HYBRIDON INC
SC 13E4/A, 1998-03-30
BIOLOGICAL PRODUCTS, (NO DIAGNOSTIC SUBSTANCES)
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                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                 SCHEDULE 13E-4

                          ISSUER TENDER OFFER STATEMENT
                      (PURSUANT TO SECTION 13(E)(1) OF THE
                        SECURITIES EXCHANGE ACT OF 1934)

                                (AMENDMENT NO. 1)

                                 HYBRIDON, INC.
                  (NAME OF ISSUER AND PERSON FILING STATEMENT)

                   9% CONVERTIBLE SUBORDINATED NOTES DUE 2004
                       (TITLE OF EACH CLASS OF SECURITIES)

                 44860M-AA-6; -AB-4; -AC-2; -AD-0; -AE-8; -AF-5
                   (CUSIP NUMBERS OF EACH CLASS OF SECURITIES)

                            E. ANDREWS GRINSTEAD, III
                 CHAIRMAN, PRESIDENT AND CHIEF EXECUTIVE OFFICER
                               620 MEMORIAL DRIVE
                               CAMBRIDGE, MA 02139
                                 (617) 528-7000
            (NAME, ADDRESS AND TELEPHONE NUMBER OF PERSON AUTHORIZED
             TO RECEIVE NOTICES AND COMMUNICATIONS ON BEHALF OF THE
                            PERSON FILING STATEMENT)

                                  With Copy to:

                              MONICA C. LORD, ESQ.
                        KRAMER, LEVIN, NAFTALIS & FRANKEL
                                919 THIRD AVENUE
                            NEW YORK, NEW YORK 10022
                                 (212) 715-9100

                                FEBRUARY 6, 1998
     (DATE TENDER OFFER FIRST PUBLISHED, SENT OR GIVEN TO SECURITY HOLDERS)

                            CALCULATION OF FILING FEE

    TRANSACTION VALUATION (1)                   AMOUNT OF FILING FEE (2)
    -------------------------                   ------------------------
           $51,594,664                                   $10,319

(1)  Solely for the  purpose of  calculating  the  filing fee and,  as  computed
pursuant to Section 13(e)(3) of the Securities Exchange Act of 1934, as amended,
and Rule  0-11(b)(1)  thereunder,  the  transaction  value equals the  aggregate
principal  amount of and accrued but unpaid interest on the securities  proposed
to be  exchanged  pursuant to the Offer  described  in the Offer to Exchange and
Amendment thereto filed as Exhibits hereto.

(2)  Represents 1/50th of 1% of the transaction value as calculated above.

[_] Check box if any part of the fee is offset as  provided  by Rule  0-11(a)(2)
and  identify  the filing with which the  offsetting  fee was  previously  paid.
Identify the previous filing by registration  statement  number,  or the Form or
Schedule and the date of its filing.

Amount Previously Paid: _____________      Filing Party: _______________________

Form or Registration No.: ___________      Date Filed: _________________________


<PAGE>


ITEM 1. SECURITY AND ISSUER.

         (a) Incorporated herein by reference to the information appearing under
         the caption "Certain  Information  Concerning Hybridon" in the Offer to
         Exchange,  dated February 6, 1998 (the  "Original  Offer to Exchange"),
         filed as Exhibit  9(a)(1)  to the  Issuer  Tender  Offer  Statement  on
         Schedule  13E-4,  as filed on February 6, 1998 (the "Original  Schedule
         13E-4").

         (b)  Incorporated  herein by reference to the information  appearing on
         the  front  cover  of  the  Original  Offer  to  Exchange,  and  to the
         information appearing under the captions  "Introduction," "Terms of the
         Offer--Amount  of  Notes;  Consideration;   Expiration  Date;  Interest
         Payment" and "Transactions and Agreements  Concerning the Notes" in the
         Original Offer to Exchange.  Also  incorporated  herein by reference to
         the   information   appearing   under  the   captions   "Introduction,"
         "Alternative  Consideration"  and "Alternative  Equity Offering" in the
         Amendment,  dated  March  30,  1998  (the  "Amendment  to the  Offer to
         Exchange"), to the Original Offer to Exchange, filed as Exhibit 9(a)(6)
         to this  Amendment No. 1 (this  "Amendment  to Schedule  13E-4") to the
         Original Schedule 13E-4.

         (c) Incorporated herein by reference to the information appearing under
         the caption  "Price Range of Hybridon  Common Stock;  Dividends" in the
         Original  Offer to  Exchange  and under  the  caption  "Price  Range of
         Hybridon Common Stock" in the Amendment to the Offer to Exchange.

         (d) Not applicable.

ITEM 2. SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION.

         (a) Incorporated herein by reference to the information appearing under
         the  caption  "Source  and  Amount  of  Consideration"  in  each of the
         Original Offer to Exchange and the Amendment to the Offer to Exchange.

         (b) Not applicable.

ITEM 3.  PURPOSE OF THE  TENDER  OFFER AND PLANS OR  PROPOSALS  OF THE ISSUER OR
AFFILIATE.

Incorporated herein by reference to the information  appearing under the caption
"Purpose of the Offer;  Certain  Effects of the Offer" in the Original  Offer to
Exchange and under the captions "Introduction,"  "Alternative Consideration" and
"Alternative Equity Offering" in the Amendment to the Offer to Exchange.

ITEM 4. INTEREST IN SECURITIES OF THE ISSUER.

Incorporated herein by reference to the information  appearing under the caption
"Transactions  and  Agreements  Concerning  the Notes" in the Original  Offer to
Exchange.

ITEM 5. CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH RESPECT TO
THE ISSUER'S SECURITIES.

Incorporated herein by reference to the information appearing under the captions
"Transactions  and  Agreements  Concerning  the  Notes,"  "Purpose of the Offer;
Certain  Effects of the Offer" and "Fees and Expenses" in the Original  Offer to
Exchange and under the  captions  "Introduction,"  "Alternative  Consideration,"
"Alternative Equity Offering" and "Ancillary Agreements" in the Amendment to the
Offer to Exchange.

ITEM 6. PERSONS RETAINED, EMPLOYED OR TO BE COMPENSATED.

Incorporated herein by reference to the information  appearing under the caption
"Fees and Expenses" in the Offer to Exchange.

ITEM 7. FINANCIAL INFORMATION.

         (a)  Incorporated  herein  by  reference  to the  financial  statements
         included in the Annual Report on Form 10-K for the year ended  December
         31, 1996 of Hybridon,  Inc.  ("Hybridon"),  and the Quarterly Report on
         Form  10-Q  for  the  quarterly  period  ended  September  30,  1997 of
         Hybridon,  each of which was attached to the Original Schedule 13E-4 as
         an  Exhibit,  and  to  the  information  appearing  under  the  caption
         "Selected  Consolidated Financial Information" in the Original Offer to
         Exchange  and  under  the  caption  "Selected   Consolidated  Financial
         Information" in the Amendment to the Offer to Exchange.

         (b) Incorporated herein by reference to the information appearing under
         the  caption  "Selected  Consolidated  Financial  Information"  in  the
         Original Offer to Exchange and under the caption "Selected Consolidated
         Financial Information" in the Amendment to the Offer to Exchange.

ITEM 8. ADDITIONAL INFORMATION.

         (a)  Not applicable.

         (b) Not applicable.

         (c) Not applicable.

         (d) Not applicable.


                                        2

<PAGE>

         (e) Incorporated herein by reference to the information appearing under
         the captions "Certain Information Concerning Hybridon," "Purpose of the
         Offer;   Effects  of  the  Offer"  and   "Transactions  and  Agreements
         Concerning the Notes" in the Original  Offer to Exchange,  and also see
         Exhibits 9(a)(1), 9(a)(2), 9(a)(5), 9(a)(6) and 9(a)(7) hereto.

ITEM 9. MATERIAL TO BE FILED AS EXHIBITS.

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

9(a)(1) Offer to Exchange,  dated  February 6, 1998.*  
9(a)(2) Form of Exchange Agreement  and  Letter of  Transmittal.*  
9(a)(3) Form of Notice of  Guaranteed Delivery.*  
9(a)(4) Form of press  release,  dated  February 6, 1998,  issued by Hybridon.*
9(a)(5) Press  release,  dated March 9, 1998,  issued by Hybridon.+
9(a)(6) Amendment, dated March 30, 1998, to the Offer to Exchange.+
9(a)(7) Form of Amendment, dated March 30, 1998, to the Exchange Agreement and 
        Letter of Transmittal.+
9(b)    Not applicable.
9(c)    Not applicable.
9(d)    Not applicable.
9(e)    Not applicable.
9(f)    Not applicable.
9(g)(1) Annual Report on Form 10-K for the fiscal year ended December 31, 1996 
        filed by Hybridon, incorporated by reference to Annex D attached to the 
        Original Offer to Exchange.*
9(g)(2) Quarterly Report on Form 10-Q for the fiscal quarter ended September 30,
        1997 filed by Hybridon, incorporated by reference to Annex E
        attached to the Original Offer to Exchange.*
9(g)(3) Consent of Arthur Andersen LLP.+
- ------------------
*    Previously filed.
+    Filed herewith.


                                    SIGNATURE


After due inquiry and to the best of my knowledge and belief, I certify that the
information set forth in this Amendment to Schedule 13E-4 is true,  complete and
correct.

Dated:  March 30, 1998

                                        HYBRIDON, INC.



                                       By: /s/ E. Andrews Grinstead III
                                       --------------------------------
                                       Name: E. Andrews Grinstead III
                                       Title: Chairman, President and
                                       Chief Executive Officer


                                        3



                                Exhibit 9(a)(5)


Hybridon  Extends the Exchange Offer for its 9% Convertible  Subordinated  Notes
Due 2004

     CAMBRIDGE, Mass., March 9 -- Hybridon, Inc. (OTC Bulletin Board: HYBN) (the
"Company") today announced that it will extend for an additional twenty business
days the currently  pending  exchange offer to the holders of its 9% Convertible
Subordinated  Notes  due 2004 (the "9%  Notes")  to  exchange  such 9% Notes for
Series A Preferred  Stock and certain  warrants  of the Company  (the  "Exchange
Offer").  The new expiration  date of the Exchange  Offer,  which was previously
scheduled to expire at 12:00 a.m.,  New York City time,  March 9, 1998,  will be
12:00 a.m., New York City time, April 6, 1998.

     This  announcement  is  neither  an offer to  purchase  or  exchange  nor a
solicitation  of an offer to sell or exchange the 9% Notes.  The offers are made
solely by the Offer to Exchange,  dated as of February 6, 1998,  and are subject
to certain conditions specified therein.

     Holders of 9% Notes who have  questions or requests for  assistance  should
call the Company's Corporate Counsel,  Cheryl M. Northrup, at 617-528-7000.  The
Company has filed with the Securities and Exchange Commission (the "Commission")
a Schedule  13e-4,  together with all exhibits  thereto  (including the Offer to
Exchange).  Copies of such Schedule  13e-4 and exhibits may be obtained from the
Company or from the web site  maintained on the World Wide Web by the Commission
at http://www.sec.gov.

     The Company, headquartered in Cambridge,  Massachusetts,  is engaged in the
discovery  and  development  of genetic  medicines  for the treatment of certain
diseases, based primarily on antisense technology. Antisense technology attempts
to  use  synthetic   segments  of  DNA  and  RNA  to  stop  the   production  of
disease-associated  proteins by  interacting  at the  genetic  level with target
strands of messenger RNA.

SOURCE  Hybridon, Inc.

CONTACT:  Lynne J. Rudert, Controller of Hybridon, 617-528-7000
          Web site:  www.hybridon.com




                                Exhibit 9(a)(6)

                                 HYBRIDON, INC.


                       AMENDMENT TO THE OFFER TO EXCHANGE
                        FOR SERIES A PREFERRED STOCK AND
                     WARRANTS OF HYBRIDON, INC. ("HYBRIDON")
                   ANY AND ALL OUTSTANDING PRINCIPAL AMOUNT OF
                AND ACCRUED BUT UNPAID INTEREST ON 9% CONVERTIBLE
                     SUBORDINATED NOTES DUE 2004 OF HYBRIDON

THE OFFER, AS AMENDED, AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT,  NEW
YORK CITY TIME, ON APRIL 10, 1998, UNLESS THE OFFER IS EXTENDED.


INTRODUCTION

         Hybridon, Inc., a Delaware corporation ("Hybridon"), is hereby amending
the  terms  of the  offer to  exchange  (the  "Offer")  with  respect  to its 9%
Convertible  Subordinated Notes due 2004 (the "Notes") set forth in its Offer to
Exchange,  dated  February 6, 1998 (the "Original  Offer to  Exchange").  Unless
otherwise provided in this Amendment (this "Amendment") to the Original Offer to
Exchange  or  unless  the  context  requires  otherwise,  the  terms  of and the
conditions  to the Offer  contained  in the  Original  Offer to Exchange  remain
unchanged.  All capitalized  terms used herein but not defined herein shall have
the respective meanings ascribed thereto in the Original Offer to Exchange.

         By a press  release  dated March 9, 1998,  Hybridon  announced  that it
extended (the "Expiration  Date Extension") the original  Expiration Date of the
Offer for an  additional 20 business  days,  or until 12:00 a.m.,  New York City
time,  on April 6, 1998.  Pursuant to Rule  13e-4(f) of the Exchange  Act,  this
Amendment  requires a 10  business  day  extension  to the Offer  which shall be
computed concurrently with the Expiration Date Extension.  Accordingly,  the new
expiration  date shall be 12:00 a.m.,  New York City time, on April 10, 1998, or
the latest time and date to which the Offer is further extended (the "Expiration
Date").

         As a result of certain  proposed changes to the  Restructuring  and the
New  Offering  under  certain  conditions  (which  changes  and  conditions  are
described  in more  detail  below),  Hybridon  is hereby  amending  the Offer to
provide for the issuance of the Alternative  Consideration (as defined below) in
exchange for principal  amount of and accrued interest on the Notes in the event
that the Equity  Conditions  (as defined and  described  below) are satisfied or
Waived (as  hereinafter  defined).  If the Equity  Conditions  are  satisfied or
Waived, all tendering Noteholders will receive the Alternative  Consideration in
lieu of the Original Consideration (as defined below). On the other hand, if the
Equity  Conditions are not satisfied or Waived,  Hybridon shall proceed with the
Restructuring and the New Offering  described in the Original Offer to Exchange,
and the consideration set forth in the Original Offer to Exchange (the "Original
Consideration") will be issued to the tendering  Noteholders upon acceptance for
exchange of the tendered Notes, upon the terms and subject to the conditions set
forth in the  Original  Offer to Exchange  and the  Exchange  Agreement  and the
Letter  of  Transmittal,  as  amended.  There  can  be  no  assurance  that  the
Alternative   Equity   Offering  will  be  consummated  or  that  the  tendering
Noteholders  will receive in the Offer the Alternative  Consideration in lieu of
the Original Consideration or vice versa.

         The alternative  consideration (the "Alternative  Consideration") being
offered per $1,000 in Exchange  Value of the Notes  tendered  consists of (i) 10
shares of Series A Preferred  Stock,  with the revised terms as described  below
under  "Alternative  Consideration--Alternative  Series A Preferred  Stock" (the
"Alternative  Series  A  Preferred  Stock"),  and  (ii)  warrants  ("Alternative
Exchange  Warrants") to purchase such number of shares of Hybridon  Common Stock
equal to 25% of the number of shares of  Hybridon  Common  Stock into which such
Alternative  Series A Preferred  Stock would be convertible  at the  Alternative
Conversion  Price (as  defined  below),  having the terms set forth  below under
"Alternative  Consideration--Alternative  Exchange  Warrants." In evaluating the
Alternative  Consideration to be issued in the event that the Equity  Conditions
are  satisfied  or Waived,  unless  otherwise  indicated  herein or the  context
indicates otherwise, the tendering Noteholders should substitute all

<PAGE>

references  to and  descriptions  of Series A Preferred  Stock and the  Exchange
Warrants  in the  Original  Offer  to  Exchange  with  the  descriptions  of the
Alternative  Series A Preferred  Stock and the  Alternative  Exchange  Warrants,
respectively,  set  forth  below.  The  descriptions  and the terms of the Offer
contained in the Original  Offer to Exchange  continue to be  applicable  if the
Equity Conditions are not satisfied or Waived.

IMPORTANT:  AS SET  FORTH IN MORE  DETAIL  IN THE  ACCOMPANYING  AMENDMENT  (THE
"AMENDMENT TO THE LETTER OF TRANSMITTAL")  TO THE EXCHANGE  AGREEMENT AND LETTER
OF TRANSMITTAL (THE "ORIGINAL LETTER OF TRANSMITTAL"),  BY EXECUTING AND SENDING
SUCH AMENDMENT TO THE LETTER OF TRANSMITTAL,  THE BENEFICIAL OWNERS OF THE NOTES
BEING SO TENDERED ARE THEREBY  MAKING  CERTAIN  REPRESENTATIONS  AND  WARRANTIES
REQUIRED IN CONNECTION  WITH  ISSUANCE OF  SECURITIES  UNDER SECTION 4(2) OF THE
SECURITIES ACT. IN ADDITION, THE REGISTERED HOLDERS AND THE BENEFICIAL OWNERS OF
SUCH NOTES ARE THEREBY MAKING CERTAIN OTHER  REPRESENTATIONS  AND WARRANTIES AND
ARE THEREBY AGREEING TO BE BOUND BY CERTAIN  COVENANTS  CONTAINED  THEREIN.  SEE
"ANCILLARY AGREEMENTS."

         IN ADDITION TO THE ORIGINAL  LETTER OF  TRANSMITTAL  AND OTHER REQUIRED
DOCUMENTS,  ALL REGISTERED HOLDERS AND BENEFICIAL OWNERS OF NOTES BEING TENDERED
MUST  EXECUTE  AND SEND  SUCH  AMENDMENT  TO THE  LETTER OF  TRANSMITTAL  TO THE
DEPOSITARY ON OR PRIOR TO THE EXPIRATION  DATE,  REGARDLESS OF WHETHER THEY HAVE
HERETOFORE  TENDERED THEIR NOTES PURSUANT TO THE OFFER.  UNLESS EACH  REGISTERED
HOLDER AND BENEFICIAL OWNER (IF DIFFERENT FROM THE REGISTERED HOLDER THEREOF) OF
THE NOTES BEING  TENDERED  EXECUTES THE AMENDMENT TO THE LETTER OF  TRANSMITTAL,
THE TENDER WILL BE DEEMED INVALID.

         ANY TENDER OF NOTES NOT ACCOMPANIED BY PROPERLY  EXECUTED  AMENDMENT TO
THE LETTER OF  TRANSMITTAL  AND ORIGINAL  LETTER OF  TRANSMITTAL  WILL BE DEEMED
INVALID.  ALL REQUIRED  DOCUMENTS  MUST BE DELIVERED  TO THE  DEPOSITARY  AT THE
ADDRESS OR THE FACSIMILE  NUMBER SHOWN ON THE BACK COVER OF THE ORIGINAL  LETTER
OF TRANSMITTAL  AND IN ACCORDANCE  WITH THE PROCEDURES SET FORTH IN THE ORIGINAL
OFFER TO EXCHANGE, AS AMENDED HEREBY, AND IN THE ORIGINAL LETTER OF TRANSMITTAL.


AVAILABILITY OF INFORMATION

         Hybridon shall provide each Noteholder the opportunity to ask questions
and receive  answers  concerning  the terms and  conditions  of the Offer and to
obtain any  additional  information  which  Hybridon  possesses  or can  acquire
without  unreasonable effort or expense that is necessary to verify the accuracy
of information furnished in connection with the Offer. The address of Hybridon's
principal executive office is 620 Memorial Drive, Cambridge, MA 02139; telephone
(617) 528-7000.


ALTERNATIVE CONSIDERATION

         In the event that the Equity  Conditions  are satisfied or Waived,  the
tendering  Noteholders will receive upon acceptance for exchange of the tendered
Notes,  in lieu of the  Original  Consideration,  10 shares  of the  Alternative
Series A Preferred  Stock and  Alternative  Exchange  Warrants to purchase  such
number of shares of Hybridon  Common  Stock equal to 25% of the number of shares
of Hybridon  Common Stock into which such  Alternative  Series A Preferred Stock
would be convertible at the Alternative  Conversion  Price.  Any tender of Notes
which involves  denominations of less than $1,000 in Exchange Value thereof will
be exchanged on a pro rata basis, except to the extent that such proration would
result in the issuance of a fractional  share of Alternative  Series A Preferred
Stock. In the event that such fractional share would result,  Hybridon shall, at
its sole discretion, either (a) round


                                      -2-
<PAGE>

such  fractional  share to the nearest  whole  number of shares  (with 0.5 being
rounded up), or (b) pay in cash an amount equal to such  fraction  multiplied by
$100 (which is the per share stated value of the Alternative  Series A Preferred
Stock).  Hybridon will not issue any fractional  shares of Alternative  Series A
Preferred  Stock in the Offer.  In the event that a tendering  Noteholder  would
otherwise  be entitled to receive a  fractional  Alternative  Exchange  Warrant,
Hybridon  shall round up such  fractional  Alternative  Exchange  Warrant to the
nearest whole number of Alternative Exchange Warrants.  The fair market value of
the Alternative Series A Preferred Stock and Alternative  Exchange Warrants will
be allocated  first to principal and then to accrued but unpaid  interest on the
principal amount of the Notes.

ALTERNATIVE SERIES A PREFERRED STOCK

         The following  summary  description of  Alternative  Series A Preferred
Stock  of  Hybridon  is  necessarily  incomplete  and is thus  qualified  in its
entirety by the form of Certificate of Designation of the  Alternative  Series A
Preferred  Stock  which  is  attached  as  Annex A to this  Amendment  and  such
Certificate of Designation is incorporated herein by reference.

         The  Certificate  of  Incorporation  of  Hybridon  permits its Board of
Directors to issue up to 5,000,000 shares of Hybridon 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.  No shares of Hybridon
Preferred  Stock  are  currently  outstanding.  In the  event  that  the  Equity
Conditions are satisfied or Waived, Hybridon will file, immediately prior to the
acceptance for exchange of the Notes tendered into the Offer, with the Secretary
of State of the State of Delaware a Certificate of  Designation  with respect to
the Alternative Series A Preferred Stock, with the following designations:


Dividend:                  6.5% per annum,  payable  on the same dates  interest
                           payments are currently to be paid with respect to the
                           Notes.  The  dividend may be paid with either cash or
                           additional  shares of Alternative  Series A Preferred
                           Stock, at the option of Hybridon.

Liquidation Preference:    $100.00 per share plus accrued but unpaid dividends.

Ranking:                   The Alternative Series A Preferred Stock ranks, as to
                           dividends and liquidation  preference,  senior to the
                           Hybridon   Common  Stock.   No  shares  of  Series  B
                           Preferred  Stock  described in the Original  Offer to
                           Exchange  will be issued in the event that the Equity
                           Conditions are satisfied or Waived.

Conversion:                The Alternative Series A Preferred Stock shall not be
                           convertible  into  Hybridon  Common  Stock  until the
                           expiration  of 12 months  after the Closing  Date (as
                           defined under "Alternative Equity Offering" below).

                           The  conversion  price  of the  Alternative  Series A
                           Preferred Stock (the "Alternative  Conversion Price")
                           shall be 212.5% of the Common  Stock  Offering  Price
                           (as defined  under  "Alternative  Equity  Offering --
                           Equity   Condition  (i)  Common  Stock   Offering  --
                           Offering  Price" below) of the Hybridon  Common Stock
                           sold  in  the  Common  Stock  Offering   (subject  to
                           antidilution adjustments set forth in the Certificate
                           of Designation for the Alternative Series A Preferred
                           Stock).  The Alternative Series A Preferred Stock has
                           no  comparable  provision  to the  Series A  One-Year
                           Reset described in the Original Offer to Exchange.


                                      -3-
<PAGE>

Mandatory Conversion
 or Redemption:            At any time after the  expiration  of 12 months after
                           the Closing Date (but only after April 1, 2000 in the
                           case of clause (ii) below),  if the closing bid price
                           of the Hybridon  Common Stock is at least 250% of the
                           then applicable  conversion  price of the Alternative
                           Series A Preferred  Stock for 20 trading  days in any
                           30  consecutive  trading day period ending three days
                           prior  to  the  date  of  notice  of   conversion  or
                           redemption,  as the  case  may be,  Hybridon  may (i)
                           cause the Alternative  Series A Preferred Stock to be
                           converted,  in whole or in part, into Hybridon Common
                           Stock at 200% of the Common Stock  Offering  Price or
                           (ii) redeem the Alternative  Series A Preferred Stock
                           for cash in an  amount  equal to  $100.00  per  share
                           (subject  to  appropriate  adjustment  to reflect any
                           stock split,  reclassification  or  reorganization of
                           the  Alternative  Series A Preferred  Stock) plus any
                           accrued but unpaid  dividends  (provided that holders
                           will have the right to convert into  Hybridon  Common
                           Stock,  at  the  Alternative  Conversion  Price,  any
                           shares  so  called  for   mandatory   conversion   or
                           redemption).

