
NATURE OF                      NATURE OF
BENEFICIAL     PERCENT OF     BENEFICIAL      PERCENT OF
NAME OF BENEFICIAL OWNER                      OWNERSHIP(1)      CLASS       OWNERSHIP(1)        CLASS
------------------------                      ------------    ----------    -------------    -----------

DIRECTORS AND EXECUTIVE OFFICERS
C. Keith Hartley............................    6,504,034(2)    27.45%          79,516(3)       12.58%
Arthur W. Berry.............................    4,648,262(4)    20.57%         129,735(5)       20.53%
Sudhir Agrawal..............................    1,125,004(6)     5.90%              --             --
Paul Z. Zamecnik............................      904,753(7)     4.87%              --             --
Youssef El-Zein.............................      621,815(8)     3.37%              --             --
James B. Wyngaarden.........................      300,448(9)     1.65%              --             --
Robert G. Andersen..........................      244,316(10)    1.34%              --             --
Nasser Menhall..............................      231,887(11)    1.28%              --             --
Camille A. Chebeir..........................        9,000(12)       *               --             --
All directors and executive officers as
a group (9 persons).......................   14,589,519       46.53%         209,251          33.11%

---------------
*  Less than 1%

40

46

(1) The number of shares beneficially owned by each director and executive
officer is determined under rules promulgated by the SEC, and the
information is not necessarily indicative of beneficial ownership for any
other purpose. Under such rules, beneficial ownership includes any shares
as to which the individual has sole or shared voting power or investment
power and also any shares which the individual has the right to acquire
within 60 days after October 2, 2000 through the exercise of any stock
option or other right. The inclusion herein of such shares, however, does
not constitute an admission that the named stockholder is a direct or
indirect beneficial owner of such shares. Unless otherwise indicated, each
person or entity named in the table has sole voting power and investment
power or shares such power, with his or her spouse, with respect to all
shares of capital stock listed as owned by such person or entity.

(2)C. Keith Hartley's holdings include the following:

- 757,699 shares of common stock owned by Founders Financial Group, L.P.

- 468,859 shares issuable upon the exercise of Class A warrants owned by
Founders

- 328,677 shares issuable upon the exercise of Class B warrants owned by
Founders

- 280,517 shares issuable upon the exercise of Class C warrants owned by
Founders

- 25,818 shares issuable upon the exercise of Class D warrants owned by
Founders

- 761,568 shares issuable upon the exercise of other warrants held by
Founders

- 1,250,000 shares issuable upon conversion of Founders' portion of the
$6,000,000 bank loan to Hybridon

- 1,870,963 shares issuable upon conversion of 79,516 shares of Series A
preferred stock owned by Founders

- 443,830 shares issuable upon conversion of $266,298 in convertible debt
owned by Founders

- 177,532 shares issuable upon conversion of $106,519 in convertible debt
owned by Founders Defined Benefit Plan

Mr. Hartley, an affiliate of Founders, may be considered a beneficial owner
of the shares beneficially owned by such entity. This amount also includes
125,000 shares issuable upon the exercise of warrants owned by Mr. Hartley.

(3)Consists of 79,516 shares of Series A preferred stock owned by Founders. Mr.
Hartley, an affiliate of Founders, may be considered a beneficial owner of
the shares beneficially owned by Founders.

(4)Includes 129,735 shares of Series A preferred stock owned by investment
advisory clients of Pecks, which clients would receive dividends and the
proceeds from the sale of such shares. Two of these clients are Delaware
State Employees Retirement Fund and Declaration of Trust for the Defined
Benefit Plan of ICI American Holdings, Inc. These shares of Series A
preferred stock are convertible into 3,052,580 shares of common stock of
Hybridon. This amount also includes a total of 208,895 shares issuable upon
the exercise of Class A warrants and a total of 394,348 shares issuable upon
the exercise of Class D warrants held by the foregoing entities. This number
also includes 627,375 shares issuable upon conversion of a portion of the
$6,000,000 bank loan to Hybridon owned by the foregoing entities. Mr. Berry
is an investment advisor to these companies and may be considered a
beneficial owner of the shares owned by such entities. Mr. Berry disclaims
beneficial ownership of these shares. This number also includes 10,000
shares issuable upon the exercise of stock options held by Mr. Berry and
355,064 shares issuable upon conversion of $213,038 in convertible debt
owned by Mr. Berry.

(5) Includes 129,735 shares of Series A preferred stock owned by investment
advisory clients of Pecks, which clients would receive dividends and the
proceeds from the sale of such shares. Mr. Berry is an investment advisor
to these companies and may be considered a beneficial owner of the shares
owned by such entities. Mr. Berry disclaims beneficial ownership of these
shares.

(6) Includes 1,107,244 shares subject to outstanding stock options which are
exercisable within the 60-day period following October 2, 2000.

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(7)Paul Zamecnik's holdings include the following:

- 178,500 shares subject to outstanding stock options which are exercisable
within the 60-day period following October 2, 2000

- 230,793 shares issuable upon the exercise of warrants

- 234,080 shares issuable upon the conversion of $230,651 in convertible
debt owned by Dr. Zamecnik

(8) Youssef El-Zein's holdings include:

- 403,080 shares issuable upon the exercise of warrants held by Mr. El-Zein

- 18,000 shares issuable upon the exercise of stock options held by Mr.
El-Zein

- 51,163 shares issuable upon the conversion of $30,698 in convertible debt
owned by Mr. El-Zein

- 149,572 shares issuable upon the conversion of $89,743 in convertible
debt that Mr. El-Zein has the right to acquire upon exercise of warrants

(9)Includes 242,590 shares subject to outstanding stock options which are
exercisable within the 60-day period following October 2, 2000, 26,121
shares issuable upon the conversion of $28,211 in convertible debt owned by
Dr. Wyngaarden, 27,737 shares issuable upon the exercise of warrants and 700
shares held by Dr. Wyngaarden's children.

(10) Includes 244,316 shares subject to outstanding stock options which are
exercisable within the 60-day period following October 2, 2000.

(11)Nasser Menhall's holdings include the following:

- 18,000 shares issuable upon the exercise of stock options held by Mr.
Menhall

- 129,677 shares issuable upon the exercise of warrants held by Mr. Menhall

- 28,613 shares issuable upon the conversion of $17,168 in convertible debt
owned by Mr. Menhall

- 21,367 shares issuable upon the conversion of $12,820 in convertible debt
that Mr. Menhall has the right to acquire upon exercise of warrants.

(12) Includes 9,000 shares subject to outstanding stock options which are
exercisable within the 60-day period following October 2, 2000.

CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

Since January 1, 1997, Hybridon has entered into or has been engaged in the
following transactions with the following Hybridon directors and officers,
stockholders who beneficially own more than 5% of the outstanding common stock
of Hybridon, and affiliates or immediate family members of those directors,
officers and 5% Stockholders.

TRANSACTIONS WITH PILLAR S.A. AND CERTAIN OF ITS AFFILIATES

Hybridon has entered into certain transactions with Pillar S.A., Pillar
Investment and Charles River Building Limited Partnership, the entity which
owned Hybridon's former headquarters in Cambridge, Massachusetts (the "Cambridge
Landlord"). Pillar S.A. and Pillar Investment are affiliates of Messrs. El-Zein
and Menhall, two directors of Hybridon. The Cambridge Landlord is an affiliate
of Messrs. El-Zein and Menhall and Mohamed El-Khereiji, a former director of
Hybridon.

In 1997 and 1998, Hybridon was a party to a consulting agreement with
Pillar S.A. dated as of March 1, 1994, under which Pillar S.A. provided Hybridon
with financial advisory and managerial services in connection with Hybridon's
overseas operations, including support services in connection with contracts and
agreements. Under the terms of the 1994 Pillar consulting agreement, Hybridon
paid Pillar S.A. consulting fees of $60,000 per month and $23,000 per month for
overhead costs, and reimbursed certain authorized out-of-pocket expenses. The
1994 Pillar consulting agreement expired on February 28, 1998. Pursuant to the
1994 Pillar consulting agreement, Hybridon issued to Pillar S.A two five year
warrants to purchase an aggregate of 40,000 shares of Hybridon common stock.

On July 8, 1995, Hybridon entered into an additional agreement with Pillar
S.A. pursuant to which Pillar S.A. agreed for a period of two years to provide
to Hybridon certain consulting, advisory and related services, in addition to
the services to be provided under the 1994 Pillar Consulting Agreement, and
serve as Hybridon's exclusive agent in connection with potential corporate
partnerships in Europe and as a non-exclusive

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placement agent of Hybridon in connection with private placements of securities
of Hybridon. On November 1, 1995, the Pillar Europe agreement was amended to
provide as follows:

- Pillar S.A. would cease to serve as Hybridon's executive agent in
connection with potential corporate partnerships in Europe, but would
continue to serve as a non-exclusive agent in that connection

- Pillar S.A. would receive a retainer of $26,470 per month for the balance
of the term of the Pillar Europe agreement

- the fees provided for in the Pillar Europe agreement would only be
payable to Pillar S.A. in connection with potential collaborations with
any French pharmaceutical company with which Hybridon was involved in
discussions during the 12-month period ended November 1, 1995 as a result
of introductions by Pillar S.A.

- any compensation payable to Pillar S.A. in connection with its services
with respect to other corporate collaborations or any placements of
securities would be negotiated on a case-by-case basis and would be
subject to the approval of the independent members of the board of
directors of Hybridon

The Pillar Europe agreement expired on April 1, 1997.

In 1998, Hybridon paid Pillar Investment a total of $300,000 under these
agreements, in the form of 150,000 shares of common stock and warrants to
purchase 37,500 shares of common stock, at an exercise price of $2.40 per share,
subject to adjustment, in lieu of cash. In 1997, Hybridon paid Pillar S.A.
$903,267 under the 1994 Pillar consulting agreement and the Pillar Europe
agreement.

Hybridon has retained Pillar Investment as placement agent in connection
with the private placements of securities of Hybridon in offshore transactions
in reliance upon an exemption from registration under Regulation S promulgated
under the Securities Act of 1933. Pillar Investment received fees consisting of
the following:

- 9% of the gross proceeds of each Regulation S Offering

- a non-accountable expense allowance equal to 4% of those gross proceeds

- the right to purchase, for nominal consideration, warrants to purchase
473,598 shares of common stock, at an exercise price of $2.40 per share,
subject to adjustment

- the right to purchase, for nominal consideration, warrants to purchase a
number of shares of the common stock of Hybridon equal to 10% of the
total number of shares of common stock sold by Hybridon for which Pillar
Investment acted as placement agent, exercisable at 120% of the relevant
common stock offering price, for a period of five years, resulting, as of
the date hereof, in the right to receive warrants to purchase 638,032
shares at $2.40 per share, subject to adjustment

- a consulting/restructuring fee of $960,000 payable in common stock of
Hybridon valued at the market price and payable in three equal
installments as net proceeds of $25,000,000, $30,000,000 and $35,000,000
are received in the aggregate from private placements effected by
Hybridon in 1998 to the extent contemplated by the consent and waiver
dated as of January 12, 1998, given by certain beneficial holders of
Hybridon's 9% convertible subordinated notes, or otherwise to the extent
contemplated by the Placement Agency agreement between Hybridon and
Pillar Investment, subject to Hybridon's receiving of a fairness opinion
regarding this: Pillar Investment may not receive compensation in excess
of the level that was approved by the holders of the 9% notes

Pillar Investment has received $1,635,400 in cash pursuant to these
arrangements and Pillar has received warrants to purchase 1,111,630 shares of
common stock.

In addition, in connection with the Regulation S offerings, Hybridon and
Pillar Investment had entered into an advisory agreement dated May 5, 1998,
under which Pillar Investment acted as Hybridon's non-exclusive financial
advisor. This agreement required Hybridon to pay an affiliate of Pillar
Investment a

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49

monthly retainer of $5,000, with a minimum engagement of 24 months beginning on
May 5, 1998, and further provides that Pillar Investment is entitled to receive
the following:

- out-of-pocket expenses,

- subject to Hybridon's receiving a fairness opinion on this matter,
300,000 shares of common stock in connection with Pillar Investment's
efforts in assisting Hybridon in restructuring its balance sheet,

- certain cash and equity success fees in the event Pillar Investment
assisted Hybridon in connection with certain financial and strategic
transactions.

This advisory agreement expired on May 5, 2000 and was not renewed.

As of April 16, 1999, Hybridon issued to Pillar Investment the stipulated
300,000 shares of common stock. Hybridon received a fairness opinion in
connection with that issuance. In addition, Hybridon was a party to a lease with
a third party dated March 23, 1994 for approximately 1,800 square feet of space
in Paris, France. Hybridon's obligations under the Paris lease was guaranteed by
Pillar S.A. Hybridon terminated the Paris lease on March 31, 1998. Pursuant to a
1999 private placement offering, Hybridon sold 8% notes to certain investors,
including some investors that Pillar Investment introduced to Hybridon. In
connection with this offering, and in lieu of any compensation due under the
financial advisory agreement between Hybridon and Pillar Investment, Hybridon
agreed to pay Pillar Investment's reasonable expenses and to issue to Pillar
Investment and its designees additional 8% notes in an aggregate principal
amount equal to 9% of the aggregate principal amount of 8% notes purchased by
those Pillar-introduced investors. Hybridon also agreed to issue to Pillar
Investment and its designees warrants to purchase additional 8% notes in an
aggregate principal amount equal to 10% of the aggregate principal amount of 8%
notes purchased by those Pillar-introduced investors. These warrants have a
strike price equal to 110% of the principal amount of the 8% notes purchasable
thereunder. Hybridon's obligations to issue the 8% notes and the warrants and to
reimburse Pillar Investment's expenses are subject to the condition precedent
that Hybridon will have had delivered to it a fairness opinion in form and
substance deemed by Hybridon, in its sole discretion, to satisfy the
requirements of the indenture relating to Hybridon's 9% notes. As of December
31, 1999, Pillar Investment had earned the right to receive $269,290 in 8% notes
and warrants to purchase an additional $298,100 in 8% notes.

TRANSACTIONS WITH THE CAMBRIDGE LANDLORD

From February 4, 1997 to September 16, 1998, Hybridon was a party to a
lease with the Cambridge Landlord for its Cambridge facilities. This lease
originally provided for an annual rent equal to $30 per square foot on a
triple-net basis, where the tenant pays taxes, insurance, and operating costs,
for the first five years, $33 per square foot on a triple-net basis for the next
five years and the greater of $30 per square foot on a triple-net basis or the
then-market value of leased property for each of the five-year renewal terms. In
connection with Hybridon's election to acquire an interest in the Cambridge
Landlord, as described below, the annual rent due under the Cambridge lease was
increased for the first five years of the lease term to $38 per square foot on a
triple-net basis, for the second five years to $42 per square foot on a
triple-net basis and for the third five years to $47 per square foot on a
triple-net basis.

On July 1, 1996, Hybridon decided to fund approximately $5.5 million of the
costs, primarily relating to tenant improvements, of the construction of the
leased premises through contributions to the capital of the Cambridge Landlord
in exchange for a limited partnership interest in the Cambridge Landlord. The
partnership interest entitled Hybridon to an approximately 32% interest in the
Cambridge Landlord. Hybridon had the right, for a period of three years ending
February 2000, to sell the partnership interest back to certain limited partners
of the Cambridge Landlord for a price equal to the greater of (1) the total cash
contribution made by Hybridon to the Cambridge Landlord or (2) the fair market
value of the partnership interest at the time.

In 1997, Hybridon had on deposit with Bank fur Vermogensanlagen und Handel
the amount of $1,034,618. In November 1997, German banking authorities imposed a
moratorium on Bank fur Vermogensanlagen und Handel and closed Bank fur
Vermogensanlagen und Handel for business. Pursuant to an agreement dated
November 28, 1997, the Cambridge Landlord agreed to assume the risk for the Bank
fur Vermogensanlagen und Handel deposit and to pay to Hybridon the amount of
$75,000 a month after each rent

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50

payment under the Cambridge lease was made until such time as $1,000,000 had
been paid to Hybridon or the Bank fur Vermogensanlagen und Handel deposit was
released.

In June 1998, Hybridon moved its headquarters from the Cambridge facility
to its facility in Milford, Massachusetts. The Cambridge facility was re-leased
in September 1998 to a third party, subject to a sublease of a portion of the
facility. As a result, Hybridon terminated the Cambridge lease and was relieved
of its substantial lease obligations under the Cambridge lease, subject to a
contingent continuing liability for any sublessee defaults. Further, in November
1998 Hybridon completed the sale of its partnership interest. As a result of
these transactions, Hybridon received $6,163,000 from the Cambridge Landlord,
which included payment for the partnership interest, the return of a portion of
the security deposit required under the Cambridge lease, and payment in full of
the Bank fur Vermogensanlagen und Handel deposit. Hybridon has agreed to
reimburse the Cambridge landlord for any cash received under this agreement, up
to the amount realized by Hybridon from the final settlement of the Bank fur
Vermogensanlagen und Handel deposit, after the moratorium is lifted. Hybridon
has subsequently sold its Milford facility and relocated to Cambridge,
Massachusetts.

TRANSACTIONS WITH FORUM CAPITAL MARKETS LLC/FOUNDERS FINANCIAL GROUP, L.P. AND
PECKS MANAGEMENT PARTNERS LTD.

In 1998, Hybridon entered into certain transactions with Forum Capital
Markets LLC (Forum), an affiliate of Mr. Purkey, a former director of Hybridon,
and entities advised by Pecks Management Partners Ltd. Mr. Berry, a principal of
Pecks, is a director of Hybridon.

Hybridon retained Forum as a placement agent of Hybridon in connection with
Hybridon's 1998 Regulation D offering of Series A preferred stock and Class D
warrants in the U.S. Forum received as compensation for its services as
placement agent with regard to the Regulation D offering and its assistance with
an exchange offer made by Hybridon to the holders of its 9% notes, 597,699
shares of common stock and warrants to purchase prior to May 4, 2003 a total of
609,194 shares of common stock exercisable at $2.40 per share, in each case
subject to adjustment. In addition, in exchange of the agreements made by Forum
consenting to the Regulation D offering and waiving certain obligations of
Hybridon to Forum, Hybridon agreed to amend Forum's warrant dated as of April 2,
1997, to purchase up to 71,301 shares of common stock of Hybridon, to change the
exercise price to $4.25 per share, subject to adjustment, and increase the
number of shares of common stock purchasable upon exercise to 588,235, in each
case subject to adjustment, and to provide that it may not be exercised until
May 5, 1999 and the transactions contemplated by those private placements and by
the exchange offer will not trigger any anti-dilution adjustments to its
exercise price or the number of shares of common stock purchasable upon
exercise.

In November 1998, Forum and entities advised by Pecks purchased Hybridon's
bank loan. In connection with the purchase of the loan, the purchasing entities
advanced an additional amount to Hybridon so as to increase the outstanding
principal amount of the loan to $6,000,000. In addition, the purchasing entities
agreed to amend the terms of the loan. This principal amount of the loan and
unpaid interest thereon is convertible, in whole or in part, at the lenders'
option into common stock at a conversion price of $2.40 per share.

In connection with the purchase of the loan, Forum received a fee of
$400,000, which Forum has reinvested by purchasing from Hybridon 160,000 shares
of common stock and warrants to purchase an additional 40,000 shares of common
stock at $3.00 per share. In addition, Forum received warrants exercisable until
maturity of the Loan to purchase 133,333 shares of common stock at $3.00 per
share.

In connection with Hybridon's offering of the 8% Convertible Notes, Forum
and the entities advised by Pecks entered into a Subordination and Intercreditor
Agreement with Hybridon and the representative of the purchasers of the notes
whereby, among other things, they agreed to subordinate their loan to the 8%
Convertible Notes, subject to certain conditions. Also in connection with this
offering, Hybridon agreed to issue warrants to purchase an aggregate of 2.75
million shares of Hybridon's common stock to designees of Pecks and Forum. These
warrants are exercisable from December 31, 2000 until December 31, 2002 at $0.60
per share.

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Founders Financial Group L.P. (Founders) owned a controlling interest in
Forum while these transactions occurred. Founders subsequently sold its interest
in Forum but Founders retained ownership of the Hybridon securities previously
held by Forum.

OTHER TRANSACTIONS AND TRANSACTIONS ASSOCIATED WITH ASSET SALE

In March 1999, Hybridon entered into consulting arrangements with each of
Mr. Powell, Dr. Zamecnik and Dr. Wyngaarden providing that each of them will act
as a consultant to Hybridon for a two-year period and will receive a consulting
fee of $20,000 per year for general consulting services. In addition, each
agreement provides that they each will receive a consulting fee of $1,500 per
day of on-site consulting services they provide at Hybridon's corporate offices,
or at an alternative site agreed upon by the parties, and at Hybridon's prior
request. Additional fees for special projects will be negotiated separately
between the parties. Each of Mr. Powell, Dr. Zamecnik and Dr. Wyngaarden also
received options to purchase 150,000 shares of Hybridon's common stock at $2.00
per share; such options will vest over a two-year period. Dr. Zamecnik has
received $26,000 in convertible notes for his 1999 consulting services and board
fees, which he may at his option convert into 43,333 shares of common stock. Mr.
Powell's consulting agreement terminated when Mr. Powell resigned from the board
of directors of Hybridon in February 2000. Dr. Wyngaarden's Consulting Agreement
was replaced with a quarterly stipend of $15,000 upon Dr. Wyngaarden's
appointment to Chairman of the Board of Directors in February 2000.

Certain persons and entities, including Dr. Zamecnik, Pillar S.A., Pillar
Limited, Founders, the entities advised by Pecks, Intercity Holdings, Mr. Bin
Laden and Nicris Limited, are entitled to certain rights with respect to the
registration under the Securities Act of certain shares of Hybridon's common
stock, including shares of common stock that may be acquired pursuant to the
exercise of options or warrants, under the terms of agreements among Hybridon
and the rightsholders. The registration agreements generally provide that in the
event Hybridon proposes to register any of its securities under the Securities
Act at any time, with certain exceptions, the rightsholders, including Pillar
S.A., Pillar Limited, Intercity Holdings, Mr. Bin Laden and Nicris Limited, but
excluding, among others, Dr. Zamecnik, have the additional right under certain
registration agreements to require Hybridon to prepare and file registration
statements under the Securities Act, if rightsholders holding specified
percentages of the registrable shares so request, and Hybridon is required to
use its best efforts to effect that registration, subject to certain conditions
and limitations.

Hybridon sold an aggregate of $1,500,000 principal amount of promissory
notes to E. Andrews Grinstead, III, Hybridon's former Chief Executive Officer,
at face value during September and November of 1999. These notes accrued
interest at 12% per annum, or at 15% upon Hybridon's election to pay this
interest in shares of common stock rather than cash, and, upon the closing of
any third-party debt financing that closed on or before March 1, 2000, were
intended to be converted into the debt sold in that financing. These notes have,
together with $40,000 in accrued interest, been converted into 8% notes of
Hybridon due 2002.

In addition, in connection with the financing conducted in December 1999,
other Hybridon directors and certain affiliates of Hybridon directors purchased
Hybridon 8% notes in the amounts set forth below:

Nicris Limited (over 5% stockholder and affiliate of Mr. Bin
Ladin)....................................................    $600,000
Darrier Hentsch & Cie (over 5% stockholder).................    $400,000
Founders Financial Group, L.P. (over 5% stockholder and
affiliate of Messrs. Hartley and Purkey)..................    $250,000
Harold L. Purkey (Former Director)..........................    $100,000
Arthur W. Berry (Director)..................................    $200,000
H. F. Powell (Former Director)..............................    $100,000
Paul Zamecnik (Director)....................................    $ 26,000

Two other principals of Founders each purchased $100,000 of the 8% notes.

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On May 30, 2000 Hybridon entered into a Line of Credit Agreement (the "Loan
Agreement") with certain lenders (the "Lenders") who provided Hybridon with a
$2,000,000 credit facility. The Lenders included directors and certain investors
of Hybridon set forth below:

Name of Lender
-----------------------------------------
Kincroft Ltd.
Oussama Salam (individually)
H.K. Properties, Ltd.
Dr. Paul Zamecnik
Global Investments Enterprises, Ltd.
Dr. James Wyngaarden
Motasim F. Hajaj
Keith Hartley
Abdelraof M. Abou Anza
Mark Germain

The Loan was intended to provide Hybridon with working capital pending the
closing of the Asset Sale. Hybridon was permitted to draw upon the facility at
any time prior to the earlier of September 30, 2000, and the date the Asset Sale
was consummated. On July 10, 2000, Hybridon drew down approximately $500,000
under the Loan Agreement and on August 10, 2000 another $500,000 was drawn down.

Loans made under the Loan Agreement matured and became due on the earlier
of September 30, 2000 or the date the Asset Sale was consummated. At the
maturity date, each Lender could elect either (a) conversion of its portion of
the loan into shares of Hybridon's common stock at the rate of one share for
each $1.08 of principal and interest then accrued (the $1.08 conversation price
being equal to the closing price of the Hybridon common stock at the time the
Lenders expressed their willingness to make the Loan), or (b) repayment of its
portion of the Loan. In the later case, such repayment was funded from the
proceeds of the Asset Sale.

Hybridon believes that the terms of the transactions described above were
no less favorable than Hybridon could have obtained from unaffiliated third
parties.

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SELLING STOCKHOLDERS

The tables set forth below, to the knowledge of Hybridon, contain certain
information as of October 2, 2000 with respect to the selling stockholders. The
table entitled "Stockholders Selling Common Stock" includes information with
respect to selling stockholders who are selling common stock in this offering.
The table entitled "Stockholders Selling Preferred Stock" includes information
with respect to selling stockholders who are selling preferred stock in this
offering. Except as noted below, no selling stockholder selling common or
preferred stock in this offering will beneficially own 1% or more of the
outstanding stock of Hybridon after the offering.

Except as described below, none of the selling stockholders holds any
position or office with, or has otherwise had a material relationship with,
Hybridon within the past three years.

STOCKHOLDERS SELLING COMMON STOCK

COMMON STOCK                     COMMON STOCK
BENEFICIALLY     COMMON STOCK    BENEFICIALLY
OWNED PRIOR TO    INCLUDED IN     OWNED AFTER
NAME OF SELLING STOCKHOLDER                          OFFERING(1)        OFFERING      OFFERING(1)
---------------------------                         --------------    ------------    ------------

Aboutakka, Faouzi.................................         5,000            5,000              0
Abu Anza, Abdul Raof M. ..........................       388,656          388,656              0
Agrawal, Sudhir(6,11,12)..........................     1,125,004           17,760      1,107,244
Alamdar, Essam Ahmad Jawadm.......................       525,804          525,804              0
Al-Battal, Abdullha...............................         9,000            4,000          5,000
Alhegian, Nouha Tarazi............................         2,500            2,500              0
Al Jalab, Saleh Ali A.............................        10,000            7,500          2,500
Al-Jindi, Nafez M.M. .............................       119,232          119,232              0
Allstate Insurance Company........................       142,780          142,780              0
Al-Sharif, Mansour S.M.A. ........................       110,355          110,355              0
Altobaishi, MAA & Malek, SS.......................        10,000           10,000              0
Alyoum Ltd. ......................................         7,500            7,500              0
Amor Ltd. ........................................         9,383            9,383              0
Angelo Gordon & Co., L.P. ........................        24,878           24,878              0
Arab Islamic Bank (E.C.)..........................       503,394          503,394              0
Awwa, Moufied.....................................         3,074            3,074              0
Bajrai International Group Ltd. ..................       481,517          481,517              0
Bajrai, Mohammed..................................       925,347          443,830              0
Bamas, Patrick....................................           129               29            100
Bank Ehinger & Cie................................         1,200            1,200              0
Berry, Arthur W.(5,11)............................     4,648,262          355,064         10,000
Bestin Worldwide Ltd. ............................           625              625              0
Bin Laden, Yahia M.A.(11,12)......................     2,439,169           13,333        310,000
Bio Capital Inc. .................................           275              275              0
Biocell BV........................................         2,452            2,452              0
Bioreliance Corporation...........................        16,697           16,697              0
Bukhari, Huda Abdulraheem.........................           625              625              0
Carset Overseas Corporation.......................       212,208          176,375         35,833
Chatain, Jacques..................................            29               29              0
Chestnut Partners.................................        62,500           62,500              0
Chkaiban, Michel..................................           300              300              0
Clapham Investments Ltd. .........................       505,563          480,063         25,500
CNA Income Shares, Inc. ..........................       391,649          391,649              0
Coakley, Aran B. .................................           400              400              0
Coakley, Elizabeth Z. ............................           400              400              0
Coakley, Gabriel D.F. ............................           400              400              0

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COMMON STOCK                     COMMON STOCK
BENEFICIALLY     COMMON STOCK    BENEFICIALLY
OWNED PRIOR TO    INCLUDED IN     OWNED AFTER
NAME OF SELLING STOCKHOLDER                          OFFERING(1)        OFFERING      OFFERING(1)
---------------------------                         --------------    ------------    ------------

Coakley, Richard B. ..............................           400              400              0
Comeca International, SA..........................         1,400            1,400              0
Compagnie Financiere De Rom.......................        50,000           50,000              0
CPR (USA).........................................        77,482           77,482              0
Crescent International Holdings...................        12,500           12,500              0
Daly, Robert W. ..................................           731              731              0
Darier Hentsch & Cie(11)..........................     1,361,215        1,361,215              0
Datamonitor.......................................        62,500           62,500              0
Daugeras, Bernard.................................            29               29              0
DeFreige, Jean....................................           600              600              0
Delaware State Employees Retirement Fund(5,11)....     2,667,952        2,667,952              0
DeVoe III, Stephen J. ............................       177,532          177,532              0
Didier, Arbant....................................           252              252              0
Duer, Thomas Fr. .................................        13,125           13,125              0
Duer, Torben......................................       125,268          125,268              0
Dumanoir, Le Pelley...............................        22,149           22,149              0
Dunn, Bruce E. ...................................           625              625              0
Eagle Constellation Fund..........................           138              138              0
El-Bahey, Wael....................................       505,539          376,464        129,075
El-Khazen, Walid..................................        17,953           17,753            200
El-Khereiji, Mohammed(8)..........................       827,713          507,173          9,000
El-Zein Youssef(2)................................       621,815          592,352         29,463
Equi Select Growth & Income Fund..................       175,594          175,594              0
Faisal Finance (Switzerland) S.A. ................        78,136           78,136              0
Finn Trunk Black..................................         4,500            3,750            750
Finova Technology Finance, Inc. ..................       896,875          896,875              0
Forest Alternative Strategies Fund II, L.P.
Series A5I(4)...................................        28,087           28,087              0
Forest Alternative Strategies Fund II, L.P.
Series A5M(4)...................................        14,067           14,067              0
Forest Alternative Strategies Fund II, L.P.
Series B-3(4)...................................           744              744              0
Forest Convertible Fund...........................        18,245           18,245              0
Forest Fulcrum Ltd.(4)............................        68,539           68,539              0
Forest Global Convertible Fund Series A5(4).......       214,993          214,993              0
Forest Greyhound(4)...............................         6,199            6,199              0
Forest Performance Fund(1)........................         7,355            7,355              0
Foundation Account No. 1..........................        73,753           73,753              0
Founders Financial Group, L.P.(4,11)..............     6,365,463        6,187,931              0
Founders Financial Group, L.P. Defined Benefit
Plan(4).........................................       177,532          177,532              0
Friedland IRA, Beth R. ...........................        44,383           44,383              0
Gaffney, Christopher..............................       443,830          443,830              0
General Motors Employees Domestic Group
Trust(11).......................................     4,015,488        4,015,488              0
Germain, Mark.....................................       105,472          105,472              0
Ghani, Mohamad Hassan Abdul.......................        67,717           67,717              0
Ghani, Khaled M.R. Abdul..........................       563,849          563,849              0
Global Investments................................        55,872           55,872              0
GPS Fund Limited..................................       105,324          105,324              0
Grant, Eric E. ...................................       177,532          177,532              0
Grinstead III, E. Andrews(7,11,12)................     3,791,502        2,777,569      1,013,933

49

55

COMMON STOCK                     COMMON STOCK
BENEFICIALLY     COMMON STOCK    BENEFICIALLY
OWNED PRIOR TO    INCLUDED IN     OWNED AFTER
NAME OF SELLING STOCKHOLDER                          OFFERING(1)        OFFERING      OFFERING(1)
---------------------------                         --------------    ------------    ------------

Guardian Life Insurance Co. of America(1).........     3,535,469        3,430,143              0
Gutrafin, SA......................................         6,400            6,400              0
Hadar, Raji Abou..................................       367,563          367,563              0
Hajaj, Motasim F. ................................       211,080          211,080              0
Hanninen, Elizabeth Chace.........................           100              100              0
Harris Investment Management......................        97,498           97,498              0
Hartley, C. Keith(4,11)...........................     6,504,034          138,570              0
HK Properties.....................................       179,749          179,749              0
Hoffman La Roche Ltd. ............................       163,678          163,678              0
Hyal Pharmaceutical Corporation...................        17,500           17,500              0
Intercity Ltd. ...................................     2,216,666        2,216,666              0
Investerinsselskabet..............................       106,520          106,520              0
Jacquin, Jean.....................................           129               29            100
Janitronics.......................................         9,145            9,145              0
Jenkins, Nicholas J.T. ...........................        13,656            5,001          8,655
JSP Holdings ApS..................................        42,405           42,405              0
Kabbani, Isam M. Khairy...........................        75,619           67,119          8,500
Karam, Paula......................................           200              200              0
Kincroft Ltd. ....................................       309,749          309,749              0
Kinetic Systems, Inc. ............................        32,648           32,648              0
Hal A Kroeger Revocable Living Trust..............           746              746              0
Laconic Trust.....................................       266,298          266,298              0
LaCoste, Allain...................................            69               15             54
LGT Bank in Liechtenstein AG......................       240,032          240,032              0
Libertyview Fund LLC..............................        15,496           15,496              0
Libertyview Plus Fund.............................        31,236           31,236              0
Lincoln National Convertible Securities Fund......       523,288          523,288              0
Lincoln National Life Insurance Co.(11)...........     1,871,819        1,348,531              0
LLC Account No. 1.................................        35,109           35,109              0
LLT Ltd.(4).......................................        28,087           28,087              0
Loxhall Limited...................................        89,167           62,500         26,667
Mallart, Alain....................................       532,595          532,595              0
Mansour, Imad Mustapha............................       219,789          219,789              0
Marcusa, Fred H. .................................         3,000              800          2,200
Martin, R. Russell(10,12).........................       292,609           56,810        235,799
Massachusetts Eye & Ear Infirmary.................        62,500           12,500         50,000
Mattar, Raja......................................       219,805          219,805              0
J.W. McConnell Family Foundation..................        66,596           66,596              0
Medici Partners, L.P. ............................        28,305           28,305              0
Mendelsohn, Robert V. ............................           690              690              0
Menhall, Nasser(2)................................       231,887          198,872         33,015
Merick, Richard L. ...............................       133,148          133,148              0
Michael Angelo, L.P. .............................        75,653           75,653              0
MicroTech Software a/s............................        57,880           57,880              0
Mills, Robert H.Y. ...............................           375              375              0
Mirra Jr., Raymond................................       218,750          218,750              0
MM Pictet & Cie...................................       150,000          150,000              0
Monpurich Inc. ...................................         1,250            1,250              0
Monumental Life Insurance Co. ....................       573,103          573,103              0
Nicris Limited(11,12).............................     2,425,836        2,115,836        310,000

50

56

COMMON STOCK                     COMMON STOCK
BENEFICIALLY     COMMON STOCK    BENEFICIALLY
OWNED PRIOR TO    INCLUDED IN     OWNED AFTER
NAME OF SELLING STOCKHOLDER                          OFFERING(1)        OFFERING      OFFERING(1)
---------------------------                         --------------    ------------    ------------

Noonan, Susan and Russo, Anthony..................        12,500           12,500              0
Norwegian Radium Hospital Research Foundation.....        37,500           37,500              0
Numitor International Corp. ......................        51,379           51,379              0
Offshore Strategies Ltd. .........................       138,746          115,217         23,529
Omari, Mohamad Khaled.............................        71,013           71,013              0
Oesterballe, Klaus................................           100              100              0
Participations Besancon...........................       155,000          125,000         30,000
People's Benefit Life Insurance Co. ..............       390,995          390,995              0
Peters, Laurence..................................        88,767           88,767              0
Pharmakinetics Laboratories, Inc. ................        11,161           11,161              0
Pillar Investment Limited(2)......................             1                1              0
Poulson, Jan......................................       403,087          196,282              0
Powell, H.F. and Jacqueline W.(9).................       177,532          177,532              0
Primedica Corporation.............................        51,918           51,918              0
Prudential Securities.............................         6,199            6,199              0
Quintiles Transnational Corp. ....................       379,175          379,175              0
Ramius Fund Ltd. .................................        66,615           66,615              0
Raphael, L.P. ....................................       333,652          333,652              0
Raymond, Johnathan................................        17,753           17,753              0
Robbins, Samuel Morrill...........................       179,132          177,532          1,600
J. Romeo & Co. ...................................           420              420              0
Russell, Andrew W. ...............................         2,667            2,667              0
Saada, Daniel.....................................         1,750            1,500            250
Salam, Oussama(11)................................     1,198,967        1,052,377        146,590
Saudah Corporation................................        20,000           20,000              0
Sayegh, Antoun....................................           300              300              0
Schaad, Mme. Daniele..............................        59,913           59,913              0
SEIF Foundation...................................       450,302          450,302              0
Seaward, William..................................         8,877            8,877              0
Semon, Francoise..................................         5,111            5,111              0
Semon, Guy........................................         5,111            5,111              0
Seranius SA.......................................           750              750              0
Shepherd, John D. ................................           690              690              0
Sidani, Abdel-Hadi................................       167,008          167,008              0
Siena Construction Corporation....................        31,250           31,250              0
Sierra Biomedical, Inc. ..........................        37,841           37,841              0
Sigler & Co. .....................................        13,653           13,653              0
Smith, Marilynn C. ...............................           750              750              0
Sobbi, Adra.......................................        24,825           23,492          1,333
Solter Corporation(8).............................       311,540          311,540              0
Southern Research Institute.......................        68,860           68,860              0
SP Pharmaceuticals LLC............................        23,197           23,197              0
Stiftung, Bodo....................................        20,322           20,322              0
Stiftung, Milton..................................         3,000            3,000              0
Stone, Barbara....................................         6,000            6,000              0
Sweidan, Mohammed Abdo............................        75,619           67,119          8,500
Tabbah, Amer and/or Souraya.......................       183,098          183,098              0
Tawfig, Fouad M.O. and Zagzoug, Hanan H. .........       315,786          315,786              0
Telefix...........................................         4,409            4,409              0
The Guardian Pension Trust Fund...................       105,326          105,326              0

51

57

COMMON STOCK                     COMMON STOCK
BENEFICIALLY     COMMON STOCK    BENEFICIALLY
OWNED PRIOR TO    INCLUDED IN     OWNED AFTER
NAME OF SELLING STOCKHOLDER                          OFFERING(1)        OFFERING      OFFERING(1)
---------------------------                         --------------    ------------    ------------

Perkin Elmer Corporation..........................       205,377          205,377              0
Thermo Electron Balanced Investment Fund..........         9,450            9,450              0
Torkildson, et al, Money Purchase Plan............           533              533              0
Transamerica Business Credit Corporation..........        93,750           93,750              0
Triumvirate Environmental, Inc. ..................        19,138           19,138              0
Trust for Defined Benefits Plan of ICI America
Holdings, Inc.(5,11)............................       967,064          967,064              0
University of Kansas..............................        29,260           29,260              0
University of Massachusetts.......................        84,450           84,450              0
Von Mallosch, Werner..............................         5,333            5,333              0
Walker Art Center.................................        10,230           10,230              0
Waznah, Abdulhakeem H. ...........................         3,750            3,750              0
Weirton Trust.....................................       152,784          152,784              0
Wilkens, Lois.....................................         6,728            6,728              0
Winchester Convertible Plus Ltd. .................       136,974          136,974              0
Wyngaarden, James B.(3,12)........................       300,448           53,958        246,590
Zamecnik, Alexandra...............................           800              400            400
Zamecnik, Paul C. and Mary V.(3)..................       904,753          726,453        178,300
Zazove Convertible Fund, L.P. ....................       168,099          168,099              0
Zazove High Yield Convertible Securities Fund,
L.P. ...........................................        24,579           24,579              0
Zeneca Holdings(5)................................       648,182          648,182              0
3111440 Canada Inc. ..............................           500              500              0
----------       ----------      ---------
Total.............................................    68,510,951       49,949,865      3,990,680
==========       ==========      =========

---------------
NOTES:

(1) Includes common stock issuable upon the exercise of stock options,
warrants, convertible preferred stock and convertible debt.

(2) Mr. Nasser Menhall and Mr. Youssef El-Zein, members of the board of
directors of Hybridon, are principals of Pillar Investment Limited. See the
"Certain Relationships and Related Transactions" section for a description
of services that Pillar has provided to Hybridon.

(3) Dr. Paul C. Zamecnik and Dr. James B. Wyngaarden are members of the board
of directors and consultants to Hybridon.

(4) Mr. C. Keith Hartley, a member of the board of directors of Hybridon, is an
affiliate of Founders Financial Group, L.P. See the "Certain Relationships
and Related Transactions" section for a description of services that
Founders has provided to Hybridon.

(5) Mr. Arthur W. Berry, a member of the board of directors of Hybridon, serves
as investment advisor to this selling stockholder. See the "Certain
Relationships and Related Transactions" section for a description of
transactions with entities advised by Peck's Management Partners Ltd.

(6)Dr. Sudhir Agrawal is President and a member of the board of directors of
Hybridon.

(7)Mr. E. Andrews Grinstead is a former President, Chief Executive Officer and
director of Hybridon.

(8)Mr. Mohammed El-Khereiji is a former member of the board of directors of
Hybridon and is an affiliate of this shareholder.

(9)Mr. H. F. Powell is a former member of the board of directors and consultant
to Hybridon.

(10)Dr. R. Russell Martin is Senior Vice President of Drug Development of
Hybridon.

(11)These selling shareholders beneficially own more that 5% of the outstanding
shares of Hybridon's common stock before the offering. See the "Security
Ownership of Certain Beneficial Owners and Management" section of this Form
S-1.