Class Voting Rights:       Hybridon shall not,  without the affirmative  vote or
                           consent  of  the  holders  of at  least  50%  of  all
                           outstanding  Alternative  Series A  Preferred  Stock,
                           voting  separately  as a class,  (i) amend,  alter or
                           repeal   any   provision   of  the   Certificate   of
                           Incorporation  or  the  By-laws  of  Hybridon  so  as
                           adversely to affect the relative rights, preferences,
                           qualifications,  limitations or  restrictions  of the
                           Alternative   Series  A  Preferred  Stock  (with  the
                           issuance  of  securities  ranking  prior  to, or pari
                           passu with, the Alternative  Series A Preferred Stock
                           (A)  upon a  Liquidation  Event  (as  defined  in the
                           Certificate of Designation for  Alternative  Series A
                           Preferred  Stock) or (B) with  respect to the payment
                           of dividends or  distributions,  not being considered
                           to so adversely affect),  or (ii) authorize or issue,
                           or increase the authorized amount of, the Alternative
                           Series A Preferred Stock,  other than the Alternative
                           Series A Preferred  Stock issuable in connection with
                           the transactions  described under "Alternative Equity
                           Offering" below, issuable in the Offer or issuable as
                           dividends on any shares of the  Alternative  Series A
                           Preferred Stock.


         HOLDERS OF  ALTERNATIVE  SERIES A  PREFERRED  STOCK TO BE ISSUED IN THE
OFFER  WILL NOT BE  ENTITLED  TO RECEIVE  ANY RESET  WARRANTS  DESCRIBED  IN THE
ORIGINAL  OFFER  TO  EXCHANGE.  SEE  "TERMS  OF THE  OFFER--CONSIDERATION  BEING
OFFERED--RESET WARRANTS" IN THE ORIGINAL OFFER TO EXCHANGE.

         Also    see    "Alternative    Equity     Offering--Preferred     Stock
Offering--Indenture Change of Control Prohibition."


ALTERNATIVE EXCHANGE WARRANTS

         The following summary description of the Alternative  Exchange Warrants
of Hybridon which may be issued in the Offer is necessarily  incomplete and thus
is qualified in its entirety by the form of Warrant  Agreement (the "Alternative
Warrant  Agreement")  which  is  attached  as  Annex  B to  this  Amendment  and
incorporated herein by reference.

         In the event that the Alternative Equity Offering is consummated,  each
tendering  Noteholder will receive upon acceptance for exchange by Hybridon,  in
addition to shares of the Alternative  Series A Preferred Stock, the Alternative
Exchange  Warrants to purchase a number of shares of Hybridon Common Stock equal
to 25% of the  number  of  shares  of  Hybridon  Common  Stock  into  which  the
Alternative Series A Preferred Stock issued to such


                                      -4-
<PAGE>

Noteholder  pursuant  to the  Offer  would  be  convertible  at the  Alternative
Conversion  Price.  The  Alternative  Exchange  Warrants  shall  be  exercisable
commencing  12  months  after  the  Closing  Date  for a  period  of four  years
thereafter,  at 212.5% of the  Common  Stock  Offering  Price.  The  Alternative
Exchange  Warrants are not subject to redemption at the option of Hybridon under
any circumstances.

         Also    see    "Alternative    Equity     Offering--Preferred     Stock
Offering--Indenture Change of Control Prohibition."


REGISTRATION RIGHTS

         The following  summary  description  of the  registration  rights to be
granted to the tendering Noteholders in connection with the Offer is necessarily
incomplete  and thus is qualified in its entirety by the  applicable  provisions
contained in the Amendment to the Letter of Transmittal  and such provisions are
incorporated herein by reference.

         The registration rights to be granted to the tendering Noteholders with
respect to the Alternative  Consideration  is identical to those set forth under
the caption  "Terms of the  Offer--Consideration  Being Offered --  Registration
Rights" in the  Original  Offer to  Exchange,  except that in the event that the
Alternative  Consideration is issued in the Offer Hybridon will agree to use its
best efforts to file a  Registration  Statement no later than the earlier of (i)
60 days  following the Closing Date and (ii) the date on which any  registration
statement  under the  Securities  Act is filed in  respect  of the resale of any
security sold in the Alternative Equity Offering.


ALTERNATIVE EQUITY OFFERING

         The Alternative Equity Offering is an alternative  restructuring to the
Restructuring of Hybridon's capital structure described in the Original Offer to
Exchange  which is  conditioned  upon the  satisfaction  or Waiver of the Equity
Conditions set forth below (the "Alternative  Equity Offering").  If successful,
the  Alternative  Equity  Offering is expected to enable Hybridon to raise up to
$30,000,000 (less fees,  commissions and expenses) in cash for use in Hybridon's
operations  and to reduce its debt  service  obligations,  and will  improve the
financial  position of Hybridon by reducing  the  indebtedness  of Hybridon  for
financial reporting purposes,  and thereby improve the chances of Hybridon being
able to comply with the quantitative criteria for the listing of Hybridon Common
Stock on the Nasdaq Stock Market.

         Hybridon  will  first  attempt to  consummate  the  Alternative  Equity
Offering,  but if the same cannot be accomplished  in a timely manner,  Hybridon
intends to continue to proceed with the Restructuring  and the New Offering.  To
date, Hybridon has raised  approximately $4.8 million in gross proceeds from the
New Offering (the "New Offering Proceeds"). See "Recent Developments" below.

         There are three conditions precedent to the Alternative Equity Offering
(the "Equity Conditions"), the consummation of which must take place, if at all,
no later  than the date on which  Hybridon  accepts  for  exchange  at least $40
million  principal  amount of the Notes pursuant to the Offer (the date on which
the Alternative  Equity Offering is consummated  being referred to herein as the
"Closing  Date").  Prior to  acceptance  for exchange of the  tendered  Notes by
Hybridon,  any of the Equity  Conditions  may be waived by the mutual consent of
Hybridon and the person  selected by the tendering  Noteholders  to serve as the
initial  Designated  Director  ("Waived" or "Waiver" as used herein meaning such
waiver). The Equity Conditions are as follows:

         (i)   Hybridon  raises gross  proceeds from the sale (the "Common Stock
               Offering") of Qualified  Securities (as hereinafter defined under
               the caption "Equity  Condition (i) -- Common Stock  Offering") in
               an amount, and sells a number of Qualified  Securities,  mutually
               acceptable  to Hybridon and the person  selected by the tendering
               Noteholders to serve as the initial Designated Director;


                                      -5-
<PAGE>

         (ii)  Hybridon  raises  gross  proceeds  from the sale (the  "Preferred
               Stock  Offering")  of shares of  Alternative  Series A  Preferred
               Stock (the terms of which shall be identical  to the  Alternative
               Series A Preferred  Stock  constituting a part of the Alternative
               Consideration)  and warrants  (the terms of which shall be as set
               forth below in "Equity Condition (ii) -- Preferred Stock Offering
               -- Preferred  Warrants")  in an amount equal to or exceeding  $10
               million; and

         (iii) Hybridon  exchanges  (the "Offering  Notes  Exchange") all of the
               then outstanding principal amount of and interest on the Offering
               Notes and the warrants  issued  therewith  for shares of Hybridon
               Common  Stock and  warrants  upon the terms set forth below under
               the caption "Equity Condition (iii) -- Offering Notes Exchange."

         The summary terms of the transactions referred to above are as follows:


1.   EQUITY CONDITION (I)--
     COMMON STOCK OFFERING

     SECURITIES                     Hybridon   Common   Stock,   together   with
                                    applicable   warrants  as  described   below
                                    (collectively, "Qualified Securities").


     OFFERING                       SIZE An  amount  in  gross  proceeds,  and a
                                    number  of  Qualified  Securities,  mutually
                                    acceptable   to  Hybridon   and  the  person
                                    selected  by the  tendering  Noteholders  to
                                    serve as the Designated Director.

     COMMON STOCK OFFERING PRICE    The  greater of (a) 85% of the Market  Price
                                    (as  defined  below)  determined  as of  the
                                    Closing  Date,  or (b) $2.00 per share  (the
                                    "Common  Stock  Offering  Price").  As  used
                                    herein,  the term "Market  Price"  refers to
                                    the  average  reported  closing bid price of
                                    Hybridon  Common  Stock for the five trading
                                    days immediately preceding the Closing Date.

     COMMON WARRANTS                Purchasers in the Common Stock Offering will
                                    receive  warrants  to  purchase   additional
                                    shares of Hybridon Common Stock equal to 25%
                                    of the number of shares of  Hybridon  Common
                                    Stock   purchased   in  the   Common   Stock
                                    Offering,  exercisable at 120% of the Common
                                    Stock  Offering  Price  for a period of five
                                    years  commencing on the Closing Date. These
                                    warrants   are   not   subject   to  a  call
                                    provision.


                                      -6-
<PAGE>

     CONTRACTUAL RIGHT TO 
     LIQUIDATION PUT                Each  purchaser in the Common Stock Offering
                                    shall  have  the  right  (the   "Liquidation
                                    Put"),  pari passu with  participants in the
                                    Offering Notes Exchange, to require Hybridon
                                    to repurchase with cash the number of shares
                                    of  Hybridon   Common  Stock  sold  to  such
                                    purchaser in the Alternative Equity Offering
                                    at the Common Stock Offering Price. However,
                                    each such  purchaser  will  covenant  not to
                                    exercise  the  Liquidation  Put  unless  (a)
                                    Hybridon  liquidates,  dissolves or winds up
                                    its   affairs    pursuant   to    applicable
                                    bankruptcy  law,   whether   voluntarily  or
                                    involuntarily,  (b)  all of  the  securities
                                    issued under the  Indenture  relating to the
                                    9%  Notes  have  been  paid in  full  and no
                                    obligations remain under such Indenture, (c)
                                    all other  indebtedness  and  obligations of
                                    Hybridon (including, without limitation, the
                                    indebtedness under Hybridon's loan agreement
                                    with   Silicon   Valley   Bank  (the   "Loan
                                    Agreement"))  has been paid in full, and (d)
                                    all  rights of the  holders of any series or
                                    class of  capital  stock  ranking  prior and
                                    senior to the  Hybridon  Common  Stock  with
                                    respect to liquidation  (including,  without
                                    limitation,   the   Alternative   Series   A
                                    Preferred  Stock)  have  been  satisfied  in
                                    full.

     CLOSING                        DATE The Closing Date, upon the consummation
                                    of the  closing  of each  other  transaction
                                    forming  a part  of the  Alternative  Equity
                                    Offering.  See above  regarding  the  Equity
                                    Conditions.

     LOCK-UP                        Those  Qualified   Securities  sold  in  the
                                    Common Stock Offering pursuant to Regulation
                                    S under the  Securities Act and the Hybridon
                                    Common  Stock into which any such  Qualified
                                    Securities  are  exercisable  (collectively,
                                    the "Lock-up Securities") will be subject to
                                    a  "lock-up"  for a  period  ending  on  the
                                    one-year  anniversary  of the Closing  Date,
                                    except to the  extent  such  securities  are
                                    sold or transferred pursuant to an effective
                                    registration  statement.  In  addition,  for
                                    each purchaser in the Common Stock Offering,
                                    75% of such purchaser's  Lock-up  Securities
                                    shall  be  subject  to a  "lock-up"  for the
                                    first three months  following  the effective
                                    date   of   the   applicable    registration
                                    statement  (the  "Common   Lock-up   Date").
                                    Thereafter,  50% of such  securities will be
                                    subject to such a "lock-up" until six months
                                    following  the Common  Lock-up  Date and the
                                    remaining  25% of  such  securities  will be
                                    "locked-up"  until nine months following the
                                    Common Lock-up Date.


                                      -7-
<PAGE>

                                    Furthermore,  purchasers in the Common Stock
                                    Offering  (including   participants  in  the
                                    Offering Notes Exchange) will be prohibited,
                                    from the date that each such  purchaser  was
                                    first   contacted   with   respect   to  the
                                    potential    purchase   of   the   Qualified
                                    Securities  through the last date upon which
                                    such purchaser holds any Lock-up Securities,
                                    from  (i)  selling   "short"  or   "shorting
                                    against   the  box"  (as  those   terms  are
                                    generally understood) any equity security of
                                    Hybridon or (ii)  otherwise  engaging in any
                                    transaction  which involves  hedging of such
                                    purchaser's  position in the  securities  of
                                    Hybridon.

     COMMON PLACEMENT AGENT                           
     COMPENSATION                   The  placement  agent for the  Common  Stock
                                    Offering (the "Common Placement Agent") will
                                    receive  fees  consisting  of  (i) 9% of the
                                    gross  proceeds of the Common Stock Offering
                                    (the  "Common  Gross   Proceeds"),   (ii)  a
                                    non-accountable  expense  allowance equal to
                                    4% of the Common Gross  Proceeds,  and (iii)
                                    warrants to  purchase  such number of shares
                                    of Hybridon Common Stock equal to 10% of the
                                    aggregate   number  of  shares  of  Hybridon
                                    Common   Stock  sold  in  the  Common  Stock
                                    Offering,  exercisable at 120% of the Common
                                    Stock  Offering  Price  for a period of five
                                    years  from  the  Closing  Date,   provided,
                                    however,   that  in  no  event   shall   the
                                    Placement  Agent  be  permitted  to  receive
                                    compensation  in excess  of the level  which
                                    would  not  result  in a  breach  under  the
                                    Indenture.

2.   EQUITY CONDITION (II)--
     PREFERRED STOCK OFFERING

     SECURITIES                     Alternative   Series  A   Preferred   Stock,
                                    together   with   applicable   warrants   as
                                    described  below  (collectively,  "Preferred
                                    Offering Securities").

     OFFERING                       SIZE $10.0  million  in gross cash  proceeds
                                    (exclusive  of  the  reinvestment  described
                                    below under the caption "Preferred Placement
                                    Agent Compensation").

     OFFERING                       PRICE  70%  of  the  stated   value  of  the
                                    Alternative Series A Preferred Stock, or $70
                                    per share.

     DIVIDEND                       6.5% per  annum,  payable  on the same dates
                                    interest  payments are  currently  paid with
                                    respect to the Notes.  The  dividend  may be
                                    paid either in cash or additional  shares of
                                    the Alternative Series A Preferred Stock (at
                                    its full stated value).

     CONVERSION                     See "Alternative  Consideration--Alternative
                                    Series A Preferred Stock--Conversion."


                                      -8-
<PAGE>

     PREFERRED WARRANTS             Purchasers  of  the  Alternative   Series  A
                                    Preferred   Stock  in  the  Preferred  Stock
                                    Offering shall receive  warrants to purchase
                                    a number of shares of Hybridon  Common Stock
                                    equal  to  25%  of the  number  of  Hybridon
                                    Common  Stock into which  their  Alternative
                                    Series A Preferred  Stock is  convertible at
                                    the  Alternative   Conversion   Price.  Such
                                    warrants shall be exercisable  commencing 12
                                    months after the Closing Date at 120% of the
                                    Common Stock Offering Price and for a period
                                    of four years thereafter. These warrants are
                                    not subject to a call provision.

     MANDATORY CONVERSION OR 
     REDEMPTION                     See "Alternative  Consideration--Alternative
                                    Series    A    Preferred    Stock--Mandatory
                                    Conversion or Redemption."

     CLOSING DATE                   The Closing Date,  upon the  consummation of
                                    the   closing  of  each  other   transaction
                                    forming  a part  of the  Alternative  Equity
                                    Offering.  See above  regarding  the  Equity
                                    Conditions.

     INDENTURE CHANGE OF CONTROL                      
     PROHIBITION                    The   Certificate  of  Designation  for  the
                                    Alternative Series A Preferred Stock and the
                                    Alternative  Warrant  Agreement with respect
                                    to  the  Offer  shall   contain   provisions
                                    designed to ensure that no change of control
                                    event is triggered under the Indenture.

     OTHER RESTRICTIONS             Purchasers in the Preferred  Stock  Offering
                                    will be prohibited,  from the date that each
                                    such  purchaser  was  first  contacted  with
                                    respect  to  the   potential   purchase   of
                                    Preferred  Offering  Securities  through the
                                    last date upon  which such  purchaser  holds
                                    such, or any underlying, securities from (i)
                                    selling  "short" or  "shorting  against  the
                                    box"   (as   those   terms   are   generally
                                    understood)  any equity security of Hybridon
                                    or   (ii)   otherwise    engaging   in   any
                                    transaction  which involves  hedging of such
                                    purchaser's  position in the  securities  of
                                    Hybridon;   provided,   however,  that  such
                                    purchaser  may  have  an   aggregate   short
                                    position  covering  a   number  of   shares 
                                    of   Hybridon   Common   Stock   fewer  than
                                    the  quotient  of  (a)  the  product  of (x)
                                    the number of shares of Alternative Series A
                                    Preferred  Stock  owned  by  such  purchaser
                                    multiplied  by (y) the Dividend  Base Amount
                                    (as   defined   in   the    Certificate   of
                                    Designation  with respect to the Alternative
                                    Series A  Preferred  Stock),  divided by (b)
                                    the  Alternative  Conversion  Price  then in
                                    effect.


                                      -9-
<PAGE>

     PREFERRED PLACEMENT AGENT     
     COMPENSATION                   The placement  agent for the Preferred Stock
                                    Offering (the "Preferred  Placement  Agent")
                                    will  receive fees  consisting  of (i) 9% of
                                    the gross  proceeds of the  Preferred  Stock
                                    Offering (the "Preferred  Gross  Proceeds"),
                                    (ii)  a  non-accountable  expense  allowance
                                    equal to 4% of the Preferred Gross Proceeds,
                                    and (iii)  warrants to purchase  such number
                                    of shares of Hybridon  Common Stock equal to
                                    10% of the  number  of  shares  of  Hybridon
                                    Common  Stock  into  which  the  Alternative
                                    Series  A   Preferred   Stock  sold  in  the
                                    Preferred  Stock  Offering is convertible at
                                    the Alternative  Conversion Price, provided,
                                    however,   that  in  no  event   shall   the
                                    Preferred  Placement Agent receive an amount
                                    of equity securities of Hybridon which could
                                    result  in  the  Preferred  Placement  Agent
                                    being deemed as an  "affiliate" of Hybridon,
                                    as such term is  defined  in the  Indenture,
                                    after   taking   into   account   all  other
                                    securities   beneficially   owned   by   the
                                    Preferred  Placement  Agent.  Such  warrants
                                    shall be  exercisable  commencing  12 months
                                    after the Closing  Date for a period of four
                                    years thereafter, and shall have an exercise
                                    price  equal  to  120% of the  Common  Stock
                                    Offering Price.

                                    The Preferred  Placement Agent has agreed to
                                    reinvest  all of its  fees  (other  than the
                                    out-of-pocket  expenses  incurred  by it) by
                                    purchasing    from   Hybridon    shares   of
                                    Alternative  Series A Preferred Stock at the
                                    offering  price  thereof  in  the  Preferred
                                    Stock   Offering,   and   the   accompanying
                                    warrants to be sold in the  Preferred  Stock
                                    Offering.

                                    Hybridon   has   been   informed   that  the
                                    Preferred Placement Agent and its affiliates
                                    beneficially    own    an    aggregate    of
                                    approximately $5 million in principal amount
                                    of the Notes.

3.   EQUITY CONDITION (III)--
     OFFERING NOTES EXCHANGE

     HYBRIDON COMMON STOCK          The principal of and accrued interest on the
                                    Offering  Notes and the warrants sold in the
                                    New  Offering  shall  be  exchanged  for (a)
                                    Hybridon  Common  Stock at the Common  Stock
                                    Offering   Price  and  (b)  the   applicable
                                    warrants  described  below.   Purchasers  of
                                    Units in the Note Offering are not obligated
                                    to accept the Offering Notes  Exchange,  and
                                    there can be no assurance  that they will do
                                    so.


                                      -10-
<PAGE>

     WARRANTS                       The warrants  issued with the Offering Notes
                                    in the New Offering  will be  exchanged  for
                                    warrants  identical  to the  warrants  to be
                                    sold in the Common  Stock  Offering,  except
                                    that such warrants are  exercisable for such
                                    number of shares of  Hybridon  Common  Stock
                                    equal  to 30% of the  number  of  shares  of
                                    Hybridon Common Stock issued in exchange for
                                    the Offering Notes.

     CONTRACTUAL RIGHT TO 
     LIQUIDATION                    PUT The  holders of  Hybridon  Common  Stock
                                    acquired in the Offering Notes Exchange will
                                    be entitled to the Liquidation Put described
                                    above  under   "Equity   Condition   (i)  --
                                    Contractual Right to Liquidation Put."

     CLOSING                        DATE The Closing Date, upon the consummation
                                    of the  closing  of each  other  transaction
                                    forming  a part  of the  Alternative  Equity
                                    Offering.  See above  regarding  the  Equity
                                    Conditions.

     LOCK-UP                        See "Equity  Condition  (i) -- Common  Stock
                                    Offering -- Lock-up".


LIMITATIONS ON RESALE OF HYBRIDON STOCK

         The  Series  A  Preferred  Stock  and  the  Exchange  Warrants,  or the
Alternative Series A Preferred Stock and the Alternative  Exchange Warrants,  as
the case may be, to be issued in exchange for the Notes in the Offer, as well as
the Hybridon  Common Stock  issuable  upon  conversion or exercise of any of the
foregoing  securities,  shall  have  the  status  of  securities  acquired  in a
transaction under the so-called "private placement" exemption under Section 4(2)
of the Securities Act and cannot be resold by the tendering  Noteholders without
registration  under the Securities Act or an exemption  therefrom.  Hybridon has
agreed to use its best efforts to file a shelf registration  statement under the
Securities  Act of the  Series A  Preferred  Stock or the  Alternative  Series A
Preferred  Stock, as the case may be, and the Hybridon  Common Stock  underlying
Series A Preferred Stock and the Exchange Warrants,  or the Alternative Series A
Preferred Stock and the Alternative  Exchange Warrants,  as the case may be. See
"Alternative  Consideration--Registration  Rights"  and  "Terms  of the Offer --
Consideration  Being Offered --  Registration  Rights" in the Original  Offer to
Exchange. Prior to the effectiveness of the registration statement covering such
securities,  however,  the  holders  thereof  may not sell  any such  securities
without an exemption from registration under the Securities Act.

         Each  certificate  representing  the  Series A  Preferred  Stock or the
Exchange  Warrants,  or  the  Alternative  Series  A  Preferred  Stock  and  the
Alternative Exchange Warrants, as the case may be, and the Hybridon Common Stock
issuable  upon  conversion  or exercise  thereof,  shall contain a legend to the
effect that the securities  represented by such  certificate  have the status of
securities  acquired in  transaction  under an  exemption of Section 4(2) of the
Securities  Act and cannot be resold without  registration  under the Securities
Act or an exemption therefrom.


                                      -11-
<PAGE>

ANCILLARY AGREEMENTS

         In addition to the description  appearing under the caption "Purpose of
the Offer; Certain Effects of the  Offer--Ancillary  Agreements" in the Original
Offer to Exchange with respect to the ancillary agreements to be entered into by
the  tendering   Noteholders,   in  case  the  Alternative  Equity  Offering  is
consummated,   the  following   modifications  to  such  description   shall  be
applicable:

         (i)      Under the caption  "Purpose of the Offer;  Certain  Effects of
                  the Offer--Ancillary Agreements--Certain Sale Restrictions" in
                  the Original  Offer to Exchange,  substitute all references to
                  the term "Series A Preferred Stock" with "Alternative Series A
                  Preferred Stock";

         (ii)     Under the caption  "Purpose of the Offer;  Certain  Effects of
                  the Offer--Ancillary  Agreements--Restrictions on Indebtedness
                  and Senior Equity  Issuances;  Affiliate  Transactions" in the
                  Original  Offer to Exchange,  substitute all references to the
                  term  "Restructuring  Trigger" with the term "the consummation
                  of  the  Alternative  Equity  Offering,"  and  substitute  all
                  references  to  the  term  "Series  A  Preferred  Stock"  with
                  "Alternative Series A Preferred Stock";

         (iii)    Under the caption  "Purpose of the Offer;  Certain  Effects of
                  the Offer--Ancillary  Agreements--Board  Seat" in the Original
                  Offer to Exchange,  substitute in its entirety the description
                  appearing thereunder with the following:

                           Following the consummation of the Alternative  Equity
                           Offering,  for  so  long  as  at  least  50%  of  the
                           Alternative Series A Preferred Stock initially issued
                           in the Offer remains outstanding, the holders of such
                           Alternative  Series A Preferred  Stock  issued in the
                           Offer shall be entitled to  designate  one member for
                           nomination to the Board of Directors of Hybridon (the
                           "Designated Director"), provided that such nominee is
                           reasonably   acceptable  to  Hybridon.   The  initial
                           Designated  Director  shall be Mr. Art Berry  (unless
                           the holders of a majority of the Alternative Series A
                           Preferred  Stock  to be  issued  in the  Offer  shall
                           instruct  otherwise in the Amendment to the Letter of
                           Transmittal,  in which case, the person receiving the
                           most  votes   thereon   shall   become  the   initial
                           Designated  Director),   to  hold  office  until  his
                           successor is duly elected and  qualified or until his
                           earlier resignation or removal; and

         (iv)     Under the caption  "Purpose of the Offer;  Certain  Effects of
                  the Offer--Ancillary  Agreements--Board  Seat" in the Original
                  Offer  to  Exchange,  substitute  all  references  to the term
                  "Series  A  Preferred  Stock"  with   "Alternative   Series  A
                  Preferred Stock."

         In addition,  the  accompanying  Amendment to the Letter of Transmittal
contains  certain  representations  and  warranties  which  must  be made by the
beneficial  owners of the Notes being  tendered which are required in connection
with the issuance of securities under Section 4(2) of the Securities Act. If any
such beneficial  owner is not an "accredited  investor" (as such term is defined
in Rule 501 under the Securities  Act), such beneficial  owner must certify that
he,  either alone or with his purchaser  representative  (who, if any, must meet
the criteria set forth in Rule 501(h) under the  Securities  Act),  possess such
knowledge and experience in financial and business matters that he is capable of
evaluating the merits and risks of the Offer. In addition, such beneficial owner
must make certain representations as to investment intent. UNLESS SUCH AMENDMENT
IS  EXECUTED BY BOTH THE  REGISTERED  HOLDER AND  BENEFICIAL  OWNER OF THE NOTES
BEING TENDERED, SUCH TENDER WILL BE DEEMED INVALID.