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58

(12) These selling stockholders will beneficially own greater than 1% of
Hybridon's common stock (which for purposes of this calculation includes
common stock issuable upon exercise of options or warrants within 60 days
after October 2, 2000) after the offering, as follows:

PERCENTAGE OF
OUTSTANDING COMMON
STOCK BENEFICIALLY
OWNED AFTER
SELLING STOCKHOLDER                             THE OFFERING
-------------------                          ------------------

Agrawal, Sudhir..........................           5.81%
Grinstead III, E. Andrews................           5.35%
Nicris Limited...........................           1.73%
Bin Laden, Yahia M.A.....................           1.73%
Wyngaarden, James B......................           1.36%
Martin, R. Russell.......................           1.30%

STOCKHOLDERS SELLING PREFERRED STOCK

CONVERTIBLE         CONVERTIBLE         CONVERTIBLE
PREFERRED STOCK        PREFERRED        PREFERRED STOCK
BENEFICIALLY OWNED    STOCK INCLUDED    BENEFICIALLY OWNED
NAME OF SELLING STOCKHOLDER                    PRIOR TO OFFERING      IN OFFERING        AFTER OFFERING
---------------------------                    ------------------    --------------    ------------------

Allstate Insurance Company...................         2,117               2,117               --
Angelo Gordon & Co., L.P. ...................           135                 135               --
CNA Income Shares, Inc. .....................        12,694              12,694               --
Delaware State Employees Retirement Fund(2,
3).........................................        80,942              80,942               --
Equi Select Growth & Income Fund.............         6,145               6,145               --
Forest Alternative Strategies Fund II, L.P.
Series A5I1................................           983                 983               --
Forest Alternative Strategies Fund II, L.P.
Series A5M1................................           493                 493               --
Forest Convertible Fund(1)...................           775                 775               --
Forest Fulcrum Ltd.(1).......................         2,057               2,057               --
Forest Global Convertible Fund Series
A5(1)......................................         8,083               8,083               --
Forest Performance Fund(1)...................           147                 147               --
Foundation Account No.(1)....................         2,581               2,581               --
Founders Financial Group, L.P.(1,3)..........        79,516              79,516               --
General Motors Employees Domestic Group
Trust(1,3).................................       125,676             125,676               --
GPS Fund Limited.............................         3,686               3,686               --
Guardian Life Insurance Co. of America(3)....       120,051             120,051               --
Harris Investment Management.................         3,412               3,412               --
J.W. McConnell Family Foundation.............           408                 408               --
Libertyview Plus Fund........................            10                  10               --
Lincoln National Convertible Securities
Fund.......................................        18,314              18,314               --
Lincoln National Life Insurance Co.(3).......        47,197              47,197               --
LLC Account No.(1)...........................         1,229               1,229               --
LLT Ltd.(1)..................................           983                 983               --
Medici Partners, L.P. .......................           116                 116               --
Michael Angelo, L.P. ........................           368                 368               --
Monumental Life Insurance Co. ...............        18,052              18,052               --
Offshore Strategies Ltd. ....................         2,262               2,262               --
People's Benefit Life Insurance Co. .........        10,313              10,313               --
Ramius Fund, Ltd. ...........................           987                 987               --
Raphael, L.P. ...............................        11,678              11,678               --

53

59

CONVERTIBLE         CONVERTIBLE         CONVERTIBLE
PREFERRED STOCK        PREFERRED        PREFERRED STOCK
BENEFICIALLY OWNED    STOCK INCLUDED    BENEFICIALLY OWNED
NAME OF SELLING STOCKHOLDER                    PRIOR TO OFFERING      IN OFFERING        AFTER OFFERING
---------------------------                    ------------------    --------------    ------------------

Sigler & Co. ................................           580                 580               --
Telefix (First Delta)........................            20                  20               --
The Guardian Pension Trust Fund..............         3,686               3,686               --
Thermo Electron Balanced Investment Fund.....           402                 402               --
Trust for Defined Benefits Plan of ICI
America Holdings, Inc(2,3).................        29,223              29,223               --
Weirton Trust................................         5,347               5,347               --
Wilkens, Lois................................           235                 235               --
Winchester Convertible Plus Ltd. ............         4,794               4,794               --
Zazove Convertible Securities Fund, L.P. ....         5,883               5,883               --
Zazove High Yield Convertible Securities
Fund, L.P. ................................           860                 860               --
Zeneca Holdings(2)...........................        19,570              19,570               --
Total........................................       632,010             632,010               --

---------------

NOTES:

(1) Mr. C. Keith Hartley, a member of the board of directors of Hybridon, is an
affiliate of Founders Financial Group L.P. See the "Certain Relationships
and Related Transactions" section for a description of services that
Founders has provided to Hybridon.

(2) Mr. Arthur W. Berry, a member of the board of directors of Hybridon, serves
as investment advisor to this selling stockholder. See the "Certain
Relationships and Related Transactions" section for a description of
transactions with entities advised by Peck's Management Partners Ltd.

(3)These selling shareholders beneficially own more that 5% of the outstanding
shares of Hybridon's common stock before the offering. See the "Security
Ownership of Certain Beneficial Owners and Management" section of this Form
S-1.

DESCRIPTION OF CAPITAL STOCK

The authorized capital stock of Hybridon consists of 100,000,000 shares of
common stock and 5,000,000 shares of preferred stock, par value $.01 per share,
of which 1,500,000 have been designated as convertible preferred stock. On
October 2, 2000, there were issued and outstanding 17,944,949 shares of common
stock and 632,010 shares of convertible preferred stock.

There follows a brief summary of the terms of the common stock and the
convertible preferred stock. For further information please refer to the
restated certificate of incorporation of Hybridon, including the certificate of
designation for the Series A preferred stock, which is filed as an exhibit to
the registration statement.

COMMON STOCK

Holders of common stock are entitled to one vote for each share held on all
matters submitted to a vote of stockholders and do not have cumulative voting
rights. Accordingly, holders of a majority of the shares of common stock
entitled to vote in any election of directors may elect all of the directors
standing for election. Holders of common stock are entitled to receive ratably
any such dividends declared by the board of directors out of legally available
funds, subject to any preferential dividend rights of the preferred stock or
other securities. Upon the liquidation, dissolution or winding up of Hybridon,
the holders of common stock are entitled to receive ratably the net assets of
Hybridon available after the payment of all debts and other liabilities and
subject to the prior rights of any outstanding shares of preferred stock and to
the Liquidation Put Right described in the next paragraph. Holders of common
stock have no preemptive, subscription, redemption or conversion rights. The
rights, preferences and privileges of holders of common stock are subject

54

60

to, and may be adversely affected by, the rights of the holders of shares of any
series of preferred stock that Hybridon may designate and issue in the future,
and the rights of creditors of Hybridon.

Pursuant to the terms of the 1998 Unit Purchase Agreement, the initial
purchasers of certain of the shares of common stock sold in the Regulation S and
the Regulation D offerings (those shares, the "Put Shares" those purchasers, the
"Liquidation Put Holders") have the right to put those shares back to Hybridon
upon the liquidation of Hybridon, but only after all other indebtedness and
obligations of Hybridon and all rights of any holders of any capital stock
ranking prior and senior to the common stock with respect to liquidation have
been satisfied in full (that right, the "Liquidation Put"). The Liquidation Put
is not transferable, and therefore purchasers of common stock pursuant to this
prospectus will not be able to exercise the Liquidation Put with respect to
those shares. Any Liquidation Put Holders that have not sold or otherwise
transferred any Put Shares will, however, be able to exercise the Liquidation
Put with respect to those Put Shares upon a liquidation of Hybridon.
Consequently, in the event of liquidation of Hybridon, holders of shares of
common stock that are not subject to the Liquidation Put right may receive
smaller liquidation distributions per share than they would have had no
Liquidation Put Holders exercised the Liquidation Put. As of October 2, 2000,
there were 6,227,038 outstanding Liquidation Put Shares held in the name of
Liquidation Put Holders.

PREFERRED STOCK

Under the terms of the restated certificate of incorporation, the board of
directors is authorized, subject to any limitations prescribed by law, without
stockholder approval, to issue up to 5,000,000 shares of preferred stock in one
or more series with such rights, preferences, privileges and restrictions,
including voting rights, dividend rights, conversion rights, redemption
privileges and liquidation preferences, as the board of directors determines.

SERIES A PREFERRED STOCK

Dividends.  Each share of Series A preferred stock is entitled to receive
cumulative semi-annual dividends payable, at the option of Hybridon, in cash or
additional shares of convertible preferred stock, at the rate of 6.5% per annum
plus accrued but unpaid dividends. Dividends accrue from the date of issuance
and paid semi-annually on April 1 and October 1 of each year or, if any such day
is not a business day, on the next business day. Dividends are paid, at the
election of Hybridon, either in cash or additional shares of convertible
preferred stock. In calculating the number of shares of convertible preferred
stock to be paid with respect to each dividend, the convertible preferred stock
is valued at $100.00 per share, subject to appropriate adjustment to reflect any
stock split, combination, reclassification or reorganization of the convertible
preferred stock.

Liquidation Preference.  In the event of one of the following: (1)
liquidation, dissolution or winding up of Hybridon, whether voluntary or
involuntary, (2) a sale or other disposition of all or substantially all of the
assets of Hybridon, or (3) any consolidation, merger, combination,
reorganization or other transaction in which Hybridon is not the surviving
entity or if stock constituting more than 50% of Hybridon's voting power is
exchanged for or changed into stock or securities of another entity, cash, or
any other property (a "Merger Transaction") (items (1), (2) and (3) of this
sentence being collectively referred to as a "Liquidation Event"), after payment
of debts and other liabilities of Hybridon, the holders of shares of convertible
preferred stock will be entitled to be paid out of Hybridon's available assets,
before any payment to holders of shares ranking junior to the convertible
preferred stock, an amount equal to the Dividend Base Amount. In the case of a
Merger Transaction, however, this payment may be made in cash, property or
securities of the entity surviving the Merger Transaction. If upon any
Liquidation Event, whether voluntary or involuntary, the assets to be
distributed to the holders of the convertible preferred stock are insufficient
to permit the payment to such shareholders of the full amount owed, then all of
Hybridon's available assets will be distributed ratably to the holders of the
convertible preferred stock. All shares of convertible preferred stock rank, as
to payment upon the occurrence of any Liquidation Event, senior to the common
stock and senior to all other series of preferred stock, unless the terms of any
Series provides otherwise.

Right of Conversion.  Commencing after May 5, 1999, shares of convertible
preferred stock became convertible, at the option of the holder, into shares of
common stock or other securities and property. The

55

61

initial conversion price per share of common stock (the "Conversion Price") is
$4.25, and is subject to adjustment as described below. The rate at which each
share of convertible preferred stock is convertible at any time into common
stock (the "Conversion Rate") will be determined by dividing the then-existing
Conversion Price into the "Dividend Base Amount" of a share of convertible
preferred stock, which is equal to $100 plus accrued but unpaid dividend,
subject to adjustment to reflect any stock split, combination, reclassification
or reorganization of the convertible preferred stock.

Adjustment of Conversion Rate and Conversion Price.  As of June 15, 1999,
each share of convertible preferred stock was convertible into approximately
23.53 shares of common stock. In order to preserve the economic value of shares
of convertible preferred stock, the Conversion Price will be adjusted if
Hybridon does the following;

- pays a dividend or makes a distribution on any class of capital stock in
shares of its common stock;

- subdivides its outstanding common stock into a greater number of shares;

- combines its outstanding common stock into a smaller number of shares;

- issues shares of common stock or preferred stock to any holder of common
stock or preferred stock rights to acquire shares of common stock or
preferred stock at a price per share less than the market price (as
defined);

- pays or distributes to the holders of common stock or preferred stock
assets, properties, or rights to acquire Hybridon Capital Stock at a
price per share less than the market price; or

- makes a distribution consistently solely of cash to the holders of any
class of capital stock where, during a specified 12-month period, the
cash distribution exceeds 10% of the product of the market price of the
common stock multiplied by the total outstanding common stock.

Exceptions to Adjustments.  No adjustment will, however, be made to either
the Conversion Rate or the Conversion Price for issuances of common stock or
preferred stock or cash paid to holders of shares of convertible preferred stock
(1) as payment for accrued dividends or (2) as a mandatory conversion or
mandatory redemption payment as described below.

Other Changes in Conversion Rate.  Hybridon from time to time may increase
the Conversion Rate by any amount for any period of time if the period is at
least 20 days and if the increase is irrevocable during the period. Whenever the
Conversion Rate is so increased, Hybridon will notify registered holders.

Hybridon may also increase the Conversion Rate in order to avoid or
diminish any income tax to holders of common stock resulting from any dividend
or distribution of stock or issuance of rights or warrants to purchase or
subscribe for stock or from any event treated as such for income tax purposes.

The Conversion Price may not be adjusted to an amount less than $.001 per
share, the current par value of the common stock into which the convertible
preferred stock is convertible.

Mandatory Conversion and Redemption.  Upon giving notice to the holders of
the convertible preferred stock, Hybridon may, at its option, cause the
convertible preferred stock to be converted in whole or in part, on a pro rata
basis, into shares of common stock using a Conversion Price equal to $4.00 if
the closing bid price of the common stock equals or exceeds 250% of the
Conversion Price for at least 20 trading days in any period of 30 consecutive
trading days.

At any time after April 1, 2000, Hybridon may, at its option, redeem the
convertible preferred stock for cash equal to the Dividend Base Amount.

Class Voting Rights.  Hybridon shall not, without the affirmative vote or
consent of the holders of at least 50% of all outstanding shares of convertible
preferred stock, voting separately as a class, (1) amend, alter or repeal any
provision of the restated certificate of incorporation or bylaws so as adversely
to affect the rights of the convertible preferred stock (except that the
issuance of securities ranking prior to, or pari passu with, the convertible
preferred stock (A) upon a Liquidation Event or (B) with respect to the payment
of dividends or distributions will not be considered to affect adversely the
relative rights of the convertible preferred stock), or (2) authorize or issue,
or increase the authorized amount of, the convertible preferred stock, other
than the convertible preferred stock issuable as dividends on the convertible
preferred stock.

56

62

Preemptive Rights.  The convertible preferred stock is not entitled to any
preemptive or subscription rights in respect of any securities of Hybridon.

Restrictions on Change of Control.  So long as any of Hybridon's 9% notes
remain outstanding, no holder of any shares of convertible preferred stock will,
without the prior written consent of Hybridon, be granted voting rights, be
entitled to receive any voting securities of Hybridon, or be entitled to
exercise any conversion rights if that could, in Hybridon's reasonable judgment,
either alone or in conjunction with other issuances or holdings of capital
stock, warrants or convertible securities of Hybridon, result in a Change of
Control (as defined in the Indenture).

TRANSFER AGENT AND REGISTRAR

The transfer agent and registrar for the capital stock is Mellon Investor
Services.

DELAWARE LAW AND CERTAIN PROVISIONS OF HYBRIDON'S RESTATED
CERTIFICATE OF INCORPORATION, BYLAWS AND INDEBTEDNESS

Hybridon is subject to the provisions of Section 203 of the Delaware
General Corporation Law, which prohibits a publicly-held Delaware corporation
from engaging in a "business combination" with an "interested stockholder" for a
period of three years after the date of the transaction in which the person
became an interested stockholder, unless the business combination is approved in
a prescribed manner. A "business combination" includes mergers, asset sales and
other transactions resulting in a financial benefit to the interested
stockholder. Subject to certain exceptions, an "interested stockholder" is a
person who, together with affiliates and associates, owns, or within three years
did own, 15% or more of the corporation's voting stock. The existence of this
provision could deter certain business combinations, including transactions that
might otherwise result in holders of voting stock being paid a premium over the
market price for their shares.

The restated certificate of incorporation provides for the division of the
board of directors into three classes as nearly equal in size as possible, with
the classes having staggered three-year terms. In addition, the restated
certificate of incorporation provides that directors may be removed only for
cause by the affirmative vote of the holders of at least two-thirds of the
shares of capital stock entitled to vote. Under the restated certificate of
incorporation, any vacancy on the board of directors, however occurring,
including a vacancy resulting from an enlargement of the board, may filled only
by vote of a majority of the directors then in office. The classification of the
board of directors and the limitations on the removal of directors and filling
of vacancies could have the effect of making it more difficult for anyone to
acquire, or of discouraging anyone from acquiring, control of Hybridon.

The restated certificate of incorporation also requires that any action
required or permitted to be taken by the stockholders of Hybridon at an annual
meeting or special meeting of stockholders may be taken only if it is properly
brought before that meeting and may not be taken by written action in lieu of a
meeting and will require reasonable advance notice by a stockholder of a
proposal or director nomination which that stockholder desires to present at any
annual or special meeting of stockholders. The restated certificate of
incorporation further provides that special meetings of the stockholders may be
called only by the Chief Executive Officer or, if none, the President of
Hybridon, or by the board of directors. Under Hybridon's bylaws, in order for
any matter to be considered "properly brought" before a meeting, a stockholder
must comply with certain requirements regarding advance notice to Hybridon. The
foregoing provisions could have the effect of delaying until the next
stockholders meeting any given stockholder action, even though it might be
favored by the holders of a majority of the outstanding voting securities of
Hybridon. These provisions may also discourage any person or entity from making
a tender offer for Shares of common stock, because such person or entity, even
if it acquired a majority of the outstanding voting securities of Hybridon,
would be able to take action as a stockholder only at a duly called stockholders
meeting, and not by written consent.

The Delaware General Corporation Law provides generally that the
affirmative vote of a majority of the shares entitled to vote on any matter is
required to amend a corporation's certificate of incorporation or bylaws, unless
a corporation's certificate of incorporation or by-law requires a greater
percentage. The restated certificate of incorporation and the bylaws require the
affirmative vote of the holders of at least 75% of the shares of capital stock
of Hybridon issued and outstanding and entitled to vote to amend or repeal any
of the
57

63

provisions described in the prior two paragraphs. Moreover, the board of
directors has the authority, without further action by the stockholders, to fix
the rights and preferences of, and to issue shares of, any preferred stock other
than the convertible preferred stock.

In addition to these provisions of Delaware law, the restated certificate
of incorporation and the bylaws, the terms of Hybridon's outstanding 9% notes,
which were issued in the aggregate original principal amount of $50.0 million
and of which approximately $1.3 million in principal amount remains outstanding,
require Hybridon, upon a Change of Control of Hybridon, as defined in the
indenture for the 9% notes, to offer to repurchase the 9% notes at a repurchase
price equal to 150% of the principal amount thereof, plus accrued and unpaid
interest to the date of repurchase. This provision, together with the provisions
of the restated certificate of incorporation described above and other
provisions of the restated certificate of incorporation, may have the effect of
deterring takeovers or delaying or preventing changes in control or management
of Hybridon, including transactions in which stockholders might otherwise
receive a premium for their shares over then current market prices. In addition,
these provisions may limit the ability of stockholders to approve transactions
that they may deem to be in their best interests.

PLAN OF DISTRIBUTION

The securities offered in this prospectus may be sold from time to time by
the selling stockholders or their pledgees, donees, transferees or other
successors in interest. Sales of the securities may be effected on the NASD OTC
Bulletin Board or in negotiated transactions at prices then prevailing or
related to the then-current market price, or at negotiated prices.

The securities may be sold directly or through brokers or dealers by means
of one or more of the following methods:

- block trades in which the broker or dealer attempts to sell shares as
agent but may position and resell a portion of the block as principal to
facilitate the transaction;

- purchases by a broker or dealer as principal and resales by that broker
or dealer for its own account pursuant to this prospectus, including
resale to another broker or dealer;

- ordinary brokerage transactions and transactions in which the broker
solicits purchasers.

In effecting sales, brokers and dealers engaged by selling stockholders may
arrange for other brokers or dealers to participate. Brokers or dealers may
receive commissions or discounts from selling stockholders or, if any such
broker or dealer acts as agent for the purchaser of any securities, from that
purchaser in amounts to be negotiated. A broker-dealer may agree with the
selling stockholders to sell a specified number of securities at a stipulated
price per share, and, to the extent that broker-dealer is unable to do so acting
as agent for the selling stockholders, to purchase as principal any unsold
securities at the price required to fulfill the broker-dealer commitment to the
selling stockholders. Broker-dealers who acquire securities as principal may
thereafter resell those securities.

The selling stockholders and any broker-dealers participating in
distribution of the securities may be deemed "underwriters" within the meaning
of Section 2(11) of the Securities Act, and any profit on the sale of securities
by the selling stockholders and any commissions or discounts given to
broker-dealers may be deemed underwriting commissions or discounts under the
Securities Act. In addition, any of the securities that qualify for sale
pursuant to Rule 144 may be sold under Rule 144 rather than pursuant to this
prospectus.

Hybridon has agreed to indemnify certain of the selling stockholders, each
underwriter of certain of the securities, and each person controlling certain of
the selling stockholders within the meaning of Section 15 of the Securities Act,
against certain liabilities in connection with the offer and sale of the
securities, including liabilities under the Securities Act, and to contribute to
payments those persons may be required to make in respect of such liabilities.
Certain of the selling stockholders have agreed to indemnify, in certain
circumstances, Hybridon against certain liabilities in connection with the offer
and sale of the securities, including liabilities under the Securities Act, and
to contribute to payments Hybridon may be required to make in respect thereof.

58

64

LEGAL MATTERS

The validity of the securities offered by this prospectus will be passed
upon for Holland & Knight, LLP, Boston, Massachusetts.

EXPERTS

The consolidated financial statements of Hybridon as of December 31, 1997,
1998, and 1999 and for each of the years in the three-year period ended December
31, 1999 included in this prospectus and elsewhere in the registration statement
have been audited by Arthur Andersen LLP, independent public accountants, as
indicated in their report with respect thereto, and are included herein in
reliance upon the authority of said firm as experts in accounting and auditing.

ADDITIONAL INFORMATION

We have filed a registration statement on Form S-1 with the Securities and
Exchange Commission relating to the common stock offered by this prospectus.
This prospectus does not contain all of the information set forth in the
registration statement and the exhibits and schedules to the registration
statement. Statements contained in this prospectus concerning the contents of
any contract or other document referred to are not necessarily complete and in
each instance we refer you to the copy of the contract or other document filed
as an exhibit to the registration statement, each such statement being qualified
in all respects by such reference.

For further information with respect to us and the common stock offered in
this prospectus, please refer to the registration statement. A copy of the
registration statement can be inspected by anyone without charge at the public
reference room of the SEC, Room 1024, 450 Fifth Street, N.W., Washington, D.C.
20549, and at the SEC's Regional Offices located at 7 World Trade Center, Suite
1300, New York, New York 10048, and 500 West Madison Street, Chicago, Illinois
60601. Please call the SEC at 1-800-SEC-0330 for further information on the
operation of the public reference room. Copies of these materials can be
obtained by mail from the Public Reference Section of the SEC at 450 Fifth
Street, N.W., Washington, D.C. 20549, at prescribed rates. The SEC maintains a
Web site (http://www.sec.gov) that contains information regarding registrants
that file electronically with the SEC.

59

65

HYBRIDON, INC. AND SUBSIDIARIES

INDEX TO CONSOLIDATED FINANCIAL STATEMENTS

INDEX

PAGE
----

REPORT OF INDEPENDENT PUBLIC ACCOUNTANTS....................   F-2
CONSOLIDATED BALANCE SHEETS.................................   F-3
CONSOLIDATED STATEMENTS OF OPERATIONS.......................   F-4
CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT)...   F-5
CONSOLIDATED STATEMENTS OF CASH FLOWS.......................   F-8
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS..................  F-10

F-1

66

REPORT OF INDEPENDENT PUBLIC ACCOUNTANTS

To Hybridon, Inc.:

We have audited the accompanying consolidated balance sheets of Hybridon,
Inc. (a Delaware corporation) and subsidiaries as of December 31, 1998 and 1999
and the related consolidated statements of operations, stockholders' equity
(deficit) and cash flows for each of the three years in the period ended
December 31, 1999. These consolidated financial statements are the
responsibility of Hybridon, Inc. and subsidiaries' management. Our
responsibility is to express an opinion on these financial statements based on
our audits.

We conducted our audits in accordance with auditing standards generally
accepted in the United States. Those standards require that we plan and perform
the audit to obtain reasonable assurance about whether the financial statements
are free of material misstatement. An audit includes examining, on a test basis,
evidence supporting the amounts and disclosures in the financial statements. An
audit also includes assessing the accounting principles used and significant
estimates made by management, as well as evaluating the overall financial
statement presentation. We believe that our audits provide a reasonable basis
for our opinion.

In our opinion, the financial statements referred to above present fairly,
in all material respects, the financial position of Hybridon, Inc. and
subsidiaries as of December 31, 1998 and 1999 and the results of their
operations and their cash flows for each of the three years in the period ended
December 31, 1999 in conformity with accounting principles generally accepted in
the United States.

/s/ ARTHUR ANDERSEN LLP

Boston, Massachusetts

February 25, 2000

(Except with respect to the matters discussed in Notes 1 and 15, as to which the
date is September 21, 2000)

F-2

67

HYBRIDON, INC. AND SUBSIDIARIES

CONSOLIDATED BALANCE SHEETS

DECEMBER 31,
-----------------------------   SEPTEMBER 30,
1998            1999            2000
-------------   -------------   -------------
(UNAUDITED)

ASSETS
CURRENT ASSETS:
Cash and cash equivalents.................................  $   5,607,882   $   2,551,671   $   5,236,326
Receivables...............................................        311,222         196,528              --
Prepaid expenses and other current assets.................        311,257         101,914          44,991
-------------   -------------   -------------
Total current assets...............................      6,230,361       2,850,113       5,281,317
-------------   -------------   -------------
PROPERTY AND EQUIPMENT, AT COST:
Leasehold improvements....................................        150,342         150,342         150,342
Laboratory equipment and other............................      6,693,478       5,249,621       5,200,727
-------------   -------------   -------------
6,843,820       5,399,963       5,351,069
Less -- Accumulated depreciation and amortization.........      6,287,291       5,229,514       5,285,197
-------------   -------------   -------------
556,529         170,449          65,872
-------------   -------------   -------------
OTHER ASSETS:
Deferred financing costs and other assets.................        522,374       1,325,149       1,083,109
Restricted cash...........................................             --              --       5,000,000
Note receivable from officer..............................        258,650         270,050              --
-------------   -------------   -------------
781,024       1,595,199       6,083,109
-------------   -------------   -------------
NET ASSETS FROM DISCONTINUED OPERATIONS.....................      7,523,687       6,101,518              --
-------------   -------------   -------------
$  15,091,601   $  10,717,279   $  11,430,298
=============   =============   =============

LIABILITIES AND STOCKHOLDERS' EQUITY (DEFICIT)
CURRENT LIABILITIES:
Current portion of long-term debt.........................  $   6,000,000   $   6,000,000   $   6,000,000
Accounts payable..........................................      1,927,290       1,263,943         793,290
Accrued expenses..........................................      3,609,533       2,119,864       1,740,946
-------------   -------------   -------------
Total current liabilities..........................     11,536,823       9,383,807       8,534,236
-------------   -------------   -------------
LINE OF CREDIT..............................................             --              --         231,167
-------------   -------------   -------------
9% CONVERTIBLE SUBORDINATED NOTES PAYABLE...................      1,306,000       1,306,000       1,306,000
-------------   -------------   -------------
8% CONVERTIBLE SUBORDINATED NOTES PAYABLE...................             --       6,099,775       7,736,943
-------------   -------------   -------------
COMMITMENTS AND CONTINGENCIES (Notes 7 and 11)
STOCKHOLDERS' EQUITY (DEFICIT):
Preferred stock, $0.01 par value --
Authorized -- 5,000,000 shares
Series A convertible preferred stock --
Designated -- 1,500,000 shares
Issued and outstanding -- 641,259, 661,856 and 612,115
shares at December 31, 1998 and 1999, and September
30, 2000, respectively (Liquidation preference of
$64,820,459 at September 30, 2000).................          6,413           6,618           6,121
Common stock, $0.001 par value --
Authorized -- 100,000,000 shares
Issued and outstanding -- 15,304,825, 16,260,722 and
17,924,949 shares at December 31, 1998 and 1999, and
September 30, 2000, respectively......................         15,305          16,261          17,925
Additional paid-in capital................................    241,632,024     247,813,331     251,769,929
Accumulated deficit.......................................   (238,447,837)   (253,183,130)   (257,781,132)
Deferred compensation.....................................       (957,127)       (725,383)       (390,891)
-------------   -------------   -------------
Total stockholders' equity (deficit)...............      2,248,778      (6,072,303)     (6,378,048)
-------------   -------------   -------------
$  15,091,601   $  10,717,279   $  11,430,298
=============   =============   =============

The accompanying notes are an integral part of these consolidated financial
statements.
F-3

68

HYBRIDON, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF OPERATIONS

YEARS ENDED                       NINE MONTHS ENDED
DECEMBER 31,                        SEPTEMBER 30,
------------------------------------------   --------------------------
1997           1998           1999           1999          2000
------------   ------------   ------------   ------------   -----------
(UNAUDITED)
(IN THOUSANDS, EXCEPT PER SHARE DATA)

REVENUES:
Service revenue.....................  $         --   $    375,000   $    365,000   $    295,000   $    70,000
Research and development............       945,000      1,099,915        600,000        450,000            --
Royalty and other income............            --             --        122,544        106,950        76,529
Interest income.....................     1,079,122        148,067         92,202         81,724        66,012
------------   ------------   ------------   ------------   -----------
Total revenues...............     2,024,122      1,622,982      1,179,746        933,674       212,541
------------   ------------   ------------   ------------   -----------
OPERATING EXPENSES:
Research and development............    35,326,230     14,182,952      5,783,092      4,524,896     2,793,949
General and administrative..........    11,026,748      6,572,502      3,663,811      2,946,564     2,339,897
Interest............................     4,277,882      2,819,659        683,134        511,131     1,856,677
Restructuring.......................    10,345,464             --             --             --            --
------------   ------------   ------------   ------------   -----------
Total operating expenses..........    60,976,324     23,575,113     10,130,037      7,982,591     6,990,523
------------   ------------   ------------   ------------   -----------
Loss from continuing
operations.................   (58,952,202)   (21,952,131)    (8,950,291)    (7,048,917)   (6,777,982)
------------   ------------   ------------   ------------   -----------
Income (loss) from
discontinued operations....   (10,509,124)    (4,028,242)    (1,552,751)    (1,283,539)    5,292,154
------------   ------------   ------------   ------------   -----------
LOSS BEFORE EXTRAORDINARY GAIN........   (69,461,326)   (25,980,373)   (10,503,042)    (8,332,456)   (1,485,828)
------------   ------------   ------------   ------------   -----------
EXTRAORDINARY ITEM:
Gain on conversion of 9% convertible
Subordinated notes payable........            --      8,876,685             --             --            --
------------   ------------   ------------   ------------   -----------
NET LOSS..............................   (69,461,326)   (17,103,688)   (10,503,042)    (8,332,456)   (1,485,828)
ACCRETION OF PREFERRED STOCK
DIVIDEND............................                   (2,689,048)    (4,232,251)    (3,193,851)   (3,112,174)
------------   ------------   ------------   ------------   -----------
NET LOSS TO COMMON STOCKHOLDERS.......  $(69,461,326)  $(19,792,736)  $(14,735,293)  $(11,526,307)  $(4,598,002)
============   ============   ============   ============   ===========
BASIC AND DILUTED NET LOSS PER COMMON
SHARE FROM:
Continuing operations...............  $     (11.67)  $      (1.85)  $      (0.57)  $      (0.45)  $     (0.40)
Discontinued operations.............         (2.08)         (0.34)         (0.10)         (0.08)         0.31
Extraordinary gain..................            --           0.75             --             --            --
------------   ------------   ------------   ------------   -----------
Net loss per share..................        (13.76)         (1.44)         (0.66)         (0.53)        (0.09)
Accretion of preferred stock
dividends.........................            --          (0.23)         (0.27)         (0.20)        (0.18)
------------   ------------   ------------   ------------   -----------
Net loss per share applicable to
common Stockholders...............  $     (13.76)  $      (1.67)  $      (0.93)  $      (0.74)  $     (0.27)
============   ============   ============   ============   ===========
SHARES USED IN COMPUTING BASIC AND
DILUTED NET LOSS PER COMMON SHARE...     5,049,840     11,859,350     15,810,664     15,653,562    17,130,454
============   ============   ============   ============   ===========

The accompanying notes are an integral part of these consolidated financial
statements.

F-4

69

HYBRIDON, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT)

CONVERTIBLE           SERIES A CONVERTIBLE
PREFERRED STOCK           PREFERRED STOCK
----------------------    ----------------------
NUMBER OF    $0.01 PAR    NUMBER OF    $0.01 PAR
SHARES        VALUE       SHARES        VALUE
---------    ---------    ---------    ---------

BALANCE, DECEMBER 31, 1996................................     $--          --              --      $   --
Issuance of common stock related to the exercise of
stock options.........................................     --           --              --          --
Issuance of common stock related to the exercise of
warrants..............................................     --           --              --          --
Issuance of common stock for services rendered..........     --           --              --          --
Deferred compensation related to grants of stock options
to nonemployees.......................................     --           --              --          --
Amortization of deferred compensation...................     --           --              --          --
Net loss................................................     --           --              --          --
--            --        -------      ------
BALANCE, DECEMBER 31, 1997................................     --           --              --          --
Issuance of Series A convertible preferred stock and
attached warrants in exchange for conversion of 9%
convertible subordinated notes payable and accrued
interest, net of issuance costs of $1,195,398.........     --           --         510,504       5,105
Issuance of common stock and attached warrants in
exchange for conversion of accounts payable and other
obligations...........................................     --           --              --          --
Issuance of Series A convertible preferred stock........     --           --         114,285       1,143
Issuance of common stock to placement agent.............     --           --              --          --
Issuance of common stock and attached warrants in
exchange for conversion of convertible notes payable,
net of issuance cost of $566,167......................     --           --              --          --
Issuance of common stock and attached warrants, net of
issuance costs of $1,069,970..........................     --           --              --          --
Issuance of common stock for services rendered..........     --           --              --          --
Deferred compensation related to grants of stock options
to nonemployees, net of terminations..................     --           --              --          --
Issuance of warrants in connection with notes payable...     --           --              --          --
Accretion and issuance of Series A convertible preferred
stock dividends.......................................     --           --          16,470         165
Amortization of deferred compensation...................     --           --              --          --
Net loss................................................     --           --              --          --
--            --        -------      ------
BALANCE, DECEMBER 31, 1998................................     --           --         641,259       6,413
Issuance of common stock to placement agents............     --           --              --          --
Conversion of Series A convertible preferred stock into
common stock..........................................     --           --         (21,076)       (211)
Issuance of warrants in connection with notes payable...     --           --              --          --
Accretion and issuance of Series A convertible preferred
stock dividends.......................................     --           --          41,673         416
Fair value of stock options to nonemployees.............     --           --              --          --
Amortization of deferred compensation...................     --           --              --          --
Net loss................................................     --           --              --          --
--            --        -------      ------
BALANCE, DECEMBER 31, 1999................................     --           --         661,856       6,618
Exercise of common stock options........................     --           --              --          --
Retirement of common stock..............................     --           --              --          --
Accretion and issuance of Series A convertible preferred
stock dividends.......................................     --           --          21,468         215
Issuance of warrants in connection with line of
credit................................................     --           --              --          --
Conversion of Series A convertible preferred stock into
common stock..........................................     --           --         (71,209)       (712)
Amortization of deferred compensation...................     --           --              --          --
Net loss................................................     --           --              --          --
--            --        -------      ------
BALANCE, SEPTEMBER 30, 2000...............................     $--          --         612,115      $6,121
==            ==        =======      ======

The accompanying notes are an integral part of these consolidated financial
statements.

F-5

70

HYBRIDON, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT)

COMMON STOCK                                                          TOTAL
-----------------------    ADDITIONAL                                   STOCKHOLDERS
NUMBER OF    $0.001 PAR     PAID-IN       ACCUMULATED      DEFERRED        EQUITY
SHARES       VALUE        CAPITAL         DEFICIT      COMPENSATION    (DEFICIT)
----------   ----------   ------------   -------------   ------------   ------------

BALANCE, DECEMBER 31,
1996......................   5,029,315    $ 5,029     $173,247,476   $(149,193,775)  $(1,203,926)   $ 22,854,804
Issuance of common stock
related to the exercise
of stock options........      25,005         26           86,300              --            --          86,326
Issuance of common stock
related to the exercise
of warrants.............         330         --            9,075              --            --           9,075
Issuance of common stock
for services rendered...       5,000          5          146,869              --            --         146,874
Deferred compensation
related to grants of
stock options to
nonemployees............          --         --          205,978              --      (205,978)             --
Amortization of deferred
compensation............          --         --               --              --       316,067         316,067
Net loss..................          --         --               --     (69,461,326)           --     (69,461,326)
----------    -------     ------------   -------------   -----------    ------------
BALANCE, DECEMBER 31,
1997......................   5,059,650      5,060      173,695,698    (218,655,101)   (1,093,837)    (46,048,180)
Issuance of Series A
convertible preferred
stock and attached
warrants in exchange for
conversion of 9%
convertible subordinated
notes payable and
accrued interest, net of
issuance costs of
$1,195,398..............          --         --       38,729,489              --            --      38,734,594
Issuance of common stock
and attached warrants in
exchange for conversion
of accounts payable and
other obligations.......   3,217,154      3,217        5,931,341              --            --       5,934,558
Issuance of Series A
convertible preferred
stock...................          --         --        7,998,817              --            --       7,999,960
Issuance of common stock
to placement agent......     597,699        598        1,194,800              --            --       1,195,398
Issuance of common stock
and attached warrants in
exchange for conversion
of convertible notes
payable, net of issuance
cost of $566,167........   3,157,322      3,157        4,230,676              --            --       4,233,833
Issuance of common stock
and attached warrants,
net of issuance costs of
$1,069,970..............   3,223,000      3,223        6,873,453              --            --       6,876,676
Issuance of common stock
for services rendered...      50,000         50           93,700              --            --          93,750
Deferred compensation
related to grants of
stock options to
nonemployees, net of
terminations............          --         --          109,734              --      (109,734)             --
Issuance of warrants in
connection with notes
payable.................          --         --           85,433              --            --          85,433

F-6

71

HYBRIDON, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) -- (CONTINUED)

COMMON STOCK                                                          TOTAL
-----------------------    ADDITIONAL                                   STOCKHOLDERS
NUMBER OF    $0.001 PAR     PAID-IN       ACCUMULATED      DEFERRED        EQUITY
SHARES       VALUE        CAPITAL         DEFICIT      COMPENSATION    (DEFICIT)
----------   ----------   ------------   -------------   ------------   ------------

Accretion and issuance of
Series A convertible
preferred stock
dividends...............          --         --        2,688,883      (2,689,048)           --              --
Amortization of deferred
compensation............          --         --               --              --       246,444         246,444
Net loss..................          --         --               --     (17,103,688)           --     (17,103,688)
----------    -------     ------------   -------------   -----------    ------------
BALANCE, DECEMBER 31,
1998......................  15,304,825     15,305      241,632,024    (238,447,837)     (957,127)      2,248,778
Issuance of common stock
to placement agents.....     460,000        460          999,540              --            --       1,000,000
Conversion of Series A
convertible preferred
stock into common
stock...................     495,897        496             (285)             --            --              --
Issuance of warrants in
connection with notes
payable.................          --         --          547,328              --            --         547,328
Accretion and issuance of
Series A convertible
preferred stock
dividends...............          --         --        4,231,835      (4,232,251)           --              --
Fair value of stock
options to
nonemployees............          --         --          402,889              --            --         402,889
Amortization of deferred
compensation............          --         --               --              --       231,744         231,744
Net loss..................          --         --               --     (10,503,042)           --     (10,503,042)
----------    -------     ------------   -------------   -----------    ------------
BALANCE, DECEMBER 31,
1999......................  16,260,722     16,261      247,813,331    (253,183,130)     (725,383)     (6,072,303)
Exercise of common stock
options (unaudited).....     229,407        230          114,475              --            --         114,705
Retirement of common stock
(unaudited).............    (250,000)      (250)              --              --            --            (250)
Accretion and issuance of
Series A convertible
preferred stock
dividends (unaudited)...          --         --        3,111,959      (3,112,174)           --              --
Issuance of warrants in
connection with line of
credit (unaudited)......          --         --          731,136              --            --         731,136
Conversion of Series A
convertible preferred
stock into common stock
(unaudited).............   1,684,820      1,684             (972)             --            --              --
Amortization of deferred
compensation
(unaudited).............          --         --               --              --       334,492         334,492
Net loss (unaudited)......          --         --               --      (1,485,828)           --      (1,485,828)
----------    -------     ------------   -------------   -----------    ------------
BALANCE, SEPTEMBER 30, 2000
(UNAUDITED)...............  17,924,949    $17,925     $251,769,929   $(257,781,132)  $  (390,891)   $ (6,378,048)
==========    =======     ============   =============   ===========    ============

The accompanying notes are an integral part of these consolidated financial
statements.
F-7

72

HYBRIDON, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF CASH FLOWS

NINE MONTHS ENDED
YEARS ENDED DECEMBER 31,                  SEPTEMBER 30,
------------------------------------------   -------------------------
1997           1998           1999          1999          2000
------------   ------------   ------------   -----------   -----------
(UNAUDITED)

CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss.............................  $(69,461,326)  $(17,103,688)  $(10,503,042)  $(8,332,456)  $(1,485,828)
Income (loss) from discontinued
operations.........................   (10,509,124)    (4,028,242)    (1,552,751)   (1,283,539)    5,292,154
------------   ------------   ------------   -----------   -----------
Loss from continuing operations......   (58,952,202)   (13,075,446)    (8,950,291)   (7,048,917)   (6,777,982)
Adjustments to reconcile net loss to
net cash used in operating
activities --
Extraordinary gain on exchange of
9% convertible subordinated notes
payable..........................            --     (8,876,685)            --            --            --
Depreciation and amortization......     1,937,793      2,120,212        394,381       353,576       104,636
Amortization of deferred
compensation.....................       316,067        246,444        634,633       576,697       334,492
Amortization of deferred financing
costs............................       479,737        160,813        123,140        80,951       343,442
Interest expenses related to the
issuance of common stock
warrants.........................            --             --             --            --       731,136
Non cash interest expense..........            --             --         65,485            --       151,077
Issuance of common stock for
services rendered................       146,874         93,750             --            --            --
Write down of assets related to
restructuring charge.............     1,255,000             --             --            --            --
Changes in operating assets and
liabilities -
Accounts receivable..............            --       (511,652)       114,694       122,028       196,528
Prepaid expenses and other
current assets................       539,499        894,998        209,341       209,073        56,923
Note receivable from officer.....        70,728        (11,400)       (11,400)       (8,550)           --
Accounts payable and accrued
expenses......................     9,800,635       (276,463)    (1,153,013)     (824,600)     (579,832)
Deferred revenue.................       (86,250)            --             --            --            --
------------   ------------   ------------   -----------   -----------
Net cash used in continuing
operating activities........   (44,492,119)   (19,235,429)    (8,573,030)   (6,539,742)   (5,439,580)
------------   ------------   ------------   -----------   -----------
Net cash provided by (used in)
discontinued operations.....    (9,129,580)    (4,090,858)      (130,581)      440,341      (156,326)
------------   ------------   ------------   -----------   -----------
CASH FLOWS FROM INVESTING ACTIVITIES:
Increase in other assets.............     3,785,146             --             --            --      (101,401)
Proceeds from sale of discontinued
operations.........................            --             --             --            --    11,550,000
Purchases of property and
equipment..........................    (4,944,425)       114,576         (8,303)       (8,302)           --
Proceeds from sale of property and
equipment..........................            --        714,400             --            --            --
Proceeds from sale of real estate
partnership........................            --      5,450,000             --            --            --
------------   ------------   ------------   -----------   -----------
Net cash (used in) provided by
investing activities........    (1,159,279)     6,278,976         (8,303)       (8,302)   11,448,599
------------   ------------   ------------   -----------   -----------

F-8

73

NINE MONTHS ENDED
YEARS ENDED DECEMBER 31,                  SEPTEMBER 30,
------------------------------------------   -------------------------
1997           1998           1999          1999          2000
------------   ------------   ------------   -----------   -----------
(UNAUDITED)

CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from issuance of Series
A convertible preferred stock......            --      7,999,960             --            --            --
Net proceeds from issuance of common
stock..............................        86,326      6,876,676             --            --       114,705
Net borrowings under line of
credit.............................            --             --             --            --       231,167
Proceeds from notes payable..........            --      6,000,000             --            --            --
Proceeds from issuance of convertible
promissory notes payable...........            --             --             --            --     1,486,090
Proceeds from issuance of convertible
notes payable and warrants.........    50,000,000      4,233,833      4,534,290            --            --

Proceeds from related party notes
payable............................            --             --      1,500,000     1,000,000            --
Proceeds from issuance of common
stock related to stock warrants....         9,075             --             --            --            --
Proceeds from sale/leaseback of fixed
assets.............................       632,426             --             --            --            --
Payments on long-term debt...........    (1,082,651)    (7,234,300)            --            --            --
Increase in deferred financing
costs..............................    (2,820,790)      (400,000)      (378,587)           --            --
(Increase) decrease in restricted
cash and other assets..............    (2,474,948)     2,976,822             --            --    (5,000,000)
------------   ------------   ------------   -----------   -----------
Net cash provided by (used in)
financing activities........    44,349,438     20,452,991      5,655,703     1,000,000    (3,168,038)
------------   ------------   ------------   -----------   -----------
NET (DECREASE) INCREASE IN CASH AND
CASH EQUIVALENTS.....................   (10,431,540)     3,405,680     (3,056,211)   (5,107,703)    2,684,655
CASH AND CASH EQUIVALENTS, BEGINNING OF
PERIOD...............................    12,633,742      2,202,202      5,607,882     5,607,882     2,551,671
------------   ------------   ------------   -----------   -----------
CASH AND CASH EQUIVALENTS, END OF
PERIOD...............................  $  2,202,202   $  5,607,882   $  2,551,671   $   500,179   $ 5,236,326
============   ============   ============   ===========   ===========

The accompanying notes are an integral part of these consolidated financial
statements.
F-9

74

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(1) ORGANIZATION

Hybridon, Inc. (the Company) was incorporated in the State of Delaware on
May 25, 1989. The Company is engaged in the discovery and development of novel
genetic medicines based primarily on antisense technology.

Since inception, the Company has been engaged primarily in research and
development efforts, development of its manufacturing capabilities and
organizational efforts, including recruiting of scientific and management
personnel and raising capital. To date, the Company has not received revenue
from the sale of biopharmaceutical products developed by it based on antisense
technology. In order to commercialize its own products, the Company will need to
address a number of technological challenges and comply with comprehensive
regulatory requirements. Accordingly, it is not possible to predict the amount
of funds that will be required or the length of time that will pass before the
Company receives revenues from sales of any of these products. All revenues
received by the Company to date have been derived from collaboration and
licensing agreements, interest on investment funds and revenues from the custom
contract manufacturing of synthetic DNA and reagent products by the Company's
Hybridon Specialty Products business prior to the disposal thereof.

On September 21, 2000, the Company completed the sale (see Note 15) of its
Hybridon Specialty Products business to a subsidiary of Avecia, Inc. of
Manchester, United Kingdom, for up to $15.0 million (the Asset Sale).

On May 30, 2000, the Company entered into a Line of Credit (LOC) Agreement
(see Note 16(g)) pursuant to which certain lenders (the LOC Lenders) agreed to
provide the Company with an 8%, $2.0 million credit facility (the line of credit
or LOC), which provided the Company with working capital pending the closing of
the Asset Sale. On July 10, 2000 and August 10, 2000, the Company drew down
approximately $0.5 million each under the LOC, representing a total draw down of
$1.0 million. On September 28, 2000, the Company repaid approximately $0.8
million in cash and converted the remaining amount, approximately $0.2 million,
to common stock in October 2000.

The Company's existing cash resources are expected to be sufficient to
operate into the third quarter of 2001, at which time it expects to collect the
second installment of the proceeds from the Asset Sale in the amount of $3.0
million, which should enable it to sustain its operations through the year 2001.
The Company will be required to raise substantial additional funds from external
sources to support its operations in 2002 and beyond.

(2) SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

(a) Unaudited Interim Financial Statements

The unaudited interim financial statements included herein have been
prepared by the Company, without audit, pursuant to the rules and regulations of
the Securities and Exchange Commission and include, in the opinion of
management, all adjustments, consisting of normal, recurring adjustments,
necessary for a fair presentation of interim period results. The results for the
interim periods presented are not necessarily indicative of results to be
expected for the full fiscal year.

(b) Management Estimates and Uncertainties

The preparation of financial statements in conformity with generally
accepted accounting principles requires management to make estimates and
assumptions that affect the reported amounts of assets and liabilities and
disclosure of contingent assets and liabilities at the date of the financial
statements and the reported amounts of revenues and expenses during the
reporting period. Actual results could differ from those estimates.

F-10

75
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)

The Company is subject to a number of risks and uncertainties similar to
those of other companies of the same size within the biotechnology industry,
such as uncertainty with clinical trials, uncertainty of additional funding and
history of operating losses.

(c) Principles of Consolidation

The accompanying consolidated financial statements include the results of
the Company and its subsidiaries: Hybridon S.A. (Europe), a French corporation
and Hybridon Canada, Inc., an inactive majority-owned subsidiary. The
consolidated financial statements also reflect the Company's approximately 22%
interest in MethylGene, Inc. (MethylGene) and the Company's approximately 28%
interest in OriGenix Technologies Inc. (OriGenix), both Canadian corporations
that are accounted for under the equity method (see Notes 8 and 9,
respectively). All material intercompany balances and transactions have been
eliminated in consolidation.

(d) Cash Equivalents

The Company considers all highly liquid investments with maturities of 90
days or less when purchased to be cash equivalents. Cash and cash equivalents at
December 31, 1998 and 1999 and September 30, 2000 consist of the following (at
amortized cost, which approximates fair market value):

DECEMBER 31
------------------------    SEPTEMBER 30
1998          1999           2000
----------    ----------    ------------

Cash and cash equivalents --
Cash and money market funds.................  $3,865,365    $  505,794    $ 4,723,160
Corporate bond*.............................   1,742,517     2,045,877      5,513,166
----------    ----------    -----------
Total cash and cash equivalents.....  $5,607,882    $2,551,671    $10,236,326
==========    ==========    ===========

---------------

*Includes restricted cash of $5,000,000 at September 30, 2000 (See Note 5(f))

(e) Depreciation and Amortization

Depreciation and amortization are computed using the straight-line method
based on the estimated useful lives of the related assets as follows:

ESTIMATED
ASSET CLASSIFICATION                                           USEFUL LIFE
--------------------                                          -------------

Leasehold improvements......................................  Life of lease
Laboratory equipment and other..............................    3-5 years

F-11

76
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)

(f) Accrued Expenses

At December 31, 1998 and 1999 and September 30, 2000, accrued expenses
consist of the following:

DECEMBER 31
------------------------    SEPTEMBER 30
1998          1999           2000
----------    ----------    ------------

Restructuring (Note 3)........................  $  469,485    $       --     $       --
Interest......................................      29,385        25,496        368,248
Payroll and related costs.....................     725,532       552,710        249,834
Outside research and clinical costs...........     797,593       452,633         54,450
Professional fees.............................     149,957       150,000        125,000
Contingent stock (Notes 5(a) and 10(b)).......   1,000,000            --             --
Other.........................................     437,581       939,025        943,414
----------    ----------     ----------
$3,609,533    $2,119,864     $1,740,946
==========    ==========     ==========

(g) Reclassifications

Certain amounts in the prior-period consolidated financial statements have
been reclassified to conform to the current period's presentation.

(h) Revenue Recognition

The Company has recorded revenue under the consulting and research
agreements discussed in Notes 6 and 8. Revenue is recognized as earned on the
straight-line basis over the term of the agreement, which approximates when work
is performed and costs are incurred. Revenues from service sales are recognized
when the services are performed.

(i) Research and Development Expenses

The Company charges research and development expenses to operations as
incurred.

(j) Patent Costs

The Company charges patent expenses to operations as incurred.

(k) Comprehensive Loss

The Company applies Statement of Financial Accounting Standards (SFAS) No.
130, Reporting Comprehensive Income. Comprehensive loss is defined as the change
in equity of a business enterprise during a period from transactions and other
events and circumstances from nonowner sources. The Company's comprehensive loss
is the same as the reported net loss for all periods presented.

(l) Net Loss per Common Share

The Company applies SFAS No 128, Earnings per Share. Under SFAS No. 128,
basic net loss per common share is computed using the weighted average number of
shares of common stock outstanding during the period. Diluted net loss per
common share is the same as basic net loss per common share as the effects of
the Company's potential common stock equivalents are antidilutive. Antidilutive
securities, which consist of stock options, warrants and convertible preferred
stock and convertible debt instruments (on an as-converted basis) that are not
included in diluted net loss per common share were 2,404,561, 27,774,883,
32,854,153 and 49,787,247 for 1997, 1998, 1999, and the nine months ended
September 30, 2000, respectively.

F-12

77
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)

(m) Segment Reporting

The Company applies SFAS No. 131, Disclosures About Segments of an
Enterprise and Related Information. SFAS No. 131 establishes standards for
reporting information regarding operating segments in annual financial
statements and requires selected information for those segments to be presented
in interim financial reports issued to stockholders. SFAS No. 131 also
establishes standards for related disclosures about products and services and
geographic areas. To date, the Company has viewed its operations and manages its
business as principally one operating segment. As a result, the financial
information disclosed herein represents all of the material financial
information related to the Company's principal operating segment. All of the
Company's revenues are generated in the United States and substantially all
assets are located in the United States.

(n) New Accounting Pronouncement

In March 1999, the Financial Accounting Standards Board (FASB) issued a
proposed interpretation, Accounting for Certain Transactions Involving Stock
Compensation -- An Interpretation of APB Opinion No. 25 (the Proposed
Interpretation). The Proposed Interpretation would clarify the application of
Accounting Principles Board (APB) Opinion No. 25, Accounting for Stock Issued to
Employees, in certain situations, as defined. The Proposed Interpretation would
be effective upon issuance (expected to be in early 2000) but would cover
certain events that occur after December 15, 1998. To the extent that events
covered by this Proposed Interpretation occur during the period after December
15, 1998, but before issuance of the final interpretation, the effects of
applying this Proposed Interpretation would be recognized on a prospective basis
from the effective date. Accordingly, upon initial application of the final
interpretation, (a) no adjustments would be made to financial statements for
periods before the effective date and (b) no expense would be recognized for any
additional compensation cost measured that is attributable to periods before the
effective date. The adoption of the Proposed Interpretation will affect the
accounting for stock options repriced during fiscal year 1999 (see Note 10(f)).

The Securities and Exchange Commission issued Staff Accounting Bulletin
(SAB) No. 101, Revenue Recognition, in December 1999. The Company is required to
adopt this new accounting guidance through a cumulative charge to operations, in
accordance with APB Opinion No. 20, Accounting Changes, no later than the second
quarter of fiscal 2000. The Company believes that the adoption of the guidance
provided in SAB No. 101 will not have a material impact on future operating
results.

(3) RESTRUCTURING

Beginning in July 1997, the Company implemented a restructuring plan to
reduce expenditures on a phased basis in an effort to conserve its cash
resources. As part of this restructuring plan, in addition to terminating the
clinical development of GEM 91, the Company's first generation antisense drug
for the treatment of AIDS and HIV infection, the Company reduced or suspended
selected programs unrelated to its four core advanced chemistry antisense drug
research development programs. In connection with the reduction in programs, the
Company accrued termination fees related to research contracts and wrote off
assets related to programs that were suspended or canceled. As part of the
restructuring, all outside testing, public relations, travel and entertainment
and consulting arrangements were reviewed and where appropriate the terms were
renegotiated, contracts cancelled or the terms were significantly reduced. As a
result of the implementation of these changes, the Company terminated the
employment of 84 employees, of which 50 were related to the Company's continuing
operations, at its Massachusetts facilities since July 1997. The Company also
closed its operations in Paris, France, and terminated 11 employees at that
location.

In connection with the restructuring, the Company entered into different
subleasing arrangements. During 1997, the Company subleased substantial portions
of each of its facilities in Cambridge, Massachusetts (including a portion of
its former headquarters located at 620 Memorial Drive, the Cambridge Lease). The
Company incurred expenses relating to these subleases for broker fees and
renovation expenses incurred in

F-13

78
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)

preparing the Cambridge Lease space for the new tenant. In addition, the Company
accrued the estimated lease loss of subleasing the Cambridge Lease, which were
vacated during 1998. The Company also subleased its office in Paris, France, and
accrued the estimated lease loss.

The following are the significant components of the $10,345,000 charge for
restructuring (in thousands) relating to the Company's continuing operations:

RESTRUCTURING
CHARGE
-------------

Estimated loss on facility leases...........................       $ 6,372
Employee severance, benefits and related costs..............         2,063
Write-down of assets to net realizable value................           946
Termination costs of certain development programs...........           964
-------
$10,345
=======

The total cash impact of the restructuring was approximately $4,490,000,
and was paid as of December 31, 1999.

(4) NOTE RECEIVABLE FROM OFFICER

At December 31, 1998 and 1999, the Company has a note receivable and
accrued interest from an officer, of $258,650 and $270,050, respectively. The
note has an interest rate of 6.0% per annum and matures in April 2001.

(5) LONG-TERM DEBT

(a) Note Payable

During November 1998, the Company entered into a $6,000,000 note payable
with Forum Capital Markets, LLC (currently Founders Financial Group,
L.P.)(Founders) and certain investors associated with Pecks Management Partners
Ltd. (collectively, the Lenders). The terms of the note payable are as follows:
(i) the maturity is November 30, 2003; (ii) the interest rate is 8%; (iii)
interest is payable monthly in arrears, with the principal due in full at
maturity of the loan; (iv) the note payable is convertible, at the Lender's
option, in whole or in part, into shares of common stock at a conversion price
equal to $2.40 per share; (v) the note includes a minimum liquidity, as defined,
covenant of $2,000,000 and (vi) the note payable may not be prepaid, in whole or
in part, at any time prior to December 1, 2000. On December 1, 1999, the Company
received a waiver for noncompliance with the minimum tangible net worth covenant
effective December 31, 1999. In addition, the Lenders also agreed to waive
compliance with all covenants for the period January 1, 2000 through March 31,
2000. The Company has received additional waivers for non-compliance with these
same covenants for the period from September 30, 2000 to December 31, 2000. The
Company has classified the outstanding balance of $6,000,000 at December 31,
1999 and September 30, 2000 as a current liability in the accompanying
consolidated balance sheets as it does not currently have the financing to
remain in compliance with the financial covenants. In connection with the
issuance of the note payable, Forum received $400,000, which was reinvested by
Founders to purchase 160,000 shares of common stock with 40,000 attached
warrants at an exercise price of $3.00 per share. The Company has recorded the
$400,000 as a deferred financing cost, which will be amortized to interest
expense over the term of the note. In addition, Forum received warrants to
purchase 133,333 shares of common stock of the Company at $3.00 per share. The
Company computed the value of the warrants to be $85,433, by using the
Black-Scholes option pricing model. The Company has recorded this $85,433 as a
deferred financing cost, which will be amortized to interest expense over the
term of the note.

F-14

79
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)

(b) Capital Lease Obligations

The Company had entered into various capital leases for equipment. During
1998, the Company settled its capital lease obligations in full through the
issuance of common stock and warrants (see Note 10(b)).

(c) 9% Convertible Subordinated Notes Payable

On April 2, 1997, the Company issued $50,000,000 of 9% convertible
subordinated notes Payable (9% Notes). Under the terms of the 9% Notes, the
Company must make semiannual interest payments on the outstanding principal
balance through the maturity date of April 1, 2004. If the 9% Notes are
converted prior to April 1, 2000, the noteholders are entitled to receive
accrued interest from the date of the most recent interest payment through the
conversion date. The 9% Notes are subordinate to substantially all of the
Company's existing indebtedness. The 9% Notes are convertible at any time prior
to the maturity date at a conversion price equal to $35.0625 per share, subject
to adjustment under certain circumstances, as defined.

Beginning April 1, 2000, the Company may redeem the 9% Notes at its option
for a 4.5% premium over the original issuance price provided that from April 1,
2000 to March 31, 2001, the 9% Notes may not be redeemed unless the closing
price of the common stock equals or exceeds 150% of the conversion price for a
period of at least 20 out of 30 consecutive trading days and the 9% Notes are
redeemed within 60 days after such trading period. The premium decreases by 1.5%
each year through March 31, 2003. Upon a change of control of the Company, as
defined, the Company will be required to offer to repurchase the 9% Notes at
150% of the original issuance price.

On May 5, 1998, holders of $48,694,000 of principal and $2,361,850 of
accrued interest tendered such principal and accrued interest on the 9% Notes to
the Company for 510,505 shares of Series A convertible preferred stock and
warrants to purchase 3,002,958 shares of common stock with an exercise price of
$4.25 per share. In accordance with SFAS No. 15, Accounting by Debtors and
Creditors for Troubled Debt Restructurings, the Company recorded an
extraordinary gain of $8,876,685 related to the exchange. The extraordinary gain
represents the difference between the carrying value of the 9% Notes plus
accrued interest, less $2,249,173 of deferred financing costs written off, and
the fair value of the Series A convertible preferred stock, as determined by the
per share sales price of Series A convertible preferred stock sold in the 1998
Unit Financing (see Note 10(b)), and warrants to purchase common stock issued by
the Company.

(d) 8% Convertible Notes Payable

In December 1999, the Company completed an offering of the 8% Convertible
Notes Payable (8% Notes). As of December 31, 1999, the Company had received
approximately $5.7 million in principal with respect to the 8% Notes. Subsequent
to December 31, 1999, the Company received approximately an additional $1.2
million in principal of 8% Notes. In connection with the closing of the 8% Notes
in December, the Company converted the outstanding balance of the promissory
notes payable to the Company's chief executive officer into 8% Notes (see Note
5(e)). Under the terms of the 8% Notes, the Company must make semiannual
interest payments on the outstanding principal balance through the maturity date
of November 30, 2002. The 8% Notes are convertible at any time prior to the
maturity date at a conversion price equal to $0.60 per share of common stock
(the Conversion Ratio), subject to adjustment under certain circumstances, as
defined. If the 8% Notes are prepaid before the maturity date, all noteholders
are entitled to receive a warrant to purchase the number of shares of common
stock equal to the number of shares of common stock that would be issued using
the Conversion Ratio.

In connection with the 8% Notes, the Company must comply with certain
covenants, including making all payments of interest when due and maintaining
consolidated cash balances of at least $1.5 million as of the last day of any
calendar month. At September 30, 2000 the Company is in compliance with the
covenant regarding consolidated cash balances. If an event of default occurs, as
defined, the noteholders may declare the unpaid principal and interest due and
payable immediately. If the Company defaults with respect to payment of
interest, the Company will be required to pay interest at a default rate equal
to 12%. On July 10, 2000, the

F-15

80
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)

holders of the 8% notes entered into an amendment (See Note 5(f)) to the
Subordination and Intercreditor Agreement.

In addition, in connection with the issuance of the 8% Notes, the holders
of the note payable to Lenders (see Note 5(a)) received a warrant to purchase
2,750,000 shares of the Company's common stock at $0.60 per share. The warrant
was granted as consideration to the Lenders for relinquishing their seniority
upon liquidation of the Company to the holders of the 8% Notes. The Company
computed the value of the warrants to be $547,328, by using the Black-Scholes
option pricing model. The Company has recorded the $547,328 as a deferred
financing cost, which will be amortized to interest expense over the term of the
8% Notes.

(e) Related Party Notes Payable

During September 1999, the Company entered into two $500,000 promissory
notes payable to the Company's chief executive officer (the Officer). During
November 1999, the Company entered into an additional $500,000 promissory note
payable to the Officer. In connection with the issuance of the 8% Notes (see
Note 5(d)), the Company converted the principal balance of $1,500,000, and the
accrued but unpaid interest of $46,502 into 8% Notes.

(f) $2.0 Million Line of Credit

On May 30, 2000, the Company entered into a LOC Agreement pursuant to which
the LOC Lenders agreed to provide the Company with the Line of Credit (see Note
1). The LOC was intended to provide the Company with working capital pending the
closing of the Asset Sale. On July 10, 2000 and August 10, 2000, the Company
drew down approximately $0.5 million each of these dates under the LOC,
representing a total draw down of $1.0 million.

On September 28, 2000, following the close of the transaction with a
subsidiary of Avecia, the Company received a Notice of Repayment from the LOC
Lenders and repaid approximately $0.8 million of principal and interest in cash
and $0.2 million of principal and interest in equivalent shares of common stock
at $1.08 per share (214,043 shares) in October 2000, pursuant to the terms of
the original agreement. The Company has no additional borrowing capacity under
this LOC.

The LOC Lenders, the holders of the 8% Convertible Notes (Note 5(d)), and
the Lender (Note 5(a)) on July 10, 2000 entered into an amendment (the
Amendment) to the Subordination and Intercreditor Agreement. In the Amendment
all parties to the Subordination and Intercreditor Agreement agreed to release
their lien on the portion of the collateral that includes assets to be conveyed
in the Asset Sale. In return for this partial release, the Company undertook in
the Amendment that upon consummation of the Asset Sale it would set aside from
the proceeds thereof the sum of $5.0 million with which it will purchase a money
market instrument and pledge the same as collateral to secure its obligation to
the holders of the 8% Convertible Notes and the Lenders. The amount of the
pledge will be reduced as the Company's obligations are converted to equity or
repaid. The Company is entitled to collect and keep interest income generated by
the money market account. The lenders that are party to the Subordination and
Intercreditor Agreement, as amended, will continue to have a lien on
substantially all of the Company's assets remaining after the Asset Sale.

In connection with the LOC, the Company has agreed (a) to issue to the
representatives of the LOC Lenders warrants to purchase up to 500,000 shares of
common stock at an exercise price of $1.08 per share and (b) to issue to the LOC
Lenders, proportionate to their respective interests in the LOC, warrants to
purchase 1,000,000 shares of common stock at an exercise price of $1.08 per
share. The Company computed the value of the warrants to be $731,136, using the
Black-Scholes option pricing model. The Company has amortized this amount to
interest expense over the term of the LOC.

F-16

81
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)

(6) G.D. SEARLE & CO. AGREEMENT

In January 1996, the Company and G.D. Searle & Co. (Searle) entered into a
collaboration relating to research and development of therapeutic antisense
compounds. The Company and Searle were investigating antisense inhibitors of
MDM2, a protein involved in programmed cell death, or apoptosis. In March 2000,
the Company announced that Searle had elected not to extend its collaboration
agreement with the Company.

During 1997, 1998 and 1999, the Company earned $600,000 each year, in
research and development revenues from Searle. Under the collaboration, Searle
also purchased 200,000 shares of common stock in the Company at the offering
price of $50.00 per share.

(7) LICENSING AGREEMENT

The Company has entered into a licensing agreement with the Worcester
Foundation for Biomedical Research, Inc., which has merged with the University
of Massachusetts Medical Center, under which the Company has received exclusive
licenses to technology in certain patents and patent applications. The Company
is required to make royalty payments based on future sales of products employing
the technology or falling under claims of a patent, as well as a specified
percentage of sublicense income received related to the licensed technology.
Additionally, the Company is required to pay an annual maintenance fee through
the life of the patents.

(8) INVESTMENT IN METHYLGENE, INC.

In January 1996, the Company and certain institutional investors formed a
Quebec company, MethylGene, Inc. (MethylGene) to develop and market certain
compounds and procedures to be agreed upon by the Company and MethylGene.

The Company has granted to MethylGene exclusive worldwide licenses and
sublicenses in respect of certain technology relating to the MethylGene fields.
These fields are defined as (i) antisense compounds to inhibit DNA
methyltransferase for the treatment of cancers; (ii) other methods of inhibiting
DNA methyltransferase for the treatment of any indications and (iii) antisense
compounds to inhibit a second molecular target other than DNA methyltransferase
for the treatment of cancers, to be agreed upon by the Company and MethylGene.
In addition, the Company and MethylGene have entered into a supply agreement
pursuant to which MethylGene is obligated to purchase from the Company all
required formulated bulk oligonucleotides at specified transfer prices.

The Company acquired a 49% interest in MethylGene for approximately
$734,000 and the Canadian investors acquired a 51% interest in MethylGene for a
total of approximately $5,500,000. The institutional investors have the right to
exchange all (but not less than all) of their shares of stock in MethylGene for
an aggregate of 100,000 shares of Hybridon common stock (subject to adjustment
for stock splits, stock dividends and the like). This option is exercisable only
during a 90-day period commencing on the earlier of the date five years after
the closing of the institutional investors' investment in MethylGene or the date
on which MethylGene ceases operations. During 1998, MethylGene raised additional
proceeds from outside investors that decreased the Company's interest to 30%.

In May 1998, this agreement was amended to grant MethylGene a nonexclusive
right to use any and all antisense chemistries discovered by the Company or any
of its affiliates for a period commencing on May 5, 1998 and ending on the
earlier of (i) the effective date of termination by MethylGene of its contract
for development services to be provided by the Company; (ii) May 5, 1999, unless
MethylGene exercises its option to continue contracting for development services
provided by the Company or (iii) May 5, 2000. As additional consideration for
this nonexclusive right, MethylGene is required to pay the Company certain
milestone amounts, as defined, and transfer 300,000 shares of MethylGene's Class
B shares to the Company. The Company has placed no value on these shares. During
1997, 1998 and 1999, the Company recognized zero, $875,000 and $285,000,
respectively, of revenue related to this agreement.

F-17

82
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)

(9) ORIGENIX TECHNOLOGIES, INC.

In January 1999, the Company and certain institutional investors formed a
Montreal company, OriGenix to develop and market drugs for the treatment of
infectious diseases.

The Company received a 49% interest in OriGenix in exchange for certain
research and development efforts previously undertaken by the Company that were
made available to OriGenix. The Company also licensed certain antisense
compounds and other technology to OriGenix. During 1999, OriGenix raised
additional proceeds from institutional investors that reduced the Company's
ownership interest to 40%. The institutional investors acquired a 51% interest
in OriGenix for a total of approximately $4.0 million. The Company accounted for
their investment in OriGenix under the equity method. During 1999, the Company
recognized $80,000 of service revenue from sales to OriGenix.

(10) STOCKHOLDERS' EQUITY (DEFICIT)

(a) Common Stock

The Company has 100,000,000 authorized shares of common stock, $.001 par
value, of which 16,260,722 shares were issued and outstanding at December 31,
1999.

(b) 1998 Unit Financing

On May 5, 1998, the Company completed a private offering of equity
securities raising total gross proceeds of $26,681,164 from the issuance of
9,597,476 shares of common stock, 114,285 shares of Series A convertible
preferred stock and warrants to purchase 3,329,486 shares of common stock at
$2.40 per share. The gross proceeds include the conversion of $5,934,558 of
accounts payable, capital lease obligations and other obligations into common
stock. The Company incurred $1,636,137 of cash expenses related to the private
offering and issued 597,699 shares of common stock and warrants to purchase
1,720,825 shares of common stock at $2.40 per share to the placement agents. The
compensation received by Pillar, a company affiliated with certain directors of
the Company, with respect to the offshore component of the private offering
(Offshore Offering) consisted of (i) 9% of gross proceeds of such Offshore
Offerings and (ii) a nonaccountable expense allowance equal to 4% of gross
proceeds of such Offshore Offering. Pillar received $1,636,137 and warrants to
purchase 1,111,630 shares of common stock at $2.40 per share.

In addition, Pillar is entitled to 300,000 shares of common stock, in
connection with its efforts in assisting the Company in restructuring its
balance sheet. The Company has recorded $600,000 of general and administrative
expense in the accompanying consolidated statement of operations during 1998,
which represents the value of the common stock on May 5, 1998 with an offsetting
amount to accrued expenses for the shares to be issued. These shares were issued
in 1999.

(c) Units Issued to Primedica Corporation

In connection with the unit financing (see Note 10(b)), the Company issued
250,000 shares of common stock and 62,500 warrants to purchase common stock to
Primedica Corporation (Primedica) for future services to be provided. The
services shall commence upon the Company's request after (i) the Company
securities are listed on a nationally recognized exchange, and (ii) the average
closing price of the Company's common stock is at least $2.00 per share for the
twenty-day trading period preceding the contract commencement date. In the event
that the Company does not use these services as a result of the failure to meet
the contract conditions, Primedica shall forfeit to the Company all or part of
the common stock and warrants held by Primedica. The Company recorded these
shares as issued and outstanding during 1998 at par value. The Company will
record the value of these services as the services are rendered.

F-18

83
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)

(d) Warrants

The Company has the following warrants outstanding and exercisable for the
purchase of common stock at December 31, 1999:

OUTSTANDING    EXERCISE PRICE    EXERCISABLE      EXERCISABLE
EXPIRATION DATE                SHARES         PER SHARE         SHARES       PRICE PER SHARE
---------------              -----------    --------------    -----------    ---------------

January 23, 2000 - October 25, 2000....     293,679      $      50.00        293,679         $50.00
February 28, 2000......................      20,000             37.50         20,000          37.50
December 31, 2001......................      13,000             34.49         13,000          34.49
April 2, 2002 - May 4, 2003............   8,641,510       2.40 - 4.25      8,641,510           2.53
December 31, 2002......................   2,750,000              0.60             --             --
November 30, 2003......................     173,333              3.00        173,333           3.00
----------                        ---------
11,891,522                        9,141,522
==========                        =========
Weighted average exercise price per
share.............................                  $       3.35                        $ 4.19
============                        ======

(e) Stock Options

In 1990 and 1995, the Company established the 1990 Stock Option Plan (the
1990 Option Plan) and the 1995 Stock Option Plan (the 1995 Option Plan),
respectively, which provide for the grant of incentive stock options and
nonqualified stock options. Options granted under these plans vest over various
periods and expire no later than 10 years from the date of grant. However, under
the 1990 Option Plan, in the event of a change in control (as defined in the
1990 Plan), the exercise dates of all options then outstanding shall be
accelerated in full and any restrictions on exercising outstanding options
issued pursuant to the 1990 Option Plan shall terminate. In October 1995, the
Company terminated the issuance of additional options under the 1990 Option
Plan. As of December 31, 1999, options to purchase a total of 365,379 shares of
common stock remained outstanding under the 1990 Option Plan.

A total of 700,000 shares of common stock may be issued upon the exercise
of options granted under the 1995 Option Plan. The maximum number of shares with
respect to which options may be granted to any employee under the 1995 Option
Plan shall not exceed 500,000 shares of common stock during any calendar year.
The Compensation Committee of the Board of Directors has the authority to select
the employees to whom options are granted and determine the terms of each
option, including (i) the number of shares of common stock subject to the
option; (ii) when the option becomes exercisable; (iii) the option exercise
price, which in the case of incentive stock options must be at least 100% (110%
in the case of incentive stock options granted to a stockholder owning in excess
of 10% of the Company's common stock) of the fair market value of the common
stock as of the date of grant and (iv) the duration of the options which in the
case of incentive stock options may not exceed 10 years. As of December 31,
1999, options to purchase a total of 497,704 shares of common stock remained
outstanding under the 1995 Option Plan.

In October 1995, the Company adopted the 1995 Director Stock Option Plan
(the Director Plan). A total of 400,000 shares of common stock may be issued
upon the exercise of options granted under the Director Plan. Under the terms of
the Director Plan, options to purchase 1,000 shares of common stock were granted
to eligible directors upon the closing of the Company's initial public offering
at the fair market value of the common stock on the date of the closing.
Thereafter, options to purchase 1,000 shares of common stock will be granted to
each eligible director on May 1 of each year commencing in 1997. All options
will vest on the first anniversary of the date of grant or, in the case of
annual options, on April 30 of each year with respect to options granted in the
previous year. As of December 31, 1999, options to purchase a total of 89,000
shares of common stock remained outstanding under the Director Plan.

In May 1997, the Company adopted the 1997 Stock Option Plan (the 1997
Option Plan) and has reserved and may issue up to 6,500,000 shares for the grant
of incentive and nonqualified stock options. The

F-19

84
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)

maximum number of shares with respect to which options may be granted to any
employee under the 1997 Option Plan shall not exceed 500,000 shares of common
stock during any calendar year. The Compensation Committee of the Board of
Directors has the authority to select the employees to whom options are granted
and determine the terms of each option, including (i) the number of shares of
common stock subject to the option; (ii) when the option becomes exercisable;
(iii) the option exercise price, which in the case of incentive stock options
must be at least 100% (110% in the case of incentive stock) of the fair market
value of the common stock as of the date of grant and (iv) the duration of the
option, which in the case of incentive stock options may not exceed ten years.
As of December 31, 1999, options to purchase a total of 4,437,466 shares of
common stock remained outstanding under the 1997 Option Plan.

As of December 31, 1999, 2,575,830 options remain available for grant under
the 1995 Option Plan, the Director Plan and the 1997 Option Plan.

Stock option activity for the three years ended December 31, 1999 is
summarized as follows:

WEIGHTED
NUMBER      EXERCISE PRICE     AVERAGE PRICE
OF SHARES        PER SHARE         PER SHARE
----------    ---------------    -------------

Outstanding, December 31, 1996....................   1,136,388    $ 1.25 - $65.60       $38.05
Granted.........................................     315,675     27.50 -  32.50        30.75
Exercised.......................................     (25,005)     1.25 -  40.00        12.60
Terminated......................................    (236,561)     2.50 -  65.60        40.35
----------    ---------------       ------
Outstanding, December 31, 1997....................   1,190,497      1.25 -  65.60        36.18
Granted.........................................   2,513,000      2.00 -   3.13         2.00
Terminated......................................    (242,765)     2.50 -  57.85        37.79
----------    ---------------       ------
Outstanding, December 31, 1998....................   3,460,732      1.25 -  65.60        11.25
Granted.........................................   7,640,650      0.44 -   2.00         0.85
Terminated......................................  (5,711,832)     0.44 -  65.60         7.53
----------    ---------------       ------
Outstanding, December 31, 1999....................   5,389,550    $ 0.50 - $ 2.00       $ 0.50
==========    ===============       ======
Exercisable, December 31, 1997....................     740,780    $ 1.25 - $65.50       $34.40
==========    ===============       ======
Exercisable, December 31, 1998....................   1,650,021    $ 1.25 - $65.60       $17.13
==========    ===============       ======
Exercisable, December 31, 1999....................   2,772,099    $ 0.50 - $ 2.00       $ 0.50
==========    ===============       ======

OPTIONS OUTSTANDING                 OPTIONS EXERCISABLE
------------------------------------------   -----------------------
WEIGHTED                  WEIGHTED
WEIGHTED        AVERAGE                   AVERAGE
RANGE OF                     AVERAGE        EXERCISE                  EXERCISE
EXERCISE     NUMBER         REMAINING       PRICE PER     NUMBER      PRICE PER
PRICES    OUTSTANDING   CONTRACTUAL LIFE     SHARE     OUTSTANDING     SHARE
--------   -----------   ----------------   ---------   -----------   ---------

$0.50      5,385,550          8.39           $0.50      2,771,974      $0.50
2.00          4,000          9.81            2.00            125       2.00
---------                         -----      ---------      -----
5,389,550                         $0.50      2,772,099      $0.50
=========                         =====      =========      =====

In 1997 and 1998, the Company recorded $205,978 and $109,734, respectively,
of deferred compensation related to grants to nonemployees, net of terminations.
In accordance with Emerging Issues Task Force (EITF) No. 96-18, Accounting for
Equity Instruments That Are Issued to Other Than Employees for Acquiring, or in
Conjunction with Selling Goods or Services, the Company will measure the value
of options as they vest using the Black-Scholes option pricing model. The
Company has recorded compensation expense of $316,067, $246,444 and $634,633 in
1997, 1998 and 1999, respectively, related to these grants to nonemployees.

F-20

85
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)

In October 1995, the FASB issued SFAS No. 123, Accounting for Stock-Based
Compensation. SFAS No. 123 requires the measurement of the fair value of stock
options or warrants granted to employees to be included in the statement of
operations or disclosed in the notes to financial statements. The Company has
determined that it will continue to account for stock-based compensation for
employees under APB Opinion No. 25 and elect the disclosure-only alternative
under SFAS No. 123.

The Company has computed the pro forma disclosures require by SFAS No. 123
for all stock options and warrants granted to employees after January 1, 1995
using the Black-Scholes option pricing model. The assumptions used for the three
years ended December 31, 1999 are as follows:

1997       1998       1999
-------    -------    -------

Risk free interest rate.................................     6.22%      5.15%      6.12%
Expected dividend yield.................................       --         --         --
Expected lives..........................................  6 years    6 years    6 years
Expected volatility.....................................       60%        60%        60%

The Black-Scholes option pricing model was developed for use in estimating
the fair value of traded options, which have no vesting restrictions and are
fully transferable. In addition, option pricing models require the input of
highly subjective assumptions including expected stock price volatility. Because
the Company's employee stock options have characteristics significantly
different from those of traded options, and because changes in the subjective
input assumptions can materially affect the fair value estimate, in management's
opinion, the existing models do not necessarily provide a reliable single
measure of the fair value of its employee stock options.

The effect of applying SFAS No. 123 for the three years ended December 31,
1999 would be as follows:

1997            1998            1999
------------    ------------    ------------

Net loss to applicable common
stockholders, as reported..............  $(69,461,326)   $(19,792,736)   $(14,735,293)
============    ============    ============
Pro forma net loss applicable to common
stockholders...........................  $(73,402,170)   $(23,131,304)   $(18,647,864)
============    ============    ============
Basic and Diluted net loss per common
shares --
As reported............................  $     (13.76)   $      (1.67)   $      (0.93)
============    ============    ============
Pro forma..............................  $     (14.54)   $      (1.95)   $      (1.18)
============    ============    ============

(f) Repricing

In September 1999, the Company's Board of Directors authorized the
repricing of options to purchase 5,251,827 shares of common stock to $0.50 per
share, which represented the market value on the date of the repricing. As
discussed in Note 2(m), these options will be subject to variable plan
accounting, as defined in the Proposed Interpretation, if the Proposed
Interpretation is adopted in its current form. The repriced options have been
reflected as grants and cancellations in the stock option activity for the year
ended December 31, 1999. The Proposed Interpretation was adopted in the form of
FASB Interpretation No. 44 Accounting for Certain Transactions involving Stock
Compensation (FIN 44) and became effective on July 1, 2000. The Company is
following the provisions of FIN 44 and will mark to market the repriced options
at each reporting date. As of September 30, 2000, the Company has not recognized
any compensation expense related to the repriced options as the fair market
value to the Company's common stock at September 30, 2000 was below the fair
market value on the effective date of FIN 44.

F-21

86
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)

(g) Employee Stock Purchase Plan

In October 1995, the Company adopted the 1995 Employee Stock Purchase Plan
(the Purchase Plan), under which up to 100,000 shares of common stock may be
issued to participating employees of the Company, as defined, or its
subsidiaries.

On the first day of a designated payroll deduction period (the Offering
Period), the Company will grant to each eligible employee who has elected to
participate in the Purchase Plan an option to purchase shares of common stock as
follows: the employee may authorize an amount (a whole percentage from 1% to 10%
of such employee's regular pay) to be deducted by the Company from such pay
during the Offering Period. On the last day of the Offering Period, the employee
is deemed to have exercised the option, at the option exercise price, to the
extent of accumulated payroll deductions. Under the terms of the Purchase Plan,
the option price is an amount equal to 85% of the fair market value per share of
the common stock on either the first day or the last day of the Offering Period,
whichever is lower. In no event may an employee purchase in any one Offering
Period a number of shares that is more than 15% of the employee's annualized
base pay divided by 85% of the market value of a share of common stock on the
commencement date of the Offering Period. The Compensation Committee may, in its
discretion, choose an Offering Period of 12 months or less for each of the
Offerings and choose a different Offering Period for each Offering. No shares
have been issued under the Plan.

(h) Preferred Stock

The restated Certificate of Incorporation of the Company permits its Board
of Directors to issue up to 5,000,000 shares of preferred stock, par value $0.01
per share (the Preferred Stock), in one or more series, to designate the number
of shares constituting such series, and fix by resolution, the powers,
privileges, preferences and relative, optional or special rights thereof,
including liquidation preferences and dividends, and conversion and redemption
rights of each such series. During 1998, the Company designated 1,500,000 shares
as Series A convertible preferred stock.

(i) Series A Convertible Preferred Stock

The rights and preferences of the Series A convertible preferred stock are
as follows:

DIVIDENDS

The holders of the Series A convertible preferred stock, as of March
15 or September 15, are entitled to receive dividends payable at the rate
of 6.5% per annum, payable semi-annually in arrears. Such dividends shall
accrue from the date of issuance of such share and shall be paid
semi-annually on April 1 and October 1 of each year. Such dividends shall
be paid, at the election of the Company, either in cash or additional duly
authorized, fully paid and non assessable shares of Series A convertible
preferred stock. In calculating the number of shares of Series A
convertible preferred stock to be paid with respect to each dividend, the
Series A convertible preferred stock shall be valued at $100.00 per share.
During 1999, the Company recorded a total accretion of $4,232,251 for the
dividend on Series A preferred stock and issued 41,673 shares of Series A
convertible preferred stock as a dividend.

LIQUIDATION

In the event of a liquidation, dissolution or winding up of the
Company, whether voluntary or involuntary, after payment or provision for
payment of debts and other liabilities of the Company, the holder of the
Series A convertible preferred stock then outstanding shall be entitled to
be paid out of the assets of the Company available for distribution to its
stockholders, an amount equal to $100.00 per share plus all accrued but
unpaid dividends. If the assets to be distributed to the holders of the
Series A convertible preferred stock shall be insufficient to permit the
payment of the full preferential amounts, then the assets of the Company
shall be distributed ratably to the holders of the Series A convertible
F-22

87
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)

preferred stock on the basis of the number of shares of Series A
convertible preferred stock held. All shares of Series A convertible
preferred stock shall rank as to payment upon the occurrence of any
liquidation event senior to the common stock.

CONVERSION

Shares of Series A convertible preferred stock are convertible, in
whole or in part, at the option of the holder into fully paid and
nonassessable shares of common stock at $4.25 per share, subject to
adjustment as defined.

During 1999, holders of 21,076 shares of Series A convertible
preferred stock elected to convert their shares into 495,897 shares of the
Company's common stock.

MANDATORY CONVERSION

The Company at its option, may cause the Series A convertible
preferred stock to be converted in whole or in part, on a pro rata basis,
into fully paid and nonassessable shares of common stock using a conversion
price equal to $4.00 if the closing bid price, as defined, of the common
stock shall have equaled or exceeded 250% of the conversion price, $4.25,
subject to adjustment as defined, for at least 20 trading days in any 30
consecutive trading day period ending three days prior to the date of
notice of conversion (such event, the Market Trigger).

At any time after April 1, 2000, the Company, at its option, may
redeem the Series A convertible preferred stock for cash equal to $100.00
per share plus all accrued and unpaid dividends at such time, if the Market
Trigger has occurred in the period ending three days prior to the date of
notice of redemption.

(11) COMMITMENTS AND CONTINGENCIES

(a) Facilities

The Company leases its facility in Cambridge (Vassar Street),
Massachusetts, under a lease that has a 10-year term, which commenced on May 1,
1997.

On February 4, 1994, the Company entered into the Cambridge (Memorial
Drive) Lease, which is with a partnership that is affiliated with certain
directors of the Company. On July 1, 1994, the Company entered into the Milford,
Massachusetts Lease. The Company vacated the Cambridge (Memorial Drive),
Massachusetts, facility in June 1998 and moved its corporate facilities to
Milford, Massachusetts (see Note 3). The Company vacated the Milford,
Massachusetts facility in September 2000 and moved its corporate facilities to
Cambridge (Vasser Street), Massachusetts (see Note 15).

Future approximate minimum rent payments as of December 31, 1999, under
existing lease agreements through 2007, are as follows:

DECEMBER 31,                                                    AMOUNT
------------                                                  ----------

2000........................................................  $  624,000
2001........................................................     637,000
2002........................................................     620,000
2003........................................................     611,000
2004........................................................     611,000
Thereafter..................................................   1,426,000
----------
$4,529,000
==========

During 1997, 1998 and 1999, facility rent expense for continuing operations
net of sublease revenue was approximately $4,037,000, $1,363,000 and $67,000,
respectively.

F-23

88
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)

(b) Related-Party Agreements with Affiliates of Stockholders and Directors

The Company has entered into consulting agreements, stock placement
agreements and an advisory agreement with several companies that are controlled
by two shareholders and directors of the Company including Forum, S.A. Pillar
Investment N.V. (Pillar Investment), Pillar S.A. (formerly Commerce Consult
S.A.) and Pillar Investment Limited (formerly Ash Properties Limited) (Pillar
Limited). During 1997, 1998 and 1999, the Company had expensed $998,000,
$1,300,000 and $336,000, respectively, under these agreements with related
parties.

(c) Other Research and Development Agreements

The Company has entered into consulting and research agreements with
universities, research and testing organizations and individuals, under which
consulting and research support is provided to the Company. These agreements are
for varying terms and provide for certain minimum annual or per diem fees plus
reimbursable expenses to be paid during the contract periods. Future minimum
fees payable under these contracts as of December 31, 1999 are approximately as
follows:

DECEMBER 31,                                                   AMOUNT
------------                                                  --------

2000........................................................  $218,000
2001........................................................    78,000
--------
$296,000
========

Total fees and expenses under these contracts were approximately
$9,372,000, $2,011,000 and $477,000 during 1997, 1998 and 1999, respectively.

(d) Employment Agreements

The Company has entered into employment agreements with certain of its
executive officers that provide for, among other things, each officer's annual
salary, cash bonus, fringe benefits and vacation and severance arrangements.
Under the agreements, the officers are generally entitled to receive severance
payments of two to three year's base salary.

(e) Contingencies

From time to time, the Company may be exposed to various types of
litigation. The Company is not engaged in any legal proceedings that are
expected, individually or in the aggregate, to have a material adverse effect on
the Company's financial condition or results of operations.

(12) INCOME TAXES

The Company applies SFAS No. 109, Accounting for Income Taxes. At December
31, 1999, the Company had net operating loss and tax credit carryforwards for
federal income tax purposes of approximately $228,744,000 and $4,186,000,
respectively, available to reduce federal taxable income and federal income
taxes, respectively. The Tax Reform Act of 1986 (the Act), enacted in October
1986, limits the amount of net operating loss and credit carryforwards that
companies may utilize in any one year in the event of cumulative changes in
ownership over a three-year period in excess of 50%. The Company has completed
several financings since the effective date of the Act, which as of December 31,
1999, have resulted in ownership changes in excess of 50%, as defined under the
Act and which will limit the Company's ability to utilize its net operating loss
carryforwards. Ownership changes in future periods may place additional limits
on the Company's ability to utilize net operating loss and tax credit
carryforwards.