CERTAIN CONDITIONS OF THE OFFER

         Notwithstanding any other provision of the Offer,  Hybridon will not be
required  to  accept  for  exchange  or  exchange  any Notes  tendered,  and may
terminate or amend the Offer with respect thereto,  and may postpone (subject to
the  requirements of the Exchange Act for prompt payment for or return of Notes)
the exchange of Notes


                                      -12-
<PAGE>

tendered, if any of the following shall have occurred at any time after the date
of this  Amendment  to the Offer to Exchange  and prior to the  Expiration  Date
(whether  or not  such  occurrence  shall  be  continuing  at the  time  of such
termination, amendment or postponement):

                  (a) any  action or  proceeding  shall  have  been  threatened,
         instituted,  pending or taken,  or approval  shall have been  withheld,
         withdrawn or abrogated,  or any statute,  rule,  regulation,  judgment,
         order or  injunction  shall  have been  threatened,  proposed,  sought,
         promulgated,  enacted,  entered,  amended,  enforced  or  deemed  to be
         applicable to the Offer or Hybridon,  by any legislative  body,  court,
         authority,  agency or  tribunal  or any  other  person,  including  the
         Securities and Exchange  Commission (the "Commission") or the States of
         Delaware or Massachusetts,  that, in Hybridon's sole judgment, would or
         might  directly or indirectly  (i) make the acceptance for exchange of,
         or  exchange  of,  some or all of the Notes  illegal or  challenge  the
         acquisition  of such Notes or otherwise  or in any manner  relate to or
         affect the Offer, (ii) materially  impair the contemplated  benefits of
         the  Offer  to  Hybridon  or  (iii)  materially  affect  the  business,
         condition  (financial  or other),  income,  operations  or prospects of
         Hybridon,  or otherwise  materially  impair in any way the contemplated
         future conduct of the business of Hybridon;

                  (b) there shall have  occurred (i) any general  suspension  of
         trading in, or  limitation  on prices for,  securities  on any national
         securities exchange or in the over-the-counter  market, (ii) any change
         in the general political,  market,  economic or financial  condition in
         the United States or abroad that could have a material  adverse  effect
         on  Hybridon's  business,  operations,  prospects  or ability to obtain
         financing  generally  or  the  trading  in  the  equity  securities  of
         Hybridon,  (iii)  the  declaration  of  a  banking  moratorium  or  any
         suspension  of payments in respect of banks in the United States or any
         limitation on, or any event which, in Hybridon's  sole judgment,  might
         affect,  the extension of credit by lending  institutions in the United
         States,  (iv) the  commencement  of a war,  armed  hostilities or other
         international or national calamity directly or indirectly involving the
         United States,  or (v) in the case of any of the foregoing  existing at
         the time of the commencement of the Offer, in Hybridon's sole judgment,
         a material acceleration or worsening thereof; and

                  (c) the  aggregate  number  of  purchasers  or  recipients  of
         securities in the Common Stock Offering,  the Preferred Stock Offering,
         the  Offering  Notes  Exchange  and the Offer  who are not  "accredited
         investors" (as such term is defined in Rule 501  promulgated  under the
         Securities Act), excluding purchasers of securities sold in reliance on
         Regulation S under the Securities Act, shall exceed 35.

         The foregoing  conditions  are for the sole benefit of Hybridon and may
be asserted by Hybridon regardless of the circumstances (including any action or
inaction by Hybridon) giving rise to any such condition,  and any such condition
may be waived  by  Hybridon,  in whole or in part,  at any time and from time to
time in its sole discretion. The failure by Hybridon at any time to exercise any
of the foregoing  rights shall not be deemed a waiver of any such right and each
such right  shall be deemed an ongoing  right  which may be asserted at any time
and from time to time.  Any  determination  by  Hybridon  concerning  the events
described above will be final and binding on all parties.

RECENT DEVELOPMENTS

         On February 9, 1998,  Hybridon  announced  that it sold  $2,384,000  in
principal  amount of the Offering Notes and certain  warrants to purchase shares
of Hybridon Common Stock.

         Although  Hybridon  has  raised  approximately  $4.8  million  in gross
proceeds from the New Offering  described in the Original Offer to Exchange,  as
of the date hereof,  Hybridon  continues to have very limited cash resources and
substantial  obligations to lenders  (including the  Noteholders  and the Bank),
equipment lessors, real estate landlords and trade creditors. Hybridon's ability
to continue  operations in 1998 depends on its success in raising new funds.  If
Hybridon  is  unable  to  obtain a  substantial  amount  of  additional  funding
beginning in April 1998, it will be required to terminate its operations or seek
relief under applicable bankruptcy law by the end of April 1998.


                                      -13-
<PAGE>

         Hybridon has been  informed by Arthur  Andersen  LLP,  its  independent
public accountants,  that their report on Hybridon's December 31, 1997 financial
statements  will  contain  an  explanatory   fourth  paragraph   addressing  the
significant  uncertainty regarding Hybridon's ability to continue operating as a
going concern.

PRICE RANGE OF HYBRIDON COMMON STOCK

         The  high and low bid  prices  of the  Hybridon  Common  Stock  for the
quarter  ending  March 31, 1998  (through  March 27, 1998) were $3 23/64 and $1,
respectively.  The last reported bid price on the Nasdaq OTC Bulletin  Board, as
of the close of business on March 27, 1998,  for the  Hybridon  Common Stock was
$2.


                                      -14-
<PAGE>

                   SELECTED CONSOLIDATED FINANCIAL INFORMATION

                   SELECTED CONSOLIDATED FINANCIAL INFORMATION
                       IN THOUSANDS, EXCEPT PER SHARE DATA

<TABLE>
<CAPTION>
                                                                           Nine Months Ended
                            Years Ended December 31,                         September 30,
                             ----------------------      -----------------------------------------------------
                               1995         1996           1996           1997        1997            1997
                                                                                                  Pro Forma As
                                                                                   Pro Forma(1)   Adjusted (2)
                             ======================      =====================================================

<S>                          <C>           <C>           <C>           <C>           <C>           <C>     
Revenues                     $  1,405      $  4,009      $  2,946      $  3,143      $  3,143      $  3,143
                                                                                                 
Interest Expense                 (173)         (124)          (88)       (3,223)         (973)         (973)
                                                                                                 
Net Loss                      (34,547)      (46,853)      (32,458)      (49,977)      (47,727)      (47,727)
                                                                                                 
Net Loss Applicable to                                                                           
Common Stockholders (3)       (34,547)      (46,853)      (32,458)      (49,977)      (49,352)      (49,706)
                                                                                                 
Basic and Diluted Loss per                                                                       
Share (3)                    $ (11.02)     $  (9.67)     $  (6.78)     $  (9.90)     $  (9.78)     $  (4.24)
                                                                                                 
Shares used in Basic and                                                                         
Diluted Loss per Share          3,135         4,843         4,786         5,047         5,047        11,714
</TABLE>

<TABLE>
<CAPTION>
                                                                                                   Capitalization
                                                                                              As of September 30, 1997
                                                                             -----------------------------------------------------
                                                                                           In thousands, except share data
                                                                                                                     Pro Forma
                                                                                   Actual         Pro Forma (1)    As Adjusted(2)
                                                                             -----------------------------------------------------

<S>                                                                              <C>              <C>              <C>
Current Portion Long Term Debt                                                   $   8,063        $   8,063        $   8,063

Long-Term Debt, Net of Current Portion                                               3,557            3,557            3,557

9% Convertible Subordinated Notes Payable                                           50,000             --               --

Stockholders' (Deficit) Equity

   Series A Convertible Preferred Stock, $.01 par value 1,033,232
   authorized; issued and outstanding 522,500 pro forma and 678,214 shares
   pro forma as adjusted                                                               --                 5                7

    Common Stock, $.001 par value, 100,000,000 shares authorized;
   issued and outstanding 5,058,450 actual and pro forma, 15,058,450  
   pro forma as adjusted                                                                 5                5               15

   Additional Paid In Capital                                                      173,692          223,321          249,309

   Deficit Accumulated During the Development Stage                               (199,171)        (199,171)        (199,171)

   Deferred Compensation                                                            (1,148)          (1,148)          (1,148)
                                                                             -----------------------------------------------------
         Total Stockholders' (Deficit) Equity                                      (26,622)          23,012           49,012
                                                                             -----------------------------------------------------
                  Total Capitalization                                           $  34,998        $  34,632        $  60,632
                                                                             =====================================================
</TABLE>


                                      -15-
<PAGE>

OTHER FINANCIAL DATA:

<TABLE>
<CAPTION>
                                                              
                                       Years Ended                                     Nine Months Ended
                                       December 31,                                      September 30,
                                    ------------------           -------------------------------------------------------------------
                                                                      1997                   1997                      1997

                                     1995       1996                                                                 Pro Forma
                                                                     Actual              Pro Forma(1)             As Adjusted (2)
                                   ------------------------------------------------------------------------------------------------

<S>                                  <C>        <C>                  <C>                    <C>                       <C> 
Ratio of Earnings to Fixed            -            -                    _                     _                          _
Charges (4)

Book Value per Common Share          3.33       4.54                 (5.26)                 (5.78)                    (1.25)
(5)
</TABLE>

(1)  Pro forma to give  effect to the  exchange  of $50.0  million in  principal
     amount of the Notes and  $2,250,000  of accrued  interest  thereon  for the
     Alternative  Series A Preferred  Stock and the  writeoff of  $2,616,000  of
     deferred  financing  costs to  addition  paid in  capital.  There can be no
     assurance  that  $50.0  million  in  principal  amount of the Notes will be
     exchanged.  Such pro forma  adjustments  do not  reflect  the impact of the
     issuance of additional  shares of the Alternative  Series A Preferred Stock
     or  the  issuance  of  Hybridon  Common  Stock  in the  Alternative  Equity
     Offering.

(2)  Pro forma as adjusted to give  effect to the  exchange of $50.0  million in
     principal  amount of the Notes and $2,250,000 of accrued  interest  thereon
     for the Alternative Series A Preferred Stock, the writeoff of $2,616,000 of
     deferred  financing  costs to additional  paid in capital,  the issuance of
     $10.9 million of the Alternative  Series A Preferred Stock in the Preferred
     Stock  Offering,  before  estimated  issuance costs of $1.3 million and the
     issuance of $20.0 million of Hybridon  Common stock,  before issuance costs
     of $3.6 million.  Approximately $900,000 of the estimated issuance costs on
     the  Alternative  Series  A  Preferred  Stock  will  be  reinvested  in the
     Preferred Stock Offering to purchase  additional  shares of the Alternative
     Series A Preferred  Stock.  There can be no assurance that $50.0 million in
     principal  amount of the Notes will be exchanged  and $10.9  million of the
     Alternative  Series A  Preferred  Stock and the $20.0  million of  Hybridon
     Common Stock will be issued in the Alternative Equity Offering.

(3)  Basic  and  diluted  loss  per  share  is  computed  by  dividing  net loss
     applicable to common stockholders (net loss plus cumulative preferred stock
     dividends)  by the  weighted-average  number of common  shares  outstanding
     during  the  period.  Diluted  loss per share is the same as basic loss per
     share  since  the  effect  of  convertible   securities  and  common  stock
     equivalents  would be  antidilutive.  For purposes of  calculating  the Pro
     Forma As Adjusted net loss per share, the shares used in the loss per share
     calculation  assumes an offering  price of $2.00 per share for the Hybridon
     Common Stock to be issued in the Common Stock  Offering.  In addition,  the
     shares are weighted for the nine month period assuming the issuance thereof
     occurred on April 1, 1997.

(4)  For the purpose of  calculating  the ratio of  earnings  to fixed  charges,
     earnings represent Hybridon's loss from continuing operations before income
     taxes plus fixed charges.  Fixed charges consist of interest expense on all
     indebtedness  plus the interest portion of rental expense on non-cancelable
     leases  and   amortization  of  debt  issuance  costs  and  debt  discount.
     Hybridon's  earnings have been inadequate to meet its fixed charges for the
     years  ended  December  31,  1995 and 1996  and for the nine  months  ended
     September 30, 1996 and 1997 by $33.9 million,  $46.4 million, $32.1 million
     and $44.7 million,  respectively.  On a pro forma and pro forma as adjusted
     basis as described in notes (1) and (2) above, Hybridon's earnings would be
     inadequate  to meet its fixed  charges by $44.7  million in the nine months
     ended September 30, 1997.

(5)  Book value per  common  share is  computed  by  dividing  net assets by the
     number of common shares outstanding at the end of the period. Net assets is
     equal to  stockholders'  (deficit)  equity  less the  liquidation  value of
     preferred stock ($100.00 per share).


                                      -16-
<PAGE>

SOURCE AND AMOUNT OF CONSIDERATION

         Assuming that Hybridon exchanges the Alternative  Consideration for all
outstanding Notes pursuant to the Offer, the total amount of consideration to be
paid by Hybridon  will  consist in the  aggregate of (i)  approximately  678,214
shares of the Alternative  Series A Preferred Stock,  which shall be issued from
Hybridon's  authorized but unissued  shares of Hybridon  Preferred  Stock,  (ii)
Alternative  Exchange  Warrants  to  purchase  such number of shares of Hybridon
Common Stock equal to 25% of the number of shares of Hybridon  Common Stock into
which such shares of Series A Preferred Stock are convertible at the Alternative
Conversion  Price.  In  addition,  Hybridon  expects  to incur  fees  and  other
expenses. See "Fees and Expenses" in the Original Offer to Exchange.


CERTAIN FEDERAL INCOME TAX CONSEQUENCES

         In the event that the Alternative  Equity Offering is consummated,  all
references to Series A Preferred Stock and the Exchange Warrants appearing under
the caption "Certain  Federal Income Tax  Consequences" in the Original Offer to
Exchange shall be deemed to refer to the  Alternative  Series A Preferred  Stock
and the Alternative Exchange Warrants, respectively.


                                      -17-
<PAGE>

SELECTED FINANCIAL DATA

The information set forth in Item 6, Part II of the 10-K,  which was attached as
Annex D to the Original Offer to Exchange, is incorporated herein by reference.

                      SELECTED CONSOLIDATED FINANCIAL DATA
                       IN THOUSANDS, EXCEPT PER SHARE DATA

<TABLE>
<CAPTION>
                                           YEARS ENDED DECEMBER 31,                 NINE MONTHS ENDED SEPTEMBER 30,
                                          -----------------------------------------------------------------------------------------
                                                                            1996           1997            1997              1997
                                                                                                            PRO           PRO FORMA
STATEMENT OF OPERATIONS DATA:               1995            1996           ACTUAL          ACTUAL         FORMA(1)    AS ADJUSTED(2)
                                          -----------------------------------------------------------------------------------------
<S>                                       <C>             <C>             <C>             <C>             <C>             <C>     
Revenues                                  $  1,405        $  4,009        $  2,946        $  3,143        $  3,143        $  3,143
Net Loss                                   (34,547)        (46,853)        (32,458)        (49,977)        (47,727)        (47,727)
Net Loss Applicable to
   Common Shareholders(3)                  (34,547)        (46,853)        (32,458)        (49,977)        (49,352)        (49,706)
Basic and Diluted Loss per Share(3)       $ (11.02)       $  (9.67)       $  (6.78)       $  (9.90)       $  (9.78)       $  (4.24)
Shares Used in Basic and
   Diluted Loss per share                    3,135           4,843           4,786           5,047           5,047          11,714
</TABLE>

<TABLE>
<CAPTION>
                                                      AS OF DECEMBER 31,                       AS OF SEPTEMBER 30, 1997
                                                                                                                     PRO FORMA
BALANCE SHEET DATA                                  1995             1996            ACTUAL        PRO FORMA(1)    AS ADJUSTED(2)
<S>                                              <C>              <C>              <C>              <C>              <C>      
Cash, Cash Equivalents and Short-Term
   Investments(4)                                $   5,284        $  16,419        $  14,792        $  14,792        $  40,792
Working Capital (Deficit)                              210            8,999           (2,623)            (373)          25,627
Total Assets                                        19,618           41,537           46,603           43,987           69,987
Long-Term Debt, Net of Current Portion               1,145            9,032            3,557            3,557            3,557
9% convertible Subordinated Notes Payable             --               --             50,000             --               --
Deficit Accumulated During the Development
    Stage                                         (102,341)        (149,194)        (199,171)        (199,171)        (199,171)
Total Stockholders' Equity (Deficit)             $  12,447        $  22,855        $ (26,622)       $  23,012        $  49,012
</TABLE>



                             QUARTERLY FINANCAL DATA
                       IN THOUSANDS, EXCEPT PER SHARE DATA

<TABLE>
<CAPTION>
                                                                            THREE MONTHS ENDED
                                                               ----------------------------------------------------
                                                                   MARCH 31,       JUNE 30,       SEPTEMBER 30,
                                                                     1997            1997            1997
                                                               ----------------------------------------------------
<S>                                                               <C>             <C>             <C>     
Revenues                                                          $  1,059        $  1,415        $    668
Operating Expenses                                                 (15,077)        (18,941)        (19,102)
Net Loss                                                           (14,018)        (17,525)        (18,434)
Basic and Diluted Loss per Share (3)                                 (2.78)          (3.47)          (3.65)
Cash, Cash Equivalents and Short-Term Investments(4)                 2,490          28,648          14,792
Total Assets                                                        30,967          61,309          46,603
Total Current Liabilities                                           12,302           9,571          19,668
Long-Term Debt and Capital Lease Obligation, Net of Current          9,500          10,020           3,557
Portion
9% Convertible Subordinated Notes Payable                             --            50,000          50,000
Total Stockholders' Equity (Deficit)                                 9,165          (8,281)        (26,622)
</TABLE>


                                      -18-
<PAGE>

(1)  Pro forma to give  effect to the  exchange  of $50.0  million in  principal
     amount of the Notes and  $2,250,000  of accrued  interest  thereon  for the
     Alternative  Series A Preferred  Stock and the  writeoff of  $2,616,000  of
     deferred  financing  costs to additional  paid in capital.  There can be no
     assurance  that  $50.0  million  in  principal  amount of the Notes will be
     exchanged.  Such pro forma  adjustments  do not  reflect  the impact of the
     issuance of additional  shares of the Alternative  Series A Preferred Stock
     or  the  issuance  of  Hybridon  Common  Stock  in the  Alternative  Equity
     Offering.

(2)  Pro forma as adjusted to give  effect to the  exchange of $50.0  million in
     principal  amount of the Notes and $2,250,000 of accrued  interest  thereon
     for the Alternative Series A Preferred Stock, the writeoff of $2,616,000 of
     deferred  financing  costs to additional  paid in capital,  the issuance of
     $10.9 million of the Alternative  Series A Preferred Stock in the Preferred
     Stock Offering,  before estimated  issuance costs of $1.3 million,  and the
     issuance of $20.0 million of Hybridon  Common Stock,  before issuance costs
     of $3.6 million.  Approximately $900,000 of the estimated issuance costs on
     the  Alternative  Series A Preferred  Stock will be  reinvested to purchase
     additional shares of the Alternative Series A Preferred Stock. There can be
     no assurance  that $50.0  million in principal  amount of the Notes will be
     exchanged and $10.9 million of the Alternative Series A Preferred Stock and
     the  $20.0  million  of  Hybridon  Common  Stock  will  be  issued  in  the
     Alternative Equity Offering.

(3)  Basic  and  diluted  loss  per  share  is  computed  by  dividing  net loss
     applicable to common stockholders (net loss plus cumulative preferred stock
     dividends)  by the  weighted-average  number of common  shares  outstanding
     during  the  period.  Diluted  loss per share is the same as basic loss per
     share  since  the  effect  of  convertible   securities  and  common  stock
     equivalents  would be  antidilutive.  For purposes of  calculating  the Pro
     Forma As Adjusted net loss per share, the shares used in the loss per share
     calculation  assumes an offering  price of $2.00 per share for the Hybridon
     Common Stock to be issued in the Common Stock  Offering.  In addition,  the
     shares  are  weighted  for the nine  month  period  assuming  the  issuance
     occurred on April 1, 1997.

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


                     This Amendment is dated March 30, 1998


                                      -19-
<PAGE>

ANNEXES TO AMENDMENT TO THE OFFER TO EXCHANGE

Annex A Form of Certificate of Designation of the Alternative Series A Preferred
        Stock of Hybridon

Annex B Form of Warrant Agreement for the Alternative Exchange Warrants**

Annex C Current Report on Form 8-K, dated February 9, 1998, of Hybridon

- -----------------
**  Form of Warrant Certificate is attached as Exhibit A thereto.


                                      -20-

                                                                         ANNEX A
Revised
Structure
                           CERTIFICATE OF DESIGNATION

                                       for

                      SERIES A CONVERTIBLE PREFERRED STOCK

                                       of

                                  HYBRIDON INC.

                         Pursuant to Section 151 of the
                General Corporation Law of the State of Delaware


          HYBRIDON INC., a corporation  organized and existing under the laws of
the State of Delaware (the "Corporation"),  does hereby certify that pursuant to
the authority conferred on the board of directors of the Corporation (the "Board
of Directors") by the Restated Certificate of Incorporation (the "Certificate of
Incorporation")  of the  Corporation  and in accordance  with Section 151 of the
General Corporation Law of the State of Delaware, the Board of Directors adopted
the  following  resolution  establishing  a  series  of  __________/1/ shares of
preferred stock of the Corporation designated as "Series A Convertible Preferred
Stock":

          RESOLVED,  that  pursuant to the  authority  conferred on the Board of
     Directors by the Certificate of Incorporation, a series of preferred stock,
     par value $.01 per share,  of the  Corporation  is hereby  established  and
     created,  and that the  designation  and number of shares  thereof  and the
     voting and other powers,  preferences and relative participating,  optional
     or  other   special   rights  of,  the  shares  of  such   series  and  the
     qualifications, limitations and restrictions thereof are as follows:

                      Series A Convertible Preferred Stock


         1. Designation and Amount and Definitions.  (a) There shall be a series
of Preferred Stock designated as "Series A Convertible  Preferred Stock" and the
number of shares  constituting such series shall be ___________/1/.  Such series
is referred to herein as the "Series A  Preferred  Stock".  Notwithstanding  any
other  provision in this  Certificate  of  Designation of the Series A Preferred
Stock (the  "Certificate of Designation") to the contrary,  such series shall be
senior to the common stock,  par value $.001 per share of the  Corporation  (the
"Common  Stock") with respect to dividends and the  distribution  of assets upon
liquidation, dissolution or

- -------- 

/1/ To include both 9% Note exchange and private placement of Series A Preferred
Stock. Will include additional shares for PIK dividends.

<PAGE>

winding up. Such number of shares may be increased or decreased by resolution of
the Board of Directors, subject to the provisions of Section 7 hereof; provided,
however,  that no  decrease  shall  reduce  the  number  of  shares  of Series A
Preferred Stock to fewer than the number of shares then issued and outstanding.

          (b) As used in this  Certificate of  Designation,  except as otherwise
provided in  Subsection  4(c),  the  following  terms  shall have the  following
meanings:

               (i) The "Closing Bid Price" for any security for each trading day
          shall be the  reported  per share  closing bid price of such  security
          regular way on the Stock Market on such trading day, or, if there were
          no  transactions  on such  trading  day,  the average of the  reported
          closing bid and asked  prices,  regular  way, of such  security on the
          relevant Stock Market on such trading day.

               (ii) "Fair Market  Value" of any asset  (including  any security)
          means the fair  market  value  thereof as mutually  determined  by the
          Corporation  and the  holders of a majority  of the Series A Preferred
          Stock  then  outstanding.  If the  Corporation  and the  holders  of a
          majority of the Series A Preferred  Stock then  outstanding are unable
          to reach  agreement on any valuation  matter,  such valuation shall be
          submitted to and  determined  by a nationally  recognized  independent
          investment  bank selected by the Board of Directors and the holders of
          a majority of the Series A Preferred  Stock then  outstanding  (or, if
          such selection cannot be agreed upon promptly,  or in any event within
          ten days, then such valuation shall be made by a nationally recognized
          independent   investment   banking  firm   selected  by  the  American
          Arbitration  Association  in New  York  City in  accordance  with  its
          rules),  the  costs  of  which  valuation  shall  be  paid  for by the
          Corporation.

               (iii) "Market Price" shall mean the average Closing Bid Price for
          twenty  (20)  consecutive  trading  days,  ending with the trading day
          prior to the date as of which  the  Market  Price is being  determined
          (with  appropriate  adjustments  for  subdivisions  or combinations of
          shares  effected  during  such  period),  provided  that if the prices
          referred  to  in  the  definition  of  Closing  Bid  Price  cannot  be
          determined  on any trading day, the Closing Bid Price for such trading
          day will be deemed to equal Fair Market Value of such security on such
          trading day.

               (iv) "Registered Holders" shall mean, at any time, the holders of
          record of the Series A Preferred Stock.