F-24

89
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)

The federal net operating loss carryforwards and tax credit carryforwards
expire approximately as follows:

NET
OPERATING
LOSS          TAX CREDIT
EXPIRATION DATE                                            CARRYFORWARDS    CARRYFORWARDS
---------------                                            -------------    -------------

December 31,
2005...................................................  $    666,000      $   15,000
2006...................................................     3,040,000          88,000
2007...................................................     7,897,000         278,000
2008...................................................    18,300,000         627,000
2009...................................................    25,670,000         689,000
2010...................................................    36,134,000         496,000
2011...................................................    44,947,000         493,000
2012...................................................    60,087,000         750,000
2018...................................................    21,366,000         500,000
2019...................................................    10,637,000         250,000
------------      ----------
$228,744,000      $4,186,000
============      ==========

As of December 31, 1998 and 1999, the components of the deferred tax assets
are approximately as follows:

1998            1999
------------    ------------

Operating loss carryforwards............................  $ 87,243,000    $ 91,498,000
Temporary differences...................................     3,461,000       3,378,000
Tax credit carryforwards................................     3,936,000       4,186,000
------------    ------------
94,640,000      99,062,000
Valuation allowance.....................................   (94,640,000)    (99,062,000)
------------    ------------
$         --    $         --
============    ============

A valuation allowance has been provided, as it is more likely than not the
Company will not realize the deferred tax asset. The net change in the total
valuation allowance during 1999 was an increase of approximately $4,422,000.

(13) EMPLOYEE BENEFIT PLAN

On October 10, 1991, the Company adopted an employee benefit plan under
Section 401(k) of the Internal Revenue Code. The plan allows employees to make
contributions up to a specified percentage of their compensation. Under the
plan, the Company may, but is not obligated to, match a portion of the
employees' contributions up to a defined maximum. The Company is currently
matching 50% of employee contributions to the plan, up to 6% of the employee's
annual base salary and charged to continuing operations approximately $195,000,
$166,000 and $54,000 during 1997, 1998 and 1999, respectively.

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90
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)

(14) SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION

Supplemental disclosure of cash flow information for the following periods
presented are as follows:

DECEMBER 31,                     SEPTEMBER 30,
-------------------------------------   -----------------------
1997         1998          1999         1999         2000
----------   -----------   ----------   ----------   ----------
(UNAUDITED)

Cash paid during the period for
interest..........................  $3,264,596   $ 1,666,127   $  753,620   $  532,564   $  592,898
==========   ===========   ==========   ==========   ==========
Purchase of property and equipment
under capital leases..............  $2,374,502   $        --   $       --   $       --   $       --
==========   ===========   ==========   ==========   ==========
Conversion of preferred stock into
common stock......................  $       --   $        --   $      496   $       --   $       --
==========   ===========   ==========   ==========   ==========
Deferred compensation related to
grants of stock options to
nonemployees, net of
terminations......................  $  205,978   $   109,734   $       --   $       --   $       --
==========   ===========   ==========   ==========   ==========
Issuance of Series A convertible
preferred stock and attached
warrants in exchange for
conversion of 9% convertible
subordinated notes payable and
accrued interest..................  $       --   $51,055,850   $       --   $       --   $       --
==========   ===========   ==========   ==========   ==========
Accretion of Series A convertible
preferred stock dividends.........  $       --   $ 2,689,048   $4,232,251   $3,193,851   $3,112,174
==========   ===========   ==========   ==========   ==========
Issuance of common stock and
attached warrants in exchange for
conversion of convertible
promissory notes payable..........  $       --   $ 4,800,000   $       --   $       --   $       --
==========   ===========   ==========   ==========   ==========
Issuance of common stock and
attached warrants in exchange for
conversion of accounts payable and
other obligations.................  $       --   $ 5,934,558   $       --   $       --   $       --
==========   ===========   ==========   ==========   ==========
Issuance of common stock in lieu of
services..........................  $       --   $        --   $1,000,000   $1,000,000   $       --
==========   ===========   ==========   ==========   ==========

(15) ASSET SALE

On September 21, 2000, the Company completed the sale of its Hybridon
Specialty Products business, which manufactures, markets and sells
oligonucleotides to a subsidiary of Avecia, Inc. of Manchester, United Kingdom,
for up to $15.0 million. The Company recorded a gain of approximately $6.1
million on the Asset Sale at the time of closing, comprised of net proceeds of
approximately $11.5 million, plus an approximately $0.5 million reserve for
certain indemnity purposes, less estimated transaction and other costs of
approximately $1.1 million and the book value of the net assets sold. The
remaining $3.0 million is subject to certain performance contingencies and will
be recorded as a gain when earned and received. The transaction costs consist
principally of legal and accounting fees, severance arrangements with certain
employees, and other estimated costs associated with consummating the sale. As a
condition of the Asset Sale requested by Avecia, the Company held a special
meeting of shareholders on September 12, 2000, and obtained the approval of the
Asset Sale by the common and preferred stock and the debt holders.

At the closing, the Company received $12.0 million of the proceeds, less a
$450,000 reserve, that was to be held for 30 days as security for the value of
the purchased inventory and against prepayments for uncompleted work received by
the Company in advance of the sale. In October the Company received $176,144 of
that amount; the remaining $273,856 is currently subject to negotiation.
Consequently, the

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91
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)

remaining amount is not included in the calculation of the gain on the Asset
Sale, which is computed as follows:

Proceeds...................................................                $12,000,000
Property and equipment sold, net...........................  $4,894,887
Security deposit...........................................      90,000
----------
Net book value of assets sold..............................   4,984,887
Current liabilities assumed by the buyer...................     (88,969)
Long term liabilities assumed by the buyer.................    (324,555)
----------
Net assets sold............................................                 (4,571,363)
Inventory reserve holdback.................................                   (273,856)
Transaction and other costs................................                 (1,053,722)
-----------
Gain on sale..........................................                $ 6,101,059
===========

The consolidated financial statements of the Company have been restated to
reflect the financial results of the Hybridon Specialty Products business as a
discontinued operation for the years ended December 31, 1997, 1998, and 1999,
the nine months ended September 30, 1999 and 2000 and as of December 31, 1999
and 1998 and September 30, 2000. Reported revenues, expenses and cash flows
exclude the operating results of the discontinued operations. Revenues from
discontinued operations for the years ended December 31, 1997, 1998, 1999 and
for the nine months ended September 30, 1999 and 2000 are approximately
$2,024,000, $1,623,000, $5,821,000, $4,349,000 and $2,950,000, respectively. The
net income from discontinued operations, as presented on the consolidated
statement of operations for the nine months ended September 30, 2000, includes
the gain on sale as calculated above of $6.1 million as well as the operating
loss from discontinued operations for the nine months ended September 30, 2000,
totaling $0.8 million. For all other periods presented, the net loss relates
solely to the operating results of the Hybridon Specialty Products business.

The Company plans to use the proceeds of the Asset Sale for current
operating expenses, including payment of certain current liabilities.

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92

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

ITEM 13.  OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION.

Estimated expenses (other than underwriting discounts and commissions)
payable in connection with the sale of the shares of Series A convertible
preferred stock, $.01 par value per share (the "Convertible Preferred Stock")
and shares of common stock, $.001 par value per share (the "Common Stock" and,
together with the Convertible Preferred Stock, the "Securities") offered hereby
are as follows:

SEC Registration fee........................................    $  38,000
Printing and engraving expenses.............................       45,000
Legal fees and expenses.....................................       75,000
Accounting fees and expenses................................       25,000
Blue Sky fees and expenses (including legal fees)...........          500
Transfer agent and registrar fees and expenses..............       10,000
Miscellaneous...............................................       10,000
Total.............................................

The Registrant will bear all expenses shown above.

ITEM 14.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

Article EIGHTH of the Registrant's Restated Certificate of Incorporation
provides that no director of the Registrant shall be personally liable for any
monetary damages for any breach of fiduciary duty as a director, except to the
extent that the Delaware General Corporation Law prohibits the elimination or
limitation of liability of directors for breach of fiduciary duty.

Article NINTH of the Registrant's Restated Certificate of Incorporation
provides that a director or officer of the Registrant (a) shall be indemnified
by the Registrant against all expenses (including attorneys' fees), judgments,
fines and amounts paid in settlement incurred in connection with any litigation
or other legal proceeding (other than an action by or in the right of the
Registrant) brought against him by virtue of his position as a director or
officer of the Registrant if he acted in good faith and in a manner he
reasonably believed to be in, or not opposed to, the best interests of the
Registrant, and, with respect to any criminal action or proceeding, had no
reasonable cause to believe his conduct was unlawful and (b) shall be
indemnified by the Registrant against all expenses (including attorneys' fees)
and amounts paid in settlement incurred in connection with any action by or in
the right of the Registrant brought against him by virtue of his position as a
director or officer of the Registrant if he acted in good faith and in a manner
he reasonably believed to be in, or not opposed to, the best interests of the
Registrant, except that no indemnification shall be made with respect to any
matter as to which such person shall have been adjudged to be liable to the
Registrant, unless a court determines that, despite such adjudication but in
view of all of the circumstances, he is entitled to indemnification of such
expenses. Notwithstanding the foregoing, to the extent that a director or
officer has been successful, on the merits or otherwise, including, without
limitation, the dismissal of an action without prejudice, he is required to be
indemnified by the Registrant against all expenses (including attorneys' fees)
incurred in connection therewith. Expenses shall be advanced to a director or
officer at his request, provided that he undertakes to repay the amount advanced
if it is ultimately determined that he is not entitled to indemnification for
such expenses.

Indemnification is required to be made unless the Registrant determines
that the applicable standard of conduct required for indemnification has not
been met. In the event of a determination by the Registrant that the director or
officer did not meet the applicable standard of conduct required for
indemnification, or if the Registrant fails to make an indemnification payment
within 60 days after such payment is claimed by such person, such person is
permitted to petition the court to make an independent determination as to
whether such person is entitled to indemnification. As a condition precedent to
the right of indemnification, the

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93

director or officer must give the Registrant notice of the action for which
indemnity is sought and the Registrant has the right to participate in such
action or assume the defense thereof.

Article NINTH of the Registrant's Restated Certificate of Incorporation
further provides that the indemnification provided therein is not exclusive, and
provides that in the event that the Delaware General Corporation Law is amended
to expand the indemnification permitted to directors or officers the Registrant
must indemnify those persons to the full extent permitted by such law as so
amended.

Section 145 of the Delaware General Corporation Law provides that a
corporation has the power to indemnify a director, officer, employee or agent of
the corporation and certain other persons serving at the request of the
corporation in related capacities against amounts paid and expenses incurred in
connection with an action or proceeding to which he is or is threatened to be
made a party by reason of such position, if such person shall have acted in good
faith and in a manner he reasonably believed to be in or not opposed to the best
interests of the corporation, and, in any criminal proceeding, if such person
had no reasonable cause to believe his conduct was unlawful; provided that, in
the case of actions brought by or in the right of the corporation, no
indemnification shall be made with respect to any matter as to which such person
shall have been adjudged to be liable to the corporation unless and only to the
extent that the adjudicating court determines that such indemnification is
proper under the circumstances.

Hybridon is a party to an indemnification agreement with Mr. Grinstead.
Such agreement provides that Mr. Grinstead shall be indemnified by the
Registrant (a) against all expenses (as defined in the agreement), judgments,
fines, penalties and amounts paid in settlement actually and reasonably incurred
in connection with any legal proceeding (other than one brought by or on behalf
of the Registrant) if Mr. Grinstead acted in good faith and in a manner which he
reasonably believed to be in, or not opposed to, the best interests of the
Registrant, and, with respect to any criminal proceeding, had no reasonable
cause to believe that his conduct was unlawful and (b) against all expenses and
amounts paid in settlement actually and reasonably incurred in connection with a
legal proceeding brought by or on behalf of the Registrant if he acted in good
faith and in a manner which he reasonably believed to be in, or not opposed to,
the best interests of the Registrant, except that no indemnification shall be
made in respect of any claim, issue or matter as to which Mr. Grinstead has been
adjudged to be liable. If, with respect to such proceedings, Mr. Grinstead is
successful on the merits or otherwise, he shall be reimbursed for all expenses.
Mr. Grinstead is required to provide notice to the Registrant of any threatened
or pending litigation, and the Registrant has the right to participate in such
action or assume the defense thereof.

Hybridon has obtained directors and officers insurance for the benefit of
its directors and its officers.

ITEM 15.  RECENT SALES OF UNREGISTERED SECURITIES.

In the three years preceding the filing of this registration statement,
Hybridon has issued and sold its Common Stock, warrants to purchase its Common
Stock, Convertible Subordinated Notes and Series A Convertible Preferred Stock,
to certain investors in transactions that were not registered under the
Securities Act of 1933, as amended (the "Securities Act"):

UNREGISTERED OFFERINGS PURSUANT TO SECTION 4(2) UNDER THE 1933 ACT

The securities issued in each of the following transactions (items (1)
through (10)) were offered and sold in reliance upon the exemption from
registration under Section 4(2) of the Securities Act, relating to sales by an
issuer not involving a public offering. The securities issued in each of the
following transactions were offered and sold solely to persons who were
"accredited investors" as that term is defined in Regulation D promulgated under
the Securities Act.

(1) On January 20, 1997, Hybridon issued 25,000 shares of Common Stock to
an investment bank as compensation under a financial advisory services agreement
dated that date. These shares were offered and sold to an "accredited investor"
(as that term is defined in Regulation D promulgated under the Securities Act)
in reliance upon the exemption from registration under Section 4(2) of the
Securities Act relating to sales by an issuer not involving any public offering.

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94

(2) On January 25, 1997, Hybridon sold 1,650 shares of Common Stock to one
investor upon exercise by such investor of warrants to purchase Common Stock for
an aggregate purchase price of $9,075. These shares were offered and sold to an
"accredited investor" (as that term is defined in Regulation D promulgated under
the Securities Act) in reliance upon the exemption from registration under
Section 4(2) of the Securities Act relating to sales by an issuer not involving
any public offering.

(3) On April 2, 1997, Hybridon issued to an investment bank $50,000,000 of
its 9% Notes. These 9% Notes were offered and sold to an "accredited investor"
(as that term is defined in Regulation D promulgated under the Securities Act)
in reliance upon the exemption from registration under Section 4(2) of the
Securities Act relating to sales by an issuer not involving any public offering.

(4) On April 2, 1997, Hybridon issued to an investment bank warrants to
purchase 71,301 shares of Common Stock at an exercise price of $35.0625 per
share. These warrants were offered and sold to an "accredited investor" (as that
term is defined in Regulation D promulgated under the Securities Act) in
reliance upon the exemption from registration under Section 4(2) of the
Securities Act relating to sales by an issuer not involving any public offering.

(5) On December 10, 1997, Hybridon issued to Dr. Paul Zamecnik, a Director
of Hybridon, 50,000 shares of Common Stock of Hybridon.

(6) On May 5, 1998, Hybridon accepted $48,694,000 principal amount of its
9% Notes tendered to Hybridon in exchange for 510,505 shares of Series A
preferred stock (the "Series A Preferred Stock") and warrants (the "Class A
Warrants") to purchase 3,002,958 shares of common stock, par value $.001 per
share (the "Common Stock"), of Hybridon (the "Exchange Offer"). As a result of
the Exchange Offer, there is approximately $1.3 million principal amount of the
9% Notes outstanding.

Pursuant to the Exchange Offer, which commenced on February 6, 1998, all
tendering Noteholders received per $1,000 principal amount of the 9% Notes
(including accrued but unpaid interest on the 9% Notes) (i) 10 shares of Series
A Preferred Stock and (ii) Class A Warrants to purchase such number of shares of
Common Stock equal to 25% of the number of shares of Hybridon's Common Stock
into which the Series A Preferred Stock issued to such Noteholder pursuant to
the Exchange Offer would be convertible.

The Convertible Preferred Stock ranks, as to dividends and liquidation
preference, senior to Hybridon's Common Stock. The Convertible Preferred Stock
issued in the Exchange Offer and in the Regulation D Offering, as defined below,
as well as the Convertible Preferred Stock that was issued as a dividend on
September 30, 1998, will be convertible into an aggregate of 15,088,200 shares
of Common Stock, subject to adjustment, beginning May 5, 1999.

The Class A Warrants will be exercisable commencing on May 5, 1999 for a
period of four years thereafter at $4.25 per share of Common Stock, subject to
adjustment. The Class A Warrants are not subject to redemption at the option of
Hybridon under any circumstances.

The Exchange Offer was undertaken by Hybridon as part of Hybridon's new
business plan contemplating a restructuring of its capital structure to reduce
debt service obligations, a significant reduction in its burn rate and an
infusion of additional equity capital.

(7) On May 5, 1998, Hybridon closed a private placement (the "Regulation D
Offering") of (i) 114,285 shares of Series A Preferred Stock, which sold at $70
per share, and (ii) Class D warrants (the "Class D Warrants") to purchase
672,273 shares of Hybridon's Common Stock, subject to adjustment, for an
aggregate amount of approximately $8 million.

The Class D Warrants will be exercisable commencing on May 5, 1999 until
May 4, 2003 at $2.40 per share of Common Stock, subject to adjustment.

The net proceeds to Hybridon from the Regulation D Offering are presently
used for general corporate purposes, primarily research and product development
activities, including costs of preparing investigational new drug applications
and conducting preclinical studies and clinical trials, the payment of payroll
and other accounts payable and for debt service required under Hybridon's debt
obligations. The amounts actually

II-3

95

expended by Hybridon and the purposes of such expenditures may vary
significantly depending upon numerous factors, including the progress of
Hybridon's research, drug discovery and development programs, the results of
preclinical studies and clinical trials, the timing of regulatory approvals,
sales of DNA products and reagents to third parties manufactured on a custom
contract basis by the HSP Division and margins on such sales, technological
advances, determinations as to the commercial potential of Hybridon's compounds
and the status of competitive products. In addition, expenditures will also
depend upon the establishment of collaborative research arrangements with other
companies, the availability of other financing and other factors. Under certain
circumstances, Hybridon may be required to use net proceeds to repay
indebtedness under its bank credit facility.

(8) On May 5, 1998, Hybridon closed a private placement of units (the "Unit
Offering") consisting of (i) 2,754,654 shares of Common Stock, and (ii) Class C
warrants (the "Class C Warrants") to purchase 788,649 shares of Common Stock,
subject to adjustment, which securities were issued in consideration of the
cancellation (or reduction) of accounts payable, capital lease and other
obligations aggregating $5,509,308.

The Class C Warrants are exercisable at $2.40 per share, subject to
adjustment from time to time, until May 4, 2003.

(9) On May 5, 1998, Hybridon sold to Dr. Paul Zamecnik 100,000 shares of
Common Stock and Class C Warrants to purchase 25,000 shares of Common Stock,
subject to adjustment, for a purchase price of $200,000.

The net proceeds of this offering were used to reduce accounts payable,
capital lease and other obligations.

(10) On May 5, 1998, Hybridon issued to certain suppliers a total of
362,500 shares of Common Stock and Class C Warrants to purchase a total of
90,625 shares of Common Stock. These issuances were in consideration of (i)
payment to Hybridon of a total of $362.50, the par value of all such issued
Common Stock, and (ii) the subsequent furnishing of specified services to
Hybridon by each supplier. The extent to which the suppliers have completed
performing the specified services varies.

(11) On December 12, 1998, Hybridon issued to Dr. Paul Zamecnik 50,000
shares of Common Stock in recognition of Dr. Zamecnik's extraordinary
contribution to Hybridon.

(12) On April 16, 1999, Hybridon issued to Pillar Investments Limited
300,000 shares of Common Stock in connection with Pillar's efforts in assisting
Hybridon with restructuring its balance sheet.

(13) On May 1, 1999, Hybridon issued to Founders Financial Group LP
(Formerly Forum Capital Markets LLC) ("Founders") 160,000 shares of Common Stock
and warrants to purchase 173,333 shares of Common Stock, as a reinvestment by
Forum of a $400,000 fee paid to Founders in connection with the purchase of a
bank loan to Hybridon.

The Common Stock issued to Dr. Paul Zamecnik and to the certain suppliers
and the Common Stock underlying the Class C Warrants issued to such persons are
subject to a "lock-up" period ending on May 5, 1999, except to the extent such
securities are sold or transferred pursuant to a Registration Statement. After
Hybridon files a Registration Statement under the Securities Act, 75% of each
holder's Units and the underlying securities will be subject to an additional
"lock-up" for the first three months following the Effective Date; thereafter,
50% of such securities will be subject to an additional "lock-up" until six
months following the Effective Date; and the remaining 25% of such securities
will be "locked-up" until nine months following the Effective Date.

(14) In October 1999, Hybridon sold approximately $455,000 principal amount
of promissory notes at face value to certain "accredited investors," in reliance
upon the exemption from registration under Section 4(2) of the Securities Act
relating to sales by an issuer not involving any public offering.

(15) In September and November 1999, Hybridon sold an aggregate of $1.5
million principal amount of promissory notes at face value to E. Andrews
Grinstead, III, Hybridon's Chief Executive Officer, in reliance

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96

upon the exemption from registration under Section 4(2) of the Securities Act
relating to sales by an issuer not involving any public offering.

(16) On December 13, 1999, Hybridon sold an aggregate of $5.1 million
principal amount of 8% Notes to purchasers in a private placement transaction.
These 8% Notes were offered and sold to "accredited investors" in reliance upon
the exemption from registration under Section 4(2) of the Securities Act
relating to sales by an issuer not involving any public offering.

(17) As of December 31, 1999, the $455,000 indebtedness under the October
1999 loan agreement were converted into 8% Notes, in reliance upon the exemption
from registration under Section 4(2) of the Securities Act relating to sales by
an issuer not involving any public offering.

(18) As of December 31, 1999, the $1.5 million principal amount of
promissory notes held by Mr. Grinstead, automatically converted into 8% Notes,
in reliance upon the exemption from registration under Section 4(2) of the
Securities Act relating to sales by an issuer not involving any public offering.

(19) As of December 7, 1999, in connection with the Subordination and
Intercreditor Agreement by and among Hybridon, the representative of the
purchasers of the 8% Notes, Founders and the entities advised by Pecks, whereby,
among other things, the $6,000,000 Forum loan was subordinated to the 8% Notes,
Hybridon issued warrants to purchase an aggregate of 2.75 million shares of
Hybridon common stock to designees of Pecks and Founders. These warrants were
offered and sold to "accredited investors" in reliance upon the exemption from
registration under Section 4(2) of the Securities Act relating to sales by an
issuer not involving any public offering.

(20) In connection with the December 13, 1999 private placement of 8%
Notes, Hybridon agreed, subject to certain conditions, to issue to Pillar
Investment Limited or its designees, 8% Notes in an aggregate principal amount
equal to 9% of the aggregate principal amount of 8% Notes sold to investors
introduced to Hybridon by Pillar and warrants to purchase an aggregate principal
amount of 8% Notes equal to 10% of the 8% Notes sold to investors introduced to
Hybridon by Pillar. These notes and warrants were offered and sold to
"accredited investors" in reliance upon the exemption from registration under
Section 4(2) of the Securities Act relating to sales by an issuer not involving
any public offering.

(21) In November, 1998, Founders and certain investors associated with
Pecks Management Partners Ltd. (Pecks) (collectively, the Lenders) purchased
Hybridon's note payable to a bank and loaned an additional $3,200,000, to
Hybridon for general corporate purposes, increasing the outstanding principal
amount to $6,000,000. These 8% notes are convertible, at the Lender's option,
into up to 2,500,000 shares of Common Stock at a conversion price of $2.40 per
share. These notes were offered and sold to "accredited investors" in reliance
upon the exemption from registration under Section 4(2) of the Securities Act
relating to sales by an issuer not involving any public offering.

(22) On May 30, 2000, the Board of Directors of Hybridon approved a Line of
Credit Agreement with certain lenders who provided Hybridon with a $2,000,000
credit facility in a private placement transaction. This 8% convertible loan was
used to provide working capital pending the closing of the sale of Hybridon's
Hybridon Specialty Products (HSP) manufacturing operation. On September 30,
2000, two of the lenders, Dr. Paul Zamecnik and Dr. James Wyngaarden, elected to
convert their shares of the loan, including accrued interest, into shares of
Common Stock. Dr. Zamecnik converted $202,956 into 187,922 shares of Common
Stock. Dr. Wyngaarden converted $28,211 into 26,121 shares of Common Stock. The
portion of the loan owned by other lenders was repaid with interest.

(23) Hybridon agreed to issue to the $2,000,000 credit facility lenders
warrants to purchase 1,000,000 shares of Common Stock at a price of $1.08 per
share. Hybridon also agreed to issue warrants to purchase up to 500,000 shares
of Common Stock at a price of $1.08 per share to the representatives of the
lenders. The convertible loans made under the $2,000,000 credit facility and the
related warrants were offered and sold to "accredited investors" in reliance
upon the exemption from registration under Section 4(2) of the Securities Act
relating to sales by an issuer not involving any public offering.

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97

UNREGISTERED OFFERINGS PURSUANT TO REGULATION S UNDER THE SECURITIES ACT

The securities issued by Hybridon in each of the following transactions
were offered and sold in reliance upon an exemption from registration under
Regulation S promulgated under the Securities Act, relating to sales by an
issuer in offshore transactions (the "Regulation S Offerings"). The securities
issued in each of the following Regulation S Offerings were offered and sold
solely to persons who were "accredited investors" as that term is defined in
Regulation D promulgated under the Securities Act.

(21) On January 15, 1998, Hybridon commenced a private placement of units
(the "Units"), each Unit consisting of 14% Convertible Subordinated Notes Due
2007 (the "14% Notes") and warrants (the "Equity Warrants") to purchase shares
of Hybridon's Common Stock (the "14% Note Offering"). The 14% Notes were subject
to both mandatory and optional conversion into shares of Series B preferred
stock, under certain circumstances which, in turn, were convertible into Common
Stock (the "Series B Preferred Stock").

On January 23, 1998, as part of the 14% Note Offering, Hybridon sold
$2,230,000 in principal amount of 14% Notes and Equity Warrants.

On February 9, 1998, as part of the 14% Note Offering, Hybridon sold
$2,384,000 in principal amount of 14% Notes and Equity Warrants.

On March 27, 1998, as part of the 14% Note Offering, Hybridon sold $200,000
in principal amount of 14% Notes and Equity Warrants.

On April 21, 1998, as part of the 14% Note Offering, Hybridon sold $300,000
in principal amount of 14% Notes and Equity Warrants.

On April 24, 1998, as part of the 14% Note Offering, Hybridon sold
$1,020,000 in principal amount of 14% Notes and Equity Warrants.

In each of the above closings, the 14% Notes were issued at face value.

(22) On May 5, 1998, Hybridon closed a private placement of 3,223,000
shares of Common Stock and Class B warrants to purchase 805,750 shares of
Hybridon's Common Stock, subject to adjustment, for aggregate gross proceeds of
$6,446,000.

The Class B warrants are exercisable for a period of five years at $2.40
per share of Common Stock, subject to adjustment from time to time.

(23) Hybridon has exchanged all of the 14% Notes issued, including any
right to interest thereon, and all Equity Warrants issued together with the 14%
Notes, for 3,157,322 shares of Common Stock and Class B Warrants to purchase
947,195 shares of Common Stock.

The net proceeds to Hybridon from these offerings were used and continue to
be used for general corporate purposes, primarily research and product
development activities, including costs of preparing investigational new drug
applications and conducting preclinical studies and clinical trials, the payment
of payroll and other accounts payable and for debt service required under
Hybridon's debt obligations. The amounts actually expended by Hybridon and the
purposes of such expenditures may vary significantly depending upon numerous
factors, including the progress of Hybridon's research, drug discovery and
development programs, the results of preclinical studies and clinical trials,
the timing of regulatory approvals, sales of DNA products and reagents to third
parties manufactured on a custom contract basis by the HSP Division and margins
on such sales, technological advances, determinations as to the commercial
potential of Hybridon's compounds and the status of competitive products. In
addition, expenditures will also depend upon the establishment of collaborative
research arrangements with other companies, the availability of other financing
and other factors. Under certain circumstances, Hybridon may be required to use
net proceeds to repay indebtedness under its bank credit facility.

II-6

98

ITEM 16.  EXHIBITS AND FINANCIAL STATEMENT SCHEDULES

(a) Exhibits:

EXHIBIT INDEX

EXHIBIT NO.                           DESCRIPTION
-----------                           -----------

3.1(1)  Restated Certificate of Incorporation of the Registrant, as
amended.
3.2(2)  Amended and Restated Bylaws of the Registrant.
3.3(3)  Form of Certificate of Designation of Series A Preferred
Stock.
3.4(3)  Form of Certificate of Designation of Series B Preferred
Stock.
4.1(2)  Specimen Certificate for shares of Common Stock, $.001 par
value, of the Registrant.
4.2(4)  Indenture dated as of March 26, 1997 between Forum Capital
Markets LLC and the Registrant.
4.3(7)  Certificate of Designation of Series A Preferred Stock, par
value $.01 per share, dated May 5, 1998.
4.4(7)  Class A Warrant Agreement dated May 5, 1998.
4.5(7)  Class B Warrant Agreement dated May 5, 1998.
4.6(7)  Class C Warrant Agreement dated May 5, 1998.
4.7(7)  Class D Warrant Agreement dated May 5, 1998.
5.1     Opinion of Holland & Knight LLP with respect to validity of
the Securities being offered.
+10.1(2)  License Agreement dated February 21, 1990 and restated as of
September 8, 1993 between the Registrant and the Worcester
Foundation for Biomedical Research, Inc., as amended.
+10.2(2)  Patent License Agreement dated September 21, 1995 between
the Registrant and National Institutes of Health.
+10.3(2)  Patent License Agreement effective as of October 13, 1994
between the Registrant and McGill University.
+10.4(2)  License Agreement effective as of October 25, 1995 between
the Registrant and the General Hospital Corporation.
+10.5(2)  License Agreement dated as of October 30, 1995 between the
Registrant and Yoon S. Cho-Chung.
+10.6(2)  Collaborative Study Agreement effective as of December 30,
1992 between the Registrant and Medtronic, Inc.
+10.7(2)  System Design and Procurement Agreement dated as of December
16, 1994 between the Registrant and Pharmacia Biotech, Inc.
10.8(2)  Lease dated March 10, 1994 between the Registrant and
Laborer's Pension/Milford Investment Corporation for space
located at 155 Fortune Boulevard, Milford, Massachusetts,
including Note in the original principal amount of $750,000.
10.9(2)  Registration Rights Agreement dated as of February 21, 1990
between the Registrant, the Worcester Foundation for
Biomedical Research, Inc. and Paul C. Zamecnik.
10.10(2)  Registration Rights Agreement dated as of June 25, 1990
between the Registrant and Nigel L. Webb.
10.11(2)  Registration Rights Agreement dated as of February 6, 1992
between the Registrant and E. Andrews Grinstead, III.
10.12(2)  Registration Rights Agreement dated as of February 6, 1992
between the Registrant and Anthony J. Payne.
++10.13(2)  1990 Stock Option Plan, as amended.
++10.14(2)  1995 Stock Option Plan.

II-7

99

EXHIBIT NO.                           DESCRIPTION
-----------                           -----------

++10.15(2)  1995 Director Stock Plan.
++10.16(2)  1995 Employee Stock Purchase Plan.
10.17(2)  Form of Warrant originally issued to Pillar Investment
Limited to purchase shares of Common Stock issued as
placement commissions in connection with the sale of shares
of Series F Convertible Preferred Stock and in consideration
of financial advisory service, as amended.
10.18(2)  Warrant issued to Pillar S.A. to purchase 100,000 shares of
Common Stock dated as of March 1, 1994, as amended.
10.19(2)  Warrant issued to Pillar S.A. to purchase 100,000 shares of
Common Stock dated as of March 1, 1995.
10.20(2)  Form of Warrant issued to Pillar Investment Limited to
purchase shares of Common Stock issued as placement
commissions in connection with the sale of Units pursuant to
the Series G Agreement.
++10.21(5)  Employment Agreement dated as of March 1, 1997 between the
Registrant and E. Andrews Grinstead, III.
10.22(2)  Indemnification Agreement dated as of February 6, 1992
between the Registrant and E. Andrews Grinstead, III.
++10.23(6)  Employment Agreement dated March 1, 1997 between the
Registrant and Dr. Sudhir Agrawal.
++10.24(2)  Consulting Agreement dated as of February 21, 1990 between
the Registrant and Dr. Paul C. Zamecnik.
10.25(2)  Master Lease Agreement dated as of March 1, 1994 between the
Registrant and General Electric Capital Corporation.
+10.26(6)  Research, Development and License Agreement dated as of
January 24, 1996 between the Registrant and G.D. Searle &
Co.
+10.27(6)  Manufacturing and Supply Agreement dated as of January 24,
1996 between the Registrant and G.D. Searle & Co.
10.28(6)  Registration Rights Agreement dated as of January 24, 1996
between the Registrant and G.D. Searle & Co.
10.29(5)  Loan and Security Agreement dated as of December 31, 1996
between the Registrant and Silicon Valley Bank.
10.30(7)  First Amendment to Loan and Security Agreement dated March
30, 1998 between Hybridon, Inc. and Silicon Valley Bank.
10.31(8)  Second Amendment to Loan and Security Agreement dated May
19, 1998, effective as of April 30, 1998, between Hybridon,
Inc. and Silicon Valley Bank.
10.32(9)  Third Amendment to Loan and Security Agreement dated
September 18, 1998 between Hybridon, Inc. and Silicon Valley
Bank.
10.33(9)  Fourth Amendment to Loan and Security Agreement dated
October 30, 1998, effective as of September 29, 1998 between
Hybridon, Inc. and Silicon Valley Bank.
10.34(12) Fifth Amendment to Loan and Security Agreement dated
December 4, 1998 between Hybridon, Inc. and Silicon Valley
Bank.
10.35(5)  Warrant issued to Silicon Valley Bank to purchase 65,000
shares of Common Stock dated as of December 31, 1996.
10.36(5)  Registration Rights Agreement dated as of December 31, 1996
between the Registrant and Silicon Valley Bank.

II-8

100

EXHIBIT NO.                           DESCRIPTION
-----------                           -----------

+10.37(5)  Supply and Sales Agreement dated as of September 1, 1996
between the Registrant and P.E. Applied Biosystems.
10.38(2)  Registration Rights Agreement dated as of March 26, 1997
between Forum Capital Markets LLC and the Registrant.
10.39(2)  Warrant Agreement dated as of March 26, 1997 between Forum
Capital Markets LLC and the Registrant.
+10.40(6)  Amendment No. 1 to License Agreement, dated as of February
21, 1990 and restated as of September 8, 1993, by and
between the Worcester Foundation for Biomedical Research,
Inc. and the Registrant, dated as of November 26, 1996.
10.41(10) Letter Agreement dated May 12, 1997 between the Registrant
and Pillar S.A. amending the Consulting Agreement dated as
of March 1, 1994 between the Registrant and Pillar S.A.
10.42(10) Amendment dated July 15, 1997 to the Series G Convertible
Preferred Stock and Warrant Purchase Agreement dated as of
September 9, 1994 among the Registrant and certain
purchasers, as amended.
10.43(1)  Consent Agreement dated January 15, 1998 between Silicon
Valley Bank and the Registrant relating to the Silicon
Agreement.
10.44(11) Letter Agreement between the Registrant and Forum Capital
Markets LLC and Pecks Management Partners Ltd. for the
purchase of the Loan and Security Agreement with Silicon
Valley Bank.
10.45(7)  Financial Advisory Agreement between Registrant and Pillar
Investments Ltd. dated May 5, 1998.
10.46(7)  Placement Agency Agreement between Registrant and Pillar
Investments Ltd. dated as of January 15, 1998.
+++10.47(12) Licensing Agreement dated March 12, 1999 by and between
Hybridon, Inc. and Integrated DNA Technologies, Inc.
+++10.48(13) Licensing Agreement dated September 7, 1999 by and between
Hybridon, Inc. and Genzyme Corporation.
10.49(13) Form of loan agreement relating to a loan in the amount of
$454,901 made to Hybridon, Inc. in October 1999 by various
parties.
10.50(13) Form of promissory note relating to a loan in the amount of
$454,901 made to Hybridon, Inc. in October 1999 by various
parties.
10.51(13) Loan Agreement dated as of September 1, 1999, between
Hybridon, Inc. and E. Andrews Grinstead, III.
10.52(13) Term promissory note in the amount of $500,000 dated
September 1, 1999, by Hybridon, Inc. in favor of E. Andrews
Grinstead, III.
10.53(13) Term promissory note in the amount of $500,000 dated
September 27, 1999, by Hybridon, Inc. in favor of E. Andrews
Grinstead, III.
10.54(11) Subordination and Intercreditor Agreement by and among
Hybridon, the holders of Notes due 2002, Forum and entities
advised by Pecks, dated as of December 7, 1999.
10.55(11) Letter Agreement between Hybridon and Pillar Investments
dated December 10, 1999.
10.56(11) Form of Subscription Agreements dated as of December 13,
1999, by and among Hybridon and the purchasers of Notes due
2002.
10.57     First Amended and Restated Subordination and Intercreditor
Agreement by and among Hybridon, the holders of Notes due
2002, Forum and entities advised by Pecks.

II-9

101

EXHIBIT NO.                           DESCRIPTION
-----------                           -----------

10.58     License Agreement dated September 20, 2000 by and between
Hybridon and Boston Biosystems, Inc.
10.59     Assignment of Coexclusive License dated September 20, 2000
by and between Hybridon and the Public Health Service.
10.60     Oligonucleotide Purification Patent License Agreement dated
September 20, 2000 by and between Hybridon and Boston
Biosystems, Inc.
10.61(14) Asset Purchase Agreement dated June 29, 2000 by and between
Hybridon and Boston Biosystems, Inc.
+++10.62     Assignment of Patent Rights dated September 20, 2000 by and
between Hybridon and Boston Biosystems, Inc.
+++10.63     PNT Monomer Patent License and Option Agreement dated
September 20, 2000 by and between Hybridon and Boston
Biosystems, Inc.
+++10.64     Agreement Relating to Patents Forming Part of Acquired
Assets but to be Licensed Back to Hybridon for the Purposes
of OriGenix Agreements dated September 20, 2000 by and
between Hybridon and Boston Biosystems, Inc.
21.1(2)  Subsidiaries of the Registrant.
23.1     Consent of Arthur Andersen LLP.
23.2     Consent of Holland & Knight LLP (included in Exhibit 5).
23.2(11) Consent of McDonnell Boehnen Hulbert & Berghoff.
27.1     Financial Data Schedule [EDGAR] -- Nine Months Ended
September 30, 2000.
27.2     Financial Data Schedule [EDGAR] -- Restated.

---------------
(1) Incorporated by reference to Exhibits to the Registrant's Annual Report on
Form 10-K for the year ended December 31, 1997.

(2) Incorporated by reference to Exhibits to the Registrant's Registration
Statement on Form S-1 (File No. 33-99024).

(3) Incorporated by reference to Exhibit 9(a)(1) to the Registrant's Schedule
13E-4 dated February 6, 1998.

(4) Incorporated by reference to Exhibits to the Registrant's Current Report on
Form 8-K dated April 2, 1997.

(5) Incorporated by reference to Exhibits to the Registrant's Annual Report on
Form 10-K for the year ended December 31, 1996.

(6) Incorporated by reference to Exhibits to the Registrant's Annual Report on
Form 10-K for the year ended December 31, 1995.

(7) Incorporated by reference to Exhibits to the Registrant's Quarterly Report
on Form 10-Q for the period ended March 31, 1998.

(8) Incorporated by reference to Exhibits to the Registrant's Quarterly Report
on Form 10-Q for the period ended June 30, 1998.

(9) Incorporated by reference to Exhibits to the Registrant's Quarterly Report
on Form 10-Q for the period ended September 30, 1998.

(10) Incorporated by reference to Exhibits to the Registrant's Quarterly Report
on Form 10-Q for the period ended June 30, 1997.

(11) Incorporated by reference to Exhibits to the Registrant's Registration
Statement on Form S-1 (File No. 333-69649).

II-10

102

(12) Incorporated by reference to Exhibits to the Registrant's Annual Report on
Form 10-K for the year ended December 31, 1998.

(13) Incorporated by reference to Exhibits to the Registrant's Quarterly Report
on Form 10-Q for the period ended September 30, 1999.

(14)Incorporated by reference to the Registrant's Proxy Statement dated August
8, 2000.

+  Confidential treatment granted as to certain portions, which portions are
omitted and filed separately with the Commission.

++  Management contract or compensatory plan or arrangement required to be
filed as an Exhibit to the Annual Report on Form 10-K for the year ended
December 31, 1997.

+++  Confidential treatment requested as to certain portions, which portions are
omitted and filed separately with the Commission.

ITEM 17.  UNDERTAKINGS.

Insofar as indemnification for liabilities arising under the Securities Act
may be permitted to directors, officers and controlling persons of the
Registrant pursuant to provisions described in Item 14 above, or otherwise, the
Registrant has been advised that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as expressed in the
Securities Act and is, therefore, unenforceable. In the event that a claim for
indemnification against such liabilities (other than the payment by the
Registrant of expenses incurred or paid by a director, officer or controlling
person of the Registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, the Registrant will, unless in
the opinion of its counsel the matter has been settled by controlling precedent,
submit to a court of appropriate jurisdiction the question whether such
indemnification by it is against public policy as expressed in the Securities
Act and will be governed by the final adjudication of such issue.

The undersigned registrant hereby undertakes:

(1) To file, during any period in which offers or sales are being
made, a post-effective amendment to this Registration Statement;

(2) To include any Prospectus required by Section 10(a)(3) of the
Securities Act of 1933;

(3) To reflect in the Prospectus any facts or events arising after the
effective date of the Registration Statement (or the most recent
post-effective amendment thereof) which, individually or in the aggregate,
represent a fundamental change in the information set forth in the
Registration Statement. Notwithstanding the foregoing, any increase or
decrease in volume of Securities offered (if the total dollar value of
securities offered would not exceed that which was registered) and any
deviation from the low or high end of the estimated maximum offering range
may be reflected in the form of prospectus filed with the Commission
pursuant to Rule 424(b) if, in the aggregate, the changes in volume and
price represent no more than 20 percent change in the maximum aggregate
offering price set forth in the "Calculation of Registration Fee" table in
the effective registration statement;

(4) To include any material information with respect to the plan of
distribution not previously disclosed in the Registration Statement or any
material change to such information in the Registration Statement;

(5) That, for the purpose of determining any liability under the
Securities Act, each such post-effective amendment shall be deemed to be a
new Registration Statement relating to the Securities offered therein, and
the offering of such securities at that time shall be deemed to be the
initial bona fide offering thereof;

(6) To remove from registration by means of a post-effective amendment
any of the Securities being registered which remain unsold at the
termination of the offering.

II-11

103

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the
Registrant has duly caused this Registration Statement to be signed on its
behalf by the undersigned, thereunto duly authorized, on December 29, 2000.

HYBRIDON, INC.

By: /s/ SUDHIR AGRAWAL
------------------------------------
Sudhir Agrawal
President and Acting Chief
Executive Officer

Pursuant to the requirements of the Securities Act of 1933, as amended,
this Registration Statement has been signed by the following persons in the
capacities and on the dates indicated.

SIGNATURES                                                     TITLE(S)                    DATE
----------                                                     --------                    ----

/s/ SUDHIR AGRAWAL                                   President, Acting Chief         December 29, 2000
---------------------------------------------------  Executive Officer and
Dr. Sudhir Agrawal                                   Director

*                                                    Chairman and Director           December 29, 2000
---------------------------------------------------
Dr. James B. Wyngaarden

/s/ ROBERT G. ANDERSEN                               Chief Financial Officer and     December 29, 2000
---------------------------------------------------  Vice President of Operations
Mr. Robert G. Andersen                               and Planning

*                                                    Director                        December 29, 2000
---------------------------------------------------
Mr. Nasser Menhall

*                                                    Director                        December 29, 2000
---------------------------------------------------
Dr. Paul C. Zamecnik

*                                                    Director                        December 29, 2000
---------------------------------------------------
Mr. Youssef El-Zein

Director                        December   , 2000
---------------------------------------------------
Mr. Arthur W. Berry

Director                        December   , 2000
---------------------------------------------------
Mr. C. Keith Hartley

Director                        December   , 2000
---------------------------------------------------
Camille Chebeir

*By: /s/ ROBERT G. ANDERSEN
--------------------------------------------------
Robert G. Andersen
Attorney-in-fact

II-12

104

EXHIBIT INDEX

EXHIBIT NO.                           DESCRIPTION
-----------                           -----------

3.1(1)  Restated Certificate of Incorporation of the Registrant, as
amended.
3.2(2)  Amended and Restated Bylaws of the Registrant.
3.3(3)  Form of Certificate of Designation of Series A Preferred
Stock.
3.4(3)  Form of Certificate of Designation of Series B Preferred
Stock.
4.1(2)  Specimen Certificate for shares of Common Stock, $.001 par
value, of the Registrant.
4.2(4)  Indenture dated as of March 26, 1997 between Forum Capital
Markets LLC and the Registrant.
4.3(7)  Certificate of Designation of Series A Preferred Stock, par
value $.01 per share, dated May 5, 1998.
4.4(7)  Class A Warrant Agreement dated May 5, 1998.
4.5(7)  Class B Warrant Agreement dated May 5, 1998.
4.6(7)  Class C Warrant Agreement dated May 5, 1998.
4.7(7)  Class D Warrant Agreement dated May 5, 1998.
5.1     Opinion of Holland & Knight LLP with respect to validity of
the Securities being offered.
+10.1(2)  License Agreement dated February 21, 1990 and restated as of
September 8, 1993 between the Registrant and the Worcester
Foundation for Biomedical Research, Inc., as amended.
+10.2(2)  Patent License Agreement dated September 21, 1995 between
the Registrant and National Institutes of Health.
+10.3(2)  Patent License Agreement effective as of October 13, 1994
between the Registrant and McGill University.
+10.4(2)  License Agreement effective as of October 25, 1995 between
the Registrant and the General Hospital Corporation.
+10.5(2)  License Agreement dated as of October 30, 1995 between the
Registrant and Yoon S. Cho-Chung.
+10.6(2)  Collaborative Study Agreement effective as of December 30,
1992 between the Registrant and Medtronic, Inc.
+10.7(2)  System Design and Procurement Agreement dated as of December
16, 1994 between the Registrant and Pharmacia Biotech, Inc.
10.8(2)  Lease dated March 10, 1994 between the Registrant and
Laborer's Pension/Milford Investment Corporation for space
located at 155 Fortune Boulevard, Milford, Massachusetts,
including Note in the original principal amount of $750,000.
10.9(2)  Registration Rights Agreement dated as of February 21, 1990
between the Registrant, the Worcester Foundation for
Biomedical Research, Inc. and Paul C. Zamecnik.
10.10(2)  Registration Rights Agreement dated as of June 25, 1990
between the Registrant and Nigel L. Webb.
10.11(2)  Registration Rights Agreement dated as of February 6, 1992
between the Registrant and E. Andrews Grinstead, III.
10.12(2)  Registration Rights Agreement dated as of February 6, 1992
between the Registrant and Anthony J. Payne.
++10.13(2)  1990 Stock Option Plan, as amended.
++10.14(2)  1995 Stock Option Plan.
++10.15(2)  1995 Director Stock Plan.
++10.16(2)  1995 Employee Stock Purchase Plan.

II-13

105

EXHIBIT NO.                           DESCRIPTION
-----------                           -----------

10.17(2)  Form of Warrant originally issued to Pillar Investment
Limited to purchase shares of Common Stock issued as
placement commissions in connection with the sale of shares
of Series F Convertible Preferred Stock and in consideration
of financial advisory service, as amended.
10.18(2)  Warrant issued to Pillar S.A. to purchase 100,000 shares of
Common Stock dated as of March 1, 1994, as amended.
10.19(2)  Warrant issued to Pillar S.A. to purchase 100,000 shares of
Common Stock dated as of March 1, 1995.
10.20(2)  Form of Warrant issued to Pillar Investment Limited to
purchase shares of Common Stock issued as placement
commissions in connection with the sale of Units pursuant to
the Series G Agreement.
++10.21(5)  Employment Agreement dated as of March 1, 1997 between the
Registrant and E. Andrews Grinstead, III.
10.22(2)  Indemnification Agreement dated as of February 6, 1992
between the Registrant and E. Andrews Grinstead, III.
++10.23(6)  Employment Agreement dated March 1, 1997 between the
Registrant and Dr. Sudhir Agrawal.
++10.24(2)  Consulting Agreement dated as of February 21, 1990 between
the Registrant and Dr. Paul C. Zamecnik.
10.25(2)  Master Lease Agreement dated as of March 1, 1994 between the
Registrant and General Electric Capital Corporation.
+10.26(6)  Research, Development and License Agreement dated as of
January 24, 1996 between the Registrant and G.D. Searle &
Co.
+10.27(6)  Manufacturing and Supply Agreement dated as of January 24,
1996 between the Registrant and G.D. Searle & Co.
10.28(6)  Registration Rights Agreement dated as of January 24, 1996
between the Registrant and G.D. Searle & Co.
10.29(5)  Loan and Security Agreement dated as of December 31, 1996
between the Registrant and Silicon Valley Bank.
10.30(7)  First Amendment to Loan and Security Agreement dated March
30, 1998 between Hybridon, Inc. and Silicon Valley Bank.
10.31(8)  Second Amendment to Loan and Security Agreement dated May
19, 1998, effective as of April 30, 1998, between Hybridon,
Inc. and Silicon Valley Bank.
10.32(9)  Third Amendment to Loan and Security Agreement dated
September 18, 1998 between Hybridon, Inc. and Silicon Valley
Bank.
10.33(9)  Fourth Amendment to Loan and Security Agreement dated
October 30, 1998, effective as of September 29, 1998 between
Hybridon, Inc. and Silicon Valley Bank.
10.34(12) Fifth Amendment to Loan and Security Agreement dated
December 4, 1998 between Hybridon, Inc. and Silicon Valley
Bank.
10.35(5)  Warrant issued to Silicon Valley Bank to purchase 65,000
shares of Common Stock dated as of December 31, 1996.
10.36(5)  Registration Rights Agreement dated as of December 31, 1996
between the Registrant and Silicon Valley Bank.
+10.37(5)  Supply and Sales Agreement dated as of September 1, 1996
between the Registrant and P.E. Applied Biosystems.

II-14

106

EXHIBIT NO.                           DESCRIPTION
-----------                           -----------

10.38(2)  Registration Rights Agreement dated as of March 26, 1997
between Forum Capital Markets LLC and the Registrant.
10.39(2)  Warrant Agreement dated as of March 26, 1997 between Forum
Capital Markets LLC and the Registrant.
+10.40(6)  Amendment No. 1 to License Agreement, dated as of February
21, 1990 and restated as of September 8, 1993, by and
between the Worcester Foundation for Biomedical Research,
Inc. and the Registrant, dated as of November 26, 1996.
10.41(10) Letter Agreement dated May 12, 1997 between the Registrant
and Pillar S.A. amending the Consulting Agreement dated as
of March 1, 1994 between the Registrant and Pillar S.A.
10.42(10) Amendment dated July 15, 1997 to the Series G Convertible
Preferred Stock and Warrant Purchase Agreement dated as of
September 9, 1994 among the Registrant and certain
purchasers, as amended.
10.43(1)  Consent Agreement dated January 15, 1998 between Silicon
Valley Bank and the Registrant relating to the Silicon
Agreement.
10.44(11) Letter Agreement between the Registrant and Forum Capital
Markets LLC and Pecks Management Partners Ltd. for the
purchase of the Loan and Security Agreement with Silicon
Valley Bank.
10.45(7)  Financial Advisory Agreement between Registrant and Pillar
Investments Ltd. dated May 5, 1998.
10.46(7)  Placement Agency Agreement between Registrant and Pillar
Investments Ltd. dated as of January 15, 1998.
+++10.47(12) Licensing Agreement dated March 12, 1999 by and between
Hybridon, Inc. and Integrated DNA Technologies, Inc.
+++10.48(13) Licensing Agreement dated September 7, 1999 by and between
Hybridon, Inc. and Genzyme Corporation.
10.49(13) Form of loan agreement relating to a loan in the amount of
$454,901 made to Hybridon, Inc. in October 1999 by various
parties.
10.50(13) Form of promissory note relating to a loan in the amount of
$454,901 made to Hybridon, Inc. in October 1999 by various
parties.
10.51(13) Loan Agreement dated as of September 1, 1999, between
Hybridon, Inc. and E. Andrews Grinstead, III.
10.52(13) Term promissory note in the amount of $500,000 dated
September 1, 1999, by Hybridon, Inc. in favor of E. Andrews
Grinstead, III.
10.53(13) Term promissory note in the amount of $500,000 dated
September 27, 1999, by Hybridon, Inc. in favor of E. Andrews
Grinstead, III.
10.54(11) Subordination and Intercreditor Agreement by and among
Hybridon, the holders of Notes due 2002, Forum and entities
advised by Pecks, dated as of December 7, 1999.
10.55(11) Letter Agreement between Hybridon and Pillar Investments
dated December 10, 1999.
10.56(11) Form of Subscription Agreements dated as of December 13,
1999, by and among Hybridon and the purchasers of Notes due
2002.
10.57     First Amended and Restated Subordination and Intercreditor
Agreement by and among Hybridon, the holders of Notes due
2002, Forum and entities advised by Pecks.
10.58     License Agreement dated September 20, 2000 by and between
Hybridon and Boston Biosystems, Inc.

II-15

107

EXHIBIT NO.                           DESCRIPTION
-----------                           -----------

10.59     Assignment of Coexclusive License dated September 20, 2000
by and between Hybridon and the Public Health Service.
10.60     Oligonucleotide Purification Patent License Agreement dated
September 20, 2000 by and between Hybridon and Boston
Biosystems, Inc.
10.61(14) Asset Purchase Agreement dated June 29, 2000 by and between
Hybridon and Boston Biosystems, Inc.
+++10.62     Assignment of Patent Rights dated September 20, 2000 by and
between Hybridon and Boston Biosystems, Inc.
+++10.63     PNT Monomer Patent License and Option Agreement dated
September 20, 2000 by and between Hybridon and Boston
Biosystems, Inc.
+++10.64     Agreement Relating to Patents Forming Part of Acquired
Assets but to be Licensed Back to Hybridon for the Purposes
of OriGenix Agreements dated September 20, 2000 by and
between Hybridon and Boston Biosystems, Inc.
21.1(2)  Subsidiaries of the Registrant.
23.1     Consent of Arthur Andersen LLP.
23.2     Consent of Holland & Knight LLP (included in Exhibit 5).
23.2(11) Consent of McDonnell Boehnen Hulbert & Berghoff.
27.1     Financial Data Schedule [EDGAR] -- Nine Months Ended
September 30, 2000.
27.2     Financial Data Schedule [EDGAR] -- Restated.

---------------
(1) Incorporated by reference to Exhibits to the Registrant's Annual Report on
Form 10-K for the year ended December 31, 1997.

(2) Incorporated by reference to Exhibits to the Registrant's Registration
Statement on Form S-1 (File No. 33-99024).

(3) Incorporated by reference to Exhibit 9(a)(1) to the Registrant's Schedule
13E-4 dated February 6, 1998.

(4) Incorporated by reference to Exhibits to the Registrant's Current Report on
Form 8-K dated April 2, 1997.

(5) Incorporated by reference to Exhibits to the Registrant's Annual Report on
Form 10-K for the year ended December 31, 1996.

(6) Incorporated by reference to Exhibits to the Registrant's Annual Report on
Form 10-K for the year ended December 31, 1995.

(7) Incorporated by reference to Exhibits to the Registrant's Quarterly Report
on Form 10-Q for the period ended March 31, 1998.

(8) Incorporated by reference to Exhibits to the Registrant's Quarterly Report
on Form 10-Q for the period ended June 30, 1998.

(9) Incorporated by reference to Exhibits to the Registrant's Quarterly Report
on Form 10-Q for the period ended September 30, 1998.

(10) Incorporated by reference to Exhibits to the Registrant's Quarterly Report
on Form 10-Q for the period ended June 30, 1997.

(11) Incorporated by reference to Exhibits to the Registrant's Registration
Statement on Form S-1 (File No. 333-69649).

(12) Incorporated by reference to Exhibits to the Registrant's Annual Report on
Form 10-K for the year ended December 31, 1998.

II-16

108

(13) Incorporated by reference to Exhibits to the Registrant's Quarterly Report
on Form 10-Q for the period ended September 30, 1999.

(14) Incorporated by reference to Exhibits to the Registrant's Proxy Statement
dated August 8, 2000.

+  Confidential treatment granted as to certain portions, which portions are
omitted and filed separately with the Commission.

++  Management contract or compensatory plan or arrangement required to be
filed as an Exhibit to the Annual Report on Form 10-K for the year ended
December 31, 1997.

+++  Confidential treatment requested as to certain portions, which portions are
omitted and filed separately with the Commission.

II-17

1
EXHIBIT 5.1

HOLLAND & KNIGHT, LLP
ONE BEACON STREET
BOSTON, MA 02108

December 28, 2000

Hybridon, Inc.
345 Vassar Street
Cambridge, MA 02139

Amendment No. 3 to Registration Statement on Form S-1

Ladies and Gentlemen:

We have acted as counsel to Hybridon, Inc., a Delaware
corporation (the "Company"), in connection with the preparation and filing of
Amendment No. 3 to Registration Statement on Form S-1 (the "Registration
Statement") with the Securities and Exchange Commission (the "Commission"), with
respect to the registration for resale under the Securities Act of 1933, as
amended (the "Act"), of up to 724,295 shares of the Company's Series A preferred
stock, par value $.01 per share, and up to 59,387,918 shares of the Company's
common stock, par value $.01 per share (collectively, the "Shares"), issued by
the Company to the selling shareholders named in the Registration Statement.

In connection with the registration of the Shares, we have
reviewed such documents and records as we have deemed necessary to enable us to
express an opinion on the matters covered hereby. In rendering this opinion, we
have (a) assumed (i) the genuineness of all signatures on all documents examined
by us, (ii) the authenticity of all documents submitted to us as originals, and
(iii) the conformity to original documents of all documents submitted to us as
photostatic or conformed copies and the authenticity of the originals of such
copies, and (b) relied on (i) certificates of public officials and (ii) as to
matters of fact, statements and certificates of officers and representatives of
the Company.

Based upon the foregoing, we are of the opinion that the
Shares have been validly issued and are fully paid and non-assessable.

We hereby consent to the use of this opinion as an exhibit to
the Registration Statement. In giving the foregoing consent, we do not thereby
admit that we are in the category of persons whose consent is required under
Section 7 of the Act or the rules and regulations of the Commission thereunder.

Very truly yours,

/s/ Holland & Knight, LLP

1

Exhibit 10.57

FIRST AMENDED AND RESTATED 
SUBORDINATION AND INTERCREDITOR AGREEMENT

THIS FIRST AMENDED AND RESTATED SUBORDINATION AND INTERCREDITOR
AGREEMENT (this "AGREEMENT") is effective as of June ____, 2000 (the "EFFECTIVE
DATE") by and among Hybridon, Inc., a Delaware corporation ("BORROWER"), those
persons who from time to time hold the 8% senior notes (described herein) of the
Borrower due November 30, 2002 (collectively, the "SENIOR NOTEHOLDERS"), those
persons who have executed as lenders that certain Line of Credit and Security
Agreement (the "JUNE LOAN AGREEMENT"), dated as of June ____, 2000, between such
lenders and Borrower (collectively, the "SENIOR LENDERS", and together with the
Senior Noteholders, the "SENIOR SECURITY HOLDERS"), and Founders Financial Group
("FOUNDERS"), Delaware State Employees Retirement Fund, Declaration of Trust for
the Defined Benefit Plans of ICI American Holdings Inc., Declaration of Trust
for the Defined Benefit Plans of Zeneca Holdings Inc., The J.W. McConnell Family
Foundation and General Motors Employees Domestic Group Trust (said trusts,
foundation and fund being referred to collectively as the "PECKS PARTIES";
Founders and the Pecks Parties are collectively referred to as the "SUBORDINATE
LENDERS"). This Agreement amends and restates that certain Subordination and
Intercreditor Agreement, effective as of December 7, 1999, by and among the
Borrower, the Senior Noteholders and the Subordinate Lenders (the "ORIGINAL
AGREEMENT").

RECITALS:

A. Senior Security Holders have agreed to extend financial
accommodations to Borrower pursuant to the terms of the Senior Loan Documents
(defined below).

B. Subordinate Lenders are also shareholders of Borrower and have
representatives on Borrower's Board of Directors.

C. As of December 31, 1996, Borrower entered into a non-revolving term
loan with Silicon Valley Bank (the "BANK") which was evidenced, in part, by that
certain Loan and Security Agreement dated as of December 31, 1996 (the
"SUBORDINATE LOAN AGREEMENT").

D. As security for the financial accommodations made pursuant to the
Subordinate Loan Agreement, Borrower granted to Bank a security interest in
certain assets of Borrower described more fully in the Subordinate Loan
Agreement and herein.

E. Founders is the succeessor in interest to an investment portfolio
formerly held by Forum Capital Markets, LLC ("FORUM"). On or about November 20,
1998, Forum and the Pecks Parties purchased the interests of Bank in credit
facility evidenced and secured by the Subordinate Loan Agreement and the
Subordinate Loan Documents (defined herein).

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F. When the Senior Noteholders made their advances to the Borrower,
they required that Borrower and Subordinate Lenders agree to subordinate certain
obligations of Borrower to Subordinate Lenders. To reflect that agreement,
Senior Noteholders, Forum and the Pecks Parties entered into the Original
Agreement.

F. Borrower wishes to enter into an agreement with Boston Biosystems,
Inc. ("BBI"), to sell to BBI certain of Borrower's assets (the "TRANSFERRED
ASSETS") which are the subject of liens and security interests held by the
Senior Security Holders and the Subordinate Lenders upon terms and under
conditions set forth in an Asset Purchase Agreement between Borrower and BBI
(the "BBI TRANSACTION").

G. To close the BBI Transaction, Borrower wishes to obtain from the
Senior Security Holders and the Subordinate Lenders a release of the Senior
Security Holders' and the Subordinate Lenders' entire respective right, title
and interest in and to their security interests in the Transferred Assets.

H. As a condition to making their financial accommodations, Senior
Lenders have required, and the Borrower, Senior Noteholders and Subordinate
Lenders have agreed, that the obligations of Borrower to Subordinate Lenders be
further subordinated, that the Borrower's obligations to the Senior Lender's be
pari passu with its obligations to the Senior Noteholders and that other
processes be agreed to, as more fully set forth herein.

NOW, THEREFORE, in consideration of the foregoing Recitals and the
mutual covenants and agreements set forth herein, and for other good and
valuable consideration, the mutuality, receipt and sufficiency of which hereby
are acknowledged, and intending to be legally bound, the parties hereto agree as
follows:

1.       DEFINITIONS.

Certain terms used herein and not otherwise defined (including capitalized terms
used in the foregoing Recitals) shall have the following meanings:

An "ACCELERATION" shall mean the occurrence of any acceleration of the
principal and interest under any of the Borrower Obligations.

"BORROWER'S PUBLIC FILINGS" shall mean the periodic filings on Forms
10-K, 10-Q and 8-K, as filed from time to time with the U.S. Securities and
Exchange Commission.

"BORROWER OBLIGATIONS" means the Senior Obligations or the Subordinate
Obligations, as the context requires.

"COMMITTEE EVENT" shall have the meaning set forth in Section 2.2(a).

"DEFAULT" shall mean any Default or "default" under and as defined in
the Senior Loan Documents or the Subordinate Loan Documents, as the context
requires.

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"EVENT OF DEFAULT" means any Senior Event of Default or Subordinate
Event of Default, as the context requires.

"FOUNDERS REPRESENTATIVE" means Harold L. Purkey, or a successor chosen
by Founders.

"LENDERS COMMITTEE" shall have the meaning set forth in Section 2.2(a).

"PAYMENT IN FULL" or "PAID IN FULL" or any similar term(s) with respect
to any Borrower Obligation means (a) the indefeasible satisfaction and final
payment in full of such Borrower Obligation in cash or cash equivalents
reasonably acceptable to the payee and the termination of any obligation on the
part of the holder of such Borrower Obligation to make any loans or to afford
any financial accommodation to Borrower and the full and timely performance of
all other obligations to the holder of such Borrower Obligation or (b) in the
case of any Borrower Obligation consisting of contingent obligations (including
without limitation contingent obligations in respect of letters of credit or
other indemnifications under the Subordinate Loan Documents), the setting apart
of cash sufficient to discharge such portion of such Borrower Obligation in an
account for the exclusive benefit of the holders thereof, in which account such
holders shall be granted by Borrower a first priority perfected security
interest in a manner acceptable to such holders, which payment or perfected
security interest shall have been retained by the holders, in the case of each
of (a) and (b) above, for a period of time in excess of all applicable
preference or other similar periods under applicable bankruptcy, insolvency or
creditors' rights laws.

"PECKS REPRESENTATIVE" means Arthur W. Berry or a successor chosen by
the holders of a majority of the interests held by the Pecks Parties.

"REMEDY NOTIFICATION" means the written notification by Subordinate
Lenders to Senior Noteholders and/or Senior Lenders or by Senior Noteholders
and/or Senior Lenders to Subordinate Lenders of such party's desire to exercise
a Remedy following the occurrence of an Event of Default.

"REMEDY" means any the following actions by either Senior Lenders or
Subordinate Lenders:

(i) the exercise of any rights or remedies they may have under the
Subordinate Loan Documents or otherwise (other than a declaration of an
Acceleration);

(ii) the commencement or joinder with any other creditors of Borrower
in commencing any bankruptcy, reorganization, receivership or insolvency
proceeding against Borrower; or

(iii) the commencement of any action or proceeding against Borrower to
enforce or collect any Borrower Obligation, to obtain possession of
property of Borrower, to exercise control over property of Borrower or to
create, perfect or enforce any lien against property of Borrower.

3

4
"SENIOR EVENT OF DEFAULT" means any Event of Default under and as
defined in the Senior Loan Documents.

"SENIOR SECURITY HOLDERS' REPRESENTATIVE" means Youssef El-Zein (a
representative designated by Pillar Investments Ltd.) or a successor
representative chosen by the holders of a majority (measured by dollar amount)
of the Senior Obligations, outstanding from time to time.

"SENIOR LOAN DOCUMENTS" means (i) the Borrower's 8% notes, due November
30, 2002, issued to Senior Noteholders, (ii) the Subscription Agreements between
Borrower and each Senior Noteholder, (iii) the Warrant Agreements between
Borrower and the Senior Noteholders, (iv) the Line of Credit and Security
Agreement, dated as of June ____, 2000, between the Senior Lenders and Borrower
(the "Line of Credit"), and (v) all other instruments, agreements and documents
which create, evidence or secure the Senior Obligations from time to time
(including but not limited to any promissory notes, security agreements, pledge
agreements, hypothecation agreements, mortgages, financing statements, and all
other agreements of any type whatsoever), delivered by Borrower to Senior
Lenders, as such may be amended, modified, supplemented, restated, replaced or
refinanced (in any such case with any Senior Lender) from time to time,
including all such extensions, renewals, refinancings or refundings thereof,
whether or not the principal amount is increased.

"SENIOR OBLIGATIONS" means all obligations of the Borrower under the
Senior Loan Documents including but not limited to principal, interest, fees and
all other amounts owing to Senior Lenders under the Senior Loan Documents, from
time to time. Notwithstanding the foregoing, the Senior Obligations shall not
include any principal owed by the Borrower to the Senior Lenders in excess of
$10,000,000 except with the consent of the Senior Security Holders'
Representative and the Subordinate Lenders' Representatives.

"SUBORDINATE DEBT" means all principal, interest, fees and other
amounts owing to Subordinate Lenders under the Subordinate Loan Documents from
time to time, whether in respect of principal, interest or otherwise.

"SUBORDINATE EVENT OF DEFAULT" means any Event of Default under and as
defined in the Subordinate Loan Documents.

"SUBORDINATE LENDERS' REPRESENTATIVES" shall mean the Pecks
Representative and the Founders Representative.

"SUBORDINATE LOAN AGREEMENT" shall have the meaning set forth in the
Recitals.

"SUBORDINATE LOAN DOCUMENTS" means Subordinate Loan Agreement and all
other instruments, agreements and documents which create, evidence or secure the
Subordinate Obligations from time to time.

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"SUBORDINATE OBLIGATIONS" means all obligations of Borrower under the
Subordinate Loan Documents including but not limited to principal, interest,
fees and all other amounts owing to Subordinate Lenders under the Subordinate
Loan Documents, from time to time.

2.       SUBORDINATION AND INTERCREDITOR PROVISIONS.

2.1.     Subordination.

(a) Subordinate Lenders hereby consent to Borrower obtaining certain
financial accommodations from Senior Security Holders, all on a senior secured
basis.

(b) Senior Security Holders hereby acknowledge that Subordinate Lenders
have been previously granted a security interest in certain of the assets of
Borrower. Subordinate Lenders hereby acknowledge and agree that they are willing
to and hereby do subordinate the Subordinate Obligations and the collateral
securing such obligations to the Senior Obligations.

(c) Borrower and Subordinate Lenders each hereby represents and
warrants to Senior Security Holders that a true, accurate and complete copy of
all Subordinate Loan Documents has been either filed as an exhibit to Borrower's
Public Filings or otherwise provided to Senior Security Holders' Representative
or its counsel in writing, and that none of the Subordinate Loan Documents has
been amended or modified in any way from the versions so filed or provided.

(d) Subordinate Lenders agree, for themselves and each future holder of
the Subordinate Obligations, that: (i) subject to the terms hereof, the
Subordinate Debt is and shall be expressly subordinate and junior in right of
payment to all Senior Obligations until the Senior Obligations have been Paid in
Full; (ii) Subordinate Lenders shall not accept additional security or further
collateral to support the payment or performance of the Subordinate Debt, unless
the Senior Security Holders are granted a lien or security interest in such
additional collateral, and such lien or security interest in favor of Senior
Security Holders is senior to the lien of the Subordinate Lenders; and (iii)
Senior Security Holders have advanced funds in reliance upon the subordination
of the Subordinate Debt and the collateral securing such debt to the Senior
Obligations.

2.2.     Lenders Committee.

(a) Senior Security Holders and Subordinate Lenders hereby agree to
constitute a "LENDERS COMMITTEE" immediately upon the first to occur of the
following: (i) the occurrence of an Acceleration, or (ii) the occurrence of a
Remedy Notification (a "COMMITTEE EVENT").

(b) The Lenders Committee shall have three members which shall be
comprised of the Senior Security Holders' Representative and the two Subordinate
Lenders' Representatives. Any matter which, under the terms of this Agreement or
otherwise, requires a vote or action by the Lenders Committee, shall require the
affirmative votes of a majority of the members of the Lenders Committee.

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6
(c) From and after its formation following a Committee Event, the
Lenders Committee shall be charged solely with liquidating any collateral held
by any of the Senior Security Holders or Subordinate Lenders by obtaining
possession of or exerting control over such collateral, and perfecting or
enforcing liens of the Senior Security Holders and the Subordinate Lenders
against such collateral. Borrower and the Lenders Committee shall disburse any
proceeds of such liquidation according to the priorities set by this Agreement.

(d) From and after any Event of Default, neither Senior Security
Holders nor Subordinate Lenders may exercise a Remedy without first providing
not less that ten (10) days advance written notice to the other Lenders of its
desire to so exercise a Remedy (the "REMEDY NOTIFICATION"). Subsequent to the
delivery of the Remedy Notification and the resulting formation of the Lenders
Committee, then, until the date the Senior Obligations are Paid in Full,
Subordinate Lenders shall not exercise any Remedy without either (a) direction
or approval by the Lenders Committee or (b) express approval provided herein.
Similarly, at any time prior to the date the Subordinate Obligations are Paid in
Full, Senior Security Holders shall not exercise any Remedy, without either (a)
direction or approval by the Lenders Committee or (b) express approval provided
herein.

(e) If any insolvency, bankruptcy, receivership, liquidation,
reorganization or other similar proceedings are commenced by or against Borrower
or its property, if any proceedings for involuntary liquidation, dissolution or
other winding up of Borrower whether or not involving insolvency or bankruptcy
are commenced by or against Borrower (collectively, any "REORGANIZATION
PROCEEDINGS"), then Senior Security Holders shall be entitled in any such
Reorganization Proceedings to receive Payment in Full of all Senior Obligations
before Subordinate Lenders are entitled in any the Reorganization Proceedings to
receive any payment on account of the Subordinate Obligations. In any
Reorganization Proceedings, any payment or distribution of any kind or
character, whether in cash or in property to which Subordinate Lenders would be
entitled on account of the Subordinate Obligations but for the provisions of
this Agreement, shall be delivered to Senior Security Holders to the extent
necessary to make Payment in Full of all Senior Obligations remaining unpaid,
after giving effect to any concurrent payment or distribution to or for Senior
Security Holders in respect thereof. Subject to the Payment-in-Full of all
Senior Obligations, the holders of Subordinate Obligations shall be subrogated
to the rights of the holders of the Senior Obligations (to the extent of
payments or distributions made to holders of Senior Obligations pursuant to the
foregoing sentence or Section 2.3(b)) to receive payments or distributions of
the assets of Borrower applicable to the Senior Obligations. No such payments or
distributions applicable to the Senior Obligations shall, as between Borrower
and its creditors, other than the holders of Borrower Obligations, be deemed to
be a payment by Borrower to or on account of the Subordinate Obligations; and
for the purposes of such subrogation, no payments or distributions to the
holders of Senior Obligations to which the holders of Subordinate Obligations
would be entitled except for the provisions of this section shall, as between
Borrower and its creditors, other than the holders of Borrower Obligations, be
deemed to be a payment by Borrower to or on account of the Senior Obligations.

(f) Notwithstanding anything to the contrary contained herein,
Subordinate Lenders may, in any proceedings described in Section 2.2 (e), in the
name of Subordinate Lenders, file claims, proofs of claims and other instruments
of similar character necessary to enforce the 

6

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obligations of Borrower in respect of the Subordinate Obligations.
Notwithstanding anything to the contrary contained herein, Senior Security
Holders may, in any proceedings described in Section 2.2 (e), in the name of
Senior Security Holders, file claims, proofs of claims and other instruments of
similar character necessary to enforce the obligations of Borrower in respect of
the Senior Obligations. Neither this Section 2.2(f) nor any other provision
hereof shall be construed to give Subordinate Lenders any right to vote any
Borrower Obligation held by Senior Security Holders, any related claim or any
portion of such claim, whether in connection with any resolution, arrangement,
plan or reorganization, compromise, settlement, election of trustees or
otherwise, all such votes, as to Senior Obligations to be made solely on the
direction of the Senior Security Holders. Neither this Section 2.2(f) nor any
other provision hereof shall be construed to give Senior Security Holders any
right to vote any Borrower Obligation held by Subordinate Lenders, any related
claim or any portion of such claim, whether in connection with any resolution,
arrangement, plan or reorganization, compromise, settlement, election of
trustees or otherwise, all such votes, as to Subordinate Obligations to be made
solely on the direction of the Subordinate Security Holders.

2.3.     Payments of Borrower Obligations.

(a) The following provisions shall govern Subordinate Lenders' right to
receive and Borrower's right and obligation to pay any amount due and owing
under the Subordinate Loan Documents:

(i) Provided that the Subordinate Lenders' Representatives
shall not have been notified that an Acceleration shall have
occurred and be continuing or would be created thereby under
the terms of any of the Senior Loan Documents, Subordinate
Lenders may receive and Borrower may pay interest only at the
interest rate set forth in the Subordinate Loan Documents as
of the Effective Date, when due and owing on an unaccelerated
basis and not at a rate applicable upon default.

(ii) Except as expressly permitted pursuant to Section
2.3(a)(i), Subordinate Lenders shall not be entitled to
receive or retain any direct or indirect payment (in cash,
cash-equivalents, property, by set-off or otherwise) of or on
account of any Subordinate Obligation at any time prior to
Payment in Full of the Senior Obligations; provided, however,
Borrower may deliver to Subordinate Lenders' Representatives,
at any time (including during the occurrence of an Event of
Default under any of the Senior Loan Documents and/or the
Subordinate Loan Documents), the proceeds from the sale of
Subordinate Lender's Collateral, which sale shall be made in a
manner directed or approved by the Lenders Committee. Except
as expressly permitted pursuant to Section 2.3(a)(i) and (ii),
at any time that any of the Senior Obligations is outstanding,
Borrower shall not make and Subordinate Lenders shall not
receive or accept any payment (in cash, cash-equivalents,
property, by set-off, "bid in" of debt in a disposition of
collateral or otherwise) of any kind or nature with respect to
the Subordinate Obligations.

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(b) If Subordinate Lenders receive any payment with respect to the
Subordinate Obligations which Subordinate Lenders are not permitted to receive
and retain pursuant to this Agreement, then such payment shall be held in trust
for the benefit of, and shall be paid over promptly to Senior Security Holders,
for application to the payment of the Senior Obligations, in such order of
priority as Senior Security Holders' Representative shall determine. If
Subordinate Lenders pay over any payment or distribution as provided above, then
such payment or distribution shall be deemed to have been made by Borrower
directly to Senior Security Holders and not to Subordinate Lenders and no
Subordinate Obligation shall be discharged by reason of its receipt of any
payment or distribution which is so paid over to Senior Security Holders.

(c) To the extent necessary for Senior Security Holders to realize the
benefits of the subordination of the Subordinate Obligations provided for
herein, Subordinate Lenders shall execute and deliver to Senior Security
Holders' Representative such instruments or documents (together with such
assignments or endorsements as Senior Security Holders shall deem necessary), as
are consistent with the terms of this Agreement and are reasonably requested by
Senior Security Holders' Representative.

(d) In the event Subordinate Lenders at any time incur any obligation
to pay money to Borrower, Subordinate Lenders hereby irrevocably agree that they
shall pay such obligation in cash or cash equivalents in accordance with the
terms of the document or instrument governing such obligation without deduction
or set-off against the Subordinate Obligations.

2.4. Borrower's Obligations Absolute. The provisions of this Agreement
are solely for the benefit of Borrower, Senior Security Holders and Subordinate
Lenders for the purpose of defining the relative rights of the parties thereto.
Nothing herein shall impair, as between Borrower and any other party hereto, the
obligations of Borrower, which are unconditional and absolute, to Senior
Security Holders and to Subordinate Lenders, respectively.

2.5. Transfers. Any Senior Security Holder or any Subordinate Lender
may sell, assign or otherwise transfer, in whole or in part, any of the Borrower
Obligations or any interest therein to any other person or entity, but only on
the express condition that the transferee of the Borrower Obligations shall
expressly acknowledge to the other parties to this Agreement, in writing, that
it agrees to be bound by all of the terms hereof. Senior Security Holders and
Subordinate Lenders each hereby represents and warrants to the others that as of
the execution date hereof neither Senior Security Holders nor Subordinate
Lenders has transferred or entered into any agreement or understanding with a
proposed transferee that they will transfer any of the Borrower Obligations.

2.6. Liens Subordinate. (a) Subordinate Lenders agree that any liens
upon Borrower's assets securing payment of the Subordinated Debt, now or
hereafter existing, are and shall be and remain inferior and subordinate to any
liens securing payment of the Senior Obligations regardless of whether such
encumbrances in favor of the Subordinated Lenders or Senior Security Holders
presently exist or are hereafter created or attach.

(b) Senior Security Holders and Subordinate Lenders hereby agree that,
after the Lenders Committee is constituted, the Lenders Committee may file any
or all lien releases, UCC 

8

9
releases, and termination statements on behalf of the Senior Security Holders
and the Subordinate Lenders at any time Borrower, or any successor, assign or
agent of Borrower, proposes a sale of any asset that is approved by the Lenders
Committee. In furtherance thereof, the Senior Security Holders and the
Subordinate Lenders agree to execute, acknowledge and deliver any lien releases,
UCC-3 termination statements or such additional instruments or documents as may
be reasonably necessary to confirm the foregoing within three (3) business days
of the request therefor by Lenders Committee.

2.7. Additional Representations and Warranties. Subordinate Lenders and
Borrower represent and warrant to Senior Security Holders that:

(a) as of the date hereof, the total principal amount of the
Subordinate Obligations is $_______________ plus accrued but unpaid interest;

(b) except as indicated in Borrower's Public Filings or disclosed in
writing to the Senior Security Holders' Representative and its counsel, which
writing is hereby made a part hereof, as of the date hereof, to the best of
their knowledge, after due enquiry, no default or Event of Default, or event
which with notice or passage of time or both would constitute an Event of
Default exists or has occurred under the Subordinate Loan Documents;

(c) Subordinate Lenders are collectively the exclusive legal and
beneficial owner of all of the Subordinate Obligations;

(d) except as indicated in Borrower's Public Filings or disclosed in
writing to the Senior Security Holders' Representative and its counsel, which
writing is hereby made a part of this Agreement, none of the Subordinate
Obligations is subject to any lien, security interest (other than Subordinate
Lender's Collateral), financing statements, subordination, assignment or other
claim; and

(e) this Agreement constitutes the legal, valid and binding obligations
of Subordinate Lenders, enforceable in accordance with its terms.

2.8. Legends. Subordinate Lenders agree that any instrument at any time
evidencing the Subordinate Obligations, or any portion thereof, shall be
permanently marked on its face with a legend conspicuously indicating that
payment thereof is subordinate in right of payment to the Senior Obligations and
subject to the terms and conditions of this Agreement, and after being so marked
certified copies thereof shall be delivered to Senior Security Holders. In the
event any legend or endorsement is omitted, Senior Security Holders or any of
their representatives, officers or employees are hereby irrevocably authorized
on behalf of Subordinate Lenders to make the same. No specific legend, further
assignment or endorsement or delivery of notes, guarantees or instruments shall
be necessary to subject any Subordinate Obligations to the subordination thereof
contained in this Agreement.

2.9. Waiver of Covenant. Subordinate Lenders hereby waive any breaches
or defaults arising from Borrower's failure to maintain compliance with Section
6.9 of the Subordinate Loan Agreement, entitled "Minimum Liquidity", such waiver
to remain in effect so long as any amounts of Senior Obligations remain
outstanding,

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3.       AGREEMENT BY BORROWER.

(a) Borrower hereby acknowledges and agrees to the foregoing terms and
provisions, and agrees that the provisions hereof will bind Borrower, together
with its successors and assigns.

(b) Borrower acknowledges and agrees that: (i) in the event of a breach
by Borrower or Subordinate Lenders of any of the terms and provisions contained
in this Agreement, such a breach shall constitute an Event of Default, as
defined in and under the Senior Loan Documents; and (ii) it will execute and
deliver such additional documents and take such additional action as may be
necessary or desirable in the opinion of either Subordinate Lenders or Senior
Security Holders to effectuate the provisions and purposes of this Agreement.

4.       CONSENT AND RELEASE.

(a) Subordinate Lenders and Senior Noteholders each hereby consent to
the execution of, and the parties' respective performance under, the June Loan
Agreement, including: (i) the characterization of the Senior Lenders, in
addition to the Senior Noteholders, as Senior Security Holders hereunder; (ii)
the grant to the Senior Lenders of a security interest in the Collateral (as
defined in the June Loan Agreement), which interest shall be subject to the
terms and conditions of this Agreement; (iii) the repayment of the amounts due
the Senior Lenders and the Senior Noteholders on a pari passu basis; and (iv)
the concomitant further subordination of the Subordinate Lenders' security
interest in certain of the assets of Borrower to the security interest of the
Senior Lenders (in addition to the Senior Noteholders).

(b) Subject to the terms and conditions set forth in paragraphs (b) and
(c) below, upon the closing of the BBI Transaction, the Subordinated Lenders and
the Senior Security Holders each agree to forever release and surrender, in
accordance with Section 2.6(b) hereof, all right, title and interest in any
security interest such Subordinated Lender or Senior Security Holder may have in
the Transferred Assets (the "BBI SECURITY INTEREST"). Subordinate Lenders and
Senior Security Holders agree to execute and file a UCC-3 Partial Release, and
all other documents reasonably requested by Borrower, to effect as a matter of
public record the release contemplated by this

(c) As consideration for the release and surrender of the BBI Security
Interest, concurrently with the closing of the BBI Transaction, Borrower shall
invest Five Million Dollars ($5,000,000) in a segregated, interest-bearing
instrument (the "MONEY MARKET INSTRUMENT") and shall deliver and pledge the
Money Market Instrument to the Subordinated Lenders and the Senior Security
Holders as collateral securing the payment of the Subordinated Obligations and
the Senior Obligations. The pledge of the Money Market Instrument shall be
pursuant to a written Pledge Agreement to be entered into by and between the
Borrower and the Senior Security Holder's Representative, as collateral agent
for the Senior Security Holders and the Subordinated Lenders. The Money Market
Instrument shall be deemed to be "Collateral" under the Subordinated Loan
Documents and the Senior Loan Documents, and shall be subject to and governed by
the terms and conditions of this Agreement, the Senior Loan Documents and the
Subordinate Loan Documents pertaining to Borrower's collateral. Borrower shall
be entitled to 

10

11
receive any and all interest or other income generated by the Money Market
Instrument for so long as no event of default on Borrower's part has occurred
under the Subordinated Loan Documents or the Senior Loan Documents.

(d) To the extent that, and on each occasion that, the Senior Security
Holders convert all or a portion of the principal amount and interest of debt
held by them into capital stock of the Borrower pursuant to conversion rights
under the Senior Loan Documents, in the amount of One Million Dollars
($1,000,000) or more in the aggregate: (i) the pledge shall be released as to a
portion of the Money Market Instrument equal to the principal amount of debt so
converted; (ii) Borrower shall be entitled to reduce the amount of to use the
released funds as it sees fit; and (iii) the Subordinated Lenders and the Senior
Security Holders shall execute and deliver such instruments as may be necessary
to effectuate the reduction and release.

5.       MISCELLANEOUS.

5.1. Notices. Any and all notices given in connection with this
Agreement shall be deemed adequately given only if in writing and addressed to
the party for whom such notices are intended at the address set forth below. All
notices shall be sent by personal delivery, Federal Express or other over-night
messenger service, first class registered or certified mail, postage prepaid,
return receipt requested or by other means at least as fast and reliable as
first class mail. A written notice shall be deemed to have been given to the
recipient party on the earlier of (a) the date it shall be delivered to the
address required by this Agreement; (b) the date delivery shall have been
refused at the address required by this Agreement; or (c) with respect to
notices sent by mail, the date as of which the postal service shall have
indicated such notice to be undeliverable at the address required by this
Agreement. Any and all notices referred to in this Agreement, or which either
party desires to give to the other, shall be addressed as follows:

if to Borrower:                             Hybridon, Inc.
155 Fortune Blvd.
Milford, MA 01757
Attn.: President

with a copy to:                             Holland & Knight
One Beacon Street
Boston, MA.
Attn.: James Pollock, Esq.

if to Senior Security Holders:              Pillar Investments Ltd. Representative
28 Avenue de Messine
Paris, FRANCE 75008
Attn:    Youssef El-Zein

with a copy to:                             Sachnoff & Weaver, Ltd.
30 South Wacker Drive
Suite 2900
Chicago, Illinois 60606
Attn:    Lance R. Rodgers, Esq.

11

12

if to Subordinate Lenders:                      Pecks Management
1 Rockefeller Plaza, Suite 900
New York, NY  10020
Attn: Arthur W. Berry
and
Founders Financial Group
53 Forest Avenue
Old Greenwich, CT  06870
Attn: Harold L. Purkey

The above addresses may be changed by notice of such change, mailed as provided
herein, to the last address designated.

5.2. No Fiduciary Duty. Nothing in this Agreement shall be construed to
create or impose upon any Senior Security Holders any fiduciary duty to any
Subordinate Lender, or any other implied obligation to act or refrain from
acting with respect to Borrower or the Senior Obligations or the collateral
security securing the Senior Obligations in any manner contrary to what any
Senior Security Holders may determine is in its own best interests. Similarly,
nothing in this Agreement shall be construed to create or impose upon any
Subordinate Lender any fiduciary duty to any Senior Security Holders, or any
other implied obligation to act or refrain from acting with respect to Borrower
or the Subordinate Obligations or the collateral security securing the
Subordinate Obligations in any manner contrary to what any Subordinate Lender
may determine is in its own best interests.