               (v) The "Stock Market" shall mean,  with respect to any security,
          the principal national  securities  exchange on which such security is
          listed or admitted  to trading  or, if such  security is not listed or
          admitted to trading on any national  securities  exchange,  shall mean
          The Nasdaq  National  Market  System  ("NNM")  or The Nasdaq  SmallCap
          Market ("SCM" and,  together with NNM,  "Nasdaq") or, if such security
          is not quoted on Nasdaq, shall mean the OTC Bulletin Board or, if such
          security is not quoted on the OTC Bulletin Board, shall mean the over-


                                      -2-
<PAGE>

          the-counter  market as furnished by any NASD member firm selected from
          time to time by the Corporation for that purpose.

               (vi) A "trading day" shall mean a day on which the relevant Stock
          Market is open for the transaction of business.

          2. Dividends and  Distributions.  (a) The holders,  as of the Dividend
Record  Date (as  defined  below),  of the  Series A  Preferred  Stock  shall be
entitled to receive semi-annual dividends on their respective shares of Series A
Preferred Stock (aggregating, for this purpose, all shares of Series A Preferred
Stock held of record or, to the  Corporation's  knowledge,  beneficially by such
holder), payable, at the option of the Corporation, in cash or additional shares
of Series A  Preferred  Stock,  at the rate of 6.5% per annum  (computed  on the
basis of a 360-day year of twelve 30 day months) of the Dividend Base Amount (as
defined below),  payable semi-annually in arrears;  provided that, to the extent
the  declaration  or payment of such dividend is  prohibited by applicable  law,
such dividend need not be paid but shall  nevertheless  accrue and shall be paid
promptly when applicable law permits.  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 or, if any such day is not a business day, on the next succeeding
business day. Such dividends shall be paid, at the election of the  Corporation,
either in cash or  additional  duly  authorized,  fully paid and non  assessable
shares of Series A  Preferred  Stock.  In  calculating  the  number of shares of
Series A Preferred Stock to be paid with respect to each dividend,  the Series A
Preferred  Stock  shall be valued at $100.00 per share  (subject to  appropriate
adjustment  to  reflect  any  stock  split,  combination,   reclassification  or
reorganization of the Series A Preferred Stock).  Notwithstanding the foregoing,
the  Corporation  shall not be required to issue  fractional  shares of Series A
Preferred   Stock;   the  Corporation   may  elect,  in  its  sole   discretion,
independently  for each holder,  whether such number of shares (on an aggregated
basis)  will be rounded to the nearest  whole share (with .5 of a share  rounded
upward)  or whether  such  holder  will be given cash in lieu of any  fractional
shares.  The "Dividend Base Amount" of a share of Series A Preferred Stock shall
be  $100.00  plus all  accrued  but unpaid  dividends  (subject  to  appropriate
adjustment  to  reflect  any  stock  split,  combination,   reclassification  or
reorganization  of the Series A Preferred  Stock).  The  "Dividend  Record Date"
shall mean, for each semi-annual dividend,  the March 15 or September 15, as the
case may be, immediately preceding the dividend payment date.

          (b) In addition to the foregoing, subject to the rights of the holders
of any  shares of any  series  or class of  capital  stock  ranking  prior,  and
superior  to, or pari passu with,  the shares of Series A  Preferred  Stock with
respect to dividends, the holders of shares of Series A Preferred Stock shall be
entitled to receive, as, when and if declared by the Board of Directors,  out of
assets legally  available for that purpose,  dividends or distributions in cash,
stock or otherwise.

          (c) The Corporation  shall not declare any dividend or distribution on
any Junior  Stock (as defined  below) of the  Corporation  unless all  dividends
required by Section 2(a) have been or  contemporaneously  are declared and paid,
or declared  and a sum  sufficient  for the  payment  thereof set apart for such
payment, on the Series A Preferred Stock.


                                      -3-
<PAGE>

          (d) [Reserved]

          (e)  All  dividends  or  distributions  declared  upon  the  Series  A
Preferred Stock shall be declared pro rata per share.

          (f) Any reference to "distribution"  contained in this Section 2 shall
not be deemed to include any distribution  made in connection with or in lieu of
any Liquidation Event (as defined below).

          (g) No interest, or sum of money in lieu of interest, shall be payable
in respect of any dividend  payment or payments on the Series A Preferred  Stock
which may be in arrears (it being  understood that this provision does not alter
the Corporation's obligations under Section 2(a)).

          (h) So  long  as any  shares  of the  Series  A  Preferred  Stock  are
outstanding,  no dividends, except as described in the next succeeding sentence,
shall be  declared  or paid or set apart for  payment  on any class or series of
stock of the Corporation ranking, as to dividends, on a parity with the Series A
Preferred   Stock,   for  any  period   unless  all   dividends   have  been  or
contemporaneously  are declared and paid, or declared and a sum  sufficient  for
the payment thereof set apart for such payment, on the Series A Preferred Stock.
When  dividends are not paid in full or a sum sufficient for such payment is not
set apart, as aforesaid, upon the shares of the Series A Preferred Stock and any
other  class or series of stock  ranking  on a parity as to  dividends  with the
Series A Preferred Stock, all dividends  declared upon such other stock shall be
declared  pro rata so that the amounts of  dividends  per share  declared on the
Series A  Preferred  Stock and such other  stock shall in all cases bear to each
other the same  ratio  that  accrued  dividends  per share on the  shares of the
Series A Preferred Stock and on such other stock bear to each other.

          (i) So  long  as any  shares  of the  Series  A  Preferred  Stock  are
outstanding,  no other  stock of the  Corporation  ranking on a parity  with the
Series A Preferred  Stock as to dividends or upon  liquidation,  dissolution  or
winding  up  shall  be  redeemed,   purchased  or  otherwise  acquired  for  any
consideration  (or any moneys be paid to or made available for a sinking fund or
otherwise for the purchase or redemption of any shares of any such stock) by the
Corporation  unless the dividends,  if any, accrued on all outstanding shares of
the Series A Preferred Stock shall have been paid or set apart for payment.

          (j)  "Junior  Stock"  shall  mean the  Common  Stock and any shares of
preferred  stock of any series or class of the  Corporation,  whether  presently
outstanding  or  hereafter  issued,  which are  junior to the shares of Series A
Preferred Stock with respect to (i) the  distribution of assets on any voluntary
or involuntary liquidation,  dissolution or winding up of the Corporation,  (ii)
dividends or (iii) voting.

          3.  Liquidation  Preference.  (a) In the  event of a (i)  liquidation,
dissolution or winding up of the Corporation,  whether voluntary or involuntary,
(ii) a sale or other  disposition of all or  substantially  all of the assets of
the Corporation or (iii) any consolidation, merger, combination,  reorganization
or other transaction in which the Corporation is not the


                                      -4-
<PAGE>

surviving entity or shares of Common Stock  constituting in excess of 50% of the
voting  power of the  Corporation  are  exchanged  for or changed  into stock or
securities  of  another  entity,  cash  and/or  any other  property  (a  "Merger
Transaction")  (items (i),  (ii) and (iii) of this sentence  being  collectively
referred to as a "Liquidation Event"), after payment or provision for payment of
debts and other  liabilities  of the  Corporation,  the  holders of the Series A
Preferred Stock then outstanding  shall be entitled to be paid out of the assets
of the Corporation available for distribution to its stockholders,  whether such
assets are capital,  surplus, or earnings, before any payment or declaration and
setting  apart for payment of any amount  shall be made in respect of any Junior
Stock of the  Corporation,  an amount equal to the Dividend  Base Amount at such
time; provided,  however, in the case of a Merger Transaction,  such payment may
be made in cash,  property  (valued  as  provided  in  Subsection  3(b))  and/or
securities  (valued as provided in Subsection 3(b)) of the entity surviving such
Merger  Transaction.  In the  case of  property  or in the  event  that any such
securities are subject to an investment  letter or other similar  restriction on
transferability, the value of such property or securities shall be determined by
agreement  between the Corporation and the holders of a majority of the Series A
Preferred  Stock  then  outstanding.  If upon  any  Liquidation  Event,  whether
voluntary or  involuntary,  the assets to be  distributed  to the holders of the
Series A  Preferred  Stock shall be  insufficient  to permit the payment to such
shareholders of the full preferential amounts aforesaid,  then all of the assets
of the  Corporation  to be distributed  shall be so  distributed  ratably to the
holders of the Series A Preferred  Stock on the basis of the number of shares of
Series A Preferred Stock held.  Notwithstanding item (iii) of the first sentence
of this Subsection 3(a), any consolidation, merger, combination,  reorganization
or other  transaction in which the  Corporation is not the surviving  entity but
the stockholders of the Corporation immediately prior to such transaction own in
excess of 50% of the voting power of the corporation  surviving such transaction
and own amongst  themselves such interest in substantially  the same proportions
as prior to such  transaction,  shall  not be  considered  a  Liquidation  Event
provided that the surviving  corporation  shall make  appropriate  provisions to
ensure  that the  terms of this  Certificate  of  Designation  survive  any such
transaction.  All shares of Series A  Preferred  Stock  shall rank as to payment
upon the  occurrence  of any  Liquidation  Event senior to the Common Stock and,
unless the terms of such series  shall  provide  otherwise,  senior to all other
series of the Corporation's preferred stock.

          (b) Any securities or other property to be delivered to the holders of
the Series A Preferred  Stock pursuant to Subsection 3(a) hereof shall be valued
as follows:

               (i)  Securities  not  subject  to an  investment  letter or other
          similar restriction on free marketability:

                    (A) If  actively  traded  on a Stock  Market,  the per share
               value shall be deemed to be the Market  Price of such  securities
               as of the third day prior to the date of valuation.

                    (B) If not  actively  traded  on a Stock  Market,  the value
               shall be the Fair Market Value of such securities.


                                      -5-
<PAGE>

               (ii) For  securities  for which there is an active  public market
          but which are subject to an investment letter or other restrictions on
          free marketability,  the value shall be the Fair Market Value thereof,
          determined  by  discounting  appropriately  the per share Market Price
          thereof.

               (iii)  For all  other  securities,  the  value  shall be the Fair
          Market Value thereof.

          4. Conversion.

          (a) Right of Conversion.  Commencing after the expiration of 12 months
following the Alternative Equity Closing Date (as hereinafter defined),  but not
prior thereto,  the shares of Series A Preferred Stock shall be convertible,  in
whole or in part,  at the option of the holder  thereof  and upon  notice to the
Corporation as set forth in Subsection  4(b), into fully paid and  nonassessable
shares of Common Stock and such other  securities  and  property as  hereinafter
provided.   The  initial  conversion  price  per  share  of  Common  Stock  (the
"Conversion  Price"),  shall be equal to the product of 2.125  multiplied by the
per  share  price  (the  "Stated  Common  Price")  of Common  Stock  sold by the
Corporation in connection with the Alternative  Equity Offering (as such term is
defined in the  Corporation's  Offer to  Exchange  dated  February  6, 1998 (the
"Original  Offer  to  Exchange"),  as  amended  by the  Amendment  thereto  (the
"Amendment") dated March 30, 1998  (collectively,  the "Offer to Exchange")) and
shall be subject to adjustment as provided herein.  The rate at which each share
Series A  Preferred  Stock is  convertible  at any time into  Common  Stock (the
"Conversion Rate") shall be determined by dividing the then existing  Conversion
Price  (determined  in  accordance  with  this  Section  4,  including  the last
paragraph hereof) into the Dividend Base Amount.

          The Corporation shall prepare a certificate  signed by the Chairman or
President, and by the Treasurer or an Assistant Treasurer or the Secretary or an
Assistant Secretary,  of the Corporation setting forth the Conversion Rate as of
the date of the closing of the  Alternative  Equity  Offering (the  "Alternative
Equity Closing  Date"),  showing in reasonable  detail the facts upon which such
Conversion Rate is based, and such certificate shall forthwith be filed with the
transfer agent of the Series A Preferred Stock.

          (b) Conversion Procedures.  Any holder of shares of Series A Preferred
Stock  desiring to convert  such shares into Common  Stock shall  surrender  the
certificate or  certificates  evidencing such shares of Series A Preferred Stock
at the office of the  transfer  agent for the Series A  Preferred  Stock,  which
certificate or certificates,  if the Corporation shall so require, shall be duly
endorsed to the Corporation or in blank, or accompanied by proper instruments of
transfer to the  Corporation or in blank,  accompanied  by  irrevocable  written
notice to the  Corporation  that the holder  elects so to convert such shares of
Series A Preferred  Stock and  specifying  the name or names  (with  address) in
which a certificate or certificates  evidencing shares of Common Stock are to be
issued.  The  Corporation  need not deem a notice of  conversion  to be received
unless the holder complies with all the provisions  hereof. The Corporation will
instruct the transfer agent (which may be the Corporation) to make a notation of
the date that a notice of conversion is received, which date of receipt shall be
deemed to be the date of receipt for purposes hereof.


                                      -6-
<PAGE>

          The Corporation  shall,  as soon as practicable  after such deposit of
certificates  evidencing  shares of Series A Preferred Stock  accompanied by the
written  notice  and  compliance  with any other  conditions  herein  contained,
deliver at such office of such  transfer  agent to the person for whose  account
such shares of Series A Preferred Stock were so  surrendered,  or to the nominee
or nominees of such person, certificates evidencing the number of full shares of
Common  Stock to which such person  shall be entitled as  aforesaid,  subject to
Section  4(d).  Subject to the  following  provisions  of this  paragraph,  such
conversion shall be deemed to have been made as of the date of such surrender of
the  shares of  Series A  Preferred  Stock to be  converted,  and the  person or
persons entitled to receive the Common Stock deliverable upon conversion of such
Series A Preferred  Stock shall be treated for all purposes as the record holder
or  holders  of such  Common  Stock on such date;  provided,  however,  that the
Corporation  shall not be  required  to convert any shares of Series A Preferred
Stock  while the stock  transfer  books of the  Corporation  are  closed for any
purpose, but the surrender of Series A Preferred Stock for conversion during any
period  while such books are so closed  shall become  effective  for  conversion
immediately  upon the  reopening of such books as if the surrender had been made
on the date of such  reopening,  and the  conversion  shall be at the conversion
rate in effect on such date.  No  adjustments  in respect  of any  dividends  on
shares  surrendered  for  conversion  or any dividend on the Common Stock issued
upon  conversion  shall be made upon the  conversion  of any  shares of Series A
Preferred Stock.

          The Corporation shall at all times,  reserve and keep available out of
its  authorized but unissued  shares of Common Stock,  solely for the purpose of
effecting the conversion of the shares of Series A Preferred Stock,  such number
of shares of Common Stock as shall from time to time be sufficient to effect the
conversion of all outstanding shares of the Series A Preferred Stock.

          All notices of conversion  shall be  irrevocable;  provided,  however,
that if the  Corporation has sent notice of an event pursuant to Subsection 4(g)
hereof,  a holder of Series A Preferred  Stock may, at its election,  provide in
its notice of conversion that the conversion of its shares of Series A Preferred
Stock  shall  be  contingent   upon  the   occurrence  of  the  record  date  or
effectiveness  of such event (as specified by such  holder),  provided that such
notice of conversion is received by the Corporation prior to such record date or
effective date, as the case may be.

          (c) Adjustment of Conversion Rate and Conversion Price.

               (i) As used in this  Subsection  4(c), the following  terms shall
          have the following meanings:

               "Capital Stock" of any Person means the Common Stock or Preferred
          Stock of such Person.  Unless  otherwise  stated herein or the context
          otherwise  requires,  "Capital  Stock"  means  Capital  Stock  of  the
          Corporation;

               "Common Stock" of any Person other than the Corporation means the
          common equity (however  designated),  including,  without  limitation,
          common  stock  or   partnership   or   membership   interests  of,  or
          participation or interests in


                                      -7-
<PAGE>

          such  Person  (or   equivalents   thereof).   "Common  Stock"  of  the
          Corporation  means the Common Stock, par value $.001 per share, of the
          Corporation,  any successor class or classes of common equity (however
          designated) of the Corporation into or for which such Common Stock may
          hereafter be  converted,  exchanged or  reclassified  and any class or
          classes of common equity (however designated) of the Corporation which
          may be  distributed  or issued with  respect to such  Common  Stock or
          successor  class of  classes  to  holders  thereof  generally.  Unless
          otherwise  stated herein or the context  requires  otherwise,  "Common
          Stock" means Common Stock of the Corporation;

               "Current  Market  Price"  means,  when used with  respect  to any
          security as of any date, the last sale price, regular way, or, in case
          no such sale takes place on such date,  the average of the closing bid
          and asked  prices,  regular  way,  of such  security in either case as
          reported for consolidated  transactions on the New York Stock Exchange
          or, if such  security  is not listed or admitted to trading on the New
          York Stock Exchange,  as reported for consolidated  transactions  with
          respect to  securities  listed on the  principal  national  securities
          exchange  on which such  security is listed or admitted to trading or,
          if such  security is not listed or admitted to trading on any national
          securities exchange, as reported on the Nasdaq National Market, or, if
          such  security  is not  listed or  admitted  to  trading on the Nasdaq
          National Market, as reported on the Nasdaq SmallCap Market, or if such
          security  is not  listed  or  admitted  to  trading  on  any  national
          securities  exchange  or the  Nasdaq  National  Market  or the  Nasdaq
          SmallCap  Market,  the average of the high bid and low asked prices of
          such  security  in the  over-the-counter  market,  as  reported by the
          National Association of Securities Dealers,  Inc. Automated Quotations
          System or such other  system  then in use or, if such  security is not
          quoted by any such  organization,  the  average of the closing bid and
          asked  prices  of  such  security  furnished  by an NASD  member  firm
          selected  by the  Corporation.  If such  security is not quoted by any
          such organization and no such NASD member firm is able to provide such
          prices,  the Current  Market Price of such security  shall be the Fair
          Market Value thereof;

               "Fair Market Value" means, at any date as to any asset,  Property
          or right (including without  limitation,  Capital Stock of any Person,
          evidence of indebtedness or other securities, but excluding cash), the
          fair  market  value of such item as  determined  in good  faith by the
          Board of Directors, whose determination shall be conclusive; provided,
          however,   that  such  determination  is  described  in  an  Officers'
          Certificate  filed  with the  transfer  agent and that,  if there is a
          Current  Market Price for such item on such date,  "Fair Market Value"
          means such Current  Market Price  (without  giving  effect to the last
          sentence of the definition thereof);

               "GAAP"  means,  as of any  date,  generally  accepted  accounting
          principles   in  the   United   States  and  does  not   include   any
          interpretations  or regulations  that have been proposed but that have
          not become effective;


                                      -8-
<PAGE>

               "Officer" means, with respect to any Person,  the Chairman of the
          Board, the Chief Executive Officer, the President, the Chief Operating
          Officer,  the Chief Financial  Officer,  the Treasurer,  any Assistant
          Treasurer,  the Controller,  the Secretary, any Assistant Secretary or
          any Vice President of such Person;

               "Officers'  Certificate"  means a certificate signed on behalf of
          the  Corporation by two Officers,  one of whom must be the Chairman of
          the Board,  the President,  the Treasurer or a  Vice-President  of the
          Corporation;

               "Person"   means  any   individual,   corporation,   partnership,
          association,  trust or any other entity or  organization,  including a
          government or political  subdivision or any agency or  instrumentality
          thereof;

               "Preferred  Stock" of any  Person  means the class or  classes of
          equity,  ownership or participation  interests (however designated) in
          such Person, including, without limitation,  stock, share, partnership
          and  membership  interests,  which are  preferred as to the payment of
          dividends or  distributions  by, or as to the  distribution  of assets
          upon any voluntary or involuntary  liquidation or dissolution of, such
          Person (or  equivalent  thereof) over  interests of any other class of
          interests  of such  Person.  Unless  otherwise  stated  herein  or the
          context otherwise requires, "Preferred Stock" means Preferred Stock of
          the Corporation;

               "Property"  of any  Person  means  any and  all  types  of  real,
          personal, tangible,  intangible or mixed property owned by such Person
          whether or not included on the most recent consolidated  balance sheet
          of such Person in accordance with GAAP;

               "Subsidiary"  of a Person on any date  means any other  Person of
          whom such Person owns,  directly or indirectly through a Subsidiary or
          Subsidiaries of such Person,  Capital Stock with voting power,  acting
          independently and under ordinary circumstances,  entitling such person
          to elect a majority of the board of directors or other  governing body
          of such other Person.  Unless  otherwise  stated herein or the context
          otherwise   requires,   "Subsidiary"   means  a   Subsidiary   of  the
          Corporation.

               (ii)  If the  Corporation  shall  (i)  pay a  dividend  or  other
          distribution,  in Common  Stock,  on any class of Capital Stock of the
          Corporation,  (ii)  subdivide  the  outstanding  Common  Stock  into a
          greater number of shares by any means or (iii) combine the outstanding
          Common Stock into a smaller  number of shares by any means  including,
          without limitation, a reverse stock split), then in each such case the
          Conversion Price in effect immediately prior thereto shall be adjusted
          so that the  Registered  Holder of any  shares  of Series A  Preferred
          Stock  thereafter  surrendered  for  conversion  shall be  entitled to
          receive  the  number of shares of Common  Stock  that such  Registered
          Holder  would have  owned or have been  entitled  to receive  upon the
          happening  of such  event  had such  Series  A  Preferred  Stock  been
          converted  immediately  prior to the relevant record date or, if there
          is


                                      -9-
<PAGE>

          no such record date, the effective  date of such event.  An adjustment
          made  pursuant  to this  Paragraph  4(c)(ii)  shall  become  effective
          immediately   after  the  record   date  for  the   determination   of
          stockholders  entitled to receive such  dividend or  distribution  and
          shall become  effective  immediately  after the effective date of such
          subdivision or combination, as the case may be.

               (iii) If the  Corporation  shall  (i) issue or  distribute  (at a
          price per share less than the Current  Market  Price per share of such
          Capital  Stock on the date of such issuance or  distribution)  Capital
          Stock  generally to holders of Common Stock or to holders of any class
          or series of Capital Stock which is convertible  into or  exchangeable
          or exercisable for Common Stock (excluding an issuance or distribution
          of Common  Stock  described  in  Paragraph  4(c)(ii)) or (ii) issue or
          distribute  generally to such  holders  rights,  warrants,  options or
          convertible or exchangeable securities entitling the holder thereof to
          subscribe for, purchase, convert into or exchange for Capital Stock at
          a price per share less than the Current Market Price per share of such
          Capital Stock on the date of issuance or  distribution,  then, in each
          such case, at the earliest of (A) the date the Corporation enters into
          a firm contract for such issuance or distribution, (B) the record date
          for the  determination  of  stockholders  entitled to receive any such
          Capital Stock or any such rights, warrants,  options or convertible or
          exchangeable  securities  or  (C)  the  date  of  actual  issuance  or
          distribution  of any such Capital Stock or any such rights,  warrants,
          options or  convertible  or  exchangeable  securities,  the Conversion
          Price shall be reduced by multiplying  the Conversion  Price in effect
          immediately prior to such earliest date by:

                    (A) if such Capital  Stock is Common  Stock,  a fraction the
               numerator  of which is the  number  of  shares  of  Common  Stock
               outstanding,  on such  earliest date plus the number of shares of
               Common Stock which could be purchased at the Current Market Price
               per  share  of  Common  Stock  on the  date of such  issuance  or
               distribution with the aggregate  consideration (based on the Fair
               Market Value thereof)  received or receivable by the  Corporation
               either (A) in connection  with such issuance or  distribution  or
               (B) upon the  conversion,  exchange,  purchase or subscription of
               all such rights, warrants, options or convertible or exchangeable
               securities (the "Aggregate  Consideration"),  and the denominator
               of which is the number of shares of Common Stock  outstanding  on
               such  earliest  date plus the number of shares of Common Stock to
               be so issued or distributed or to be issued upon the  conversion,
               exchange,  purchase or subscription of all such rights, warrants,
               options or convertible or exchangeable securities; or

                    (B) if such  Capital  Stock is other than  Common  Stock,  a
               fraction the  numerator of which is the Current  Market Price per
               share of Common Stock on such earliest date minus an amount equal
               to (A) the  difference  between (1) the Current  Market Price per
               share of such Capital Stock multiplied by the number of shares of
               such Capital Stock to be so


                                      -10-
<PAGE>

               issued and (2) the  Aggregate  Consideration,  divided by (B) the
               number of shares of Common Stock  outstanding  on such date,  and
               the denominator of which is the Current Market Price per share of
               Common Stock on such earliest date.

          Such adjustment shall be made  successively  whenever any such Capital
          Stock,  rights,  warrants,  options  or  convertible  or  exchangeable
          securities are so issued or  distributed.  In determining  whether any
          rights,  warrants,  options or convertible or exchangeable  securities
          entitle the holders thereof to subscribe for,  purchase,  convert into
          or exchange for shares of such Capital Stock at less than such Current
          Market Price,  there shall be taken into account the Fair Market Value
          of any  consideration  received or receivable by the  Corporation  for
          such  rights,   warrants,   options  or  convertible  or  exchangeable
          securities.   If  any  right,   warrant,option   or   convertible   or
          exchangeable security, the issuance of which resulted in an adjustment
          in the Conversion  Price pursuant to this Paragraph  4(c)(iii),  shall
          expire and shall not have been exercised,  the Conversion  Price shall
          immediately upon such expiration be recomputed to the Conversion Price
          which  would  have been in effect if such  right,  warrant,  option or
          convertible or exchangeable  securities had never been  distributed or
          issued.  Notwithstanding  anything  contained in this paragraph to the
          contrary,  (i) the issuance of Capital Stock upon the exercise of such
          rights,  warrants  or options or the  conversion  or  exchange of such
          convertible or exchangeable securities will not cause an adjustment in
          the Conversion Price if no such adjustment would have been required at
          the time such right,  warrant,  option or convertible or  exchangeable
          security was issued or distributed;  provided,  however,  that, if the
          consideration  payable  upon such  exercise,  conversion  or  exchange
          and/or the Capital  Stock  receivable  thereupon are changed after the
          time of the issuance or distribution of such right, warrant, option or
          convertible or exchangeable  security then such change shall be deemed
          to be the  expiration  thereof  without  having been exercised and the
          issuance  or  distribution  of  new  options,   rights,   warrants  or
          convertible  or  exchangeable  securities  and  (ii) the  issuance  of
          convertible  preferred  stock  of the  Corporation  as a  dividend  on
          convertible  preferred  stock of the  Corporation  will  not  cause an
          adjustment in the Conversion  Price if no such  adjustment  would have
          been required at the time such underlying  convertible preferred stock
          was issued (or as a result of any subsequent modification to the terms
          thereof) and the conversion  provisions of such  convertible  stock so
          issued as a dividend  are the same as in such  underlying  convertible
          preferred stock.