5.3. Notice of Default. In addition to any other notices which may be
required hereunder, Subordinate Lenders shall give written notice to Senior
Security Holders' Representative, promptly after they become aware of the
occurrence of: (a) an Event of Default under the terms of the Subordinate Loan
Documents; (b) the cure of any such Event of Default; (c) the payment in full of
the Subordinate Debt; (d) any Acceleration of the Subordinate Debt; and (e) any
action or proceeding instituted against Borrower on account of any Event of
Default.

5.4.     Successors; Continuing Effect.

(a) This Agreement is being entered into for the benefit of, and shall
be binding upon, Borrower, each Senior Security Holders and each Subordinate
Lender and their respective successors and assigns, including each subsequent or
additional holder of Senior Obligations, or Subordinate Debt, and any
participant (whether now existing or hereafter arising) in the Senior
Obligations. The terms "Senior Security Holders" and "Subordinate Lenders" shall
include, respectively, any such subsequent or additional holder of or
participant in Senior Obligations or Subordinate Obligations whenever the
context permits. This Agreement shall inure to the benefit of and be enforceable
by any future holder or holders of the Borrower Obligations or any part of any
of the same; provided that, nothing contained in this Section 5.4 shall be
deemed to permit the transfer of the Subordinate Obligations in violation of the
provisions of Section 2.5.

12

13
(b) Senior Security Holders reserve the right to grant participations
in, or otherwise sell, assign, transfer or negotiate all or any part of, or any
interest in, the Senior Obligations and the Collateral securing same. In
connection with any participation or other transfer or assignment, Senior
Security Holders (i) may disclose to such assignee, participant or other
transferee or assignee all documents and information which Senior Security
Holders now or hereafter may have relating to the Senior Obligations or the
Collateral, and (ii) shall disclose to such participant or other transferee or
assignee the existence and terms and conditions of this Agreement.

5.5. Amendments. This Agreement may be amended only by a written
instrument executed by holders of a majorities in interest of each of the Senior
Obligations and the Subordinate Obligations and, if such amendment affects
Borrower, by Borrower.

5.6. Term. This Agreement shall remain in full force and effect until
the Payment in Full of the Senior Obligations.

5.7. Waivers. No waiver shall be deemed to be made by any party of any
of its rights hereunder unless the same shall be in writing and then only with
respect to the specific instance involved, and no such waiver shall impair or
offset the rights of the waiving party or the obligations of the party benefited
by such waiver in any other respect or at any other time.

5.8. Governing Law. This Agreement, including the validity hereof and
the rights and obligations of the parties hereunder, shall be governed by and
construed and enforced in accordance with the laws of the Commonwealth of
Massachusetts.

5.9. The Borrower May Not Impair Subordination. No right of Senior
Security Holders or Subordinate Lenders to enforce the subordination created
hereby shall be impaired by any act or failure to act by Borrower or by the
failure by Borrower to comply with this Agreement, regardless of any knowledge
which any Senior Security Holders or any Subordinate Lender may have or be
otherwise charged with.

5.10. Specific Performance. The parties hereto acknowledge that legal
remedies may be inadequate and therefore Senior Security Holders and Subordinate
Lenders are hereby authorized to demand specific performance of the provisions
of this Agreement at any time when Borrower, Senior Security Holders or
Subordinate Lenders shall have failed to comply with any provision hereof. Each
party hereto hereby irrevocably waives any defense based on the adequacy of a
remedy at law that might be asserted as a bar to such remedy of specific
performance.

5.11. Further Actions. After the execution of this Agreement each party
will execute and deliver all such documents and instruments and do all such
other acts and things as may be reasonably necessary to carry out the provisions
of this Agreement.

5.12. Agreement to Control. If any provision in any document or
instrument relating to the Senior Obligations or the Subordinate Debt differs
with the terms of this Agreement 

13

14
regarding the same or any similar matter, the provisions of this Agreement shall
control and each other provision shall be interpreted so as to give effect to
the provisions of this Agreement.

5.13. Entire Agreement. This Agreement contains the entire agreement of
the parties with respect to the subject matter hereof and supersedes all prior
written and oral agreements, and all contemporaneous oral agreements, relating
to such matters.

5.14. Severability. Any provision of this Agreement which is prohibited
or unenforceable in any jurisdiction shall, as to such jurisdiction, be
ineffective to the extent of such prohibition or unenforceability without
invalidating the remaining portions hereof or affecting the validity or
enforceability of such provision in any other jurisdiction.

5.15. Facsimile. For purposes of negotiating and finalizing this
Agreement (including any subsequent amendments thereto), any signed document
transmitted by facsimile machine ("FAX") shall be treated in all manner and
respects as an original document. The signature of any party by Fax shall be
considered for these purposes as an original signature. Any such Fax document
shall be considered to have the same binding legal effect as an original
document, provided that an original of the faxed document was mailed by first
class U.S. Mail or personally delivered to the recipient, on the date of its
transmission with proof of the fax transmission. At the request of any party,
any Fax document subject to this Agreement shall be re-executed by both parties
in an original form. The undersigned parties hereby agree that neither shall
raise the use of the Fax or the fact that any signature or document was
transmitted or communicated through the use of a Fax as a defense to the
formation of this Agreement. This Agreement may be signed in one or more
counterparts, each of which shall be an original, but all of which together
shall constitute one agreement, binding on all of the parties hereto
notwithstanding that all of the parties hereto are not signatories to the same
counterpart. Each of the undersigned parties authorizes the assembly of one or
more original copies of this Agreement through the combination of the several
executed counterpart signature pages with one or more copies of this Agreement,
including the Schedules and Exhibits, if any, to this Agreement. Each such
compilation of this Agreement shall constitute one original of this Agreement.

5.16.    Consent to Jurisdiction; Waiver of Jury Trial.

(a) BORROWER, SUBORDINATE LENDERS AND SENIOR SECURITY HOLDERS EACH
HEREBY (i) TO THE EXTENT PERMITTED BY APPLICABLE LAW, IRREVOCABLY SUBMITS TO THE
JURISDICTION OF ANY STATE OR FEDERAL COURT LOCATED IN BOSTON, MASSACHUSETTS,
OVER ANY ACTION OR PROCEEDING TO ENFORCE OR DEFEND ANY MATTER ARISING FROM OR
RELATED TO THIS AGREEMENT; (ii) IRREVOCABLY WAIVES, TO THE FULLEST EXTENT
BORROWER, SUBORDINATE LENDERS AND SENIOR LENDERS MAY EFFECTIVELY DO SO, THE
DEFENSE OF AN INCONVENIENT FORUM TO THE MAINTENANCE OF ANY SUCH ACTION OR
PROCEEDING IN ANY SUCH COURT; (iii) AGREES THAT, TO THE EXTENT PERMITTED BY
APPLICABLE LAW, A FINAL JUDGMENT IN ANY SUCH ACTION OR PROCEEDING IN ANY SUCH
COURT SHALL BE CONCLUSIVE AND MAY BE ENFORCED IN ANY OTHER JURISDICTION BY SUIT
ON THE JUDGMENT OR IN ANY OTHER MANNER PROVIDED BY LAW; AND (iv) TO 

14

15
THE EXTENT PERMITTED BY APPLICABLE LAW, AGREES NOT TO INSTITUTE ANY LEGAL ACTION
OR PROCEEDING AGAINST ANY PARTY HERETO OR ANY OF PARTY'S DIRECTORS, OFFICERS,
EMPLOYEES, AGENTS OR PROPERTY, CONCERNING ANY MATTER ARISING OUT OF OR RELATING
TO THIS AGREEMENT IN ANY COURT OTHER THAN ONE LOCATED IN BOSTON, MASSACHUSETTS.

(b) NOTHING IN THIS SECTION SHALL AFFECT OR IMPAIR SENIOR SECURITY
HOLDERS' OR SUBORDINATE LENDERS' RIGHT TO SERVE LEGAL PROCESS ON BORROWER IN ANY
MANNER PERMITTED BY LAW OR SENIOR SECURITY HOLDERS' OR SUBORDINATE LENDERS'
RIGHT TO BRING ANY ACTION OR PROCEEDING AGAINST BORROWER OR BORROWER'S PROPERTY
IN THE COURTS OF ANY OTHER JURISDICTION.

(c) BORROWER, SENIOR SECURITY HOLDERS AND SUBORDINATE LENDERS EACH
HEREBY KNOWINGLY, VOLUNTARILY AND INTENTIONALLY WAIVES THE RIGHT TO A TRIAL BY
JURY IN RESPECT OF ANY LITIGATION BASED HEREON, ARISING OUT OF, UNDER OR IN
CONNECTION WITH THIS AGREEMENT OR ANY OTHER LOAN DOCUMENT OR ANY COURSE OF
CONDUCT, COURSE OF DEALINGS, STATEMENTS (WHETHER VERBAL OR WRITTEN) OR ACTIONS
OF EITHER PARTY. EACH PARTY HERETO HEREBY EXPRESSLY ACKNOWLEDGES THIS WAIVER IS
A MATERIAL INDUCEMENT FOR SENIOR SECURITY HOLDERS TO ENTER INTO THIS AGREEMENT
AND TO MAKE THE LOANS EVIDENCED BY THE SENIOR LOAN DOCUMENTS.

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16
IN WITNESS WHEREOF, the parties hereto have executed and delivered this
Subordination Agreement as of the day, month and year first above written.

HYBRIDON, INC.

By:      /s/ Robert G. Andersen                            
--------------------------------------------------
Name:      Robert G. Andersen
Title:     Vice-President and Chief Financial Officer

SENIOR LENDERS
By: Pillar Investments Ltd, Their Representative

By:      /s/ Youssef El Zein                               
--------------------------------------------------
Name:      Youssef El Zein

SENIOR NOTEHOLDERS
By: Pillar Investments Ltd, Their Representative

By:      /s/ Youssef El Zein                               
--------------------------------------------------
Name:      Youssef El Zein

FOUNDERS FINANCIAL GROUP

By:      /s/ Harold L. Purkey                              
--------------------------------------------------
Name:      Harold L. Purkey
Title:     Partner

16

17
DELAWARE STATE EMPLOYEES RETIREMENT
FUND DECLARATION OF TRUST FOR THE DEFINED
BENEFIT PLANS OF ICI AMERICAN HOLDINGS INC
DECLARATION OF TRUST FOR THE DEFINED
BENEFIT PLANS OF ZENECA HOLDINGS INC.
THE J.W. MCCONNELL FAMILY FOUNDATION
GENERAL MOTORS EMPLOYEES DOMESTIC
GROUP TRUST

By: PECKS MANAGEMENT PARTNERS, LTD.

By:     /s/ Arthur W. Berry                       
------------------------------------------
Name:   Arthur W. Berry
Title:  Principal

17

1
Exhibit 10.58

LICENSE AGREEMENT

This Agreement, made as of this 20th day of September, 2000 is by and
between Boston Biosystems, Inc., a Delaware corporation (hereinafter,
"Licensee") and Hybridon, Inc., a Delaware corporation (hereinafter,
"Licensor").

W I T N E S S E T H:

WHEREAS, Licensor and Licensee are entering into an Asset Purchase
Agreement dated as of the date hereof (the "Asset Purchase Agreement"), pursuant
to which Licensee is purchasing certain of Licensee's assets in connection with
the manufacture and sale of advanced chemistry compounds and pharmaceuticals
(the "Business"); and

WHEREAS, Licensor has adopted and is using the trade names and
trademarks used in the operation of the Business as set forth on SCHEDULE A
attached hereto (hereinafter, the "Names & Marks") in connection with its
current operation of the Business; and

WHEREAS, Licensor wishes to grant, and Licensee wishes to accept a
non-exclusive, royalty-free license providing for use by the Licensee of the
Names & Marks in connection with its operation of the Business for a period of
one (1) year commencing on the date hereof;

NOW, THEREFORE, in consideration of the mutual covenants herein
contained, and for other good and valuable consideration, the receipt and
adequacy of which are acknowledged, the parties hereby agree as follows:

1.       LICENSE

1.1 Licensor hereby grants to Licensee a non-exclusive, royalty-free,
worldwide license, for a term of one (1) year commencing on the date hereof, to
use the Names & Marks in connection with Licensee's operation of the Business,
primarily for the purpose of any packaging or marketing materials, for the
limited purposes of facilitating a smooth transition of the Business from the
Licensor to Licensee pursuant to the terms of the Asset Purchase Agreement,
subject to the terms and conditions contained herein.

1.2 Licensee may (i) engage, employ or otherwise retain the services of
third parties to operate the Business using the Names &Marks, subject to the
quality control provision in Section 4 below, but may not transfer said license
rights to any other third party without the consent of Licensor, which consent
shall not be unreasonably withheld, or (ii) assign any or all of its rights and
interests in the Names and Marks hereunder to one or more of its Affiliates (as
defined in Rule 12b-2 of the regulations promulgated under the Securities
Exchange Act); PROVIDED, that in the event of (i) or (ii) the Licensee shall
nonetheless remain responsible for the performance of all of its obligations
hereunder.

2
2.       TERMINATION

2.1 This Agreement may be terminated by each of the parties hereto in
accordance with the following provisions:

(i) Licensee shall have the right and option to terminate this
Agreement, for its convenience, by providing two (2) months written notice
thereof to Licensor.

(ii) In the event of any material breach of this agreement by either
party hereto, the other party shall have the right, without limitation of any
other right it may have on account of such failure, to terminate this Agreement
by first giving the breaching party thirty (30) days written notice of its
intention to terminate, specifying the cause of default, and if the defaulting
party shall not remedy such failure during such thirty (30) day period, then the
other party may give further written notice to the defaulting party, terminating
the Agreement, in which event this Agreement shall be terminated on the date
specified in such further notice.

2.2 Notwithstanding the above, this Agreement shall terminate
automatically without notice upon any of the following events:

(i) An assignment for the benefit of creditors of Licensee.

(ii) The appointment of a receiver or trustee to manage the affairs of
the Licensee unless removed within sixty (60) days.

(iii) The involuntary or voluntary bankruptcy of the Licensee, unless
stayed within sixty (60) days.

3.       OBLIGATIONS OF LICENSOR.

3.1 Licensor agrees to police the use of the Names & Marks, or
colorable imitations thereof, by others. It shall be in Licensor's sole
discretion, however, as to whether to bring, maintain or settle an infringement
action against a third party.

4.       QUALITY CONTROL.

4.1 Licensee agrees that its operation of the Business while utilizing
the Names & Marks will comply with generally recognized industry standards with
respect to the manufacture and sale of advanced chemistry compounds and
pharmaceuticals.

5. INDEMNIFICATION. To the extent a claim or action is brought against
the Licensor based on or related to Licensee's use of the Names and Marks or its
failure to observe or perform its obligations under this Agreement, Licensee
shall defend and hold the Licensor harmless from and against any and all claims,
liabilities, judgments, damages, costs and expenses, including reasonable
attorneys' fees, suffered by or awarded against the Licensor.

-2-

3
6.       MISCELLANEOUS.

6.1 This Agreement contains the entire Agreement between the parties
regarding the subject matter hereof and supersedes all prior Agreements, whether
oral or written. No amendment to this Agreement may be made except by a writing
signed by both parties.

6.2 No provision hereof may be waived unless in writing signed by both
parties affixing their signatures to this document. Waiver of any one provision
herein shall not be deemed to be a waiver of any other provision herein.

6.3 This Agreement shall be governed in accordance with the laws of the
State of Delaware.

6.4 Any notice, request, information or other document required to be
provided hereunder shall be in writing and delivered by first class mail,
postage prepaid, or by overnight delivery service as follows:

If to Licensee:

Boston Biosystems, Inc.
75A Wiggins Avenue
Bedford, Massachusetts  01730
Attn: Michael Kallelis, Chief Operating Officer

with a copy to:

McDermott, Will & Emery
28 State Street
Boston, Massachusetts  02109
Attn:  Susan Cooke, Esq.

If to Licensor:

Hybridon, Inc.
255 Fortune Boulevard
Milford, Massachusetts
Attn:  Robert Anderson

with a copy to:

Holland & Knight
One Beacon Street
Boston, Massachusetts
Attn:  James Pollock, Esq.

-3-

4
6.5 It is the desire and intent of the parties hereto that the
provisions of this Agreement shall be enforced to the fullest extent permissible
under the laws and public policies applied in each jurisdiction in which
enforcement is sought. Accordingly, if any particular provision of this
Agreement shall be adjudicated to be invalid or unenforceable, such provision
shall be deemed amended to delete therefor the portion thus adjudicated to be
invalid or unenforceable and the Agreement shall otherwise remain in full force
and effect.

6.6 In any action, suit or other proceeding instituted to enforce,
remedy, prevent or obtain relief from a breach or violation of this Agreement,
the substantially prevailing party shall recover all of such party's reasonable
attorneys' fees incurred therein, including any and all appeals or petitions
therefrom.

6.7 Nothing contained herein shall be construed to create a joint
venture, partnership or agency between the parties and neither party may take
any action which binds the other or gives a color of authority than an act is on
behalf of the other party.

6.8 This Agreement shall inure to the benefit of and shall be binding
upon the successors and assigns of any party, and each of them.

6.9 The terms of this Agreement are the result of negotiation between
the parties. All parties to this Agreement therefore, agree that the normal rule
of construction to the effect that any ambiguities in an agreement are to be
resolved against the drafting party shall not be employed in the interpretation
of this Agreement.

6.10 The signatories here below represent they are authorized to
execute this Agreement on behalf of their respective parties.

[The remainder of this page is intentionally left blank.]

-4-

5

IN WITNESS WHEREOF, the parties hereto have approved and executed this
Agreement effective as of the date first written above.

BOSTON BIOSYSTEMS, INC.

By: /s/ Gregory S. Kurey
----------------------------------------
Name:   Gregory S. Kurey
Title:  General Counsel

HYBRIDON, INC.

By: /s/ Robert G. Andersen
----------------------------------------
Name:   Robert G. Andersen
Title:  Chief Financial Officer

By: /s/ Sudhir Agrawal
Name:   Sudhir Agrawal
Title:  President and Chief Executive
Officer

-5-

1

Exhibit 10.59

ASSIGNMENT OF COEXCLUSIVE LICENSE

WHEREAS, HYBRIDON, INC., a Delaware corporation having a principal
place of business at 155 Fortune Blvd., Milford, MA 01757 (hereafter "Assignor")
owns certain coexclusive rights and license pursuant to that certain agreement
entitled PATENT LICENSE AGREEMENT - COEXCLUSIVE, dated September 21, 1995, by
and between HYBRIDON, INC. and the PUBLIC HEALTH SERVICE (PHS), a.k.a. Patent
License Number: L-131-92, and attached hereto as Exhibit A; and

WHEREAS, Boston Biosystems, Inc., a Delaware corporation with a place
of business at 75A Wiggins Avenue, Bedford, Massachusetts 01730, (hereafter
"Assignee" which term shall include its successors, assigns, and transferees) is
desirous of obtaining all of Assignor's licenses and rights relating to said
patents,

NOW THEREFORE, be it known that in consideration of the payment by
Assignee to assignor of the sum of ten dollars ($10.00) and for other good and
valuable consideration, the receipt and sufficiency of which is hereby
acknowledged, Assignor, hereby sells, assigns, and transfers to Assignee all
rights and obligations under such license including, pursuant to the terms of
the license, including the certain letter dated June 5, 1996, which is attached
hereto as Exhibit B, a complete coexclusive rights and license to make and have
made, to use and have used, and to sell and have sold products as well as to
practice and have practiced processes under said patents for the full term or
terms for which the same may be granted.

ASSIGNOR hereby covenants that, since it obtained its rights and
licenses in said patents, no assignment, transfer, sale, agreement or
encumbrance has been entered into which would conflict with this assignment,
sale, and transfer and that any encumbrance thereon has been fully removed,
cleared and satisfied.

ASSIGNOR further covenants that, it has made all payments due,
fulfilled all of its obligations, and it has not breached the terms of the
license, and it is not aware of circumstances that might cause the license to be
terminated or the terms of the license to be varied.

IN WITNESS WHEREOF, Assignor has hereunto set its hand and seal on the
date indicated.

1

2
ASSIGNOR

HYBRIDON, INC.

By:      /s/ Robert G. Andersen                         Date: September 20, 2000
----------------------
Name:    Robert G. Andersen
Title:   Vice President and Chief Financial Officer

2

3
EXHIBIT A

PATENT LICENSE AGREEMENT - COEXCLUSIVE dated September 21, 1995 by and between
HYBRIDON and the PUBLIC Health SERVICE (PHS), a.k.a. Patent License Number:
L-131-92.

Attached

3

1

Exhibit 10.60

EXECUTION COPY

OLIGONUCLEOTIDE PURIFICATION

PATENT LICENSE AGREEMENT

dated as of September 20, 2000

by and between

HYBRIDON, INC.

and

BOSTON BIOSYSTEMS, INC.

2
OLIGONUCLEOTIDE PURIFICATION

PATENT LICENSE AGREEMENT

This OLIGONUCLEOTIDE PURIFICATION PATENT LICENSE AGREEMENT (the
"Agreement"), dated as of September 20, 2000 (the "Effective Date"), is entered
into by and between Hybridon, Inc., a Delaware corporation (the "Licensor"),
having a principal place of business located at 155 Fortune Blvd., Milford,
Massachusetts 01757 (hereinafter referred to as "HYBRIDON") and Boston
Biosystems, Inc., a Delaware corporation (the "Licensee"), having a principal
place of business located at 75A Wiggins Avenue, Bedford, Massachusetts 01730
(hereinafter referred to as "BBI"). HYBRIDON and BBI are sometimes referred to
herein individually as a "Party" and collectively as the "Parties", and all
references to "HYBRIDON" and "BBI " shall include their respective Affiliates,
where appropriate under the terms of this Agreement.

W I T N E S S E T H:

WHEREAS HYBRIDON has entered into that certain Asset Purchase
Agreement dated ______ ("Purchase Agreement") to sell certain assets to BBI, and
HYBRIDON wishes to grant certain intellectual property rights as provided
herein;

WHEREAS, HYBRIDON owns certain patent(s) ("Selected HYBRIDON
Patent(s)") that cover processes for purifying oligonucleotide compounds;

WHEREAS, BBI desires to obtain a perpetual, royalty-free,
non-exclusive license to use the processes for purifying oligonucleotides
described and claimed in the Selected HYBRIDON Patent(s) owned by HYBRIDON.

NOW, THEREFORE, in consideration of the foregoing recitals and the
mutual covenants and agreements contained herein, the parties hereto, intending
to be legally bound, do hereby agree as follows:

ARTICLE I

DEFINITIONS

SECTION 1.01. Definitions. The following terms, when capitalized,
shall have the following meanings (such meanings to be equally applicable to
both the singular and plural forms of the terms defined) as used in this
Agreement:

"Affiliate(s)" means any person, corporation, partnership, firm,
joint venture or other entity now currently existing or which may be formed in
the future, which directly or indirectly, through one or more intermediaries,
controls, is controlled by, or is under common control with, HYBRIDON, BBI, or
AVECIA HOLDINGS PLC, as the case may be. As used in this definition, "control"
means direct or indirect ownership of an entity, whether through the ownership
of more than 50% of the outstanding voting securities or by contract or
otherwise.

"AVECIA HOLDINGS PLC" or "AVECIA HOLDINGS" is a company organized
under the laws of United Kingdom, and its registered office address is PO Box
42, Hexagon House, Blackley, Manchester, M9 8ZS, United Kingdom.

-2-

3
EXECUTION COPY

"Change of Control" of a Party means the occurrence of any of the
following with respect to such Party at any time after the date hereof:

(a) any Third Party (other than the Affiliates on the
date hereof) shall have become the beneficial owner of securities representing 
more than 50% of the aggregate voting power of the then outstanding voting 
securities of such Party; or

(b) any sale by such Party of: (i) HYBRIDON; or (ii) all
or substantially all of such Party's pharmaceutical and/or healthcare assets; or
(iii) all or substantially all of such Party's assets other than its 
pharmaceutical and/or healthcare assets.

"Confidential Information" shall have the meaning set forth in
Article III.

"Control" or "Controlled" shall refer to possession of the ability
to grant a license or sublicense of patent rights, know-how or other intangible
rights as provided for herein without violating the terms of any agreement or
other arrangement with any Third Party.

"Effective Date" shall have the meaning set forth in the Recitals to
this Agreement.

"Field" or "Field of Use" means the purification and manufacture of
oligonucleotides and products containing oligonucleotides.

"Licensed Process(es)" means a process for purifying or
manufacturing oligonucleotides as described and claimed in the HYBRIDON
Patent(s) set forth in Exhibit A.

"Process(es)" means Licensed Processes.

"Patent" means United States and foreign patents, applications and
provisional applications for United States and foreign patents, and all
reexaminations, reissues, extensions, term restorations, divisionals,
continuations and continuations-in-part thereof.

"Selected HYBRIDON Patent(s)", "HYBRIDON Patent(s), Selected
HYBRIDON Patent Application(s)" or "HYBRIDON Patent Application(s)" shall mean
any Patent or patent application set forth in Exhibit A, including any foreign,
international or domestic counterpart and issued patents or patent applications
arising therefrom, as well as any divisional, continuation or
continuation-in-part thereof.

"Technical Information" means all know-how, trade secrets,
inventions, data, technology, and other information now owned or licensed by
HYBRIDON, or hereafter acquired or licensed by HYBRIDON during the term of this
Agreement, in connection with the Licensed Process, including, but not limited
to, (i) medical, chemical and other scientific data; (ii) processes and analytic
methodology used in the development, testing and analysis of the Licensed
Process; and (iii) packaging, manufacturing, advertising and marketing data.

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"Territory" means worldwide.

"Third Party" or "Third Parties" means any entity other than
HYBRIDON, BBI or AVECIA HOLDINGS, and their respective Affiliates.

ARTICLE II

LICENSE AND ROYALTIES

SECTION 2.01. Grant. Subject to the terms and conditions of this
Agreement, HYBRIDON hereby grants to BBI and AVECIA HOLDINGS' Affiliates a
non-exclusive, paid up, royalty-free, perpetual right and license with no right
to sublicense during the term of this Agreement to: carry out the
oligonucleotide purification or manufacturing process subject matter described
and claimed in the Selected HYBRIDON Patent(s); and to provide, offer for sale,
import or sell oligonucleotides purified or made by the Licensed Process within
the Field of Use in the Territory.

SECTION 2.02. Know-how License Grant. HYBRIDON hereby grants BBI and
AVECIA HOLDINGS' Affiliates a paid-up, non-exclusive license in the Territory,
with a right to use HYBRIDON know-how solely for the purposes of the Licensed
Process within the Field of Use in the Territory. BBI or AVECIA HOLDINGS'
Affiliates will reimburse HYBRIDON for all reasonable and customary expenses
incurred at BBI's or AVECIA HOLDINGS' Affiliates' request, including a
reasonable consulting hourly rate for time required of HYBRIDON personnel.

ARTICLE III

CONFIDENTIALITY

SECTION 3.01. Confidentiality; Exceptions. Except to the extent
expressly authorized by this Agreement or otherwise agreed in writing, the
Parties agree that, for the term of this Agreement and for five (5) years
thereafter, they shall keep confidential the existence of this Agreement and
shall not publish or otherwise disclose or use for any purpose other than as
provided for in this Agreement any information and materials furnished to it by
the other Party pursuant to this Agreement, or any provisions of this Agreement
that are the subject of an Effective order of the Securities Exchange Commission
granting confidential treatment pursuant to the Securities Act of 1934, as
amended (collectively, "Confidential Information"), except to the extent that it
can be established by the receiving Party that such Confidential Information:

(a) was already known to the receiving Party, other than under an
obligation of confidentiality, at the time of disclosure by the other Party;

(b) was generally available to the public or otherwise part of the
public domain at the time of its disclosure to the receiving Party;

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(c) became generally available to the public or otherwise part of
the public domain after its disclosure and other than through any act or
omission of the receiving Party in breach of this Agreement; or

(d) was disclosed to the receiving Party, other than under an
obligation of confidentiality, by a Third Party who had no obligation to the
disclosing Party not to disclose such information to others.

SECTION 3.02. Authorized Disclosure. Each Party may disclose
Confidential Information hereunder to the extent such disclosure is reasonably
necessary in filing or prosecuting patent applications, prosecuting or defending
litigation, complying with applicable governmental regulations or conducting
pre-clinical or clinical trials, provided that if a Party is required by law or
regulation to make any such disclosures of the other Party's Confidential
Information it will, except where impracticable for necessary disclosures, for
example in the event of medical emergency, give reasonable advance notice to the
other Party of such disclosure requirement and, except to the extent
inappropriate in the case of patent applications, will use its reasonable
efforts to secure confidential treatment of such Confidential Information
required to be disclosed. In addition, and with prior written notice to the
other Party of each Third Party with whom a confidential disclosure agreement is
being entered into, each Party shall be entitled to disclose, under a binder of
confidentiality containing provisions as protective as those of this Article,
Confidential Information to any Third Party for the purpose of carrying out the
purposes of this Agreement. Nothing in this Article shall restrict any Party
from using for any purpose any Confidential Information independently developed
by it during the term of this Agreement. BBI and AVECIA HOLDINGS' Affiliates may
disclose the existence, but not the terms, of this Agreement to its customers or
potential customers for the purpose of assuring its customers or potential
customers of the existence of the rights conveyed herein.

SECTION 3.03. Publicity Review. Subject to the further provisions of
this Section, no Party shall originate any written publicity, news release, or
other announcement or statement relating to this Agreement or to performance
hereunder or the existence of an arrangement between the Parties (collectively,
"Written Disclosure"), without the prior prompt review and written approval of
the other, which approval shall not be unreasonably withheld or delayed.
Notwithstanding the foregoing provisions of this Section, any Party may make any
public Written Disclosure it believes in good faith based upon the advice of
counsel is required by applicable law or any listing or trading agreement
concerning its publicly traded securities, provided that prior to making such
Written Disclosure, the disclosing Party shall provide the other Party with a
copy of the materials proposed to be disclosed and provide the receiving Party
with an opportunity to promptly review the proposed Written Disclosure. To the
extent that the receiving Party reasonably requests that any information in the
materials proposed to be disclosed be deleted, the disclosing Party shall
request confidential treatment of such information pursuant to Rule 406 of the
Securities Act of 1933 or Rule 26b-2 of the Securities Exchange Act of 1934, as
applicable (or any other applicable regulation relating to the confidential
treatment of information), so that there be omitted from the materials that are
publicly filed any information that the receiving Party reasonably requests to
be deleted. The terms of this Agreement may also be disclosed to (i) government
agencies where required by law, or (ii) Third Parties with the prior written
consent of the other Party, which consent shall not be unreasonably withheld or
delayed, so long as such disclosure is made under a binder of confidentiality
and so long as highly sensitive terms and 

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conditions such as financial terms are extracted from the Agreement or not
disclosed upon the request of the other Party. All Written Disclosures shall be
factual and as brief as is reasonable under the circumstances. Upon request by
either Party, the Parties agree to prepare a mutually agreed press release and
question and answer document with respect to this Agreement. Each Party agrees
that all Written Disclosures and oral statements relating hereto shall be
consistent with the answers specified in such question and answer document.

SECTION 3.04. Survival. This Article shall survive the termination
or expiration of this Agreement for a period of five (5) years.

ARTICLE IV

INTELLECTUAL PROPERTY AND PATENT RIGHTS

SECTION 4.01. Notice. Each of the parties shall promptly notify the
other in writing if it: (i) receives any notice or becomes aware of any
information that in any way affects the other party's rights under this
Agreement; or (ii) becomes aware of any actual or suspected infringement,
misappropriation or misuse by a Third Party of the HYBRIDON Patent(s) and
HYBRIDON Patent Application(s) in the Territory and within the Field of Use.

SECTION 4.02. Assistance. At HYBRIDON's request and HYBRIDON's
expense, BBI and AVECIA HOLDINGS' Affiliates shall take all reasonable steps and
shall provide such materials, cooperation and assistance as may be reasonably
required to assist HYBRIDON in maintaining and enforcing HYBRIDON's right in and
to the Intellectual Property.

SECTION 4.03. Maintenance Fees. Should HYBRIDON decline to pay any
or all of the required maintenance fees on the HYBRIDON Patent(s) and HYBRIDON
Patent Application(s) or otherwise to prosecute or maintain the HYBRIDON
Patent(s) and HYBRIDON Patent Application(s), it shall give BBI or AVECIA
HOLDINGS' Affiliates thirty (30) days notice of its decision, and BBI and AVECIA
HOLDINGS' Affiliates shall have the right (but not the obligation) to pay such
maintenance fees or to prosecute or maintain such HYBRIDON Patent(s) and
HYBRIDON Patent Application(s). If BBI and AVECIA HOLDINGS' Affiliates elects to
pay such maintenance fees, HYBRIDON agrees to assign all right, title and
interest in and to the HYBRIDON Patent(s) and HYBRIDON Patent Application(s) to
BBI and AVECIA HOLDINGS' Affiliates without further consideration.

SECTION 4.04. Infringement.

(a) HYBRIDON's Rights to Enforce. HYBRIDON shall have the right (but
not the obligation), in its sole discretion, to take action at its own expense
against actual or suspected infringers of the HYBRIDON Patent(s) and HYBRIDON
Patent Application(s) in the Field of Use in the Territory, and any and all
recoveries resulting from such actions by HYBRIDON shall be retained by
HYBRIDON. At HYBRIDON's request, and at HYBRIDON's expense, BBI and AVECIA
HOLDINGS' Affiliates shall take all reasonable steps and shall provide any
materials, cooperation and assistance as may be reasonably required to assist
HYBRIDON in taking action against actual or suspected infringers in 

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the Field of Use in the Territory. BBI and AVECIA HOLDINGS' Affiliates shall
join any such action as a necessary and indispensable party if so required.

SECTION 4.05.  Defense and Settlement of Third Party Claims.

(a) Defense in the Territory. If a Third Party asserts that a
patent, trademark or other intangible right owned by it is infringed as a result
of the operation of any Licensed Process in the Territory, BBI and AVECIA
HOLDINGS' Affiliates will be solely responsible for defending against any such
assertions at its cost and expense.

(b) Settlement with a Third Party. If BBI and AVECIA HOLDINGS'
Affiliates must defend a Third Party claim with respect to a Licensed Process,
then BBI and AVECIA HOLDINGS' Affiliates shall also have the right to control
settlement of such claim.

ARTICLE V

INDEMNIFICATION; LIMITATION OF LIABILITY

SECTION 5.01. Indemnification by HYBRIDON. HYBRIDON shall defend,
indemnify and hold BBI and its subsidiaries and AVECIA HOLDINGS' Affiliates, and
its and their officers, directors, shareholders, employees and agents harmless
and shall pay all losses, damages, fees, expenses or costs (including reasonable
attorneys' fees) incurred by them based upon any claim or action alleging
HYBRIDON's breach of its obligations, representations, warranties or covenants
hereunder unless BBI's or AVECIA HOLDINGS' Affiliates' negligence caused the
losses, damages, fees, expenses or costs.

SECTION 5.02. Indemnification by BBI and AVECIA HOLDINGS'
Affiliates. BBI and AVECIA HOLDINGS' Affiliates shall defend, indemnify and hold
HYBRIDON and its officers, directors, shareholders, employees and agents
harmless and shall pay all losses, damages, fees, expenses or costs (including
reasonable attorney's fees) incurred by them based upon any claim or action
alleging BBI's and AVECIA HOLDINGS' Affiliates' breach of its obligations,
representations, warranties or covenants hereunder unless HYBRIDON's negligence
caused the losses, damages, fees, expenses or costs.

SECTION 5.03. Limitation of Liability. EXCEPT AS SET FORTH IN
SECTION 7.03 HEREIN, NEITHER PARTY SHALL BE LIABLE TO THE OTHER PARTY OR ANY
THIRD PARTY FOR ANY SPECIAL, CONSEQUENTIAL, EXEMPLARY OR INCIDENTAL DAMAGES
(INCLUDING LOST OR ANTICIPATED REVENUES OR PROFITS RELATING TO THE SAME),
ARISING FROM ANY CLAIM RELATING TO THIS AGREEMENT, THE HYBRIDON PATENT(S) AND
HYBRIDON PATENT APPLICATION(S) OR ANY IMPROVEMENT, WHETHER SUCH CLAIM IS BASED
ON WARRANTY, CONTRACT, TORT (INCLUDING NEGLIGENCE OR STRICT LIABILITY) OR
OTHERWISE, EVEN IF AN AUTHORIZED REPRESENTATIVE OF SUCH PARTY IS ADVISED OF THE
POSSIBILITY OR LIKELIHOOD OF SAME.

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ARTICLE VI

DISPUTE RESOLUTION.

SECTION 6.01. Disputes. The Parties recognize that disputes as to
certain matters may from time to time arise during the term of this Agreement
which relate to either Party's rights and/or obligations hereunder or
thereunder. It is the intent of the Parties to establish procedures to
facilitate the resolution of disputes arising under this Agreement in an
expedient manner by mutual cooperation and without resort to litigation. To
accomplish this objective, the Parties agree to follow the procedures set forth
in this Article if and when a dispute arises under this Agreement.

SECTION 6.02. Good Faith. The parties shall negotiate in good faith
to resolve the dispute.

SECTION 6.03. Personal Meeting. If the dispute remains unresolved,
executives from the interested business units or division of the parties shall
meet in person, at a mutually agreed upon time and place, to negotiate in good
faith to resolve the dispute. If the dispute continues to remain unresolved for
more than sixty (60) days from the date the parties met to negotiate pursuant to
this Section, then either party may pursue other dispute resolution procedures,
including the institution of arbitration as more fully set forth herein.

SECTION 6.04. Alternative Dispute Resolution. Any dispute
controversy or claim arising out of or relating to the validity, construction,
enforceability or performance of this Agreement, including disputes relating to
an alleged breach or to termination of this Agreement, but excluding (i) any
dispute, controversy or claim arising out of or relating to the validity,
enforceability, or infringement of any HYBRIDON Patent(s) or any BBI and AVECIA
HOLDINGS' Affiliates' Patent(s) and (ii) other than disputes which are expressly
prohibited herein from being resolved by this mechanism, shall be settled by
binding Alternative Dispute Resolution ("ADR") in the manner described below:

(a) If a Party intends to begin an ADR to resolve a dispute, such
Party shall provide written notice (the "ADR Request") to counsel for the other
Party informing such other Party of such intention and the issues to be
resolved. From the date of the ADR Request and until such time as any matter has
been finally settled by ADR, the running of the time periods contained in
SECTION 6.05 as to which a Party must cure a breach of this Agreement shall be
suspended as to the subject matter of the dispute.

(b) Within fifteen (15) business days after receipt of the ADR
Request, the other Party may, by written notice to counsel for the Party
initiating ADR, add additional issues to be resolved.

SECTION 6.05. Arbitration Procedures. An ADR initiated under this
Agreement will proceed in accordance with the Commercial Arbitration Rules of
the American Arbitration Association then in effect, insofar as such rules are
not inconsistent with the provisions expressly set forth in this Agreement,
unless the Parties mutually agree otherwise, and pursuant to the following
procedures:

(a) Notice of the demand for arbitration will be filed in writing
with the other Party and with the American Arbitration Association. The
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of one (1) arbitrator mutually agreed to by the Parties and the decision shall
be final and binding on the Parties and their legal successors.

(b) The arbitrator may, at his discretion, provide for discovery by
the Parties, not to exceed four (4) months from the date of filing of the Notice
of Arbitration.

(c) Any arbitration hearing shall be conducted in Wilmington,
Delaware. The governing law will be as specified herein. The arbitrator will
have authority to award both legal and equitable relief but not to award
punitive damages.

(d) All costs and fees of the arbitration, other than each Party's
legal fees and expenses, will be allocated by the arbitrators. Subject to
subsection (c), each Party shall bear its own legal fees and expenses.

(e) A final written decision by the arbitrator will be rendered not
later than thirty (30) days following the completion of the hearing.

(f) The ADR proceeding shall be confidential and the arbitrator
shall issue appropriate protective orders to safeguard each Party's confidential
information. Except as required by law, no Party shall make (or instruct the
arbitrator to make) any public announcement with respect to the proceedings or
decision of the arbitrator without prior written consent of each other Party.
The existence of any dispute submitted to ADR, and the award, shall be kept in
confidence by the Parties and the arbitrator, except as required in connection
with the enforcement of such award or as otherwise required by applicable law.

SECTION 6.06. Survivability. Any duty to arbitrate under this
Agreement shall remain in effect and enforceable after termination of this
Agreement for any reason.

SECTION 6.07. Jurisdiction. For the purposes of this Article, each
Party agrees to abide by the award rendered in any arbitration, and the Parties
agree to accept the jurisdiction of any court having jurisdiction over the
Parties for the purposes of enforcing awards entered pursuant to this Article
and for enforcing the agreements reflected in this Article.

SECTION 6.08. Equitable Remedies. Nothing in this Section shall
prevent either party from pursuing a temporary restraining order, injunctive
relief or other equitable relief against the other party at any time if the
allegedly aggrieved party believes that a breach or a threatened breach of this
Agreement would cause it irreparable harm provided that the other party is given
thirty (30) days written notice prior to equitable relief being sought.

ARTICLE VII

REPRESENTATIONS AND WARRANTIES

SECTION 7.01. HYBRIDON represents, warrants and covenants that:

(a) HYBRIDON is a corporation duly organized, existing and in good
standing under the laws of the State of Delaware, with full right, power and
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and perform this Agreement and to grant all of the rights, powers and
authorities herein granted.

(b) The execution, delivery, and performance of this Agreement do
not conflict with, violate, or breach any agreement to which HYBRIDON is a
party, or HYBRIDON's articles of incorporation or bylaws.

(c) The issued HYBRIDON Patent(s) are valid and enforceable.

(d) This Agreement has been duly executed and delivered by HYBRIDON
and is a legal, valid, and binding obligation enforceable against HYBRIDON in
accordance with its terms.

(e) HYBRIDON knows of no fact which does or could materially
adversely affect the rights granted to BBI and AVECIA HOLDINGS' Affiliates
hereunder, except as disclosed herein.

(f) Right of BBI and AVECIA HOLDINGS' Affiliates to Monitor HYBRIDON
Patent Application(s). HYBRIDON covenants that during the term of this
Agreement, HYBRIDON shall provide BBI and AVECIA HOLDINGS' Affiliates with
copies of all substantive communications to and from patent offices regarding
HYBRIDON Patent(s) and HYBRIDON Patent Application(s) promptly after the receipt
thereof.

SECTION 7.02. BBI represents, warrants and covenants that:

(a) BBI is a corporation duly organized, existing, and in good
standing under the laws of the State of Delaware, with full right, power and
authority to enter into and perform this Agreement and to grant all of the
rights, powers, and authorities herein granted.

(b) The execution, delivery, and performance of this Agreement do
not conflict with, violate, or breach any agreement to which BBI is a party, or
BBI's certificate of incorporation or bylaws.

(c) This Agreement has been duly executed and delivered by BBI, and
is a legal, valid, and binding obligation enforceable against BBI and AVECIA
HOLDINGS' Affiliates in accordance with its terms.

SECTION 7.03. Effect of Representations, Warranties and Covenants.
The Parties agree that if the representations and warranties made by HYBRIDON
under this Article are not true and accurate, or if the covenants made by
HYBRIDON under this Article are not upheld and complied with, and BBI or AVECIA
HOLDINGS' Affiliates incurs reasonably foreseeable damages, liabilities, costs
or other expenses as a result of such falsity or non- compliance, then HYBRIDON
shall indemnify and hold BBI and AVECIA HOLDINGS' Affiliates harmless from and
against any such reasonably foreseeable damages, liabilities, costs or other
expenses incurred as a result of such falsity or such non-compliance.

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ARTICLE VIII

TERM AND TERMINATION

SECTION 8.01. Term. This Agreement shall commence as of the
Effective Date and shall remain in force, unless terminated as provided herein.

(a) Loss of Patent Rights. The provisions of this Agreement shall
continue in effect until the date on which the last to expire, lapse or be
declared invalid or unenforceable HYBRIDON Patent(s) expires, lapses or is
declared invalid or unenforceable by a court of last resort.