               Notwithstanding  any contained in this Certificate of Designation
          to the contrary,  options, rights or warrants issued or distributed by
          the Corporation,  including  options,  rights or warrants  distributed
          prior to the date of filing of this  Certificate  of  Designation,  to
          holders of Common Stock  generally  which,  until the  occurrence of a
          specified  event or events (a "Trigger  Event"),  (i) are deemed to be
          transferred with Common Stock,  (ii) are not exercisable and (iii) are
          also issued on a pro rata basis with  respect to future  issuances  of
          Common Stock,  shall be deemed not to have been issued or  distributed
          for purposes of this


                                      -11-
<PAGE>

          Subsection 4(c) (and no adjustment to the Conversion  Price under this
          Subsection 4(c) will be required) until the occurrence of the earliest
          Trigger Event.  Upon the occurrence of a Trigger Event,  such options,
          rights or warrants shall continue to be deemed not to have been issued
          or distributed for purposes of this Subsection 4(c) (and no adjustment
          to the Conversion  Price under this  Subsection 4(c) will be required)
          if and for so long as each Registered  Holder who thereafter  converts
          such Registered Holder's Series A Preferred Stock shall be entitled to
          receive  upon such  conversion,  in  addition  to the shares of Common
          Stock issuable upon such conversion,  a number of such options, rights
          or  warrants,  as the case may be,  equal to the  number  of  options,
          rights or warrants to which a holder of the number of shares of Common
          Stock  equal to the  number of shares of Common  Stock  issuable  upon
          conversion of such  Registered  Holder's  Series A Preferred  Stock is
          entitled to receive at the time of such  conversion in accordance with
          the terms and provisions  of, and applicable to, such options,  rights
          or  warrants.  Upon the  expiration  of any such  options,  rights  or
          warrants  or at such  time,  if any,  as a  Registered  Holder  is not
          entitled to receive such options,  rights or warrants upon  conversion
          of such Registered  Holder's  Series A Preferred  Stock, an adjustment
          (if  any is  required)  to the  Conversion  Price  shall  be  made  in
          accordance with this Paragraph  4(c)(iii) with respect to the issuance
          of all such  options,  rights and  warrants as of the date of issuance
          thereof, but subject to the provisions of the preceding paragraph,  if
          any such option, right or warrant, including any such options right or
          warrants  distributed  prior to the date of filing of this Certificate
          of  Designation,  are subject to events,  upon the occurrence of which
          such  options,  rights or  warrants  become  exercisable  to  purchase
          different  securities,  evidence of indebtedness,  cash, Properties or
          other  assets or  different  amounts  thereof,  then,  subject  to the
          preceding  provision of this paragraph,  the date of the occurrence of
          any and each such event shall be deemed to be the date of distribution
          and record date with  respect to new options,  right or warrants  with
          such new  purchase  rights (and a  termination  or  expiration  of the
          existing  options,  rights or warrants without exercise  thereof).  In
          addition, in the event of any distribution (or deemed distribution) of
          options,  rights or warrants,  or any Trigger  Event or other event of
          the type described in the preceding sentence,  that required (or would
          have  required but for the  provisions  of Paragraph  4(c)(vi) or this
          paragraph) an adjustment to the Conversion Price under this Subsection
          4(c) and such options,  rights or warrants shall  thereafter have been
          redeemed  or  repurchased  without  having  been  exercised,  then the
          Conversion  Price shall be adjusted upon such redemption or repurchase
          to give effect to such distribution,  Trigger Event or other event, as
          the case may, as though it had instead been a cash distribution, equal
          on a per share  basis to the  result of the  aggregate  redemption  or
          repurchase  price  received  by  holders  of such  options,  rights or
          warrants  divided by the number of shares of Common Stock  outstanding
          as of the date of such  repurchase or  redemption,  made to holders of
          Common  Stock   generally  as  of  the  date  of  such  redemption  or
          repurchase.

               (iv) If the Corporation shall pay or distribute, as a dividend or
          otherwise, generally to holders of Common Stock or any class or series
          of Capital


                                      -12-
<PAGE>

          Stock which is convertible  into or exercisable  or  exchangeable  for
          Common  Stock any assets,  Properties  or rights  (including,  without
          limitation,   evidences  of  indebtedness  of  the  Corporation,   any
          Subsidiary  or any  other  Person,  cash or  Capital  Stock  or  other
          securities of the Corporation, any Subsidiary or any other Person, but
          excluding  payments  and  distributions  as  described  in  Paragraphs
          4(c)(ii) or (iii),  dividends and  distributions  in connection with a
          Liquidation  Event  and   distributions   consisting  solely  of  cash
          described in Paragraph 4(c)(v)), then in each such case the Conversion
          Price shall be reduced by multiplying  the Conversion  Price in effect
          immediately  prior to the date of such  payment or  distribution  by a
          fraction, the numerator of which is the Current Market Price per share
          of  Common  Stock  on  the  record  date  for  the   determination  of
          stockholders entitled to receive such payment or distribution less the
          Fair Market Value per share of Common Stock on such record date of the
          assets,  Properties  or  rights  so  paid  or  distributed,   and  the
          denominator  of which is the Current  Market Price per share of Common
          Stock on such record date.  Such  adjustment  shall  become  effective
          immediately  after such record date.  For  purposes of this  Paragraph
          4(c)(iv),  such Fair Market Value per share shall equal the  aggregate
          Fair Market  Value on such record  date of the assets,  Properties  or
          rights  so paid or  distributed  divided  by the  number  of shares of
          Common Stock outstanding on such record date. For all purposes of this
          Certificate of Designation,  adjustments to any security's  conversion
          or exercise price pursuant to such security's original terms shall not
          be deemed a distribution or dividend to holders thereof.

               (v) If the Corporation  shall,  by dividend or otherwise,  make a
          distribution   (other  than  in  connection   with  the   liquidation,
          dissolution  or  winding  up of  the  Corporation  in  its  entirety),
          generally to holders of Common Stock or any class or series of Capital
          Stock which is convertible  into or exercisable  or  exchangeable  for
          Common Stock,  consisting  solely of cash where (x) the sum of (i) the
          aggregate  amount for such cash plus (ii) the aggregate  amount of all
          cash so distributed  (by dividend or otherwise) to such holders within
          the  12-month  period  ending  on  the  record  date  for  determining
          stockholder  entitled to receive  such  distribution  with  respect to
          which no adjustment has been made to the Conversion  Price pursuant to
          this  Paragraph   4(c)(v)  exceeds  (y)  10%  of  the  result  of  the
          multiplication  of (1) the  Current  Market  Price per share of Common
          Stock on such  record  date  times (2) the  number of shares of Common
          Stock outstanding on such record date, then the Conversion Price shall
          be reduced,  effective immediately prior to the opening of business on
          the day following  such record date,  by  multiplying  the  Conversion
          Price in effect  immediately prior to the close of business on the day
          prior to such record date by a fraction, the numerator of which is the
          Current  Market  Price per share of Common  Stock on such  record date
          less the  aggregate  amount of cash per share so  distributed  and the
          denominator of which is such Current Market Price; provided,  however,
          that, if the aggregate amount of cash per share is equal to or greater
          than  such  Current  Market  Price,  then,  in lieu  of the  foregoing
          adjustment,  adequate provisions shall be made so that each Registered
          Holder shall have the right to receive upon  conversion  (with respect
          to each share of Common Stock issued upon such


                                      -13-
<PAGE>

          conversion   and  in  addition  to  the  Common  Stock  issuable  upon
          conversion)  the  aggregate  amount of cash per share such  Registered
          Holder  would have  received  had such  Registered  Holder's  Series A
          Preferred Stock been converted  immediately prior to such record date.
          In no event shall the Conversion  Price be increased  pursuant to this
          Paragraph 4(c)(v); provided, however, that if such distribution is not
          so made, the  Conversion  Price shall be adjusted to be the Conversion
          Price  which  would have been in effect if such  distribution  had not
          been declared.  For purposes of this Paragraph 4(c)(v), such aggregate
          amount of cash per share shall equal such sum divided by the number of
          shares of Common Stock outstanding on such record date.

               (vi) The provisions of this Subsection 4(c) shall similarly apply
          to all  successive  events of the type  described  in this  Subsection
          4(c).  Notwithstanding  anything contained herein to the contrary,  no
          adjustment  in the  Conversion  Price  shall be  required  unless such
          adjustment would require an increase or decrease of at least 1% in the
          Conversion  Price  then  in  effect;   provided,   however,  that  any
          adjustments  which  by  reason  of  this  Paragraph  4(c)(vi)  are not
          required to be made shall be carried forward and taken into account in
          any subsequent adjustment. All calculations under this Section 4 shall
          be made by the Corporation and shall be made to the nearest cent or to
          the  nearest  one  hundredth  of a share,  as the case may be, and the
          transfer agent shall be entitled to rely conclusively thereon.  Except
          as provided in this Section 4, no adjustment in the  Conversion  Price
          will be made  for the  issuance  of  Common  Stock  or any  securities
          convertible  into or  exchangeable  for Common  Stock or carrying  the
          right to purchase  Common Stock or any  securities so  convertible  or
          exchangeable.

               (vii)  Whenever  the  Conversion  Price is  adjusted  as provided
          herein, the Corporation shall promptly file with the transfer agent an
          Officers'  Certificate  setting forth the  Conversion  Price in effect
          after such adjustment and setting forth a brief statement of the facts
          requiring such  adjustment.  Promptly after delivery of such Officers'
          Certificate,  the Corporation  shall give or cause to be given to each
          Registered  Holder a notice of such adjustment of the Conversion Price
          setting forth the adjusted Conversion Price and the date on which such
          adjustment becomes effective.

               (viii) Notwithstanding anything contained herein to the contrary,
          in any case in which this  Subsection 4(c) provides that an adjustment
          in the Conversion  Price shall become  effective  immediately  after a
          record  date  for an  event,  the  Corporation  may  defer  until  the
          occurrence of such event (i) issuing to the  Registered  Holder of any
          Series A Preferred  Stock  converted after such record date and before
          the  occurrence  of such event the  additional  shares of Common Stock
          issuable upon such conversion by reason of the adjustment  required by
          such  event  over and  above the  number  of  shares  of Common  Stock
          issuable upon such conversion  before giving effect to such adjustment
          and (ii) paying to such  Registered  Holder any amount in cash in lieu
          of any fractional share of Common Stock pursuant to Subsection 4(d).


                                      -14-
<PAGE>

               (ix) Notwithstanding any other provision hereof, no adjustment to
          the  Conversion  Price shall be made upon the  issuance or exercise or
          conversion of (1) options or warrants to purchase,  in the  aggregate,
          up to 25% of the securities sold in the offerings of securities of the
          Corporation described in the Original Offer to Exchange or any options
          or warrants  described in the Amendment in respect of the  Alternative
          Equity  Offering,  in each case issued to (or to the  designee of) any
          placement  agent or financial  advisor (such options or warrants,  the
          "Offering  Warrants"),  (2) any equity  securities  or warrants of the
          Corporation  (including,  without  limitation,  the Series A Preferred
          Stock,  warrants and equity securities  underlying warrants) issued in
          exchange  for 9%  Convertible  Subordinated  Notes  due 2004  (the "9%
          Notes") of the Corporation or accrued  interest thereon or pursuant to
          the conversion or exercise provisions thereof, (3) any warrants issued
          in connection  with the offerings  described in the Original  Offer to
          Exchange or the  Amendment  (collectively,  the  "Offering"),  (4) any
          warrants  issued to Forum Capital  Markets,  LLC ("Forum") in exchange
          for or in  addition  to, or any  amendment  to, any  warrants  held by
          Forum, in each case,  pursuant to a letter  agreement dated January 5,
          1998,  between the  Corporation  and Forum,  and any other warrants to
          purchase Common Stock or shares of Common Stock issued to Forum or its
          designee, (5) any Series A Preferred Stock issued in the Offering, (6)
          any Capital  Stock  issued or cash paid as  dividends  on the Series A
          Preferred  Stock or (7) any Capital Stock issued or cash paid upon the
          mandatory  conversion or redemption of any Series A Preferred Stock in
          accordance with Section 5 of this Certificate of Designation.

          (d) No Fractional  Shares. No fractional shares or scrip  representing
fractional  shares of Common Stock shall be issued upon  conversion  of Series A
Preferred  Stock.  If more than one  certificate  evidencing  shares of Series A
Preferred  Stock shall be  surrendered  for  conversion  at one time by the same
holder,  the number of full shares  issuable  upon  conversion  thereof shall be
computed  on the basis of the  aggregate  number of shares of Series A Preferred
Stock so  surrendered.  Instead of any  fractional  share of Common  Stock which
would otherwise be issuable upon  conversion of such aggregate  number of shares
of Series A Preferred  Stock, the Corporation may elect, in its sole discretion,
independently  for each  holder,  whether  such number of shares of Common Stock
will be rounded to the nearest whole share (with a .5 of a share rounded upward)
or whether such holder will be given cash, in lieu of any fractional  share,  in
an amount equal to the same  fraction of the Market Price of the Common Stock as
of the close of business on the day of conversion.

          (e) [Reserved]

          (f) Reservation of Shares;  Transfer Taxes, Etc. The Corporation shall
at all times  reserve and keep  available,  out of its  authorized  and unissued
shares of Common Stock,  solely for the purpose of effecting  the  conversion of
the Series A Preferred Stock,  such number of shares of its Common Stock free of
preemptive  rights as shall be sufficient to effect the conversion of all shares
of Series A Preferred Stock from time to time outstanding. The Corporation shall
use its best efforts from time to time, in accordance with the laws of the State
of Delaware to increase  the  authorized  number of shares of Common Stock if at
any time the


                                      -15-
<PAGE>

number of shares of authorized,  unissued and unreserved  Common Stock shall not
be sufficient to permit the  conversion  of all the  then-outstanding  shares of
Series A Preferred Stock.

          The Corporation  shall pay any and all issue or other taxes (excluding
any income  taxes)  that may be payable in respect of any issue or  delivery  of
shares of Common  Stock on  conversion  of the  Series A  Preferred  Stock.  The
Corporation shall not, however,  be required to pay any tax which may be payable
in respect of any transfer involved in the issue or delivery of Common Stock (or
other  securities  or  assets)  in a name other than that in which the shares of
Series A Preferred  Stock so  converted  were  registered,  and no such issue or
delivery  shall be made  unless and until the person  requesting  such issue has
paid to the  Corporation  the  amount  of such  tax or has  established,  to the
satisfaction  of the  Corporation,  that  such tax has been  paid or need not be
paid.

          (g) Prior Notice of Certain Events. In case:

               (i) the  Corporation  shall  declare any  dividend  (or any other
          distribution); or

               (ii) the Corporation  shall authorize the granting to the holders
          of Common Stock of rights or warrants to subscribe for or purchase any
          shares of stock of any class or of any other rights or warrants; or

               (iii) of any  reclassification  of  Common  Stock  (other  than a
          subdivision  or  combination  of the  outstanding  Common Stock,  or a
          change in par value, or from par value to no par value, or from no par
          value to par value); or

               (iv) of any consolidation or merger to which the Corporation is a
          party and for which approval of any  stockholders  of the  Corporation
          shall be required,  or of the sale or transfer of all or substantially
          all of  the  assets  of the  Corporation  or of any  compulsory  share
          exchange whereby the Common Stock is converted into other  securities,
          cash or other property; or

               (v) of any Liquidation Event;

then the  Corporation  shall cause to be filed with the  transfer  agent for the
Series A  Preferred  Stock,  and  shall  cause to be  mailed  to the  Registered
Holders,  at their last  addresses as they shall appear upon the stock  transfer
books of the Corporation,  at least 20 days prior to the applicable  record date
hereinafter  specified, a notice stating (x) the date on which a record (if any)
is to be taken for the  purpose of such  dividend.  distribution  or granting of
rights or warrants or, if a record is not to be taken,  the date as of which the
holders of Common Stock of record to be entitled to such dividend, distribution,
rights  or  warrants  are  to be  determined  and a  description  of  the  cash,
securities or other  property to be received by such holders upon such dividend,
distribution  or  granting  of rights or  warrants or (y) the date on which such
reclassification,  consolidation,  merger,  sale,  transfer,  share  exchange or
Liquidation  Event is expected to become  effective,  the date as of which it is
expected  that  holders of Common  Stock of record shall be entitled to exchange
their shares of Common Stock for securities or other property deliverable


                                      -16-
<PAGE>

upon  such  exchange  or  Liquidation  Event  and the  consideration,  including
securities or other property, to be received by such holders upon such exchange;
provided,  however, that no failure to mail such notice or any defect therein or
in the  mailing  thereof  shall  affect the  validity  of the  corporate  action
required to be specified in such notice.

          (h) Other Changes in Conversion  Rate.  The  Corporation  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, the Corporation shall mail
to the  Registered  Holders a notice of the increase at least 15 days before the
date the increased Conversion Rate takes effect, and such notice shall state the
increased Conversion Rate and the period it will be in effect.

          The  Corporation  may make such increases in the  Conversion  Rate, in
addition to those  required or allowed by this Section 4, as shall be determined
by it, as evidenced by a resolution of the Board of  Directors,  to be advisable
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.

          Notwithstanding  anything to the contrary herein, in no case shall the
Conversion Price be adjusted to an amount less than $.001 per share, the current
par value of the  Common  Stock  into  which  the  Series A  Preferred  Stock is
convertible.

          (i)  Ambiguities/Errors.  The Board of  Directors  of the  Corporation
shall  have the power to  resolve  any  ambiguity  or  correct  any error in the
provisions  relating to the  convertibility of the Series A Preferred Stock, and
its actions in so doing shall be final and conclusive.

          5.  Mandatory  Conversion  and  Redemption.  (a) At any time after the
expiration  of  12  months  after  the  Alternative  Equity  Closing  Date,  the
Corporation  at its  option,  may  cause  the  Series  A  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 200% of
the Stated Common Price if the Closing Bid Price (or, if the price referenced in
the definition of Closing Bid Price cannot be determined, the Fair Market Value)
of the Common Stock shall have equalled or exceeded 250% of the Conversion Price
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").  Any shares of Series A Preferred Stock so converted shall be treated
as having been  surrendered  by the holder  thereof for  conversion  pursuant to
Section 4 on the date of such mandatory  conversion (unless previously converted
at the option of the holder).

          (b) At any time after April 1, 2000, the  Corporation,  at its option,
may redeem  the Series A  Preferred  Stock for cash equal to the  Dividend  Base
Amount at such time,  if the Market  Trigger has  occurred in the period  ending
three  days  prior  to the  date of  notice  of  redemption  (unless  previously
converted at the option of the holder).


                                      -17-
<PAGE>

          (c) No greater than 60 nor fewer than 20 days prior to the date of any
such  mandatory  conversion or redemption,  notice by first class mail,  postage
prepaid, shall be given to the holders of record of the Series A Preferred Stock
to be converted or redeemed,  addressed to such holders at their last  addresses
as shown on the stock transfer books of the Corporation.  Each such notice shall
specify the date fixed for  conversion  or  redemption,  the place or places for
surrender  of  shares  of  Series  A  Preferred  Stock  and the  then  effective
Conversion Rate pursuant to Section 4.

          Any notice which is mailed as herein  provided  shall be  conclusively
presumed to have been duly given by the Corporation on the date deposited in the
mail,  whether or not the holder of the Series A Preferred  Stock  receives such
notice;  and failure properly to give such notice by mail, or any defect in such
notice,  to the  holders of the shares to be  converted  or  redeemed  shall not
affect the validity of the  proceedings  for the conversion or redemption of any
other  shares  of  Series A  Preferred  Stock.  On or after  the date  fixed for
conversion or redemption  (the "Take-Out  Date") as stated in such notice,  each
holder  of  shares  called to be  converted  or  redeemed  shall  surrender  the
certificate evidencing such shares to the Corporation at the place designated in
such notice for conversion or redemption.  After the mailing of such notice, but
before the Take-Out Date as stated therein,  all rights  whatsoever with respect
to the shares so called for  conversion or  redemption  (except the right of the
holders to convert  such  shares  pursuant  to Section 4 and to have such shares
converted or redeemed,  as the case may be, upon surrender of their certificates
therefor,  pursuant to this Section 5) shall terminate. On or after the Take-Out
Date,  notwithstanding  that the  certificates  evidencing  any shares  properly
called for conversion or redemption shall not have been surrendered, such shares
shall no longer be deemed  outstanding and all rights whatsoever with respect to
the shares so called  for  conversion  or  redemption  (except  the right of the
holders to have such  shares  converted  or  redeemed,  as the case may be, upon
surrender  of their  certificates  therefor,  pursuant to this  Section 5) shall
terminate.

          6.   Outstanding   Shares.   For  purposes  of  this   Certificate  of
Designation,  a share of Series A Preferred Stock, when issued,  shall be deemed
outstanding  except  (i) from the date,  or the deemed  date,  of  surrender  of
certificates evidencing shares of Series A Preferred Stock, all shares of Series
A Preferred Stock converted into Common Stock or redeemed  pursuant to Section 5
and (ii)  from the date of  registration  of  transfer,  all  shares of Series A
Preferred  Stock  held of record by the  Corporation  or any  subsidiary  of the
Corporation.

          7.  Class  Voting  Rights.  The  Corporation  shall not,  without  the
affirmative  vote or consent of the  holders of at least 50% of all  outstanding
Series A Preferred  Stock,  voting  separately as a class,  (i) amend,  alter or
repeal any provision of the  Certificate of  Incorporation  or the Bylaws of the
Corporation  so  as  adversely  to  affect  the  relative  rights,  preferences,
qualifications,  limitations or restrictions of the Series A Preferred Stock (it
being understood that the issuance of securities ranking prior to, or pari passu
with,  the Series A  Preferred  Stock (A) upon a  Liquidation  Event or (B) with
respect to the payment of dividends  or  distributions  shall not be  considered
adversely  to  affect  such  relative   rights,   preferences,   qualifications,
limitations  or  restrictions);  or (ii)  authorize  or issue,  or increase  the
authorized  amount of, Series A Preferred  Stock,  other than Series A Preferred
Stock issuable in connection with the Offering,


                                      -18-
<PAGE>

issuable in  exchange  for 9% Notes or accrued  interest  thereon or issuable as
dividends on Series A Preferred Stock.

          8.  Status of  Acquired  Shares.  Shares of Series A  Preferred  Stock
received upon  conversion  or  redemption  pursuant to Section 4 or Section 5 or
otherwise  acquired  by the  Corporation  will  be  restored  to the  status  of
authorized but unissued  shares of Preferred  Stock,  without  designation as to
class,  and may  thereafter  be issued,  but not as shares of Series A Preferred
Stock.

          9. Preemptive  Rights. The Series A Preferred Stock is not entitled to
any  preemptive  or  subscription  rights in  respect of any  securities  of the
Corporation.

          10.  Severability  of Provisions.  Whenever  possible,  each provision
hereof  shall be  interpreted  in a manner as to be  effective  and valid  under
applicable  law,  but if any  provision  hereof is held to be  prohibited  by or
invalid under  applicable law, such provision  shall be ineffective  only to the
extent of such  prohibition or  invalidity,  without  invalidating  or otherwise
adversely  affecting the remaining  provisions  hereof.  If a court of competent
jurisdiction  should  determine  that a  provision  hereof  would  be  valid  or
enforceable  if a period of time were  extended  or  shortened  or a  particular
percentage were increased or decreased, then such court may make such changes as
shall be necessary to render the provision in question effective and valid under
applicable law.

          11. Restrictions on Change of Control. Notwithstanding anything to the
contrary contained in this Certificate of Designation, without the prior written
consent of the  Corporation,  so long as any 9% Notes remain  outstanding  under
that certain Indenture dated as of March 26, 1997 (as amended,  the "Indenture")
in respect of the 9% Notes,  no holder of Series A  Preferred  Stock  shall have
voting rights granted hereunder, be entitled to receive any voting securities of
the Corporation pursuant hereto or be entitled to exercise any of the conversion
rights set forth herein  (each,  a "Restricted  Event"),  to the extent that any
such Restricted Event could, in the Corporation's  reasonable  judgment,  either
alone or in  conjunction  with other  issuances  or holdings  of capital  stock,
warrants or  convertible  securities of the  Corporation,  result in a Change of
Control (as defined in the Indenture).


                            [Signature page follows]


                                      -19-
<PAGE>

          IN  WITNESS  WHEREOF,  ____________,  __________  of the  Corporation,
acting for and on behalf of the  Corporation,  has hereunto  subscribed his name
this ____ day of ________, 1998.


                                       HYBRIDON, INC.



                                       By:
                                          --------------------------------
                                       Name:
                                       Title:

                                      -20-
<PAGE>

[Revised Structure]
                                                                         ANNEX B

                            FORM OF WARRANT AGREEMENT

          AGREEMENT,  dated as of this  ______th day of ________,  1998,  by and
among  HYBRIDON,  INC.,  a Delaware  corporation  ("Company"),  and  CHASEMELLON
SHAREHOLDER SERVICES, L.L.C., a New Jersey limited liability company, as warrant
agent ("Warrant Agent").

                               W I T N E S S E T H

          WHEREAS,  the Company has accepted 9% Convertible  Subordinated  Notes
Due 2004  ("9%  Notes")  of the  Company  in  exchange  for  shares  of Series A
Convertible Preferred Stock, par value $0.01 per share, (the "Series A Preferred
Stock") of the Company  and  warrants  to be issued  pursuant to this  Agreement
("Class A  Warrants")  pursuant to an Offer to Exchange  dated  February 6, 1998
(the "Original Offer to Exchange")  disseminated to all of the holders of the 9%
Notes (as  subsequently  amended by the  Amendment  thereto dated March 30, 1998
(the  "Amendment"),  the  "Offer  to  Exchange,"  and such  exchange  offer,  as
subsequently amended by the Amendment, the "Exchange Offer");

          WHEREAS,  pursuant  to the  Exchange  Offer,  the  Company may issue a
number of Class A Warrants  equal to the Warrant  Coverage  Quantity (as defined
below);

          WHEREAS, each Class A Warrant initially entitles the Registered Holder
(as  defined  below)  thereof to purchase  one (1) share of Common  Stock at the
Purchase Price (as defined below);

          WHEREAS, the Company desires the Warrant Agent to act on behalf of the
Company,  and the  Warrant  Agent is willing so to act, in  connection  with the
issuance,  registration,  transfer,  exchange  and  redemption  of the  Class  A
Warrants,  the issuance of certificates  representing the Class A Warrants,  the
exercise of the Class A Warrants, and the rights of the holders thereof;

          NOW  THEREFORE,  in  consideration  of the  premises  and  the  mutual
agreements  hereinafter  set forth and for the purpose of defining the terms and
provisions of the Class A Warrants and the certificates representing the Class A
Warrants and the respective  rights and  obligations  thereunder of the Company,
the holders of  certificates  representing  the Class A Warrants and the Warrant
Agent, the parties hereto agree as follows:

          SECTION 1. Definitions. As used herein, the following terms shall have
the following meanings, unless the context shall otherwise require:

          (a)  "Common  Stock"  shall  mean  stock of the  Company of any class,
whether now or hereafter  authorized,  which has the right to participate in the
distribution of earnings and

<PAGE>

assets of the Company  without  limit as to amount or  percentage,  which at the
date hereof  consisted of  100,000,000  authorized  shares of Common Stock,  par
value $.001 per share.

          (b) The  "Closing  Bid  Price,"  for each  trading  day,  shall be the
reported  per share  closing  bid price of the Common  Stock  regular way on the
Stock  Market on such  trading  day or, if there  were no  transactions  on such
trading day,  shall mean the average of the  reported per share  closing bid and
asked  prices,  regular  way,  of the Common  Stock on the Stock  Market on such
trading day.

          (c) "Corporate  Office" shall mean the office of the Warrant Agent (or
its successor) at which, at any particular time, its principal business shall be
administered,  which office is located at the date hereof at 85 Challenger Road,
Overpeck Centre, Ridgefield Park, New Jersey, 07660.

          (d) "Exercise Date" shall mean, as to any Class A Warrant, the date on
which the Warrant  Agent shall have  received  both (a) the Warrant  Certificate
representing  such Class A Warrant,  with the  subscription  form  thereon  duly
executed by the  Registered  Holder  thereof or his attorney duly  authorized in
writing,  and (b) payment in cash, or by official  bank or certified  check made
payable to the  Company,  of an amount in lawful  money of the United  States of
America equal to the applicable Purchase Price.

          (e) [Reserved]

          (f) "Fair Market Value"  means,  with respect to any security or other
asset,  the fair market value set by, or determined in a manner  established by,
the Board of Directors of the Company.

          (g) "Initial  Warrant  Exercise  Date" shall mean,  as to each Class A
Warrant,  the date which is 12 months after the Alternative  Equity Closing Date
(as hereinafter defined).

          (h)  "Market  Price"  shall mean the average  Closing  Bid Price,  for
twenty (20) consecutive  trading days,  ending with the trading day prior to the
date as of  which  the  Market  Price  is  being  determined  (with  appropriate
adjustments  for  subdivisions  or  combinations  of shares effected during such
period),  provided that if the prices  referred to in the  definition of Closing
Bid Price cannot be determined  for such period,  "Market Price" shall mean Fair
Market Value.

          (i) The  "Purchase  Price"  per share of Common  Stock  shall mean the
product of 2.125  multiplied  by the per share price of Common Stock sold by the
Company in  connection  with the  Alternative  Equity  Offering (as such term is
defined in the  Amendment),  subject to adjustment from time to time pursuant to
the  provisions of Section 9, and subject to the  Company's  right to reduce the
Purchase Price upon notice to all Registered Holders.

          (j) [Reserved]


                                      -2-
<PAGE>

          (k)  "Registered  Holder" shall mean, as to any Class A Warrant and as
of any particular  date, the person in whose name the  certificate  representing
the Class A Warrant shall be registered on that date on the books  maintained by
the Warrant Agent pursuant to Section 6.

          (l) The "Stock  Market" shall mean the principal  national  securities
exchange  on which the Common  Stock is listed or admitted to trading or, if the
Common  Stock is not listed or  admitted to trading on any  national  securities
exchange,  shall mean The Nasdaq  National  Market System or The Nasdaq SmallCap
Market (collectively, "Nasdaq") or, if the Common Stock is not quoted on Nasdaq,
shall mean the OTC  Bulletin  Board or, if the Common Stock is not quoted on the
OTC Bulletin Board, shall mean the  over-the-counter  market as furnished by any
NASD member firm selected from time to time by the Company for that purpose.

          (m) A "trading day" shall mean a day on which the Stock Market is open
for the transaction of business.

          (n)  "Transfer  Agent" shall mean  ChaseMellon  Shareholder  Services,
L.L.C., as the Company's transfer agent, or its authorized successor, as such.

          (o) "Warrant Coverage  Quantity" shall mean 25% of the quotient of (i)
the initial  aggregate  Dividend Base Amount (as defined in the  Certificate  of
Designation  for the Series A Preferred  Stock) of the Series A Preferred  Stock
issued  pursuant  to the  Exchange  Offer,  divided by (ii) the  Purchase  Price
without giving effect to any  adjustments to such Purchase Price occurring after
the date hereof.

          (p) "Warrant  Expiration Date" shall mean 5:00 P.M. (New York time) on
the day prior to the fourth  anniversary of the Initial  Warrant  Exercise Date;
provided  that if such date shall in the State of New York be a holiday or a day
on which banks are  authorized or required to close,  then  "Warrant  Expiration
Date" shall mean 5:00 P.M.  (New York time) on the next  following  day which in
the  State  of New York is  neither  a  holiday  nor a day on  which  banks  are
authorized  or required to close.  Upon notice to all  Registered  Holders,  the
Company shall have the right to extend the Warrant Expiration Date.

          (q) Unless  otherwise  stated,  section  references  used  within this
Warrant Agreement refer to sections of this Warrant Agreement.

          SECTION 2. Warrants and Issuance of Warrant Certificates.

          (a) A Class A Warrant initially shall entitle the Registered Holder of
the Warrant Certificate  representing such Class A Warrant to purchase one share
of Common Stock upon the exercise thereof,  in accordance with the terms hereof,
subject to modification and adjustment as provided in Section 9.

          (b) The Class A Warrants  issued  pursuant to the Exchange  Offer will
immediately be detachable and separately  transferable from the shares of Series
A Preferred Stock also issued pursuant thereto.


                                      -3-
<PAGE>

          (c)  Within  five  business  days  after  the date  that 9% Notes  are
irrevocably  exchanged  pursuant to the  Exchange  Offer,  Warrant  Certificates
representing  the  number  of Class A  Warrants  to be  issued  pursuant  to the
Exchange  Offer shall be executed  by the Company and  delivered  to the Warrant
Agent.  Within five business days of receipt of the Warrant  Certificates by the
Warrant  Agent,  the Warrant  Agent shall send the Warrant  Certificates  to the
Registered  Holders.  The  Company  shall issue a written  order,  signed by its
Chairman of the Board,  President or any Vice  President and by its Secretary or
an  Assistant  Secretary,  to the  Warrant  Agent  directing  that  the  Warrant
Certificates  shall be countersigned,  issued and delivered by the Warrant Agent
in accordance with the preceding sentence.

          (d) From time to time, until the Warrant Expiration Date, the Transfer
Agent shall countersign and deliver stock  certificates in required whole number
denominations of Common Stock,  subject to adjustment as described herein,  upon
the exercise of Class A Warrants in accordance with this Agreement.

          (e) From time to time, until the Warrant  Expiration Date, the Warrant
Agent shall  countersign  and deliver  Warrant  Certificates  in required  whole
number  denominations  to the persons  entitled  thereto in connection  with any
transfer or exchange  permitted under this  Agreement;  provided that no Warrant
Certificates  shall be issued except (i) those initially issued hereunder,  (ii)
those issued on or after the Initial Warrant Exercise Date, upon the exercise of
fewer than all Class A  Warrants  represented  by any  Warrant  Certificate,  to
evidence any  unexercised  Class A Warrants  held by the  exercising  Registered
Holder,  (iii) those issued upon any transfer or exchange pursuant to Section 6;
(iv) those issued in replacement of lost, stolen, destroyed or mutilated Warrant
Certificates pursuant to Section 7 and (v) at the option of the Company, in such
form as may be approved by its Board of Directors, to reflect any adjustment to,
or change  in:  the  Purchase  Price;  the  number  of  shares  of Common  Stock
purchasable  upon  exercise of the Class A Warrants;  or the Warrant  Expiration
Date.

          SECTION 3. Form and Execution of Warrant Certificates.

          (a) The  Warrant  Certificates  shall  be  substantially  in the  form
annexed  hereto as Exhibit A (the  provisions  of which are hereby  incorporated
herein) and may have such letters,  numbers or other marks of  identification or
designation and such legends, summaries or endorsements printed, lithographed or
engraved thereon as the Company may deem appropriate and as are not inconsistent
with the provisions of this Agreement,  or as may be required to comply with any
law or with any rule or  regulation  made  pursuant  thereto or with any rule or
regulation of any stock exchange on which the Class A Warrants may be listed, or
to  conform  to  usage  or  to  the  requirements  of  Section  2.  The  Warrant
Certificates  shall be dated the date of issuance  thereof (whether upon initial
issuance, transfer, exchange or in lieu of mutilated, lost, stolen, or destroyed
Warrant  Certificates) and issued in registered form. Warrant Certificates shall
be  numbered   serially  with  the  letters  AW  on  Class  A  Warrants  of  all
denominations.

          (b) Warrant Certificates shall be executed on behalf of the Company by
its Chairman of the Board,  President or any Vice President and by its Secretary
or an Assistant  Secretary,  by manual  signatures  or by  facsimile  signatures
printed thereon. Warrant Certificates


                                      -4-
<PAGE>

shall be manually  countersigned by the Warrant Agent and shall not be valid for
any  purpose  unless so  countersigned.  In case any  officer of the Company who
shall have signed any of the Warrant  Certificates  shall cease to be an officer
of the  Company  or to hold the  particular  office  referenced  in the  Warrant
Certificate  before the date of issuance of the Warrant  Certificates  or before
countersignature  by the Warrant Agent and issuance and delivery  thereof,  such
Warrant  Certificates  may  nevertheless be  countersigned by the Warrant Agent,
issued  and  delivered  with the same  force and effect as though the person who
signed such Warrant  Certificates had not ceased to be an officer of the Company
or to hold such office.  After  countersignature  by the Warrant Agent,  Warrant
Certificates  shall be delivered by the Warrant Agent to the  Registered  Holder
without further action by the Company, except as otherwise provided herein.

          SECTION 4.  Exercise.  Each Class A Warrant  may be  exercised  by the
Registered  Holder thereof at any time on or after the Initial Warrant  Exercise
Date, but not after the Warrant  Expiration  Date, upon the terms and subject to
the  conditions set forth herein and in the applicable  Warrant  Certificate.  A
Class A Warrant shall be deemed to have been exercised  immediately prior to the
close of business on the  Exercise  Date and the person  entitled to receive the
securities  deliverable  upon such exercise shall be treated for all purposes as
the holder of those  securities  upon the  exercise of the Class A Warrant as of
the close of business on the Exercise  Date. As soon as  practicable on or after
the Exercise  Date,  the Warrant Agent shall deposit the proceeds  received from
the exercise of a Class A Warrant and shall notify the Company in writing of the
exercise of the Class A Warrants.  Promptly  following,  and in any event within
five  business  days after the date of such notice from the Warrant  Agent,  the
Warrant Agent, on behalf of the Company,  shall cause to be issued and delivered
by the Transfer Agent, to the person or persons  entitled to receive the same, a
certificate or certificates  for the securities  deliverable  upon such exercise
(plus a  certificate  for any  remaining  unexercised  Class A  Warrants  of the
Registered  Holder). In the case of payment made in the form of a check drawn on
an account of such  investment  banks and brokerage  houses as the Company shall
approve in writing to the Warrant Agent,  certificates  shall promptly be issued
without  prior  notice to the  Company nor any delay.  Upon the  exercise of any
Class A Warrant and  clearance of the funds  received,  the Warrant  Agent shall
promptly  remit the  payment  received  for the Class A  Warrant  (the  "Warrant
Proceeds") to the Company or as the Company may otherwise direct in writing.

          SECTION 5. Reservation of Shares; Listing; Payment of Taxes; etc.

          (a) The Company  covenants  that it will at all times reserve and keep
available out of its  authorized  Common Stock,  solely for the purpose of issue
upon  exercise  of Class A Warrants,  such  number of shares of Common  Stock as
shall then be issuable  upon the exercise of all  outstanding  Class A Warrants.
The Company  covenants  that all shares of Common  Stock which shall be issuable
upon exercise of the Class A Warrants shall,  at the time of delivery  (assuming
full payment of the Purchase Price thereof),  be duly and validly issued,  fully
paid,  nonassessable  and free from all issuance  taxes,  liens and charges with
respect to the issue  thereof  including,  without  limitation,  adverse  claims
whatsoever  (with  the  exception  of  claims  arising  through  the acts of the
Registered  Holders themselves and except as arising from applicable Federal and
state  securities  laws) and that the Company shall have paid all taxes, if any,
in respect of the original  issuance  thereof  (except as otherwise  provided in
Subsection 5(c)).


                                      -5-
<PAGE>

          (b)  The  Registered  Holders  of  Class A  Warrants  shall  have  the
registration  rights  provided  in the Offer to  Exchange.  The Class A Warrants
shall not be exercisable in any state where such exercise would be unlawful.

          (c) The Company shall pay all documentary,  stamp or similar taxes and
other  similar  governmental  charges (but in no case income  taxes) that may be
imposed  with  respect to the  issuance of Class A Warrants,  or the issuance or
delivery of any shares upon exercise of the Class A Warrants; provided, however,
that if the shares of Common  Stock are to be delivered in a name other than the
name of the Registered Holder of the Warrant Certificate  representing any Class
A Warrant being exercised, then no such delivery shall be made unless the person
requesting  the same has paid to the Warrant Agent the amount of transfer  taxes
or charges incident thereto, if any.

          (d) The Warrant Agent is hereby irrevocably  authorized to requisition
the Company's  Transfer  Agent from time to time for  certificates  representing
shares of Common Stock  issuable upon exercise of the Class A Warrants,  and the
Company  will  authorize  the  Transfer  Agent to  comply  with all such  proper
requisitions.  The Company will file with the Warrant Agent a statement  setting
forth the name and  address of the  Transfer  Agent of the Company for shares of
Common Stock issuable upon exercise of the Class A Warrants.

          SECTION 6. Exchange and Registration of Transfer.

          (a)  Warrant   Certificates   may  be  exchanged   for  other  Warrant
Certificates  representing an equal aggregate  number of Class A Warrants of the
same class or may be transferred in whole or in part. Warrant Certificates to be
exchanged shall be surrendered to the Warrant Agent at its Corporate Office, and
upon satisfaction of the terms and provisions hereof, the Company shall execute,
and the Warrant Agent shall countersign, issue and deliver in exchange therefor,
the Warrant  Certificate  or Warrant  Certificates  that the  Registered  Holder
making the exchange shall be entitled to receive.

          (b) The Warrant Agent shall keep at its office books in which, subject
to such reasonable  regulations as it may prescribe,  it shall register  Warrant
Certificates and any transfers  thereof in accordance with its regular practice.
Upon due presentment for registration of transfer of any Warrant  Certificate at
such office,  the Company  shall  execute and the Warrant  Agent shall issue and
deliver to the transferee or transferees,  a new Warrant  Certificate or Warrant
Certificates representing an equal aggregate number of Class A Warrants.

          (c)  With   respect  to  all  Warrant   Certificates   presented   for
registration or transfer, or for exchange or exercise,  the subscription form on
the reverse  thereof  shall be duly  endorsed,  or be  accompanied  by a written
instrument or instruments of transfer and subscription,  in form satisfactory to
the Company and the Warrant Agent, duly executed by the Registered Holder or his
attorney-in-fact duly authorized in writing.

          (d) A service  charge may be imposed by the  Warrant  Agent on holders
for any exchange or  registration  of transfer of Warrant  Certificates  of such
holders. In addition, the


                                      -6-
<PAGE>

Company may require  payment by such holder of a sum sufficient to cover any tax
or governmental or other charge that may be imposed in connection therewith.

          (e) All Warrant Certificates surrendered for exercise, or for exchange
in case of mutilated Warrant  Certificates,  shall be promptly  cancelled by the
Warrant  Agent  and  thereafter  retained  by  the  Warrant  Agent  in a  manner
consistent  with its  customary  practices  until  termination  of this  Warrant
Agreement  or  resignation  as Warrant  Agent or disposed of or destroyed at the
direction of the Company.

          (f) Prior to due presentment for registration of transfer thereof, the
Company and the Warrant  Agent may deem and treat the  Registered  Holder of any
Warrant  Certificate  as the absolute  owner thereof and of each Class A Warrant
represented  thereby  (notwithstanding  any  notations  of  ownership or writing
thereon  made by anyone other than a duly  authorized  officer of the Company or
the Warrant  Agent) for all  purposes and shall not be affected by any notice to
the contrary.

          SECTION 7. Loss or  Mutilation.  Upon receipt by the Warrant  Agent of
evidence satisfactory to it of the ownership of and loss, theft,  destruction or
mutilation  of  any  Warrant   Certificate  and  (in  case  of  loss,  theft  or
destruction)  of indemnity  satisfactory  to it, and (in the case of mutilation)
upon  surrender  and  cancellation  thereof,  the Company  shall execute and the
Warrant  Agent shall ( in the absence of notice to the  Company  and/or  Warrant
Agent that the Warrant  Certificate  has been acquired by a bona fide purchaser)
countersign  and deliver to the Registered  Holder in lieu thereof a new Warrant
Certificate  of like tenor  representing  an equal  aggregate  number of Class A
Warrants. Applicants for a substitute Warrant Certificate shall comply with such
other  reasonable  regulations  and pay such  other  reasonable  charges  as the
Warrant Agent may prescribe.

          SECTION 8. [Reserved]

          SECTION 9. Adjustment of Purchase Price and Number of Shares of Common
Stock or Class A Warrants.  Upon, and only upon, each adjustment of the Purchase
Price  pursuant to this  Section 9, the total  number of shares of Common  Stock
purchasable  upon the  exercise  of each Class A Warrant  shall  (subject to the
provisions contained in Subsection 9(c)) be such number of shares (calculated to
the nearest tenth) purchasable at the Purchase Price in effect immediately prior
to such adjustment multiplied by a fraction, the numerator of which shall be the
Purchase  Price  in  effect   immediately  prior  to  such  adjustment  and  the
denominator  of which shall be the Purchase  Price in effect  immediately  after
such adjustment.

          (a) The Company may elect,  upon any  adjustment of the Purchase Price
hereunder, to adjust the number of Class A Warrants outstanding,  in lieu of the
adjustment in the number of shares of Common Stock purchasable upon the exercise
of each  Class A  Warrant  as  herein  provided,  so that  each  Class A Warrant
outstanding  after such  adjustment  shall  represent  the right to purchase one
share of  Common  Stock.  Each  Class A  Warrant  held of  record  prior to such
adjustment of the number of Class A Warrants shall become that number of Class A
Warrants (calculated to the nearest tenth) equal to a fraction, the numerator of
which shall be the Purchase Price in effect immediately prior to such adjustment
and the denominator


                                      -7-
<PAGE>

of  which  shall  be  the  Purchase  Price  in  effect  immediately  after  such
adjustment.  Upon each adjustment of the number of Class A Warrants  pursuant to
this  Section 9, the Company  shall,  as promptly  as  practicable,  cause to be
distributed to each  Registered  Holder of Warrant  Certificates  on the date of
such  adjustment  Warrant  Certificates  evidencing,  subject to Section 10, the
number of additional  Class A Warrants to which such Holder shall be entitled as
a result of such  adjustment  or,  at the  option  of the  Company,  cause to be
distributed  to such  Holder in  substitution  and  replacement  for the Warrant
Certificates  held by him prior to the date of  adjustment  (and upon  surrender
thereof,  if required by the Company) new Warrant  Certificates  evidencing  the
number of Class A Warrants  to which such Holder  shall be  entitled  after such
adjustment.

          (b)  Irrespective  of any adjustments or changes in the Purchase Price
or the number of shares of Common Stock purchasable upon exercise of the Class A
Warrants,  the Warrant  Certificates  theretofore  and thereafter  issued shall,
unless the Company shall  exercise its option to issue new Warrant  Certificates
pursuant to Subsection  2(e),  continue to express the same  Purchase  Price per
share, number of shares purchasable  thereunder as when the same were originally
issued.

          (c) As used in this  Section  9, the  following  terms  shall have the
following meanings:

               "Capital Stock" of any Person means the Common Stock or Preferred
          Stock of such Person.  Unless  otherwise  stated herein or the context
          otherwise  requires,  "Capital  Stock"  means  Capital  Stock  of  the
          Company;

               "Common  Stock" of any Person  other than the  Company  means the
          common equity (however  designated),  including,  without  limitation,
          common  stock  or   partnership   or   membership   interests  of,  or
          participation  or interests in such Person (or  equivalents  thereof).
          "Common Stock" of the Company means the Common Stock,  par value $.001
          per share,  of the Company,  any successor  class or classes of common
          equity  (however  designated)  of the  Company  into or for which such
          Common Stock may hereafter be converted, exchanged or reclassified and
          any class or  classes of common  equity  (however  designated)  of the
          Company which may be distributed or issued with respect to such Common
          Stock or  successor  class of classes to  holders  thereof  generally.
          Unless  otherwise  stated  herein or the context  requires  otherwise,
          "Common Stock" means Common Stock of the Company;

               "Current  Market  Price"  means,  when used with  respect  to any
          security as of any date, the last sale price, regular way, or, in case
          no such sale takes place on such date,  the average of the closing bid
          and asked  prices,  regular  way,  of such  security in either case as
          reported for consolidated  transactions on the New York Stock Exchange
          or, if such  security  is not listed or admitted to trading on the New
          York Stock Exchange,  as reported for consolidated  transactions  with
          respect to  securities  listed on the  principal  national  securities
          exchange  on which such  security is listed or admitted to trading or,
          if such security is not listed or


                                      -8-
<PAGE>

          admitted to trading on any national securities  exchange,  as reported
          on the Nasdaq National  Market,  or, if such security is not listed or
          admitted to trading on the Nasdaq National Market,  as reported on the
          Nasdaq SmallCap Market,  or if such security is not listed or admitted
          to trading on any national  securities exchange or the Nasdaq National
          Market or the Nasdaq SmallCap Market,  the average of the high bid and
          low asked prices of such security in the  over-the-counter  market, as
          reported by the  National  Association  of  Securities  Dealers,  Inc.
          Automated  Quotations  System or such other  system then in use or, if
          such security is not quoted by any such  organization,  the average of
          the closing bid and asked prices of such security furnished by an NASD
          member firm selected by the Company. If such security is not quoted by
          any such  organization and no such NASD member firm is able to provide
          such prices,  the Current  Market Price of such security  shall be the
          Fair Market Value thereof;

               "Fair Market Value" means, at any date as to any asset,  Property
          or right (including without  limitation,  Capital Stock of any Person,
          evidence of indebtedness or other securities, but excluding cash), the
          fair  market  value of such item as  determined  in good  faith by the
          Board of Directors, whose determination shall be conclusive; provided,
          however,   that  such  determination  is  described  in  an  Officers'
          Certificate  filed  with the  transfer  agent and that,  if there is a
          Current  Market  Pricefor such item on such date,  "Fair Market Value"
          means such Current  Market Price  (without  giving  effect to the last
          sentence of the definition thereof);

               "GAAP"  means,  as of any  date,  generally  accepted  accounting
          principles   in  the   United   States  and  does  not   include   any
          interpretations  or regulations  that have been proposed but that have
          not become effective;

               "Officer" means, with respect to any Person,  the Chairman of the
          Board, the Chief Executive Officer, the President, the Chief Operating
          Officer,  the Chief Financial  Officer,  the Treasurer,  any Assistant
          Treasurer,  the Controller,  the Secretary, any Assistant Secretary or
          any Vice President of such Person;

               "Officers'  Certificate"  means a certificate signed on behalf of
          the Company by two  Officers,  one of whom must be the Chairman of the
          Board,  the  President,  the  Treasurer  or a  Vice-President  of  the
          Company;

               "Person"   means  any   individual,   corporation,   partnership,
          association,  trust or any other entity or  organization,  including a
          government or political  subdivision or any agency or  instrumentality
          thereof;

               "Preferred  Stock" of any  Person  means the class or  classes of
          equity,  ownership or participation  interests (however designated) in
          such Person, including, without limitation,  stock, share, partnership
          and  membership  interests,  which are  preferred as to the payment of
          dividends or  distributions  by, or as to the  distribution  of assets
          upon any voluntary or involuntary liquidation or


                                      -9-
<PAGE>

          dissolution of, such Person (or equivalent  thereof) over interests of
          any other class of interests of such Person.  Unless  otherwise stated
          herein or the context  otherwise  requires,  "Preferred  Stock"  means
          Preferred Stock of the Company;

               "Property"  of any  Person  means  any and  all  types  of  real,
          personal, tangible,  intangible or mixed property owned by such Person
          whether or not included on the most recent consolidated  balance sheet
          of such Person in accordance with GAAP;

               "Subsidiary"  of a Person on any date  means any other  Person of
          whom such Person owns,  directly or indirectly through a Subsidiary or
          Subsidiaries of such Person,  Capital Stock with voting power,  acting
          independently and under ordinary circumstances,  entitling such person
          to elect a majority of the board of directors or other  governing body
          of such other Person.  Unless  otherwise  stated herein or the context
          otherwise requires, "Subsidiary" means a Subsidiary of the Company.