(b) Insolvency. This Agreement will terminate should such BBI and
AVECIA HOLDINGS' Affiliates file a petition of any type as to its bankruptcy, be
declared bankrupt, become insolvent, make an assignment for the benefit of
creditors, go into liquidation or receivership, or otherwise lose legal control
of its business.

(c) Breach. Either party may terminate this Agreement by giving
notice in writing to the other party in the event such other party is in
material breach of this Agreement and subject to use of Dispute Resolution
procedure of Article VI such other party has failed to cure such breach within
sixty (60) calendar days of receipt of written notice thereof from such party.

(d) Survivability. Termination, relinquishment or expiration of the
Agreement for any reason shall be without prejudice to any rights which shall
have accrued to the benefit of either Party prior to such termination,
relinquishment or expiration, including damages arising from any breach
hereunder. Such termination, relinquishment or expiration shall not relieve
either Party from obligations which are expressly indicated to survive
termination or expiration of the Agreement.

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ARTICLE IX

BANKRUPTCY

SECTION 9.01. HYBRIDON shall maintain all HYBRIDON Patent(s) and
HYBRIDON Patent Application(s) licensed hereunder in accordance with the
provisions of SECTION 4.03. All rights and licenses granted under or pursuant to
this Agreement by HYBRIDON to BBI and AVECIA HOLDINGS' Affiliates are, and shall
otherwise be deemed to be, for purposes of Section 365(n) of the Bankruptcy
Code, licenses of rights to "intellectual property" as defined under Section
101(56) of the Bankruptcy Code. The parties agree that BBI and AVECIA HOLDINGS'
Affiliates, as a licensee of such rights and licenses, shall retain and may
fully exercise all of its rights and elections under the Bankruptcy Code. The
parties further agree that, in the event that any proceeding shall be instituted
by or against HYBRIDON seeking to adjudicate it a bankrupt or insolvent, or
seeking liquidation, winding up, reorganization, arrangement, adjustment,
protection, relief or composition of it or its debts under any law relating to
bankruptcy, insolvency or reorganization or relief of debtors, or seeking an
entry of an order for relief or the appointment of a receiver, trustee or other
similar official for it or any substantial part of its property or it shall take
any action to authorize any of the foregoing actions (each a "Proceeding"), BBI
and AVECIA HOLDINGS' Affiliates shall have the right to retain and enforce its
rights under this Agreement, including but not limited to the following rights:

(a) the right to continue to use the HYBRIDON Patent(s), HYBRIDON
Patent Application(s), and the Licensed Product and all versions and derivatives
thereof, and all documentation and other supporting material related thereto, in
accordance with the terms and conditions of this Agreement;

(b) the right to a complete duplicate of (or complete access to, as
appropriate) all HYBRIDON Patent(s) and HYBRIDON Patent Application(s) and all
embodiments of such, and the same, if not already in BBI's or AVECIA HOLDINGS'
Affiliates' possession, shall be promptly delivered to BBI or AVECIA HOLDINGS'
Affiliates (i) upon any such commencement of a Proceeding upon written request
therefor by BBI or AVECIA HOLDINGS' Affiliates, unless HYBRIDON elects to
continue to perform all of its obligations under this Agreement; or (ii) if not
delivered under (i) above, upon the rejection of this Agreement by or on behalf
of HYBRIDON upon written request therefor by BBI and AVECIA HOLDINGS'
Affiliates; and

(c) the right to obtain from HYBRIDON all documentation and other
supporting materials related to the HYBRIDON Patent(s), HYBRIDON Patent
Application(s), and the Licensed Product and all versions and derivatives
thereof.

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ARTICLE X

MISCELLANEOUS

SECTION 10.01. Assignment.

(a) Either Party may assign any of its rights or obligations under
this Agreement in any country to any of the Affiliates and may delegate its
obligations under this Agreement in any country to any of the Affiliates;

(b) Neither Party may assign its rights or obligations under this
Agreement to non-Affiliates without the prior written consent of the other
Party, except in connection with a merger or similar reorganization or the sale
of all or substantially all of its assets relating to HYBRIDON Patent(s) and
HYBRIDON Patent Application(s).

(c) This Agreement shall be binding upon and inure to the benefit of
the successors and permitted assigns of the Parties.

SECTION 10.02. Retained Rights. Nothing in this Agreement shall
limit in any respect the right of either Party to conduct research and
development and to market products using the HYBRIDON Patent(s) and HYBRIDON
Patent Application(s) other than as herein expressly provided.

SECTION 10.03. Research and Development Entities. Either Party may
assign its rights and obligations under this Agreement to an entity or entities
(e.g., partnership or corporation) that are specifically formed for financial
purposes and that finance research and development performed by such Party.

SECTION 10.04. Consents Not Unreasonably Withheld or Delayed.
Whenever provision is made in this Agreement for either Party to secure the
consent or approval of the other, that consent or approval shall not
unreasonably be withheld or delayed.

SECTION 10.05. Force Majeure. Neither Party shall lose any rights
hereunder or be liable to the other Party for damages or losses on account of
failure of performance by the defaulting Party if the failure is occasioned by
government action, war, fire, explosion, flood, strike, lockout, embargo, act of
God, or any other cause beyond the control of the defaulting Party, provided
that the Party claiming force majeure has extended all reasonable efforts to
avoid or remedy such force majeure and has given the other Party prompt notice
describing such event, the effect thereof and the actions being taken to avoid
or remedy such force majeure; provided, however, that in no event shall a Party
be required to settle any labor dispute or disturbance.

SECTION 10.06. Notices. All notices hereunder shall be in writing
and shall be deemed given if delivered personally or by facsimile transmission
(receipt verified), telexed, mailed by registered or certified mail (return
receipt requested), postage prepaid, or sent by express courier service, to the
Parties at the following addresses (or at such other address for a Party as
shall be specified by like notice; provided that notices of a change of address
shall be Effective only upon receipt thereof).

(a)  If to HYBRIDON:

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President
HYBRIDON, INC.
155 Fortune Blvd.
Milford, MA 01757

(b)  If to BBI:

President
BOSTON BIOSYSTEMS, INC.
75A Wiggins Ave.
Bedford, MA 01730
.

SECTION 10.07. Waiver. Except as specifically provided for herein,
the waiver from time to time by either of the Parties of any of their rights or
their failure to exercise any remedy shall not operate or be construed as a
continuing waiver of same or any other of such Party's rights or remedies
provided in this Agreement.

SECTION 10.08. Severability. If any term, covenant or condition of
this Agreement or the application thereof to any Party or circumstances shall,
to any extent or in any country, be held to be invalid or unenforceable, then
(i) the remainder of this Agreement shall not be affected thereby and each term,
covenant or condition of this Agreement shall be valid and be enforced to the
fullest extent permitted by law; and (ii) the Parties hereto covenant and agree
to renegotiate any such term, covenant or application thereof in good faith.

SECTION 10.09. No Strict Construction; Ambiguities. The language
used in this Agreement shall be deemed to be the language chosen by the parties
hereto to express their mutual intent and no rule of strict construction against
either party shall apply to any term or condition of this Agreement.
Ambiguities, if any, in this Agreement shall not be construed against any Party,
irrespective of which Party may be deemed to have authored the ambiguous
provision.

SECTION 10.10. Headings. The Sections and paragraph headings
contained herein are for the purposes of convenience only and are not intended
to define or limit the contents of said Sections or paragraphs.

SECTION 10.11. Governing Law. This Agreement shall be governed by
and interpreted under the laws of the State of Delaware as applied to contracts
entered into and performed entirely in Delaware by Delaware residents.

SECTION 10.12. Further Assurances. Each of the parties agrees to
execute and deliver such other documents, including but not limited to, updating
the list of HYBRIDON Patent(s) and HYBRIDON Patent Application(s) set forth in
Exhibit A, and to take all such actions as the other party, its successors,
assigns or other legal representatives may reasonably request to effect the
terms of this Agreement.

SECTION 10.13. Counterparts. This Agreement may be executed in one
or more counterparts, each of which shall be deemed an original, but all of
which together shall constitute one and the same instrument.

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SECTION 10.14. Entire Agreement; Amendments. This Agreement,
including all Exhibits attached hereto and thereto, and all documents delivered
concurrently herewith and therewith, set forth all the covenants, promises,
agreements, warranties, representations, conditions and understandings between
the Parties hereto and supersede and terminate all prior agreements and
understandings between the Parties. Both Parties acknowledge that in deciding to
enter into the Agreement and to consummate the transaction contemplated thereby
neither has relied upon any statement or representations, written or oral, other
than those explicitly set forth therein.

SECTION 10.15. Independent Contractors. The status of the Parties
under this Agreement shall be that of independent contractors. Neither Party
shall have the right to enter into any agreements on behalf of the other Party,
nor shall it represent to any person that it has any such right or authority.
Nothing in this Agreement shall be construed as establishing a partnership or
joint venture relationship between the Parties.

SECTION 10.16. Successors. This Agreement will be binding upon and
inure to the benefit of the parties and their respective successors and assigns
in whole or in part.

SECTION 10.17. Authority of Signatories. Each person executing this
Agreement individually and personally represents and warrants that he is duly
authorized to execute and deliver the same on behalf of the corporation for
which he is signing and that this Agreement is binding upon the corporation in
accordance with its terms.

IN WITNESS WHEREOF, HYBRIDON and BBI have caused this Agreement to
be executed as of the date first written above by their respective officers
thereunto duly authorized.

[SIGNATURE PAGES TO FOLLOW]

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EXECUTION COPY

HYBRIDON, INC.

By: /s/ Robert G. Andersen
Name: Robert G. Andersen
Title: Chief Financial Officer

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EXECUTION COPY

BOSTON BIOSYSTEMS, INC.

By:  /s/ Gregory S. Kurey
Name: Gregory S. Kurey
Title: General Counsel

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EXECUTION COPY

EXHIBIT A

HYBRIDON OLIGONUCLEOTIDE PURIFICATION PATENT(S)

U.S. Patent(s)

5,912,332

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1
Exhibit 10.62

CONFIDENTIAL TREATMENT REQUESTED

ASSIGNMENT OF PATENT RIGHTS

WHEREAS, HYBRIDON, INC., a corporation organized and existing under the
laws of the State of Delaware having a principal place of business at 155
Fortune Blvd. Milford, Massachusetts 01757 (hereinafter called "Assignor") is
the owner of:

See Schedule A

(hereinafter referred to collectively as "Patent Properties").

WHEREAS, BOSTON BIOSYSTEMS, INC., a corporation organized under the
laws of the State of Delaware having a principal place of business at 78A
Wiggins Avenue, Bedford, Massachusetts, 01730, (hereinafter called "Assignee"),
is desirous of acquiring the entire right, title and interest for the United
States, its territories, dependencies and possessions and in all countries
foreign to the United States, including the full right to claim for any such
application all benefits and priority rights under an applicable convention, in
and to said patents and patent application (and/or patents that may be granted
therefrom), and any continuations, divisions, reissues or extensions of the
same.

NOW, TO ALL WHOM IT MAY CONCERN: Be it known that for and in
consideration of the sum of One Dollar ($1.00) and for other good and valuable
consideration, the receipt of all of which is hereby acknowledged, the said
Assignor has sold, assigned, transferred and set over, and does hereby sell,
assign, transfer and set over, unto the said Assignee is successors and assigns,
the entire right, title and interest for the United States, its territories,
dependencies and possessions, in all countries foreign to the United States,
including the full right to claim for any possessions and in all countries
foreign to the United States, including the full right to claim for any such
application all benefits and priority rights under any applicable convention, in
and to said Patent Properties (and/or patents that may be granted therefrom),
and any divisions, continuations, reissues or extensions thereof; the same to be
held and enjoyed by said Assignee its successors and assigns, as fully and
entirely as the same would have been held and enjoyed by said Assignor had this
assignment and sale not been made, together with all claims for damages by
reason of past infringement of said Patent Properties with the right to sue for,
and collect the same for its own use and for the use of its successors, assigns
and other legal representatives.

And I do hereby authorize and request the Commissioner of Patents and
Trademarks of the United States to issue any Letters Patent of the United
States, resulting from said Patent Properties when granted, to said Assignee.

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SECURITIES AND EXCHANGE COMMISSION.
ASTERISKS DENOTE OMISSIONS.

The Assignor hereby further covenants and agrees that, at the request
and expense of the Assignee, its successors, legal representatives and assigns,
but without demanding further consideration therefor, the Assignor will (1)
assist in the prosecution of all applications for Letters Patent as herein
described and any other applications for Letters Patent that may be made; (2)
communicate any and all facts known to him respecting said patents and patent
applications; (3) testify in any legal proceeding involving said patents and
patent applications; (4) execute and acknowledge all lawful papers and legal
instruments; (5) execute all divisional, continuing, reissue and reexamination
applications; (6) make all rightful oaths; and (6) generally do any and every
lawful act deemed necessary to aid and cooperate with the Assignee, its
successors, legal representatives and assigns in perfecting and maintaining the
entire interest conveyed herein and in obtaining and enforcing proper patent or
industrial property protection for the subject matter of said patents and patent
applications in any country, particularly in cases of opposition, interference
and litigation;

The Assignor also covenants and agrees that the rights and obligations
set forth in this instrument shall be binding upon, and inure to the benefit of,
the Assignor's heirs, legal representatives, successors and assigns;

The Assignor hereby covenants that it has full right to convey the
interest herein assigned and that it has not executed and will not execute any
agreement in conflict herewith.

The undersigned hereby grants the firm of McDermott, Will & Emery the
power to insert on this Assignment any further identification that may be
necessary or desirable in order to comply with the rules of the United States
Patent and Trademark Office for recordation of this document.

The Parties hereby agree that this Assignment may be executed in two or
more counterparts each of which shall be deemed an original but all of which
together shall constitute one and the same instrument.

In testimony whereof, the Assignor and Assignee hereunto sets their
hands and seals the day and year set opposite their signatures.

2

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BY ASSIGNOR:

/s/ Robert G. Andersen
--------------------------
Date: September 19, 2000                             HYBRIDON, INC.
155 Fortune Blvd.
Milford, MA 01757

WITNESSED BY:
/s/ Sean B. Leonard

Date: September 19, 2000

State of Massachusetts              )
)    ss:
County of Suffolk                   )

This 19th day of September 2000, before me personally came the
above-named Assignor to me personally known as the individual who executed the
foregoing assignment, who acknowledged to me that he executed the same of his
own free will for the purposes therein set forth.

/s/ Shawna Hansen
--------------------------------------
My commission expires:

Shawna J. Grimm Hansen, Notary Public
Commonwealth of Massachusetts
My Commission expires 7/23/2004

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BY ASSIGNEE:

Date:  September 21, 2000                            BOSTON BIOSYSTEMS, INC.
75A Wiggins Ave.
Bedford, MA 01730

BY:      /s/ Gregory S. Kurey
--------------------------
PRINTED: Gregory S. Kurey

WITNESSED BY:

Date:
-----------------------------

Date:
-----------------------------

State of Massachusetts     )
)    ss:
County of Suffolk          )

This 21st day of September 2000, before me personally came the
above-named duly authorized representative of Assignee personally known to me as
the individual who executed the foregoing Assignment on behalf of the Assignee,
who acknowledged to me that he had the authority to execute same for the
purposes therein set forth.

/s/
-------------------------------
My commission expires:

August 25, 2006

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This Assignments should preferably be signed before: (1) a Notary Public if
within the U.S.A., (b) a U.S. Counsel if outside the U.S.A.. If neither, then it
should be signed before at least two witness. In all cases any formalities of
execution required by the by-laws of the Assignor Company and the state or
country having jurisdiction over the assignor, must be observed.

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SCHEDULE A

(1)      U.S. Patent No. 5,403,709 entitled METHOD OF SEQUENCING SYNTHETIC
OLIGNONUCLEOTIDES CONTAINING NON-PHOSPHODIESTER INTERNUCLEOTIDE
LINKAGES;

(2)      U.S. Patent No. 5,420,265 entitled SEPARATION OF PHOSPHORO-THIOATE
OLIGONUCLEOTIDES BY CAPILLARY GEL ELECTROPHORESIS;

(3)      U.S. Patent No. 5,525,470 entitled METHOD OF SEQUENCING [SHORT]
OLIGONUCLEOTIDES;

(4)      U.S. Patent No. 5,554,744 entitled METHOD FOR LOADING SOLID SUPPORTS
FOR NUCLEIC ACID SYNTHESIS;

(5)      U.S. Patent No. 5,627,277 entitled METHOD FOR ANALYZING OLIGNUCLEOTIDE
ANALOGS;

(6)      U.S. Patent No. 5,639,875 entitled IMPROVED METHOD FOR H PHOSPHONATE
SYNTHESIS OF OLIGONUCLEOTIES USING TRIPHOSGENE;

(7)      U.S. Patent No. 5,643,717 entitled ANALYTICAL TECHNIQUE FOR
OLIGONUCLEOTIDE ANALOGS;

(8)      U.S. Patent No. 5,652,103 entitled METHOD OF SEQUENCING SYNTHETIC
OLIGONUCLEOTIDES CONTAINING PHOSPHODIESTER INTERNUCLEOTIDE LINKAGES;

(9)      U.S. Patent No. 5,668,268 entitled NOVEL POLYMER SUPPORT FOR NUCLEIC
ACID SYNTHESIS;

(10)     U.S. Patent No. 5,705,629 entitled IMPROVED METHODS FOR H-PHOSPHONATE
SYNTHESIS OF MONO- AND OLIGONUCLEOTIDES;

(11)     U.S. Patent No. 5,739,314 entitled NEW METHODS OF SYNTHESIZING 2'-O-
SUBSTITUTED PYRIMIDINE RIBONUCLEOSIDES;

(12)     U.S. Patent No. 5,807,525 entitled APPARATUS AND PROCESS FOR
MULTI-STAGE SOLID-PHASE SYNTHESIS OF LONG-CHAINED ORGANIC MOLECULES;

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(13)     U.S. Patent No. 5,808,042 entitled IMPROVED PROCEDURE FOR THE
DETRITYLATION OF DMT-OLIGONUCLEOTIDES USING "DOWEX" ION EXCHANGE;

(14)     U.S. Patent No. 6,087,491 entitled EXTREMELY HIGH PURITY
OLIGONUCLEOTIDES AND METHODS OF SYNTHESIZING THEM USING DIMER BLOCKS;

(15)     U.S. Patent No. 6,096,881 entitled NOVEL SULFUR TRANSFER REAGENTS FOR
OLIGONUCLEOTIDE SYNTHESIS;

(16)     U.S. Patent Application Serial No. ***

(17)     U.S. Patent Application Serial No. ***

(18)     U.S. Patent Application Serial No. ***

(19)     U.S. Patent Application Serial No. ***

(20)     U.S. Patent Application Serial No. ***

(21)     U.S. Patent Application Serial No. ***

(22)     U.S. Patent Application Serial No. ***

(23)     U.S. Patent Application Serial No. ***

* To the extent not abandoned.

7

1

Exhibit 10.63

CONFIDENTIAL TREATMENT REQUESTED

EXECUTION COPY

PNT MONOMER PATENT LICENSE AND OPTION AGREEMENT

dated as of September 20, 2000

by and between

HYBRIDON, INC.

and

BOSTON BIOSYSTEMS, INC.

2
EXECUTION COPY

PNT MONOMER PATENT LICENSE AND OPTION AGREEMENT

This PNT MONOMER PATENT LICENSE AND OPTION AGREEMENT (the
"Agreement"), dated as of September 20, 2000 (the "Effective Date"), is entered
into by and between Hybridon, Inc., a Delaware corporation (the "Licensor"),
having a principal place of business located at 155 Fortune Blvd., Milford,
Massachusetts 01757 (hereinafter referred to as "HYBRIDON") and Boston
Biosystems, Inc., a Delaware corporation (the "Licensee"), having a principal
place of business located at 75A Wiggins Avenue, Bedford, Massachusetts 01730
(hereinafter referred to as "BBI"). HYBRIDON and BBI are sometimes referred to
herein individually as a "Party" and collectively as the "Parties", and all
references to "HYBRIDON" and "BBI " shall include their respective Affiliates,
where appropriate under the terms of this Agreement.

W I T N E S S E T H:

WHEREAS, HYBRIDON has entered into that certain Asset Purchase
Agreement dated ______ ("Purchase Agreement") to sell certain assets to BBI, and
HYBRIDON wishes to grant certain intellectual property rights as provided
herein;

WHEREAS, HYBRIDON owns certain patents ("HYBRIDON Patent(s)") and
patent applications ("HYBRIDON Patent Application(s)") that cover PNT Monomer
technology;

WHEREAS, BBI desires to obtain a royalty-free, non-exclusive license
under the HYBRIDON Patent Application(s), existing patents and any patents
arising from the HYBRIDON Patent Application(s) for non-commercial use; and an
option to enter into a royalty-bearing, non-exclusive license under existing
patents and any patents arising from the HYBRIDON Patent Application(s) for
commercial use;
and

NOW, THEREFORE, in consideration of the foregoing recitals and the
mutual covenants and agreements contained herein, the parties hereto, intending
to be legally bound, do hereby agree as follows:

ARTICLE I

DEFINITIONS

SECTION 1.01. Definitions. The following terms, when capitalized,
shall have the following meanings (such meanings to be equally applicable to
both the singular and plural forms of the terms defined) as used in this
Agreement:

"Affiliate(s)" means any person, corporation, partnership, firm,
joint venture or other entity now currently existing or which may be formed in
the future, which directly or indirectly, through one or more intermediaries,
controls, is controlled by, or is under common control with, HYBRIDON, BBI, or
AVECIA HOLDINGS PLC, as the case may be. As used in this definition, "control"
means direct or indirect ownership of an entity, whether through the ownership
of more than 50% of the outstanding voting securities or by contract or
otherwise.

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SECURITIES AND EXCHANGE COMMISSION.
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"AVECIA HOLDINGS PLC" or "AVECIA HOLDINGS" is a company organized
under the laws of United Kingdom, and its registered office address is PO Box
42, Hexagon House, Blackley, Manchester, M9 8ZS, United Kingdom.

"Change of Control" of a Party means the occurrence of any of the
following with respect to such Party at any time after the date hereof:

(a) any Third Party (other than the Affiliates on the
date hereof) shall have become the beneficial owner of securities representing
more than 50% of the aggregate voting power of the then outstanding voting
securities of such Party; or

(b) any sale by such Party of: (i) HYBRIDON; or (ii) all
or substantially all of such Party's pharmaceutical and/or healthcare assets; or
(iii) all or substantially all of such Party's assets other than its
pharmaceutical and/or healthcare assets.

"Confidential Information" shall have the meaning set forth in
Article III.

"Control" or "Controlled" shall refer to possession of the ability
to grant a license or sublicense of patent rights, know-how or other intangible
rights as provided for herein without violating the terms of any agreement or
other arrangement with any Third Party.

"Effective Date" shall have the meaning set forth in the Recitals to
this Agreement.

"Field" or "Field of Use" means the development, use, and
manufacture, of oligonucleotides and products containing oligonucleotides for
non-commercial purposes.

"HYBRIDON Patent(s)" shall mean any patent set forth in Exhibit A,
as well as those Patents issuing from the HYBRIDON Patent Application(s)
including any foreign, international or domestic counterpart and issued patents
arising therefrom, as well as any divisional, continuation or
continuation-in-part thereof.

"HYBRIDON Patent Application(s)" shall mean the Patent applications
set forth in Exhibit A, which are pending in the U. S. Patent and Trademark
Office as of the Effective Date, including any foreign, international or
domestic counterpart patent applications, as well as any divisional,
continuation or continuation-in-part thereof.

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SECURITIES AND EXCHANGE COMMISSION.
ASTERISKS DENOTE OMISSIONS.

"Licensed Product(s)" means any oligonucleotides made using PNT
Monomers as described and claimed in the HYBRIDON Patents and the HYBRIDON
Patent Applications.

"Patent" means United States and foreign patents, applications and
provisional applications for United States and foreign patents, and all
reexaminations, reissues, extensions, term restorations, divisionals,
continuations and continuations-in-part thereof.

"PNT Monomer(s)" is an abbreviation for a monomer comprising a
pentenoyl group, which is a nucleoside base protective group. The HYBRIDON
Patents and HYBRIDON Patent Applications describing and claiming PNT Monomers
are listed in Exhibit A.

"Product(s)" means Licensed Product(s).

"Royalty Bearing Sales" means the amount invoiced by BBI, AVECIA
HOLDINGS' Affiliates for sales of Licensed Product to a Third Party less (i)
discounts, including cash discounts, rebates, chargebacks, and retroactive price
reductions or allowances actually allowed or granted from the billed amount, and
fees paid to distributors (other than a distributor that is an Affiliate of such
Party), (ii) credits or allowances actually granted upon claims, rejections or
returns of such sales of such Product, including recalls, regardless of the
Party requesting such recalls, (iii) freight, postage, shipping and insurance
charges paid for delivery of such Product, to the extent billed, (iv) taxes,
duties or other governmental charges levied on or measured by the billing amount
when included in billing, as adjusted for rebates, chargebacks and refunds, and
(v) provisions for uncollectible accounts determined in accordance with such
Party's normal accounting procedures consistently applied within and across its
pharmaceutical operating units.

"Technical Information" means all know-how, trade secrets,
inventions, data, technology, and other information now owned or licensed by
HYBRIDON, or hereafter acquired or licensed by HYBRIDON during the term of this
Agreement, in connection with the Licensed Product, including, but not limited
to, (i) medical, chemical and other scientific data; (ii) processes and analytic
methodology used in the development, testing and analysis of the Licensed
Product; and (iii) packaging, manufacturing, advertising and marketing data.

"Territory" means worldwide.

"Third Party" or "Third Parties" means any entity other than
HYBRIDON, BBI or AVECIA HOLDINGS, and their respective Affiliates.

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ARTICLE II

LICENSE AND ROYALTIES

SECTION 2.01. Grant. Subject to the terms and conditions of this
Agreement, HYBRIDON hereby grants to BBI and AVECIA HOLDINGS' Affiliates a
non-exclusive, paid up, royalty free, perpetual right and license during the
term of this Agreement to use the subject matter disclosed and claimed in the
HYBRIDON Patent Application(s) to make and have made the Licensed Product within
the Field of Use in the Territory.

SECTION 2.02. Grant. Subject to the terms and conditions of this
Agreement, HYBRIDON hereby grants to BBI and AVECIA HOLDINGS' Affiliates a
non-exclusive, royalty free, perpetual right and license during the term of this
Agreement to use the subject matter disclosed and claimed in the HYBRIDON
Patent(s) to make and have made the Licensed Product within the Field of Use in
the Territory.

SECTION 2.03. Know-how License Grant. HYBRIDON grants BBI and AVECIA
HOLDINGS' Affiliates a paid-up, non-exclusive license in the Territory, with a
right to use HYBRIDON know-how solely for the purposes of manufacturing and
having manufactured, using, selling, offering for sale and importing the
Licensed Product in the Territory. BBI or AVECIA HOLDINGS' Affiliates will
reimburse HYBRIDON for all reasonable and customary expenses incurred at BBI's
or AVECIA HOLDINGS' Affiliates' request, including a reasonable consulting
hourly rate for time required of HYBRIDON personnel.

SECTION 2.04. Option Grant. Subject to the terms and conditions of
this Agreement, HYBRIDON hereby grants to BBI and AVECIA HOLDINGS' Affiliates a
*** option to negotiate a non-exclusive, royalty bearing, perpetual right and
license (the "Option License") during the term of this Agreement to use the
subject matter disclosed and claimed in the HYBRIDON Patent(s) and HYBRIDON
Patent Application(s) to make and have made, use, sell, offer for sale and
import any products deriving from the HYBRIDON Patent(s) and HYBRIDON Patent
Application(s) for any purposes within the Territory. Unless otherwise agreed,
the financial terms of the Option License shall include, without limitation, a
royalty amount that is no more than *** of the Royalty Bearing Sales ***

SECTION 2.05.  ***.

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SECURITIES AND EXCHANGE COMMISSION.
ASTERISKS DENOTE OMISSIONS.

ARTICLE III

CONFIDENTIALITY

SECTION 3.01. Confidentiality; Exceptions. Except to the extent
expressly authorized by this Agreement or otherwise agreed in writing, the
Parties agree that, for the term of this Agreement and for five (5) years
thereafter, they shall keep confidential the existence of this Agreement and
shall not publish or otherwise disclose or use for any purpose other than as
provided for in this Agreement any information and materials furnished to it by
the other Party pursuant to this Agreement, or any provisions of this Agreement
that are the subject of an Effective order of the Securities Exchange Commission
granting confidential treatment pursuant to the Securities Act of 1934, as
amended (collectively, "Confidential Information"), except to the extent that it
can be established by the receiving Party that such Confidential Information:

(a) was already known to the receiving Party as shown by written
record, other than under an obligation of confidentiality, at the time of
disclosure by the other Party;

(b) was generally available to the public or otherwise part of the
public domain at the time of its disclosure to the receiving Party as shown by
written record;

(c) became generally available to the public or otherwise part of
the public domain after its disclosure and other than through any act or
omission of the receiving Party in breach of this Agreement; or

(d) was disclosed to the receiving Party, other than under an
obligation of confidentiality, by a Third Party who had no obligation to the
disclosing Party not to disclose such information to others.

SECTION 3.02. Authorized Disclosure. Each Party may disclose
Confidential Information hereunder to the extent such disclosure is reasonably
necessary in filing or prosecuting patent applications, prosecuting or defending
litigation, complying with applicable governmental regulations or conducting
pre-clinical or clinical trials, provided that if a Party is required by law or
regulation to make any such disclosures of the other Party's Confidential
Information it will, except where impracticable for necessary disclosures, for
example in the event of medical emergency, give reasonable advance notice to the
other Party of such disclosure requirement and, except to the extent
inappropriate in the case of patent applications, will use its reasonable
efforts to secure confidential treatment of such Confidential Information
required to be disclosed. In addition, and with prior written notice to the
other Party of each Third Party with whom a confidential disclosure agreement is
being entered into, each Party shall be entitled to disclose, under a binder of
confidentiality containing provisions as protective as those of this Article,
Confidential Information to any Third Party for the purpose of carrying out the
purposes of this Agreement. Nothing in this Article shall restrict any Party
from using for any purpose any Confidential Information independently developed
by it during the term 

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of this Agreement. BBI and AVECIA HOLDINGS' Affiliates may disclose the
existence, but not the terms, of this Agreement to its customers or potential
customers for the purpose of assuring its customers or potential customers of
the existence of the rights conveyed herein.

SECTION 3.03. Publicity Review. Subject to the further provisions of
this Section, no Party shall originate any written publicity, news release, or
other announcement or statement relating to this Agreement or to performance
hereunder or the existence of an arrangement between the Parties (collectively,
"Written Disclosure"), without the prior prompt review and written approval of
the other, which approval shall not be unreasonably withheld or delayed.
Notwithstanding the foregoing provisions of this Section, any Party may make any
public Written Disclosure it believes in good faith based upon the advice of
counsel is required by applicable law or any listing or trading agreement
concerning its publicly traded securities, provided that prior to making such
Written Disclosure, the disclosing Party shall provide the other Party with a
copy of the materials proposed to be disclosed and provide the receiving Party
with an opportunity to promptly review the proposed Written Disclosure. To the
extent that the receiving Party reasonably requests that any information in the
materials proposed to be disclosed be deleted, the disclosing Party shall
request confidential treatment of such information pursuant to Rule 406 of the
Securities Act of 1933 or Rule 26b-2 of the Securities Exchange Act of 1934, as
applicable (or any other applicable regulation relating to the confidential
treatment of information), so that there be omitted from the materials that are
publicly filed any information that the receiving Party reasonably requests to
be deleted. The terms of this Agreement may also be disclosed to (i) government
agencies where required by law, or (ii) Third Parties with the prior written
consent of the other Party, which consent shall not be unreasonably withheld or
delayed, so long as such disclosure is made under a binder of confidentiality
and so long as highly sensitive terms and conditions such as financial terms are
extracted from the Agreement or not disclosed upon the request of the other
Party. All Written Disclosures shall be factual and as brief as is reasonable
under the circumstances. Upon request by either Party, the Parties agree to
prepare a mutually agreed press release and question and answer document with
respect to this Agreement. Each Party agrees that all Written Disclosures and
oral statements relating hereto shall be consistent with the answers specified
in such question and answer document.

SECTION 3.04. Survival. This Article shall survive the termination
or expiration of this Agreement for a period of five (5) years.

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ARTICLE IV

INTELLECTUAL PROPERTY AND PATENT RIGHTS

SECTION 4.01. Notice. Each of the parties shall promptly notify the
other in writing if it: (i) receives any notice or becomes aware of any
information that in any way affects the other party's rights under this
Agreement; or (ii) becomes aware of any actual or suspected infringement,
misappropriation or misuse by a Third Party of the HYBRIDON Patent(s) and
HYBRIDON Patent Application(s) in the Territory and within the Field of Use.

SECTION 4.02. Assistance. At HYBRIDON's request and HYBRIDON's
expense, BBI and AVECIA HOLDINGS' Affiliates shall take all reasonable steps and
shall provide such materials, cooperation and assistance as may be reasonably
required to assist HYBRIDON in maintaining and enforcing HYBRIDON's right in and
to the Intellectual Property.

SECTION 4.03. Maintenance Fees. Should HYBRIDON decline to pay any
or all of the required maintenance fees on the HYBRIDON Patent(s) and HYBRIDON
Patent Application(s) or otherwise to prosecute or maintain the HYBRIDON
Patent(s) and HYBRIDON Patent Application(s), it shall give BBI or AVECIA
HOLDINGS' Affiliates thirty (30) days notice of its decision, and BBI and AVECIA
HOLDINGS' Affiliates shall have the right (but not the obligation) to pay such
maintenance fees or to prosecute or maintain such HYBRIDON Patent(s) and
HYBRIDON Patent Application(s). If BBI and AVECIA HOLDINGS' Affiliates elects to
pay such maintenance fees, HYBRIDON agrees to assign all right, title and
interest in and to the HYBRIDON Patent(s) and HYBRIDON Patent Application(s) to
BBI and AVECIA HOLDINGS' Affiliates without further consideration.

SECTION 4.04. Infringement.

(a) HYBRIDON's Rights to Enforce. HYBRIDON shall have the right (but
not the obligation), in its sole discretion, to take action at its own expense
against actual or suspected infringers of the HYBRIDON Patent(s) and HYBRIDON
Patent Application(s) in the Field of Use in the Territory, and any and all
recoveries resulting from such actions by HYBRIDON shall be retained by
HYBRIDON. At HYBRIDON's request, and at HYBRIDON's expense, BBI and AVECIA
HOLDINGS' Affiliates shall take all reasonable steps and shall provide any
materials, cooperation and assistance as may be reasonably required to assist
HYBRIDON in taking action against actual or suspected infringers in the Field of
Use in the Territory. BBI and AVECIA HOLDINGS' Affiliates shall join any such
action as a necessary and indispensable party if so required.

SECTION 4.05.  Defense and Settlement of Third Party Claims.

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(a) Defense in the Territory. If a Third Party asserts that a
patent, trademark or other intangible right owned by it is infringed by any
Licensed Product in the Territory, BBI and AVECIA HOLDINGS' Affiliates will be
solely responsible for defending against any such assertions at its cost and
expense.

(b) Settlement with a Third Party. If BBI and AVECIA HOLDINGS'
Affiliates must defend a Third Party claim with respect to a Licensed Product,
then BBI and AVECIA HOLDINGS' Affiliates shall also have the right to control
settlement of such claim.

ARTICLE V

INDEMNIFICATION; LIMITATION OF LIABILITY

SECTION 5.01. Indemnification by HYBRIDON. HYBRIDON shall defend,
indemnify and hold BBI and its subsidiaries and AVECIA HOLDINGS' Affiliates, and
its and their officers, directors, shareholders, employees and agents harmless
and shall pay all losses, damages, fees, expenses or costs (including reasonable
attorneys' fees) incurred by them based upon any claim or action alleging
HYBRIDON's breach of its obligations, representations, warranties or covenants
hereunder unless BBI's or AVECIA HOLDINGS' Affiliatess negligence caused the
losses, damages, fees, expenses or costs.

SECTION 5.02. Indemnification by BBI and AVECIA HOLDINGS'
Affiliates. BBI and AVECIA HOLDINGS' Affiliates shall defend, indemnify and hold
HYBRIDON and its officers, directors, shareholders, employees and agents
harmless and shall pay all losses, damages, fees, expenses or costs (including
reasonable attorney's fees) incurred by them based upon any claim or action
alleging BBI's and AVECIA HOLDINGS' Affiliates' breach of its obligations,
representations, warranties or covenants hereunder unless HYBRIDON's negligence
caused the losses, damages, fees, expenses or costs.

SECTION 5.03 Limitation of Liability. EXCEPT AS SET FORTH IN SECTION
7.03 HEREIN, NEITHER PARTY SHALL BE LIABLE TO THE OTHER PARTY OR ANY THIRD PARTY
FOR ANY SPECIAL, CONSEQUENTIAL, EXEMPLARY OR INCIDENTAL DAMAGES (INCLUDING LOST
OR ANTICIPATED REVENUES OR PROFITS RELATING TO THE SAME), ARISING FROM ANY CLAIM
RELATING TO THIS AGREEMENT, THE HYBRIDON PATENT(S) AND HYBRIDON PATENT
APPLICATION(S) OR ANY IMPROVEMENT, WHETHER SUCH CLAIM IS BASED ON WARRANTY,
CONTRACT, TORT (INCLUDING NEGLIGENCE OR STRICT LIABILITY) OR OTHERWISE, EVEN IF
AN AUTHORIZED REPRESENTATIVE OF SUCH PARTY IS ADVISED OF THE POSSIBILITY OR
LIKELIHOOD OF SAME.

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ARTICLE VI

DISPUTE RESOLUTION.

SECTION 6.01. Disputes. The Parties recognize that disputes as to
certain matters may from time to time arise during the term of this Agreement
which relate to either Party's rights and/or obligations hereunder or
thereunder. It is the intent of the Parties to establish procedures to
facilitate the resolution of disputes arising under this Agreement in an
expedient manner by mutual cooperation and without resort to litigation. To
accomplish this objective, the Parties agree to follow the procedures set forth
in this Article if and when a dispute arises under this Agreement.

SECTION 6.02. Good Faith. The parties shall negotiate in good faith
to resolve the dispute.

SECTION 6.03. Personal Meeting. If the dispute remains unresolved,
executives from the interested business units or division of the parties shall
meet in person, at a mutually agreed upon time and place, to negotiate in good
faith to resolve the dispute. If the dispute continues to remain unresolved for
more than sixty (60) days from the date the parties met to negotiate pursuant to
this Section, then either party may pursue other dispute resolution procedures,
including the institution of arbitration as more fully set forth herein.

SECTION 6.04. Alternative Dispute Resolution. Any dispute
controversy or claim arising out of or relating to the validity, construction,
enforceability or performance of this Agreement, including disputes relating to
an alleged breach or to termination of this Agreement, but excluding (i) any
dispute, controversy or claim arising out of or relating to the validity,
enforceability, or infringement of any HYBRIDON Patent(s) or any BBI and AVECIA
HOLDINGS' Affiliates Patent(s) and (ii) other than disputes which are expressly
prohibited herein from being resolved by this mechanism, shall be settled by
binding Alternative Dispute Resolution ("ADR") in the manner described below:

(a) If a Party intends to begin an ADR to resolve a dispute, such
Party shall provide written notice (the "ADR Request") to counsel for the other
Party informing such other Party of such intention and the issues to be
resolved. From the date of the ADR Request and until such time as any matter has
been finally settled by ADR, the running of the time periods contained in
SECTION 6.05 as to which a Party must cure a breach of this Agreement shall be
suspended as to the subject matter of the dispute.

(b) Within fifteen (15) business days after receipt of the ADR
Request, the other Party may, by written notice to counsel for the Party
initiating ADR, add additional issues to be resolved.

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SECTION 6.05. Arbitration Procedures. An ADR initiated under this
Agreement will proceed in accordance with the Commercial Arbitration Rules of
the American Arbitration Association then in effect, insofar as such rules are
not inconsistent with the provisions expressly set forth in this Agreement,
unless the Parties mutually agree otherwise, and pursuant to the following
procedures:

(a) Notice of the demand for arbitration will be filed in writing
with the other Party and with the American Arbitration Association. The
arbitration panel shall consist of one (1) arbitrator mutually agreed to by the
Parties and the decision shall be final and binding on the Parties and their
legal successors.

(b) The arbitrator may, at his discretion, provide for discovery by
the Parties, not to exceed four (4) months from the date of filing of the Notice
of Arbitration.

(c) Any arbitration hearing shall be conducted in Wilmington,
Delaware. The governing law will be as specified herein. The arbitrator will
have authority to award both legal and equitable relief but not to award
punitive damages.

(d) All costs and fees of the arbitration, other than each Party's
legal fees and expenses, will be allocated by the arbitrators. Subject to
subsection (c), each Party shall bear its own legal fees and expenses.

(e) A final written decision by the arbitrator will be rendered not
later than thirty (30) days following the completion of the hearing.

(f) The ADR proceeding shall be confidential and the arbitrator
shall issue appropriate protective orders to safeguard each Party's confidential
information. Except as required by law, no Party shall make (or instruct the
arbitrator to make) any public announcement with respect to the proceedings or
decision of the arbitrator without prior written consent of each other Party.
The existence of any dispute submitted to ADR, and the award, shall be kept in
confidence by the Parties and the arbitrator, except as required in connection
with the enforcement of such award or as otherwise required by applicable law.

SECTION 6.06. Survivability. Any duty to arbitrate under this
Agreement shall remain in effect and enforceable after termination of this
Agreement for any reason.

SECTION 6.07. Jurisdiction. For the purposes of this Article, each
Party agrees to abide by the award rendered in any arbitration, and the Parties
agree to accept the jurisdiction of any court having jurisdiction over the
Parties for the purposes of enforcing awards entered pursuant to this Article
and for enforcing the agreements reflected in this Article.

SECTION 6.08. Equitable Remedies. Nothing in this Section shall
prevent either party from pursuing a temporary restraining order, injunctive
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equitable relief against the other party at any time if the allegedly aggrieved
party believes that a breach or a threatened breach of this Agreement would
cause it irreparable harm provided that the other party is given thirty (30)
days written notice prior to equitable relief being sought.

ARTICLE VII

REPRESENTATIONS AND WARRANTIES

SECTION 7.01. HYBRIDON represents, warrants and covenants that:

(a) HYBRIDON is a corporation duly organized, existing and in good
standing under the laws of the State of Delaware, with full right, power and
authority to enter into and perform this Agreement and to grant all of the
rights, powers and authorities herein granted.

(b) The execution, delivery, and performance of this Agreement do
not conflict with, violate, or breach any agreement to which HYBRIDON is a
party, or HYBRIDON's articles of incorporation or bylaws.

(c) The issued HYBRIDON Patent(s) and any that may issue from the
HYBRIDON Patent Application(s) are valid and enforceable

(d) This Agreement has been duly executed and delivered by HYBRIDON
and is a legal, valid, and binding obligation enforceable against HYBRIDON in
accordance with its terms.

(e) HYBRIDON knows of no fact which does or could materially
adversely affect the rights granted to BBI and AVECIA HOLDINGS' Affiliates
hereunder, except as disclosed herein.

(f) Right of BBI and AVECIA HOLDINGS' Affiliates to Monitor HYBRIDON
Patent Application(s). HYBRIDON covenants that during the term of this
Agreement, HYBRIDON shall provide BBI and AVECIA HOLDINGS' Affiliates with
copies of all substantive communications to and from patent offices regarding
HYBRIDON Patent(s) and HYBRIDON Patent Application(s) promptly after the receipt
thereof.

SECTION 7.02. BBI  represents, warrants and covenants that:

(a) BBI is a corporation duly organized, existing, and in good
standing under the laws of the State of Delaware, with full right, power and
authority to enter into and perform this Agreement and to grant all of the
rights, powers, and authorities herein granted.

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(b) The execution, delivery, and performance of this Agreement do
not conflict with, violate, or breach any agreement to which BBI is a party, or
BBI's certificate of incorporation or bylaws.

(c) This Agreement has been duly executed and delivered by BBI, and
is a legal, valid, and binding obligation enforceable against BBI and AVECIA
HOLDINGS' Affiliates in accordance with its terms.

SECTION 7.03. Effect of Representations, Warranties and Covenants.
The Parties agree that if the representations and warranties made by HYBRIDON
under this Article are not true and accurate, or if the covenants made by
HYBRIDON under this Article are not upheld and complied with, and BBI or AVECIA
HOLDINGS' Affiliates incurs reasonably foreseeable damages, liabilities, costs
or other expenses as a result of such falsity or non- compliance, then HYBRIDON
shall indemnify and hold BBI and AVECIA HOLDINGS' Affiliates harmless from and
against any such reasonably foreseeable damages, liabilities, costs or other
expenses incurred as a result of such falsity or such non-compliance.

ARTICLE VIII

TERM AND TERMINATION

SECTION 8.01. Term. This Agreement shall commence as of the
Effective Date and shall remain in force, unless terminated as provided herein.

(a) Loss of Patent Rights. The provisions of this Agreement shall
continue in effect until the date on which the last to expire, lapse or be
declared invalid or unenforceable HYBRIDON Patent(s) expires, lapses or is
declared invalid or unenforceable by a court of last resort.

(b) Insolvency. This Agreement will terminate should such BBI and
AVECIA HOLDINGS' Affiliates file a petition of any type as to its bankruptcy, be
declared bankrupt, become insolvent, make an assignment for the benefit of
creditors, go into liquidation or receivership, or otherwise lose legal control
of its business.

(c) Breach. Either party may terminate this Agreement by giving
notice in writing to the other party in the event such other party is in
material breach of this Agreement and subject to use of Dispute Resolution
procedure of Article VI such other party has failed to cure such breach within
sixty (30) calendar days of receipt of written notice thereof from such party.

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(d) Survivability. Termination, relinquishment or expiration of the
Agreement for any reason shall be without prejudice to any rights which shall
have accrued to the benefit of either Party prior to such termination,
relinquishment or expiration, including damages arising from any breach
hereunder. Such termination, relinquishment or expiration shall not relieve
either Party from obligations which are expressly indicated to survive
termination or expiration of the Agreement.

ARTICLE IX

BANKRUPTCY

SECTION 9.01. HYBRIDON shall maintain all HYBRIDON Patent(s) and
HYBRIDON Patent Application(s) licensed hereunder in accordance with the
provisions of SECTION 4.03. All rights and licenses granted under or pursuant to
this Agreement by HYBRIDON to BBI and AVECIA HOLDINGS' Affiliates are, and shall
otherwise be deemed to be, for purposes of Section 365(n) of the Bankruptcy
Code, licenses of rights to "intellectual property" as defined under Section
101(56) of the Bankruptcy Code. The parties agree that BBI and AVECIA HOLDINGS'
Affiliates, as a licensee of such rights and licenses, shall retain and may
fully exercise all of its rights and elections under the Bankruptcy Code. The
parties further agree that, in the event that any proceeding shall be instituted
by or against HYBRIDON seeking to adjudicate it a bankrupt or insolvent, or
seeking liquidation, winding up, reorganization, arrangement, adjustment,
protection, relief or composition of it or its debts under any law relating to
bankruptcy, insolvency or reorganization or relief of debtors, or seeking an
entry of an order for relief or the appointment of a receiver, trustee or other
similar official for it or any substantial part of its property or it shall take
any action to authorize any of the foregoing actions (each a "Proceeding"), BBI
and AVECIA HOLDINGS' Affiliates shall have the right to retain and enforce its
rights under this Agreement, including but not limited to the following rights:

(a) the right to continue to use the HYBRIDON Patent(s), HYBRIDON
Patent Application(s), and the Licensed Product and all versions and derivatives
thereof, and all documentation and other supporting material related thereto, in
accordance with the terms and conditions of this Agreement;

(b) the right to a complete duplicate of (or complete access to, as
appropriate) all HYBRIDON Patent(s) and HYBRIDON Patent Application(s) and all
embodiments of such, and the same, if not already in BBI's or AVECIA HOLDINGS'
Affiliates' possession, shall be promptly delivered to BBI or AVECIA HOLDINGS'
Affiliates (i) upon any such commencement of a Proceeding upon written request
therefor by BBI or AVECIA HOLDINGS' Affiliates, unless HYBRIDON elects to
continue to perform all of its obligations under this Agreement; or (ii) if not
delivered under (i) above, upon the rejection of this Agreement by or on behalf
of HYBRIDON upon written request therefor by BBI and AVECIA HOLDINGS'
Affiliates; and

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(c) the right to obtain from HYBRIDON all documentation and other
supporting materials related to the HYBRIDON Patent(s), HYBRIDON Patent
Application(s), and the Licensed Product and all versions and derivatives
thereof.

ARTICLE X

MISCELLANEOUS

SECTION 10.01.  Assignment.

(a) Either Party may assign any of its rights or obligations under
this Agreement in any country to any of the Affiliates and may delegate its
obligations under this Agreement in any country to any of the Affiliates;

(b) Neither Party may assign its rights or obligations under this
Agreement to non-Affiliates without the prior written consent of the other
Party, except in connection with a merger or similar reorganization or the sale
of all or substantially all of its assets relating to HYBRIDON Patent(s) and
HYBRIDON Patent Application(s).

(c) This Agreement shall be binding upon and inure to the benefit of
the successors and permitted assigns of the Parties.

SECTION 10.02. Retained Rights. Nothing in this Agreement shall
limit in any respect the right of either Party to conduct research and
development and to market products using the HYBRIDON Patent(s) and HYBRIDON
Patent Application(s) other than as herein expressly provided.

SECTION 10.03. Research and Development Entities. Either Party may
assign its rights and obligations under this Agreement to an entity or entities
(e.g., partnership or corporation) that are specifically formed for financial
purposes and that finance research and development performed by such Party.

SECTION 10.04. Consents Not Unreasonably Withheld or Delayed.
Whenever provision is made in this Agreement for either Party to secure the
consent or approval of the other, that consent or approval shall not
unreasonably be withheld or delayed.

SECTION 10.05. Force Majeure. Neither Party shall lose any rights
hereunder or be liable to the other Party for damages or losses on account of
failure of performance by the defaulting Party if the failure is occasioned by
government action, war, fire, explosion, flood, strike, lockout, embargo, act of
God, or any other cause beyond the control of the defaulting Party, provided
that the Party claiming force majeure has extended all reasonable efforts to
avoid or remedy such force majeure and has given the other Party prompt notice
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taken to avoid or remedy such force majeure; provided, however, that in no event
shall a Party be required to settle any labor dispute or disturbance.

SECTION 10.06. Notices. All notices hereunder shall be in writing
and shall be deemed given if delivered personally or by facsimile transmission
(receipt verified), telexed, mailed by registered or certified mail (return
receipt requested), postage prepaid, or sent by express courier service, to the
Parties at the following addresses (or at such other address for a Party as
shall be specified by like notice; provided that notices of a change of address
shall be Effective only upon receipt thereof).

(a)  If to HYBRIDON:

President
HYBRIDON, INC.
155 Fortune Blvd.
Milford, MA 01757

(b)  If to BBI:

BOSTON BIOSYSTEMS, INC.
75A Wiggins Ave.
Bedford, MA 01730

SECTION 10.07. Waiver. Except as specifically provided for herein,
the waiver from time to time by either of the Parties of any of their rights or
their failure to exercise any remedy shall not operate or be construed as a
continuing waiver of same or any other of such Party's rights or remedies
provided in this Agreement.

SECTION 10.08. Severability. If any term, covenant or condition of
this Agreement or the application thereof to any Party or circumstances shall,
to any extent or in any country, be held to be invalid or unenforceable, then
(i) the remainder of this Agreement shall not be affected thereby and each term,
covenant or condition of this Agreement shall be valid and be enforced to the
fullest extent permitted by law; and (ii) the Parties hereto covenant and agree
to renegotiate any such term, covenant or application thereof in good faith.

SECTION 10.09. No Strict Construction; Ambiguities. The language
used in this Agreement shall be deemed to be the language chosen by the parties
hereto to express their mutual intent and no rule of strict construction against
either party shall apply to any term or condition of this Agreement.
Ambiguities, if any, in this Agreement shall not be construed against any Party,
irrespective of which Party may be deemed to have authored the ambiguous
provision.

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SECTION 10.10. Headings. The Sections and paragraph headings
contained herein are for the purposes of convenience only and are not intended
to define or limit the contents of said Sections or paragraphs.

SECTION 10.11. Governing Law. This Agreement shall be governed by
and interpreted under the laws of the State of Delaware as applied to contracts
entered into and performed entirely in Delaware by Delaware residents.

SECTION 10.12. Further Assurances. Each of the parties agrees to
execute and deliver such other documents, including but not limited to, updating
the list of HYBRIDON Patent(s) and HYBRIDON Patent Application(s) set forth in
Exhibit A, and to take all such actions as the other party, its successors,
assigns or other legal representatives may reasonably request to effect the
terms of this Agreement.

SECTION 10.13. Counterparts. This Agreement may be executed in one
or more counterparts, each of which shall be deemed an original, but all of
which together shall constitute one and the same instrument.

SECTION 10.14. Entire Agreement; Amendments. This Agreement,
including all Exhibits attached hereto and thereto, and all documents delivered
concurrently herewith and therewith, set forth all the covenants, promises,
agreements, warranties, representations, conditions and understandings between
the Parties hereto and supersede and terminate all prior agreements and
understandings between the Parties. Both Parties acknowledge that in deciding to
enter into the Agreement and to consummate the transaction contemplated thereby
neither has relied upon any statement or representations, written or oral, other
than those explicitly set forth therein.

SECTION 10.15. Independent Contractors. The status of the Parties
under this Agreement shall be that of independent contractors. Neither Party
shall have the right to enter into any agreements on behalf of the other Party,
nor shall it represent to any person that it has any such right or authority.
Nothing in this Agreement shall be construed as establishing a partnership or
joint venture relationship between the Parties.

SECTION 10.16. Successors. This Agreement will be binding upon and
inure to the benefit of the parties and their respective successors and assigns
in whole or in part.

SECTION 10.17. Authority of Signatories. Each person executing this
Agreement individually and personally represents and warrants that he is duly
authorized to execute and deliver the same on behalf of the corporation for
which he is signing and that this Agreement is binding upon the corporation in
accordance with its terms.

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IN WITNESS WHEREOF, HYBRIDON and BBI have caused this Agreement to
be executed as of the date first written above by their respective officers
thereunto duly authorized.

[SIGNATURE PAGES TO FOLLOW]

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HYBRIDON, INC..

By:    /s/ Robert G. Andersen
------------------------------------

Name:   Robert G. Andersen

Title: Chief Financial Officer

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BOSTON BIOSYSTEMS,  INC.

By:     /s/ Gregory S. Kurey
-----------------------------

Name:  Gregory S. Kurey

Title:  General Counsel

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EXHIBIT A

HYBRIDON PNT MONOMER PATENT(S) AND PATENT APPLICATION(S)

U.S. Patent(s)
5,614,622
5,955,599
5,962,674

U.S. Patent Application(s)
***

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Exhibit 10.64

CONFIDENTIAL TREATMENT REQUESTED

EXECUTION VERSION

AGREEMENT RELATING TO PATENTS FORMING PART OF ACQUIRED ASSETS
BUT TO BE LICENSED BACK TO HYBRIDON FOR THE PURPOSES OF ORIGENIX AGREEMENTS

dated as of September 20, 2000

by and between

HYBRIDON, INC.

and

BOSTON BIOSYSTEMS, INC.

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AGREEMENT RELATING TO PATENTS FORMING PART OF ACQUIRED ASSETS
BUT TO BE LICENSED BACK TO HYBRIDON FOR THE PURPOSES OF ORIGENIX AGREEMENTS

This AGREEMENT RELATING TO PATENTS FORMING PART OF ACQUIRED ASSETS
BUT TO BE LICENSED BACK TO HYBRIDON FOR THE PURPOSES OF ORIGENIX AGREEMENTS (the
"Agreement"), dated as of September 20, 2000 (the "Effective Date"), is entered
into by and between Boston Biosystems, Inc., a Delaware corporation (the
"Licensor"), having a principal place of business located at 75A Wiggins Avenue,
Bedford, Massachusetts 01730 (hereinafter referred to as "BBI") and Hybridon,
Inc., a Delaware corporation (the "Licensee"), having a principal place of
business located at 155 Fortune Blvd., Milford, Massachusetts 01757 (hereinafter
referred to as "HYBRIDON"). HYBRIDON and BBI are sometimes referred to herein
individually as a "Party" and collectively as the "Parties", and all references
to "HYBRIDON" and "BBI" shall include their respective Affiliates, where
appropriate under the terms of this Agreement.

W I T N E S S E T H:

WHEREAS, HYBRIDON has entered into that certain Asset Purchase
Agreement dated ________________ ("Purchase Agreement") to transfer certain
patents and patent applications as listed in Appendix A attached hereto
("Patents") to BBI;

WHEREAS, HYBRIDON has granted certain rights under the Patents to
OriGenix Technologies, Inc., a corporation incorporated under the laws of the
Province of Quebec, Canada ("OriGenix") by virtue of the license and supply
agreements dated January 22, 1999 ("OriGenix License Agreement" and "OriGenix
Supply Agreement," collectively the "OriGenix Agreements"), attached hereto as
Appendix B;

WHEREAS, BBI wishes to grant, and HYBRIDON wishes to receive, a
license under the Patents to allow HYBRIDON to fulfill its obligations to
OriGenix under the OriGenix Agreements;

NOW, THEREFORE, in consideration of the foregoing recitals, the
parties hereto, intending to be legally bound, do hereby agree as follows:

ARTICLE I

DEFINITIONS

SECTION 1.01. Definitions. The following terms, when capitalized,
shall have the following meanings (such meanings to be equally applicable to
both the singular and plural forms of the terms defined) as used in this
Agreement:

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"Affiliate(s)" means any person, corporation, partnership, firm,
joint venture or other entity now currently existing or which may be formed in
the future, which directly or indirectly, through one or more intermediaries,
controls, is controlled by, or is under common control with, HYBRIDON, BBI, or
AVECIA HOLDINGS PLC, as the case may be. As used in this definition, "control"
means direct or indirect ownership of an entity, whether through the ownership
of more than 50% of the outstanding voting securities or by contract or
otherwise.

"AVECIA HOLDINGS PLC" or "AVECIA HOLDINGS" is a company organized
under the laws of United Kingdom, and its registered office address is PO Box
42, Hexagon House, Blackley, Manchester, M9 8ZS, United Kingdom.

"Confidential Information" shall have the meaning set forth in
Article III.

"Control" or "Controlled" shall refer to possession of the ability
to grant a license or sublicense of patent rights, know-how or other intangible
rights as provided for herein without violating the terms of any agreement or
other arrangement with any Third Party.

"Effective Date" shall have the meaning set forth in the Recitals to
this Agreement.

"Patent" means United States and foreign patents, applications and
provisional applications for United States and foreign patents, and all
reexaminations, reissues, extensions, term restorations, divisionals,
continuations and continuations-in-part thereof.

"Territory" means worldwide.

"Third Party" or "Third Parties" means any entity other than
HYBRIDON, BBI or AVECIA HOLDINGS, and their respective Affiliates.

ARTICLE II

LICENSE GRANT

SECTION 2.01. Subject to the terms and conditions of this Agreement,
BBI hereby grants to HYBRIDON a worldwide license with right to sublicense under
the Patents solely for the purpose of allowing HYBRIDON to fulfill all its
obligations to OriGenix under the OriGenix Agreements ("the License").

SECTION 2.02. In the event that HYBRIDON receives any lump sum,
royalty or similar payments in respect of its obligations to OriGenix under the
OriGenix Agreements (other than payments in respect of the supply of products
thereunder), to the extent that such payments relate to the Patents, HYBRIDON
shall promptly pay to 

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BBI the equivalent amount of such payments, provided that if such payments
relate in part to the Patents and in part to other patents or intellectual
property:

(a)      HYBRIDON shall promptly pay to BBI the equivalent amount of such
proportion of the payments as fairly and reasonably relates to the
Patents ("the Proportion");

(b)      In the event of any dispute between HYBRIDON and BBI as to the
Proportion, such dispute shall be referred for decision to an
independent expert agreed between the parties (and in default of
agreement appointed by BBI), such person to act as an expert and his
decision to be final and binding on the parties; and

(c)      If HYBRIDON receives a lump sum payment from OriGenix in full payment
for a license to make or have made products under the OriGenix
Agreements, HYBRIDON will pay *** of such payment to BBI, the payment
to BBI not to be less than ***.

SECTION 2.03. To the extent that any provision of this Agreement
conflicts with Hybridon's obligations under the OriGenix License Agreement, that
provision will not be enforced.

ARTICLE III

CONFIDENTIALITY

SECTION 3.01. Confidentiality; Exceptions. Except to the extent
expressly authorized by this Agreement or otherwise agreed in writing, the
Parties agree that, for the term of this Agreement and for five (5) years
thereafter, they shall keep confidential the existence of this Agreement and
shall not publish or otherwise disclose or use for any purpose other than as
provided for in this Agreement any information and materials furnished to it by
the other Party pursuant to this Agreement, or any provisions of this Agreement
that are the subject of an Effective order of the Securities Exchange Commission
granting confidential treatment pursuant to the Securities Act of 1934, as
amended (collectively, "Confidential Information"), except to the extent that it
can be established by the receiving Party that such Confidential Information:

(a) was already known to the receiving Party as shown by written
record, other than under an obligation of confidentiality, at the time of
disclosure by the other Party;

(b) was generally available to the public or otherwise part of the
public domain at the time of its disclosure to the receiving Party as shown by
written record;

(c) became generally available to the public or otherwise part of the
public domain after its disclosure and other than through any act or omission of
the receiving Party in breach of this Agreement; or

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(d) was disclosed to the receiving Party, other than under an
obligation of confidentiality, by a Third Party who had no obligation to the
disclosing Party not to disclose such information to others.

SECTION 3.02. Authorized Disclosure. Each Party may disclose
Confidential Information hereunder to the extent such disclosure is reasonably
necessary in filing or prosecuting patent applications, prosecuting or defending
litigation, complying with applicable governmental regulations or conducting
pre-clinical or clinical trials, provided that if a Party is required by law or
regulation to make any such disclosures of the other Party's Confidential
Information it will, except where impracticable for necessary disclosures, for
example in the event of medical emergency, give reasonable advance notice to the
other Party of such disclosure requirement and, except to the extent
inappropriate in the case of patent applications, will use its reasonable
efforts to secure confidential treatment of such Confidential Information
required to be disclosed. In addition, and with prior written notice to the
other Party of each Third Party with whom a confidential disclosure agreement is
being entered into, each Party shall be entitled to disclose, under a binder of
confidentiality containing provisions as protective as those of this Article,
Confidential Information to any Third Party for the purpose of carrying out the
purposes of this Agreement. Nothing in this Article shall restrict any Party
from using for any purpose any Confidential Information independently developed
by it during the term of this Agreement.

SECTION 3.03. Publicity Review. Subject to the further provisions of
this Section, no Party shall originate any written publicity, news release, or
other announcement or statement relating to this Agreement or to performance
hereunder or the existence of an arrangement between the Parties (collectively,
"Written Disclosure"), without the prior prompt review and written approval of
the other, which approval shall not be unreasonably withheld or delayed.
Notwithstanding the foregoing provisions of this Section, any Party may make any
public Written Disclosure it believes in good faith based upon the advice of
counsel is required by applicable law or any listing or trading agreement
concerning its publicly traded securities, provided that prior to making such
Written Disclosure, the disclosing Party shall provide the other Party with a
copy of the materials proposed to be disclosed and provide the receiving Party
with an opportunity to promptly review the proposed Written Disclosure. To the
extent that the receiving Party reasonably requests that any information in the
materials proposed to be disclosed be deleted, the disclosing Party shall
request confidential treatment of such information pursuant to Rule 406 of the
Securities Act of 1933 or Rule 26b-2 of the Securities Exchange Act of 1934, as
applicable (or any other applicable regulation relating to the confidential
treatment of information), so that there be omitted from the materials that are
publicly filed any information that the receiving Party reasonably requests to
be deleted. The terms of this Agreement may also be disclosed to (i) government
agencies where required by law, or (ii) Third Parties with the prior written
consent of the other Party, which consent shall not be unreasonably withheld or
delayed, so long as such disclosure is made under a binder of confidentiality
and so long as highly sensitive terms and conditions such as financial terms are
extracted from the Agreement or not disclosed upon the request of the other
Party. All Written Disclosures shall be factual and as brief 

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as is reasonable under the circumstances. Upon request by either Party, the
Parties agree to prepare a mutually agreed press release and question and answer
document with respect to this Agreement. Each Party agrees that all Written
Disclosures and oral statements relating hereto shall be consistent with the
answers specified in such question and answer document.

SECTION 3.04. Survival. This Article shall survive the termination
or expiration of this Agreement for a period of five (5) years.

ARTICLE IV

INTELLECTUAL PROPERTY AND PATENT RIGHTS

SECTION 4.01. Notice. Each of the parties shall promptly notify the
other in writing if it: (i) receives any notice or becomes aware of any
information that in any way affects the other party's rights under this
Agreement; or (ii) becomes aware of any actual or suspected infringement,
misappropriation or misuse by a Third Party of the Patents in the Territory.

SECTION 4.02. Infringement.

(a) BBI's and HYBRIDON's Rights to Enforce. BBI shall have the right
(but not the obligation), in its sole discretion, to take action at its own
expense against actual or suspected infringers of the Patents in the Territory,
and any and all recoveries resulting from such actions by BBI shall be retained
by BBI. At BBI's request, and at BBI's expense, HYBRIDON shall take all
reasonable steps and shall provide any materials, cooperation and assistance as
may be reasonably required to assist BBI in taking action against actual or
suspected infringers in the Territory. HYBRIDON shall join any such action as a
necessary and indispensable party if so required. Notwithstanding any of the
above in this Section 4.02 (a), HYBRIDON shall have all rights of enforcement
reasonably necessary for it to fulfill its obligations under Section 5.1 of the
OriGenix License Agreement. In any such action taken by HYBRIDON in fulfillment
of its obligations thereunder, at HYBRIDON's request, and at HYBRIDON's expense,
BBI shall take all reasonable steps and shall provide any materials, cooperation
and assistance as may be reasonably required to assist HYBRIDON in taking action
against actual or suspected infringers in the Territory. BBI shall join any such
action as a necessary and indispensable party if so required.

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ARTICLE V

INDEMNIFICATION; LIMITATION OF LIABILITY

SECTION 5.01. Indemnification by BBI. BBI shall defend, indemnify
and hold HYBRIDON, and its and their officers, directors, shareholders,
employees and agents harmless and shall pay all losses, damages, fees, expenses
or costs (including reasonable attorneys' fees) incurred by them based upon any
claim or action alleging BBI's breach of its obligations, representations,
warranties or covenants hereunder unless HYBRIDON's negligence caused the
losses, damages, fees, expenses or costs.

SECTION 5.02. Indemnification by HYBRIDON. HYBRIDON shall defend,
indemnify and hold BBI and its officers, directors, shareholders, employees and
agents harmless and shall pay all losses, damages, fees, expenses or costs
(including reasonable attorney's fees) incurred by them based upon any claim or
action alleging HYBRIDON's breach of its obligations, representations,
warranties or covenants hereunder unless BBI's negligence caused the losses,
damages, fees, expenses or costs.

SECTION 5.03 Limitation of Liability. EXCEPT AS SET FORTH IN SECTION
7.03 HEREIN, NEITHER PARTY SHALL BE LIABLE TO THE OTHER PARTY OR ANY THIRD PARTY
FOR ANY SPECIAL, CONSEQUENTIAL, EXEMPLARY OR INCIDENTAL DAMAGES (INCLUDING LOST
OR ANTICIPATED REVENUES OR PROFITS RELATING TO THE SAME), ARISING FROM ANY CLAIM
RELATING TO THIS AGREEMENT, THE PATENTS OR ANY IMPROVEMENT, WHETHER SUCH CLAIM
IS BASED ON WARRANTY, CONTRACT, TORT (INCLUDING NEGLIGENCE OR STRICT LIABILITY)
OR OTHERWISE, EVEN IF AN AUTHORIZED REPRESENTATIVE OF SUCH PARTY IS ADVISED OF
THE POSSIBILITY OR LIKELIHOOD OF SAME.

ARTICLE VI

DISPUTE RESOLUTION.

SECTION 6.01. Disputes. Without prejudice to the provisions in
SECTION 2.02(b), the Parties recognize that disputes as to certain matters may
from time to time arise during the term of this Agreement which relate to either
Party's rights and/or obligations hereunder or thereunder. It is the intent of
the Parties to establish procedures to facilitate the resolution of disputes
arising under this Agreement in an expedient manner by mutual cooperation and
without resort to litigation. To accomplish this objective, the Parties agree to
follow the procedures set forth in this Article if and when a dispute arises
under this Agreement.

SECTION 6.02. Good Faith. The parties shall negotiate in good faith
to resolve the dispute.

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SECTION 6.03. Personal Meeting. If the dispute remains unresolved,
executives from the interested business units or division of the parties shall
meet in person, at a mutually agreed upon time and place, to negotiate in good
faith to resolve the dispute. If the dispute continues to remain unresolved for
more than sixty (60) days from the date the parties met to negotiate pursuant to
this Section, then either party may pursue other dispute resolution procedures,
including the institution of arbitration as more fully set forth herein.

SECTION 6.04. Alternative Dispute Resolution. Any dispute
controversy or claim arising out of or relating to the validity, construction,
enforceability or performance of this Agreement, including disputes relating to
an alleged breach or to termination of this Agreement, but excluding (i) any
dispute, controversy or claim arising out of or relating to the validity,
enforceability, or infringement of any Patent and (ii) other than disputes which
are expressly prohibited herein from being resolved by this mechanism, shall be
settled by binding Alternative Dispute Resolution ("ADR") in the manner
described below:

(a) If a Party intends to begin an ADR to resolve a dispute, such
Party shall provide written notice (the "ADR Request") to counsel for the other
Party informing such other Party of such intention and the issues to be
resolved. From the date of the ADR Request and until such time as any matter has
been finally settled by ADR, the running of the time periods contained in
SECTION 6.05 as to which a Party must cure a breach of this Agreement shall be
suspended as to the subject matter of the dispute.

(b) Within sixty (60) days after receipt of the ADR Request, the
other Party may, by written notice to counsel for the Party initiating ADR, add
additional issues to be resolved.

SECTION 6.05. Arbitration Procedures. An ADR initiated under this
Agreement will proceed in accordance with the Commercial Arbitration Rules of
the American Arbitration Association then in effect, insofar as such rules are
not inconsistent with the provisions expressly set forth in this Agreement,
unless the Parties mutually agree otherwise, and pursuant to the following
procedures:

(a) Notice of the demand for arbitration will be filed in writing
with the other Party and with the American Arbitration Association. The
arbitration panel shall consist of one (1) arbitrator mutually agreed to by the
Parties and the decision shall be final and binding on the Parties and their
legal successors.

(b) The arbitrator may, at his discretion, provide for discovery by
the Parties, not to exceed four (4) months from the date of filing of the Notice
of Arbitration.

(c) Any arbitration hearing shall be conducted in Wilmington,
Delaware. The governing law will be as specified herein. The arbitrator will
have authority to award both legal and equitable relief but not to award
punitive damages.

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(d) All costs and fees of the arbitration, other than each Party's
legal fees and expenses, will be allocated by the arbitrators. Subject to
subsection (c), each Party shall bear its own legal fees and expenses.

(e) A final written decision by the arbitrator will be rendered not
later than thirty (30) days following the completion of the hearing.

(f) The ADR proceeding shall be confidential and the arbitrator
shall issue appropriate protective orders to safeguard each Party's confidential
information. Except as required by law, no Party shall make (or instruct the
arbitrator to make) any public announcement with respect to the proceedings or
decision of the arbitrator without prior written consent of each other Party.
The existence of any dispute submitted to ADR, and the award, shall be kept in
confidence by the Parties and the arbitrator, except as required in connection
with the enforcement of such award or as otherwise required by applicable law.

SECTION 6.06. Survivability. Any duty to arbitrate under this
Agreement shall remain in effect and enforceable after termination of this
Agreement for any reason.

SECTION 6.07. Jurisdiction. For the purposes of this Article, each
Party agrees to abide by the award rendered in any arbitration, and the Parties
agree to accept the jurisdiction of any court having jurisdiction over the
Parties for the purposes of enforcing awards entered pursuant to this Article
and for enforcing the agreements reflected in this Article.

SECTION 6.08. Equitable Remedies. Nothing in this Section shall
prevent either party from pursuing a temporary restraining order, injunctive
relief or other equitable relief against the other party at any time if the
allegedly aggrieved party believes that a breach or a threatened breach of this
Agreement would cause it irreparable harm provided that the other party is given
thirty (30) days written notice prior to equitable relief being sought.

ARTICLE VII

REPRESENTATIONS AND WARRANTIES

SECTION 7.01. BBI represents, warrants and covenants that:

(a) BBI is a corporation duly organized, existing and in good
standing under the laws of the State of Delaware, with full right, power and
authority to enter into and perform this Agreement and to grant all of the
rights, powers and authorities herein granted.

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(b) The execution, delivery, and performance of this Agreement do
not conflict with, violate, or breach any agreement to which BBI is a party, or
BBI's articles of incorporation or bylaws.

(c) This Agreement has been duly executed and delivered by BBI and
is a legal, valid, and binding obligation enforceable against BBI in accordance
with its terms.

(d) BBI knows of no fact which does or could materially adversely
affect the rights granted to HYBRIDON hereunder, except as disclosed herein.

SECTION 7.02. HYBRIDON  represents, warrants and covenants that:

(a) HYBRIDON is a corporation duly organized, existing, and in good
standing under the laws of the State of Delaware, with full right, power and
authority to enter into and perform this Agreement and to grant all of the
rights, powers, and authorities herein granted.

(b) The execution, delivery, and performance of this Agreement do
not conflict with, violate, or breach any agreement to which HYBRIDON is a
party, or HYBRIDON's certificate of incorporation or bylaws.

(c) This Agreement has been duly executed and delivered by HYBRIDON,
and is a legal, valid, and binding obligation enforceable against HYBRIDON in
accordance with its terms.

SECTION 7.03. Effect of Representations, Warranties and Covenants.
The Parties agree that if the representations and warranties made by BBI under
this Article are not true and accurate, or if the covenants made by BBI under
this Article are not upheld and complied with, and HYBRIDON incurs reasonably
foreseeable damages, liabilities, costs or other expenses as a result of such
falsity or non- compliance, then BBI shall indemnify and hold HYBRIDON harmless
from and against any such reasonably foreseeable damages, liabilities, costs or
other expenses incurred as a result of such falsity or such non-compliance.

ARTICLE VIII

INFORMATION AND REPORTS

SECTION 8.01.  Records of Revenues and Expenses.

(a) HYBRIDON will maintain complete and accurate records which are
relevant to payments subject to SECTION 2.02, costs, expenses and payments under
this Agreement and such records shall be open during reasonable business hours
for a period of two (2) years from creation of individual records for
examination at BBI's expense and not more often than once each year by a
certified public accountant 

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selected by BBI for the sole purpose of verifying for the BBI the correctness of
calculations and classifications of such revenues, costs, expenses or payments
made under this Agreement. In the absence of material discrepancies in any
request for reimbursement resulting from such audit, the accounting expense
shall be paid by BBI. Any records or accounting information received from
HYBRIDON shall be Confidential Information. Results of any such audit shall be
provided to both Parties.

(b) If there is a dispute between the Parties following any audit
performed pursuant to SECTION 8.01(a), either Party may refer the issue (an
"Audit Disagreement") to an independent certified public accountant for
resolution. In the event an Audit Disagreement is submitted for resolution by
either Party, the Parties shall comply with the following procedures:

(i) The Party submitting the Audit Disagreement for
resolution shall provide written notice to the other Party.

(ii) Within thirty (30) business days of the giving of
such notice, the Parties shall jointly select a recognized international
accounting firm to act as an independent expert to resolve such Audit
Disagreement.

(iii) The Audit Disagreement submitted for resolution 
shall be described by the Parties to the independent expert, which description
may be in written or oral form, within ten (10) business days of the selection
of such independent expert.

(iv)  The independent expert shall render a decision on
the matter as soon as practicable.

(v) The decision of the independent expert shall be final
and binding, unless such Audit Disagreement involves alleged fraud, breach
of this Agreement or construction or interpretation of any of the terms and
conditions hereof.

(vi) All fees and expenses of the independent expert,
including any Third Party support staff or other costs incurred with respect to
carrying out the procedures specified at the direction of the independent expert
in connection with such Audit Disagreement, shall be borne by the losing Party.

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ARTICLE IX

TERM AND TERMINATION

SECTION 9.01. Term. This Agreement shall commence as of the 
Effective Date and shall remain in force, unless terminated as provided herein.

(a) The License shall expire on the date of expiry or termination of
HYBRIDON'S obligations to OriGenix under the OriGenix Agreements with respect to
the Patents. HYBRIDON shall notify BBI of such expiry or termination.

(b) Survivability. Termination, relinquishment or expiration of the
Agreement for any reason shall be without prejudice to any rights which shall
have accrued to the benefit of either Party prior to such termination,
relinquishment or expiration, including damages arising from any breach
hereunder. Such termination, relinquishment or expiration shall not relieve
either Party from obligations which are expressly indicated to survive
termination or expiration of the Agreement.

ARTICLE X

BANKRUPTCY

SECTION 10.01. BBI shall be responsible for the maintenance of the
Patents licensed hereunder pursuant to clause 5.5 of the OriGenix License
Agreement. All rights and licenses granted under or pursuant to this Agreement
by BBI to HYBRIDON are, and shall otherwise be deemed to be, for purposes of
Section 365(n) of the Bankruptcy Code, licenses of rights to "intellectual
property" as defined under Section 101(56) of the Bankruptcy Code. The parties
agree that HYBRIDON, as a licensee of such rights and licenses, shall retain and
may fully exercise all of its rights and elections under the Bankruptcy Code.
The parties further agree that, in the event that any proceeding shall be
instituted by or against BBI seeking to adjudicate it a bankrupt or insolvent,
or seeking liquidation, winding up, reorganization, arrangement, adjustment,
protection, relief or composition of it or its debts under any law relating to
bankruptcy, insolvency or reorganization or relief of debtors, or seeking an
entry of an order for relief or the appointment of a receiver, trustee or other
similar official for it or any substantial part of its property or it shall take
any action to authorize any of the foregoing actions (each a "Proceeding"),
HYBRIDON shall have the right to retain and enforce its rights under this
Agreement.

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ARTICLE X

MISCELLANEOUS

SECTION 11.01.  Assignment.

(a) The License granted hereunder shall be personal to HYBRIDON and
shall not be assigned without the consent of BBI, except that HYBRIDON may
assign the License to any party to whom HYBRIDON assigns the OriGenix
Agreements, and provided HYBRIDON notifies BBI of such assignment.

(b) BBI shall be entitled to assign the Patents without HYBRIDON's
consent, provided that BBI also assigns the License thereunder, and provided BBI
notifies HYBRIDON of such assignment.

(c) This Agreement shall be binding upon and inure to the benefit of
the successors and permitted assigns of the Parties.

SECTION 11.02. Consents Not Unreasonably Withheld or Delayed.
Whenever provision is made in this Agreement for either Party to secure the
consent or approval of the other, that consent or approval shall not
unreasonably be withheld or delayed.

SECTION 11.03. Force Majeure. Neither Party shall lose any rights
hereunder or be liable to the other Party for damages or losses on account of
failure of performance by the defaulting Party if the failure is occasioned by
government action, war, fire, explosion, flood, strike, lockout, embargo, act of
God, or any other cause beyond the control of the defaulting Party, provided
that the Party claiming force majeure has extended all reasonable efforts to
avoid or remedy such force majeure and has given the other Party prompt notice
describing such event, the effect thereof and the actions being taken to avoid
or remedy such force majeure; provided, however, that in no event shall a Party
be required to settle any labor dispute or disturbance.

SECTION 11.04. Notices. All notices hereunder shall be in writing
and shall be deemed given if delivered personally or by facsimile transmission
(receipt verified), telexed, mailed by registered or certified mail (return
receipt requested), postage prepaid, or sent by express courier service, to the
Parties at the following addresses (or at such other address for a Party as
shall be specified by like notice; provided that notices of a change of address
shall be Effective only upon receipt thereof).

(a)  If to HYBRIDON:

President
HYBRIDON, INC.
155 Fortune Blvd.
Milford, MA 01757

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(b)  If to BBI:

BOSTON BIOSYSTEMS, INC.
75A Wiggins Ave.
Bedford, MA 01730

SECTION 11.05. Waiver. Except as specifically provided for herein,
the waiver from time to time by either of the Parties of any of their rights or
their failure to exercise any remedy shall not operate or be construed as a
continuing waiver of same or any other of such Party's rights or remedies
provided in this Agreement.

SECTION 11.06. Severability. If any term, covenant or condition of
this Agreement or the application thereof to any Party or circumstances shall,
to any extent or in any country, be held to be invalid or unenforceable, then
(i) the remainder of this Agreement shall not be affected thereby and each term,
covenant or condition of this Agreement shall be valid and be enforced to the
fullest extent permitted by law; and (ii) the Parties hereto covenant and agree
to renegotiate any such term, covenant or application thereof in good faith.

SECTION 11.07. No Strict Construction; Ambiguities. The language
used in this Agreement shall be deemed to be the language chosen by the parties
hereto to express their mutual intent and no rule of strict construction against
either party shall apply to any term or condition of this Agreement.
Ambiguities, if any, in this Agreement shall not be construed against any Party,
irrespective of which Party may be deemed to have authored the ambiguous
provision.

SECTION 11.08. Headings. The Sections and paragraph headings
contained herein are for the purposes of convenience only and are not intended
to define or limit the contents of said Sections or paragraphs.

SECTION 11.09. Governing Law. This Agreement shall be governed by
and interpreted under the laws of the State of Delaware as applied to contracts
entered into and performed entirely in Delaware by Delaware residents.

SECTION 11.10. Further Assurances. Each of the parties agrees to
execute and deliver such other documents, including but not limited to, updating
the list of Patents set forth in Appendix A, and to take all such actions as the
other party, its successors, assigns or other legal representatives may
reasonably request to effect the terms of this Agreement.

SECTION 11.11. Counterparts. This Agreement may be executed in one
or more counterparts, each of which shall be deemed an original, but all of
which together shall constitute one and the same instrument.

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SECTION 11.12. Entire Agreement; Amendments. This Agreement,
including all Appendices attached hereto and thereto, and all documents
delivered concurrently herewith and therewith, set forth all the covenants,
promises, agreements, warranties, representations, conditions and understandings
between the Parties hereto and supersede and terminate all prior agreements and
understandings between the Parties. Both Parties acknowledge that in deciding to
enter into the Agreement and to consummate the transaction contemplated thereby
neither has relied upon any statement or representations, written or oral, other
than those explicitly set forth therein.

SECTION 11.13. Independent Contractors. The status of the Parties
under this Agreement shall be that of independent contractors. Neither Party
shall have the right to enter into any agreements on behalf of the other Party,
nor shall it represent to any person that it has any such right or authority.
Nothing in this Agreement shall be construed as establishing a partnership or
joint venture relationship between the Parties.

SECTION 11.14. Successors. This Agreement will be binding upon and
inure to the benefit of the parties and their respective successors and assigns
in whole or in part.

SECTION 11.15. Authority of Signatories. Each person executing this
Agreement individually and personally represents and warrants that he is duly
authorized to execute and deliver the same on behalf of the corporation for
which he is signing and that this Agreement is binding upon the corporation in
accordance with its terms.

IN WITNESS WHEREOF, HYBRIDON and BBI have caused this Agreement to
be executed as of the date first written above by their respective officers
thereunto duly authorized.

[SIGNATURE PAGES TO FOLLOW]

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HYBRIDON, INC..

By:     /s/ Robert G. Andersen
------------------------------------

Name:   Robert G. Andersen

Title: Chief Financial Officer

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BOSTON BIOSYSTEMS,  INC.

By:   /s/ Gregory S. Kurey
------------------------------------

Name:  Gregory S. Kurey

Title:  General Counsel

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APPENDIX A - PATENTS

PATENT/APPLICATION NUMBER                           HYBRIDON CASE REFERENCE

***

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EXHIBIT 23.1

CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS

As independent public accountants, we hereby consent to the use of our
report (and to all references to our Firm) included in or made a part of this
Registration Statement.

/s/ ARTHUR ANDERSEN LLP

Boston, Massachusetts
December 29, 2000

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<COMMON>                                        17,925
<OTHER-SE>                                 (6,402,094)
<TOTAL-LIABILITY-AND-EQUITY>                11,430,298
<SALES>                                              0
<TOTAL-REVENUES>                               212,541
<CGS>                                                0
<TOTAL-COSTS>                                5,133,846
<OTHER-EXPENSES>                                     0
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                           1,856,677
<INCOME-PRETAX>                            (6,777,982)
<INCOME-TAX>                                         0
<INCOME-CONTINUING>                        (6,777,982)
<DISCONTINUED>                               5,292,154
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                               (1,485,828)
<EPS-BASIC>                                     (0.27)
<EPS-DILUTED>                                   (0.27)

<ARTICLE> 5
<RESTATED>
<CURRENCY> U.S. DOLLARS

<PERIOD-TYPE>                   9-MOS                   12-MOS                   12-MOS                   12-MOS
<FISCAL-YEAR-END>                          DEC-31-1999             DEC-31-1997             DEC-31-1998             DEC-31-1999
<PERIOD-START>                             JAN-01-1999             JAN-01-1997             JAN-01-1998             JAN-01-1999
<PERIOD-END>                               SEP-30-1999             DEC-31-1997             DEC-31-1998             DEC-31-1999
<EXCHANGE-RATE>                                      1                       1                       1                       1
<CASH>                                         500,179               1,202,202               5,607,882               2,551,671
<SECURITIES>                                         0                       0                       0                       0
<RECEIVABLES>                                  189,194                       0                 311,222                 196,528
<ALLOWANCES>                                         0                       0                       0                       0
<INVENTORY>                                          0                       0                       0                       0
<CURRENT-ASSETS>                               791,559               3,208,027               6,230,361               2,850,113
<PP                                       5,399,963              15,186,691               6,843,820               5,399,963
<DEPRECIATION>                               5,188,707               5,520,400               6,287,291               5,229,514
<TOTAL-ASSETS>                               7,511,242              30,479,810              15,091,601              10,717,279
<CURRENT-LIABILITIES>                       10,712,224              25,199,947              11,536,823               9,383,807
<BONDS>                                      1,306,000              50,000,000               1,306,000               7,405,775
<PREFERRED-MANDATORY>                                0                       0                       0                       0
<PREFERRED>                                      6,410                       0                   6,413                   6,618
<COMMON>                                        16,261                   5,060                  15,305                  16,261
<OTHER-SE>                                 (4,529,652)            (46,053,240)               2,233,473             (6,088,564)
<TOTAL-LIABILITY-AND-EQUITY>                 7,511,242              30,479,810              15,091,601              10,717,279
<SALES>                                              0                       0                       0                       0
<TOTAL-REVENUES>                               933,674               2,024,122               1,622,982               1,179,746
<CGS>                                                0                       0                       0                       0
<TOTAL-COSTS>                                7,471,460              56,698,442              20,755,454               9,446,903
<OTHER-EXPENSES>                                     0                       0                       0                       0
<LOSS-PROVISION>                                     0                       0                       0                       0
<INTEREST-EXPENSE>                             511,131               4,277,882               2,819,659                 683,134
<INCOME-PRETAX>                            (7,048,917)            (58,952,202)            (21,952,131)             (8,950,291)
<INCOME-TAX>                                         0                       0                       0                       0
<INCOME-CONTINUING>                        (7,048,917)            (58,952,202)            (21,952,131)             (8,950,291)
<DISCONTINUED>                             (1,283,539)            (10,509,124)             (4,028,242)             (1,552,751)
<EXTRAORDINARY>                                      0                       0               8,876,685                       0
<CHANGES>                                            0                       0                       0                       0
<NET-INCOME>                               (8,332,456)            (69,461,326)            (17,103,688)            (10,503,042)
<EPS-BASIC>                                     (0.74)                 (13.76)                  (1.67)                  (0.93)
<EPS-DILUTED>                                   (0.74)                 (13.76)                  (1.67)                  (0.93)