          (d) If the Company shall (i) pay a dividend or other distribution,  in
Common Stock,  on any class of Capital Stock of the Company,  (ii) subdivide the
outstanding  Common Stock into a greater  number of shares by any means or (iii)
combine  the  outstanding  Common  Stock into a smaller  number of shares by any
means including,  without limitation,  a reverse stock split), then in each such
case the Purchase Price in effect immediately prior thereto shall be adjusted so
that the Registered  Holder of any Class A Warrants  thereafter  surrendered for
exercise  shall be entitled to receive the number of shares of Common Stock that
such  Registered  Holder would have owned or have been  entitled to receive upon
the happening of such event had such Class A Warrants been exercised immediately
prior to the  relevant  record  date or, if there is no such  record  date,  the
effective  date of such event.  An adjustment  made pursuant to this  Subsection
9(d)  shall  become  effective   immediately  after  the  record  date  for  the
determination of stockholders  entitled to receive such dividend or distribution
and  shall  become  effective  immediately  after  the  effective  date  of such
subdivision or combination, as the case may be.

          (e) If the Company shall (i) issue or distribute (at a price per share
less than the Current  Market Price per share of such Capital  Stock on the date
of such issuance or  distribution)  Capital Stock generally to holders of Common
Stock or to holders of any class or series of Capital Stock which is convertible
into or exchangeable  or exercisable for Common Stock  (excluding an issuance or
distribution  of Common  Stock  described  in  Subsection  9(d) or (ii) issue or
distribute generally to such holders rights, warrants, options or convertible or
exchangeable securities entitling the holder thereof to subscribe for, purchase,
convert  into or exchange  for Capital  Stock at a price per share less than the
Current  Market Price per share of such Capital Stock on the date of issuance or
distribution,  then,  in each such  case,  at the  earliest  of (A) the date the
Company enters into a firm contract for such issuance or  distribution,  (B) the
record date for the  determination of stockholders  entitled to receive any such
Capital  Stock  or  any  such  rights,  warrants,   options  or  convertible  or
exchangeable  securities or (C) the date of actual  issuance or  distribution of
any such Capital Stock or any such rights,  warrants,  options or convertible or
exchangeable securities,  the Purchase Price shall be reduced by multiplying the
Purchase Price in effect immediately prior to such earliest date by:


                                      -10-
<PAGE>

               (i) if such  Capital  Stock  is  Common  Stock,  a  fraction  the
          numerator   of  which  is  the  number  of  shares  of  Common   Stock
          outstanding, on such earliest date plus the number of shares of Common
          Stock which could be purchased  at the Current  Market Price per share
          of Common Stock on the date of such issuance or distribution  with the
          aggregate  consideration  (based  on the Fair  Market  Value  thereof)
          received or  receivable by the Company  either (A) in connection  with
          such issuance or distribution  or (B) upon the  conversion,  exchange,
          purchase or  subscription  of all such  rights,  warrants,  options or
          convertible    or    exchangeable     securities    (the    "Aggregate
          Consideration"),  and the denominator of which is the number of shares
          of Common Stock  outstanding  on such earliest date plus the number of
          shares of Common Stock to be so issued or  distributed or to be issued
          upon the  conversion,  exchange,  purchase or subscription of all such
          rights,  warrants,  options or convertible or exchangeable securities;
          or

               (ii) if such Capital Stock is other than Common Stock, a fraction
          the numerator of which is the Current Market Price per share of Common
          Stock  on  such  earliest  date  minus  an  amount  equal  to (A)  the
          difference  between  (1) the  Current  Market  Price per share of such
          Capital Stock multiplied by the number of shares of such Capital Stock
          to be so issued and (2) the  Aggregate  Consideration,  divided by (B)
          the number of shares of Common Stock outstanding on such date, and the
          denominator  of which is the Current  Market Price per share of Common
          Stock on such earliest date.

          Such adjustment shall be made  successively  whenever any such Capital
Stock, rights,  warrants,  options or convertible or exchangeable securities are
so issued or distributed.  In determining whether any rights, warrants,  options
or  convertible  or  exchangeable  securities  entitle  the  holders  thereof to
subscribe  for,  purchase,  convert  into or exchange for shares of such Capital
Stock at less than such Current Market Price,  there shall be taken into account
the Fair Market Value of any consideration received or receivable by the Company
for such rights, warrants, options or convertible or exchangeable securities. If
any right, warrant, option or convertible or exchangeable security, the issuance
of which  resulted  in an  adjustment  in the  Purchase  Price  pursuant to this
Subsection  9(e),  shall expire and shall not have been exercised,  the Purchase
Price shall immediately upon such expiration be recomputed to the Purchase Price
which would have been in effect if such right, warrant, option or convertible or
exchangeable  securities had never been  distributed or issued.  Notwithstanding
anything  contained  in this  paragraph  to the  contrary,  (i) the  issuance of
Capital  Stock upon the  exercise  of such  rights,  warrants  or options or the
conversion or exchange of such  convertible or exchangeable  securities will not
cause an adjustment in the Purchase Price if no such adjustment  would have been
required at the time such right, warrant,  option or convertible or exchangeable
security  was  issued  or   distributed;   provided,   however,   that,  if  the
consideration  payable upon such  exercise,  conversion  or exchange  and/or the
Capital Stock receivable thereupon are changed after the time of the issuance or
distribution  of such right,  warrant,  option or  convertible  or  exchangeable
security then such change shall be deemed to be the expiration  thereof  without
having been exercised and the issuance or distribution  of new options,  rights,
warrants or  convertible  or  exchangeable  securities  and (ii) the issuance of
convertible  preferred  stock  of  the  Company  as a  dividend  on  convertible
preferred  stock of the Company  will not cause an  adjustment  in the  Purchase
Price if no such adjustment would have been required at the time such underlying


                                      -11-
<PAGE>

convertible  preferred  stock  was  issued  (or as a  result  of any  subsequent
modification  to the  terms  thereof)  and  the  conversion  provisions  of such
convertible  stock so issued as a  dividend  are the same as in such  underlying
convertible preferred stock.

          Notwithstanding  anything  contained in this Warrant  Agreement to the
contrary,  options,  rights or warrants  issued or  distributed  by the Company,
including  options,  rights or  warrants  distributed  prior to the date of this
Warrant  Agreement,  to  holders  of Common  Stock  generally  which,  until the
occurrence of a specified event or events (a "Trigger Event"), (i) are deemed to
be transferred  with Common Stock,  (ii) are not  exercisable and (iii) are also
issued on a pro rata basis with  respect to future  issuances  of Common  Stock,
shall be deemed not to have been  issued or  distributed  for  purposes  of this
Section 9 (and no adjustment to the Purchase  Price under this Section 9 will be
required)  until  the  occurrence  of  the  earliest  Trigger  Event.  Upon  the
occurrence of a Trigger Event,  such options,  rights or warrants shall continue
to be deemed not to have been issued or distributed for purposes of this Section
9 (and  no  adjustment  to the  Purchase  Price  under  this  Section  9 will be
required) if and for so long as each Registered Holder who thereafter  exercises
such Registered Holder's Class A Warrants shall be entitled to receive upon such
exercise, in addition to the shares of Common Stock issuable upon such exercise,
a number of such options,  rights or warrants,  as the case may be, equal to the
number of options,  rights or warrants to which a holder of the number of shares
of Common  Stock  equal to the number of shares of Common  Stock  issuable  upon
exercise of such Registered  Holder's Class A Warrants is entitled to receive at
the time of such  exercise in  accordance  with the terms and  provision of, and
applicable to, such options, rights or warrants. Upon the expiration of any such
options,  rights or warrants or at such time, if any, as a Registered  Holder is
not entitled to receive such  options,  rights or warrants upon exercise of such
Registered Holder's Class A Warrants,  an adjustment (if any is required) to the
Purchase  Price  shall be made in  accordance  with  this  Subsection  9(e) with
respect to the issuance of all such options,  rights and warrants as of the date
of issuance thereof,  but subject to the provisions of the preceding  paragraph,
if any such  option,  right or  warrant,  including  any such  options  right or
warrants distributed prior to the date of this Warrant Agreement, are subject to
events,  upon the  occurrence of which such options,  rights or warrants  become
exercisable to purchase different  securities,  evidence of indebtedness,  cash,
Properties or other assets or different  amounts thereof,  then,  subject to the
preceding  provision of this  paragraph,  the date of the  occurrence of any and
each such event shall be deemed to be the date of  distribution  and record date
with respect to new  options,  right or warrants  with such new purchase  rights
(and a termination  or expiration  of the existing  options,  rights or warrants
without  exercise  thereof).  In addition,  in the event of any distribution (or
deemed  distribution)  of options,  rights or warrants,  or any Trigger Event or
other event of the type described in the preceding  sentence,  that required (or
would  have  required  but  for the  provisions  of  Subsection  9(h) or of this
paragraph)  an  adjustment  to the Purchase  Price under this Section 9 and such
options,  rights or warrants shall  thereafter have been redeemed or repurchased
without  having been  exercised,  then the Purchase Price shall be adjusted upon
such redemption or repurchase to give effect to such distribution, Trigger Event
or  other  event,  as  the  case  may,  as  though  it had  instead  been a cash
distribution,  equal  on a per  share  basis  to the  result  of  the  aggregate
redemption or repurchase  price  received by holders of such options,  rights or
warrants  divided by the number of shares of Common Stock  outstanding as of the
date of such repurchase or redemption, made to holders of Common Stock generally
as of the date of such redemption or repurchase.


                                      -12-
<PAGE>

          (f)  If  the  Company  shall  pay  or  distribute,  as a  dividend  or
otherwise,  generally  to  holders  of  Common  Stock or any  class or series of
Capital Stock which is  convertible  into or  exercisable  or  exchangeable  for
Common Stock any assets,  Properties or rights (including,  without  limitation,
evidences of  indebtedness  of the Company,  any Subsidiary or any other Person,
cash or Capital Stock or other securities of the Company,  any Subsidiary or any
other  Person,   but  excluding  payments  and  distributions  as  described  in
Subsections  9(d) or (e),  dividends  and  distributions  in  connection  with a
Liquidation Event (as defined in the Certificate of Designation for the Series A
Preferred  Stock)  and  distributions  consisting  solely of cash  described  in
Subsection  9(g),  then in each such case the Purchase Price shall be reduced by
multiplying the Purchase Price in effect  immediately  prior to the date of such
payment or  distribution  by a fraction,  the  numerator of which is the Current
Market Price per share of Common Stock on the record date for the  determination
of stockholders  entitled to receive such payment or distribution  less the Fair
Market  Value per  share of  Common  Stock on such  record  date of the  assets,
Properties or rights so paid or distributed, and the denominator of which is the
Current  Market  Price per  share of  Common  Stock on such  record  date.  Such
adjustment  shall  become  effective  immediately  after such record  date.  For
purposes of this  Subsection  9(f), such Fair Market Value per share shall equal
the aggregate Fair Market Value on such record date of the assets, Properties or
rights so paid or  distributed  divided by the number of shares of Common  Stock
outstanding  on such record date.  For all  purposes of this Warrant  Agreement,
adjustments  to any  security's  exercise  or  exercise  price  pursuant to such
security's  original  terms  shall not be deemed a  distribution  or dividend to
holders thereof.

          (g)  If  the  Company  shall,   by  dividend  or  otherwise,   make  a
distribution  (other than in connection  with the  liquidation,  dissolution  or
winding up of the Company in its entirety), generally to holders of Common Stock
or any class or series of Capital Stock which is convertible into or exercisable
or exchangeable for Common Stock, consisting solely of cash where (x) the sum of
(i) the  aggregate  amount for such cash plus (ii) the  aggregate  amount of all
cash so  distributed  (by  dividend or  otherwise)  to such  holders  within the
12-month period ending on the record date for determining  stockholder  entitled
to receive such  distribution  with respect to which no adjustment has been made
to the Purchase  Price pursuant to this  Subsection  9(g) exceeds (y) 10% of the
result of the multiplication of (1) the Current Market Price per share of Common
Stock on such  record  date  times (2) the  number  of  shares  of Common  Stock
outstanding  on such  record  date,  then the  Purchase  Price shall be reduced,
effective immediately prior to the opening of business on the day following such
record date, by multiplying  the Purchase Price in effect  immediately  prior to
the close of business  on the day prior to such  record date by a fraction,  the
numerator of which is the Current Market Price per share of Common Stock on such
record date less the aggregate  amount of cash per share so distributed  and the
denominator of which is such Current Market Price;  provided,  however, that, if
the aggregate  amount of cash per share is equal to or greater than such Current
Market Price,  then, in lieu of the foregoing  adjustment,  adequate  provisions
shall be made so that each  Registered  Holder  shall  have the right to receive
upon  exercise  (with  respect to each share of Common  Stock  issued  upon such
exercise  and in  addition  to the Common  Stock  issuable  upon  exercise)  the
aggregate  amount of cash per share such  Registered  Holder would have received
had such Registered Holder's Class A Warrant been exercised immediately prior to
such record date. In no event shall the Purchase Price be increased  pursuant to
this Subsection 9(g);  provided,  however,  that if such  distribution is not so
made, the Purchase Price shall be adjusted to be the


                                      -13-
<PAGE>

Purchase Price which would have been in effect if such distribution had not been
declared.  For purposes of this Subsection  9(g), such aggregate  amount of cash
per share shall  equal such sum divided by the number of shares of Common  Stock
outstanding on such record date.

          (h) The  provisions  of this  Section 9 shall  similarly  apply to all
successive  events of the type  described  in this  Section  9.  Notwithstanding
anything  contained herein to the contrary,  no adjustment in the Purchase Price
shall be required unless such  adjustment  would require an increase or decrease
of at least 1% in the Purchase Price then in effect; provided, however, that any
adjustments  which by reason of this Subsection 9(h) are not required to be made
shall be carried  forward and taken into account in any  subsequent  adjustment.
All calculations  under this Section 9 shall be made by the Company and shall be
made to the nearest cent or to the nearest one hundredth of a share, as the case
may be, and the Transfer Agent shall be entitled to rely  conclusively  thereon.
Except as provided in this Section 9, no adjustment  in the Purchase  Price will
be made for the issuance of Common Stock or any securities  convertible  into or
exchangeable  for Common Stock or carrying the right to purchase Common Stock or
any securities so convertible or exchangeable.

          (i) Whenever the Purchase  Price is adjusted as provided  herein,  the
Company  shall  promptly  file with the Warrant  Agent an Officers'  Certificate
setting  forth the Purchase  Price in effect after such  adjustment  and setting
forth a brief statement of the facts requiring such  adjustment.  Promptly after
delivery of such  Officers'  Certificate,  the Company shall give or cause to be
given to each  Registered  Holder a notice of such  adjustment  of the  Purchase
Price  setting  forth the  adjusted  Purchase  Price and the date on which  such
adjustment becomes  effective.  The Warrant Agent may rely on the information in
such  Officers'  Certificate  as true and correct and has no duty or  obligation
independently to verify the amounts or calculations set forth therein.

          (j) Notwithstanding  anything contained herein to the contrary, in any
case in which this Section 9 provides that an  adjustment in the Purchase  Price
shall become effective immediately after a record date for an event, the Company
may  defer  (and  shall  promptly  give the  Warrant  Agent  notice  of any such
deferral)  until the  occurrence  of such event (i)  issuing  to the  Registered
Holder of any Class A Warrants  exercised  after such record date and before the
occurrence  of such event the  additional  shares of Common Stock  issuable upon
such exercise by reason of the adjustment  required by such event over and above
the number of shares of Common Stock  issuable upon such exercise  before giving
effect to such adjustment and (ii) paying to such  Registered  Holder any amount
in cash in lieu of any fractional share of Common Stock pursuant to Section 10.

          (k)  Notwithstanding  any other provision hereof, no adjustment to the
Purchase  Price shall be made upon the issuance or exercise or conversion of (1)
options or warrants to purchase,  in the aggregate,  up to 25% of the securities
sold in the  offerings of  securities  of the Company  described in the Original
Offer to  Exchange  or any options or warrants  described  in the  Amendment  in
respect of the Alternative  Equity  Offering,  in each case issued to (or to the
designee of) any placement agent or financial advisor (such options or warrants,
the "Offering  Warrants"),  (2) any equity securities or warrants of the Company
(including,  without  limitation,  the Series A Preferred  Stock,  warrants  and
equity securities underlying warrants) issued in


                                      -14-
<PAGE>

exchange for 9% Notes or accrued  interest thereon or pursuant to the conversion
or exercise provisions  thereof,  (3) any warrants issued in connection with the
offerings  described  in  the  Original  Offer  to  Exchange  or  the  Amendment
(collectively,  the  "Offering"),  (4) any  warrants  issued  to  Forum  Capital
Markets,  LLC  ("Forum") in exchange for or in addition to, or any amendment to,
any warrants held by Forum, in each case,  pursuant to a letter  agreement dated
January 5, 1998,  between  the  Company  and Forum,  and any other  warrants  to
purchase Common Stock or shares of Common Stock issued to Forum or its designee,
(5) any Series A Preferred  Stock issued in the Offering,  (6) any Capital Stock
issued or cash paid as  dividends  on the  Series A  Preferred  Stock or (7) any
Capital Stock issued or cash paid upon the mandatory conversion or redemption of
any Series A Preferred  Stock in accordance with Section 5 of the Certificate of
Designation for the Series A Preferred Stock.

          (l) Any  determination  as to whether an  adjustment  in the  Purchase
Price in effect hereunder is required pursuant to Section 9, or as to the amount
of any such  adjustment,  if required,  shall be binding upon the holders of the
Class A Warrants and the Company if made in good faith by the Board of Directors
of the Company.

          SECTION 10. Fractional  Warrants and Fractional  Shares. No fractional
shares or scrip  representing  fractional shares of Common Stock shall be issued
upon exercise of Class A Warrants. If more than one certificate evidencing Class
A Warrants shall be surrendered for exercise at one time by the same holder, the
number of full shares  issuable upon  exercise  thereof shall be computed on the
basis of the aggregate number of Class A Warrants so surrendered. Instead of any
fractional share of Common Stock which would otherwise be issuable upon exercise
of such aggregate number of Class A Warrants,  the Company may elect in its sole
discretion,  independently  for each  holder,  whether  such number of shares of
Common  Stock will be rounded to the  nearest  whole  share  (with .5 of a share
rounded  upward) or  whether  such  holder  will be given  cash,  in lieu of any
fractional share, in an amount equal to the same fraction of the Market Price of
the Common Stock as of the Exercise Date.

          SECTION  11.  Warrant  Holders Not Deemed  Stockholders.  No holder of
Class A Warrants shall, as such, be entitled to vote or to receive  dividends or
be deemed  the  holder of Common  Stock  that may at any time be  issuable  upon
exercise of such Class A Warrants for any purpose whatsoever, nor shall anything
contained herein be construed to confer upon the holder of Class A Warrants,  as
such, any of the rights of a stockholder of the Company or any right to vote for
the election of directors or upon any matter  submitted to  stockholders  at any
meeting thereof, or to give or withhold consent to any corporate action (whether
upon any  recapitalization,  issue or  reclassification  of stock, change of par
value or change of stock to no par value, consolidation, merger or conveyance or
otherwise),  or to  receive  notice of  meetings,  or to  receive  dividends  or
subscription  rights,  until  such  Holder  shall  have  exercised  such Class A
Warrants  and  been  issued  shares  of  Common  Stock  in  accordance  with the
provisions hereof.

          SECTION 12.  Rights of Action.  All rights of action  with  respect to
this  Agreement are vested in the respective  Registered  Holders of the Class A
Warrants, and any Registered Holder of a Class A Warrant, without consent of the
Warrant  Agent or of the holder of any other  Class A Warrant,  may,  in his own
behalf and for his own benefit, enforce against


                                      -15-
<PAGE>

the  Company  his right to  exercise  his Class A Warrants  for the  purchase of
shares of Common  Stock in the manner  provided in the Warrant  Certificate  and
this Agreement.

          SECTION 13. Agreement of Warrant Holders.  Every holder of any Class A
Warrant,  by his acceptance thereof,  consents and agrees with the Company,  the
Warrant Agent and every other holder of any Class A Warrant that:

          (a) The Class A Warrants are  transferable  only on the registry books
of the Warrant Agent by the Registered Holder thereof in person or by his or her
attorney  duly  authorized  in  writing  and  only if the  Warrant  Certificates
representing  such Class A Warrants are surrendered at the office of the Warrant
Agent,  duly  endorsed  or  accompanied  by  a  proper  instrument  of  transfer
satisfactory to the Warrant Agent, in its sole discretion, together with payment
of any applicable transfer taxes; and

          (b) The Company and the Warrant Agent may deem and treat the person in
whose  name the  Warrant  Certificate  is  registered  as the  holder and as the
absolute,  true and lawful owner of the Class A Warrants represented thereby for
all purposes, and neither the Company nor the Warrant Agent shall be affected by
any notice or knowledge to the contrary,  except as otherwise expressly provided
in Section 6.

          SECTION 14. Cancellation of Warrant Certificates. If the Company shall
purchase  or  acquire  any  Class A Warrant  or Class A  Warrants,  the  Warrant
Certificate  or Warrant  Certificates  evidencing  the same,  by  redemption  or
otherwise,  shall thereupon be delivered to the Warrant Agent and canceled by it
and  retired.  The Warrant  Agent shall also cancel the Warrant  Certificate  or
Warrant  Certificates  following  exercise of any or all of the Class A Warrants
represented  thereby or delivered to it for transfer,  split up,  combination or
exchange.

          SECTION 15.  Concerning  the  Warrant  Agent.  The Warrant  Agent acts
hereunder as agent and in a ministerial capacity for the Company, and its duties
shall be determined solely by the provisions  hereof. The Warrant Agent does not
hereby assume any obligation,  relationship,  agency or trust for or with any of
the holders of Warrant  Certificates  or beneficial  owners of Class A Warrants.
The Warrant Agent shall not, by issuing and delivering Warrant Certificates,  or
by any other act  hereunder,  be  deemed to make any  representations  as to the
validity,  value or  authorization  of the Warrant  Certificates  or the Class A
Warrants  represented  thereby or of any securities or other property  delivered
upon  exercise of any Class A Warrant or whether any stock issued upon  exercise
of any Class A Warrant is fully paid and nonassessable.

          The  Warrant  Agent  shall  not at any  time  be  under  any  duty  or
responsibility to any holder of Warrant Certificates to make or cause to be made
any adjustment of the Purchase Price provided in this Agreement, or to determine
whether any fact exists that may require any such  adjustments,  or with respect
to the nature or extent of any such  adjustment,  when made,  or with respect to
the  method  employed  in making  the same.  It shall not (i) be liable  for any
recital or statement of facts contained herein or for any action taken, suffered
or omitted by it in  reliance on any Warrant  Certificate  or other  document or
instrument believed by it in good


                                      -16-
<PAGE>

faith to be genuine and to have been signed or  presented by the proper party or
parties,  (ii) be  responsible  for any  failure  on the part of the  Company to
comply with any of its covenants and obligations  contained in this Agreement or
in any  Warrant  Certificate,  or (iii) be  liable  for any act or  omission  in
connection  with  this  Agreement  except  for its  own  negligence  or  willful
misconduct.

          The Warrant Agent may at any time consult with counsel satisfactory to
it (who  may be  counsel  for the  Company)  and  shall  incur no  liability  or
responsibility for any action taken,  suffered or omitted by it in good faith in
accordance with the opinion or advice of such counsel.

          Any  notice,  statement,  instruction,  request,  direction,  order or
demand of the Company shall be sufficiently evidenced by an instrument signed by
the Chairman of the Board,  President,  or any Vice President and the Secretary,
or any Assistant  Secretary  (unless other evidence in respect thereof is herein
specifically  prescribed).  The Warrant Agent shall not be liable for any action
taken,  suffered or omitted by it in  accordance  with such  notice,  statement,
instruction, request, direction, order or demand believed by it to be genuine.

          The Company  agrees to pay the Warrant Agent  reasonable  compensation
for its  services  hereunder  and to reimburse  it for its  reasonable  expenses
hereunder  as governed by a separate  agreement  to be entered  into between the
Warrant  Agent and the Company;  the Company  further  agrees to  indemnify  the
Warrant  Agent and save it harmless  against any and all  losses,  expenses  and
liabilities,   including  judgments,  costs  and  reasonable  counsel  fees  and
expenses,  for anything done or omitted by the Warrant Agent in the execution of
its duties and powers hereunder except losses,  expenses and liabilities arising
as a result of the Warrant Agent's negligence or willful misconduct.

          The  Warrant  Agent may resign its duties and be  discharged  from all
further duties and liabilities hereunder (except liabilities arising as a result
of the Warrant  Agent's own negligence or willful  misconduct),  after giving 30
days' prior  written  notice to the Company.  At least 15 days prior to the date
such resignation is to become effective, the Warrant Agent shall cause a copy of
such  notice  of  resignation  to be mailed to the  Registered  Holders  of each
Warrant  Certificate at the Company's  expense.  Upon such  resignation,  or any
inability  of the Warrant  Agent to act as such  hereunder,  the  Company  shall
appoint a new warrant  agent in writing.  If the Company shall fail to make such
appointment  within a period of 15 days after it has been notified in writing of
such resignation by the resigning  Warrant Agent,  then the Registered Holder of
any Warrant Certificate may apply to any court of competent jurisdiction for the
appointment of a new warrant agent. Any new warrant agent,  whether appointed by
the Company or by such a court,  shall be a bank or trust company having capital
and surplus,  as shown by its last published report to its stockholders,  of not
less than $10,000,000 or a stock transfer  company.  After acceptance in writing
of such  appointment  by the new warrant agent is received by the Company,  such
new  warrant  agent  shall be vested with the same  powers,  rights,  duties and
responsibilities as if it had been originally named herein as the Warrant Agent,
without any further assurance, conveyance, act or deed; but if for any reason it
shall be necessary  or  expedient to execute and deliver any further  assurance,
conveyance,  act or deed,  the same shall be done at the  expense of the Company
and shall be legally and validly executed


                                      -17-
<PAGE>

and delivered by the resigning  Warrant Agent. Not later than the effective date
of any  such  appointment,  the  Company  shall  file  notice  thereof  with the
resigning  Warrant Agent and shall  forthwith  cause a copy of such notice to be
mailed to the Registered Holder of each Warrant Certificate.

          Any entity into which the Warrant  Agent or any new warrant  agent may
be converted or merged or any entity  resulting from any  consolidation to which
the  Warrant  Agent or any new  warrant  agent  shall  be a party or any  entity
succeeding  to the trust  business  of the  Warrant  Agent  shall be a successor
warrant agent under this Agreement  without any further act,  provided that such
entity is eligible for  appointment  as successor to the Warrant Agent under the
provisions of the preceding  paragraph.  Any such successor  warrant agent shall
promptly  cause notice of its  succession  as warrant  agent to be mailed to the
Company and to the Registered Holder of each Warrant Certificate.

          The Warrant Agent, its subsidiaries and affiliates,  and any of its or
their officers or directors,  may buy and hold or sell Class A Warrants or other
securities of the Company and otherwise deal with the Company in the same manner
and to the same  extent  and with like  effects  as  though it were not  Warrant
Agent.  Nothing herein shall preclude the Warrant Agent from acting in any other
capacity for the Company or for any other legal entity.

          SECTION 16.  Modification  of  Agreement.  The parties  hereto and the
Company may by  supplemental  agreement  make any changes or corrections in this
Agreement  (i) that they  shall deem  appropriate  to cure any  ambiguity  or to
correct any  defective or  inconsistent  provision or manifest  mistake or error
herein contained;  (ii) to reflect an increase in the number of Class A Warrants
which are to be governed by this Agreement  resulting from a subsequent offering
of Company  securities which includes Class A Warrants having the same terms and
conditions as the Class A Warrants,  originally covered by or subsequently added
to this  Agreement  under this Section 16; or (iii) that they may deem necessary
or desirable and that shall not adversely affect the interests of the holders of
Warrant Certificates; provided, however, that this Agreement shall not otherwise
be modified,  supplemented  or altered in any respect except with the consent in
writing of the Registered Holders of Warrant Certificates representing more than
50% of the Class A Warrants then  outstanding;  and provided,  further,  that no
change in the number or nature of the securities  purchasable  upon the exercise
of any Class A Warrant,  or the Purchase Price therefor,  or the acceleration of
the Warrant Expiration Date, shall be made without the consent in writing of the
Registered Holder of the Warrant Certificate  representing such Class A Warrant,
other than such  changes as are  specifically  prescribed  by this  Agreement as
originally executed or are made in compliance with applicable law.

          SECTION  17.  Notices.  All  notices,  requests,  consents  and  other
communications  hereunder  shall be in writing  and shall be deemed to have been
made when  delivered or mailed by means of first class  registered  or certified
mail,  postage  prepaid as  follows:  if to the  Registered  Holder of a Warrant
Certificate,  at the  address  of such  holder  as shown on the  registry  books
maintained by the Warrant Agent;  and if to the Company,  at 620 Memorial Drive,
Cambridge,  Massachusetts,  02139,  or at such  other  address  as may have been
furnished  to the  Warrant  Agent in writing by the  Company;  if to the Warrant
Agent, at its Corporate Office, Attention: Relationship Manager.


                                      -18-
<PAGE>

          SECTION  18.  Restrictions  on  Change  of  Control.   Notwithstanding
anything to the contrary contained in this Agreement,  without the prior written
consent of the Company,  so long as any 9% Notes remain  outstanding  under that
certain  Indenture dated as of March 26, 1997 (as amended,  the  "Indenture") in
respect of the 9% Notes,  no holder of Class A  Warrants  shall be  entitled  to
exercise  such  Class A Warrants  to the  extent  such  exercise  could,  in the
Company's  reasonable  judgment,  either  alone  or in  conjunction  with  other
issuances or holdings of capital stock, other warrants or convertible securities
of the Company, result in a Change of Control (as defined in the Indenture).

          SECTION 19.  Governing Law. This  Agreement  shall be governed by, and
construed  in  accordance  with,  the  laws of the  State of New  York,  without
reference to principles of conflict of laws.

          SECTION 20. Binding  Effect.  This Agreement shall be binding upon and
inure to the  benefit of the  Company,  the Warrant  Agent and their  respective
successors  and  assigns,   and  the  holders  from  time  to  time  of  Warrant
Certificates.  Nothing in this  Agreement  is intended nor shall be construed to
confer upon any other person any right, remedy or claim, in equity or at law, or
to impose upon any other person any duty, liability or obligation.

          SECTION 21.  Termination.  This Agreement shall terminate at the close
of business on the Warrant  Expiration  Date of all the Class A Warrants or such
earlier  date upon which all Class A Warrants  have been  exercised or redeemed,
except that the Warrant  Agent shall  account to the Company for cash held by it
and Section 15 shall survive such termination.

          SECTION 22.  Counterparts.  This  Agreement may be executed in several
counterparts, which taken together shall constitute a single document.


                                      -19-
<PAGE>

                  IN WITNESS  WHEREOF,  the  parties  hereto  have  caused  this
Agreement to be duly executed as of the date first above written.

                                HYBRIDON, INC.

                                By:
                                   ---------------------------
                                   Authorized Officer



                                CHASEMELLON SHAREHOLDER
                                SERVICES, L.L.C., as Warrant Agent


                                By:
                                   ---------------------------
                                   Authorized Officer


                                      -20-
<PAGE>

                                    EXHIBIT A

                  [FORM OF FACE OF CLASS A WARRANT CERTIFICATE]

THE TERMS OF THIS  WARRANT  ARE SUBJECT TO THE TERMS OF A WARRANT  AGREEMENT,  A
COPY OF WHICH IS AVAILABLE FROM HYBRIDON,  INC. (THE "COMPANY").  THE SECURITIES
REPRESENTED  BY THIS WARRANT HAVE NOT BEEN  REGISTERED  UNDER THE UNITED  STATES
SECURITIES  ACT OF 1933, AS AMENDED (THE  "SECURITIES  ACT"),  OR ANY APPLICABLE
STATE  SECURITIES  LAWS,  AND MAY NOT BE SOLD,  OFFERED  FOR  SALE,  PLEDGED  OR
HYPOTHECATED OR OTHERWISE TRANSFERRED IN THE ABSENCE OF A REGISTRATION STATEMENT
IN  EFFECT  WITH  RESPECT  TO THE  SECURITIES  UNDER  THE  SECURITIES  ACT OR AN
EXEMPTION  FROM THE  SECURITIES  ACT.  ANY SUCH  TRANSFER MAY ALSO BE SUBJECT TO
COMPLIANCE  WITH  APPLICABLE  STATE  SECURITIES  LAWS  AND  THE  LAWS  OF  OTHER
APPLICABLE JURISDICTIONS.

No. __ _______________ Class A Warrants

                       VOID AFTER __________________, 2003

                    CLASS A WARRANT CERTIFICATE FOR PURCHASE
                                 OF COMMON STOCK

                                 HYBRIDON, INC.

         This certifies that FOR VALUE RECEIVED
- --------------------------------------------------------------------------------
____________________________  or registered assigns (the "Registered Holder") is
the owner of the  number of Class A  Warrants  ("Class  A  Warrants")  specified
above. Each Class A Warrant represented hereby initially entitles the Registered
Holder  to  purchase,  subject  to the terms  and  conditions  set forth in this
Warrant  Certificate  and the Warrant  Agreement (as hereinafter  defined),  one
fully paid and  nonassessable  share of Common Stock,  par value $.001 per share
("Common Stock"), of Hybridon, Inc., a Delaware corporation (the "Company"),  at
any time between _______________,  1999, and the Expiration Date (as hereinafter
defined),  upon the presentation and surrender of this Warrant  Certificate with
the  Subscription  Form on the reverse  hereof duly  executed,  at the corporate
office of ChaseMellon  Shareholder  Services,  L.L.C.,  as Warrant Agent, or its
successor  (the "Warrant  Agent"),  accompanied by payment of the Purchase Price
(as defined in the Warrant  Agreement)  in lawful money of the United  States of
America in cash or by  official  bank or  certified  check  made  payable to the
Company.

          This Warrant  Certificate and each Class A Warrant  represented hereby
are issued  pursuant  to,  and are  subject  in all  respects  to, the terms and
conditions set forth in the Warrant Agreement (the "Warrant  Agreement"),  dated
________ _____, 1998, by and among the Company and the Warrant Agent.

<PAGE>

          In the event of  certain  contingencies  provided  for in the  Warrant
Agreement,  the  Purchase  Price  and/or  the  number of shares of Common  Stock
subject to purchase upon the exercise of each Class A Warrant represented hereby
are subject to modification or adjustment.  Furthermore, this Warrant may not be
exercised  in certain  circumstances  described  in  Section  18 of the  Warrant
Agreement.

          Each Class A Warrant  represented  hereby is exercisable at the option
of the  Registered  Holder,  but no  fractional  shares of Common  Stock will be
issued.  In the  case of the  exercise  of  fewer  than  every  Class A  Warrant
represented  hereby, the Company shall cancel this Warrant  Certificate upon the
surrender  hereof and shall  execute and deliver a new  Warrant  Certificate  or
Warrant  Certificates of like tenor,  which the Warrant Agent shall countersign,
for the balance of such Class A Warrants.

          The term  "Expiration  Date"  shall mean 5:00 P.M.  (New York time) on
____________,  2003,  or such  earlier  date as the  Class A  Warrants  shall be
redeemed.  If such date  shall in the State of New York be a holiday or a day on
which banks are authorized to close,  then the  Expiration  Date shall mean 5:00
P.M.  (New York time) the next  following  day which in the State of New York is
not a holiday or a day on which banks are  authorized  to close.  Upon notice to
all Registered Holders of the Class A Warrants, the Company shall have the right
to extend the Expiration Date.

          The Class A Warrants  represented  hereby shall not be  exercisable in
any state where such exercise would be unlawful.

          This Warrant Certificate is exchangeable, upon the surrender hereof by
the Registered  Holder at the corporate  office of the Warrant Agent,  for a new
Warrant Certificate or Warrant  Certificates of like tenor representing an equal
aggregate number of Class A Warrants,  each of such new Warrant  Certificates to
represent  such  number  of Class A  Warrants  as shall  be  designated  by such
Registered  Holder at the time of such surrender.  Upon due presentment with any
applicable  transfer  fee  per  certificate  in  addition  to any  tax or  other
governmental  charge  imposed  in  connection  therewith,  for  registration  of
transfer of this Warrant  Certificate at such office, a new Warrant  Certificate
or  Warrant  Certificates  representing  an equal  aggregate  number  of Class A
Warrants will be issued to the transferee in exchange  therefor,  subject to the
limitations provided in the Warrant Agreement.

          The  Registered  Holder  shall  not be  entitled  to any  rights  of a
stockholder of the Company in respect of any  unexercised  Class A Warrants held
by such Registered Holder, including,  without limitation,  the right to vote or
to  receive  dividends  or other  distributions,  and shall not be  entitled  to
receive any notice of any proceedings of the Company,  except as provided in the
Warrant Agreement.

          Prior to due presentment  for  registration  of transfer  hereof,  the
Company and the Warrant  Agent may deem and treat the  Registered  Holder as the
absolute  owner  hereof  and  of  each  Class  A  Warrant   represented   hereby
(notwithstanding  any  notations of  ownership or writing  hereon made by anyone
other than a duly  authorized  officer of the Company or the Warrant  Agent) for
all purposes and shall not be affected by any notice to the contrary.


                                      -2-
<PAGE>

          This  Warrant  Certificate  shall  be  governed  by and  construed  in
accordance with the laws of the State of New York.

          This  Warrant  Certificate  is not valid unless  countersigned  by the
Warrant Agent.

          IN WITNESS WHEREOF, the Company has caused this Warrant Certificate to
be duly  executed,  manually or in facsimile,  by two of its officers  thereunto
duly authorized and a facsimile of its corporate seal to be imprinted hereon.


                                      HYBRIDON, INC.


Dated:                                By:
      ---------------------------        --------------------------------------
                                      By:
                                         --------------------------------------
                                                         [seal]



Countersigned:

CHASEMELLON SHAREHOLDER SERVICES, L.L.C.,
as Warrant Agent


By: 
    -----------------------------------
         Authorized Officer


                                      -3-
<PAGE>

                    [FORM OF REVERSE OF WARRANT CERTIFICATE]

                TRANSFER FEE: $___________ PER CERTIFICATE ISSUED

                                SUBSCRIPTION FORM

                     To Be Executed by the Registered Holder
                      in Order to Exercise Class A Warrants


          The  undersigned   Registered  Holder  hereby  irrevocably  elects  to
exercise _________ Class A Warrants represented by this Warrant Certificate, and
to purchase the securities  issuable upon the exercise of such Class A Warrants,
and requests that  certificates  for such securities shall be issued in the name
of

            PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER

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

                     [please print or type name and address]

and be delivered to

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

                     [please print or type name and address]

and if such  number of Class A  Warrants  shall not be all the Class A  Warrants
evidenced by this Warrant  Certificate,  that a new Warrant  Certificate for the
balance of such Class A Warrants be registered in the name of, and delivered to,
the Registered Holder at the address stated below.


                                      -4-
<PAGE>

The  undersigned  represents that the exercise of the within Class A Warrant was
solicited by a member of the National Association of Securities Dealers, Inc. If
not solicited by an NASD member, please write "unsolicited" in the space below.


                                         ---------------------------------------
                                         (Name of NASD Member)


Dated:                                   X
      -----------------------              -------------------------------------
                                           -------------------------------------
                                           -------------------------------------
                                                         Address


                                           -------------------------------------
                                               Taxpayer Identification Number


                                           -------------------------------------
                                                    Signature Guaranteed


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


                                      -5-
<PAGE>

                                   ASSIGNMENT

                     To Be Executed by the Registered Holder
                       in Order to Assign Class A Warrants

FOR VALUE RECEIVED, _______________________________________________ hereby
sells, assigns and transfers unto

            PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER

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

                     [please print or type name and address]

________________________________  of the Class A  Warrants  represented  by this
Warrant   Certificate,   and  hereby   irrevocably   constitutes   and  appoints
______________________________

- --------------------------------------------------------------------------------
Attorney to transfer this Warrant Certificate on the books of the Company,  with
full power of substitution in the premises.

Dated:                                   X
      -----------------------              -------------------------------------
                                                   Signature Guaranteed

THE SIGNATURE TO THE ASSIGNMENT OR THE SUBSCRIPTION  FORM MUST CORRESPOND TO THE
NAME AS WRITTEN UPON THE FACE OF THIS WARRANT  CERTIFICATE IN EVERY  PARTICULAR,
WITHOUT  ALTERATION  OR  ENLARGEMENT  OR ANY  CHANGE  WHATSOEVER,  AND  MUST  BE
GUARANTEED BY A MEMBER OF THE MEDALLION STAMP PROGRAM.

                                      -6-
<PAGE>

                                                                         ANNEX C

    As filed with the Securities and Exchange Commission on February 24, 1998
- --------------------------------------------------------------------------------

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


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

                                    FORM 8-K

                                 CURRENT REPORT

                     PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934


       Date of Report (Date of earliest event reported): February 9, 1998


                                     0-27352
                            (Commission File Number)


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


                                 HYBRIDON, INC.
             (Exact name of registrant as specified in its charter)


           Delaware                                       3072298
     (State of Incorporation)                          (IRS Employer
                                                  Identification Number)


               620 Memorial Drive, Cambridge, Massachusetts 02139
              (Address of registrant's principal executive office)


                                 (617) 528-7000
                         (Registrant's telephone number)


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

- --------------------------------------------------------------------------------
<PAGE>
ITEM 9. Sales of Equity Securities Pursuant to Regulation S

          On February 9, 1998, as part of a private  placement (the "Offering"),
Hybridon,  Inc. (the "Company") sold $2,384,000 in principal amount of Notes due
2007 (the "Offering  Notes"),  and warrants (the  "Warrants") to purchase common
stock,  par value $.001 per share, of the Company,  pursuant to the terms of the
Offering  described  in its Current  Report on Form 8-K,  and the press  release
filed as an exhibit  thereto,  dated  January  22, 1998 (the  "January  22, 1998
8-K").  The  Offering  Notes were issued at face value in offshore  transactions
pursuant to  Regulation  S  promulgated  under the  Securities  Act of 1933,  as
amended (the  "Securities  Act").  The  purchasers  of the  Offering  Notes were
accredited   investors  (as  defined  in  Regulation  D  promulgated  under  the
Securities Act).

          The terms of  conversion  of the  Offering  Notes and the terms of the
Warrants are described in the January 22, 1998 8-K.

          The net  proceeds  to the  Company  from the  Offering  are  presently
intended 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 the Company's debt obligations.

<PAGE>

                                   SIGNATURES


          Pursuant to the  requirements of the Securities  Exchange Act of 1934,
the  registrant  has duly  caused  this report to be signed on its behalf by the
undersigned, thereunto duly authorized.


                               HYBRIDON, INC.

                               By: /s/ E. ANDREWS GRINSTEAD, III
                                   ------------------------------------------
                                     Name:  E. Andrews Grinstead, III
                                     Title: Chairman of the Board, President and
                                            Chief Executive Officer

                               Date:  February 24, 1998




                                 Exhibit 9(a)(7)

                                 HYBRIDON, INC.

                                    AMENDMENT
               TO THE EXCHANGE AGREEMENT AND LETTER OF TRANSMITTAL
                 TO TENDER AND TO ENTER INTO CERTAIN AGREEMENTS
            IN RESPECT OF 9% CONVERTIBLE SUBORDINATED NOTES DUE 2004
                  OF HYBRIDON PURSUANT TO ITS OFFER TO EXCHANGE
                       DATED FEBRUARY 6, 1998, AS AMENDED
                  BY AN AMENDMENT THERETO DATED MARCH 30, 1998


THE OFFER,  AS AMENDED,  WILL EXPIRE AT 12:00  MIDNIGHT,  NEW YORK CITY TIME, ON
APRIL 10,  1998,  UNLESS  EXTENDED  (THE  "EXPIRATION  DATE").  THE OFFER MAY BE
WITHDRAWN AT ANY TIME PRIOR TO 12:00 MIDNIGHT,  NEW YORK TIME, ON THE EXPIRATION
DATE.

              Hybridon,  Inc., a Delaware  corporation  ("Hybridon"),  is hereby
amending the terms of the offer to exchange (the "Offer") with respect to its 9%
Convertible  Subordinated Notes due 2004 (the "Notes") set forth in its Offer to
Exchange,  dated  February 6, 1998 (the "Original  Offer to  Exchange").  Unless
otherwise  provided  in  this  Amendment  (this  "Amendment")  to  the  Exchange
Agreement  and the  Letter  of  Transmittal  which  was sent  together  with the
Original Offer to Exchange (the "Original Letter of Transmittal") to the holders
of the Notes or unless  the  context  requires  otherwise,  the terms of and the
conditions to the Offer  contained in the Original Letter of Transmittal and the
Original Offer to Exchange remain  unchanged.  All capitalized terms used herein
but not defined herein shall have the respective  meanings  ascribed  thereto in
the Original Offer to Exchange, as amended by the accompanying Amendment thereto
dated  March 30, 1998 (the  "Amendment";  the  Original  Offer to  Exchange,  as
amended by the Amendment, being referred to herein as the" Offer to Exchange").

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

              In the event that the Alternative Consideration is to be issued in
connection with the Offer,  any tender of Notes which involves  denominations of
less than $1,000 in  Exchange  Value  thereof  will be  exchanged  on a pro rata
basis,  except to the extent that such proration would result in the issuance of
a fractional  share of Alternative  Series A Preferred  Stock. In the event that
such fractional  share would result,  Hybridon  shall,  at its sole  discretion,
either (a) round such  fractional  share to the nearest  whole  number of shares
(with 0.5 being rounded up), or (b) pay in cash an amount equal to such fraction
multiplied by $100 (which is the per share stated value of Alternative  Series A
Preferred  Stock).  Hybridon will not issue any fractional shares of Alternative
Series A Preferred Stock in the Offer. In the event that a tendering  Noteholder
would  otherwise  be  entitled  to  receive a  fractional  Alternative  Exchange
Warrant, Hybridon shall round up such fractional Alternative Exchange Warrant to
the nearest whole number of Alternative Exchange Warrants.

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

              IN  ADDITION  TO THE  ORIGINAL  LETTER  OF  TRANSMITTAL  AND OTHER
REQUIRED DOCUMENTS,  ALL REGISTERED HOLDERS AND BENEFICIAL OWNERS OF NOTES BEING
TENDERED MUST EXECUTE AND SEND THIS  AMENDMENT TO THE  DEPOSITARY ON OR PRIOR TO
THE EXPIRATION DATE,  REGARDLESS OF WHETHER THEY HAVE HERETOFORE  TENDERED THEIR
NOTES  PURSUANT  TO THE  OFFER.  ANY  TENDER  OF NOTES NOT  ACCOMPANIED  BY THIS
AMENDMENT AND THE ORIGINAL LETTER OF TRANSMITTAL  WILL BE DEEMED  INVALID.  THIS
AMENDMENT  MUST BE DELIVERED TO THE  DEPOSITARY  AT THE ADDRESS OR THE FACSIMILE
NUMBER  SHOWN ON THE BACK COVER OF THE  ORIGINAL  LETTER OF  TRANSMITTAL  AND IN
ACCORDANCE  WITH THE PROCEDURES SET FORTH IN THE ORIGINAL OFFER TO EXCHANGE,  AS
AMENDED, AND IN THE ORIGINAL LETTER OF TRANSMITTAL.


<PAGE>

              The Original Letter of Transmittal is hereby amended as follows:

          (i)  In the event that the Alternative  Consideration  shall be issued
               in exchange for the Notes as a result of the  consummation of the
               Alternative Equity Offering, all references to Series A Preferred
               Stock and Exchange Warrants contained in Articles I, II and IV of
               the Exchange  Agreement portion of the Letter of Transmittal (the
               "Exchange  Agreement"),  and in the instructions  forming part of
               the  Letter  of   Transmittal,   shall  be  deemed  to  mean  the
               Alternative Series A Preferred Stock and the Alternative Exchange
               Warrants, respectively.

          (ii) Section  2 of  Article  II of the  Exchange  Agreement  is hereby
               amended  by  inserting  the  following  sentence  after  the last
               sentence thereof:

                    Notwithstanding  anything to the contrary  contained in this
                    Section 2 of Article  II, in the event that the  Alternative
                    Consideration  is  issued  in  exchange  for the  Notes as a
                    result  of  the  consummation  of  the  Alternative   Equity
                    Offering,  Hybridon  shall use its best efforts to file with
                    the Commission a Registration Statement pursuant to Rule 415
                    under the Securities Act no later than the earlier of (i) 60
                    days  following  the date on which  the  Alternative  Equity
                    Offering  is  consummated  and (ii)  the  date on which  any
                    registration  statement under the Securities Act is filed in
                    respect  of  the  resale  of  any   security   sold  in  the
                    Alternative Equity Offering.

         (iii) Article  III of the  Exchange  Agreement  is  hereby  amended  by
               replacing in its entirety the existing  sentence  thereunder with
               the following sentence:

                    For so long as at least 50% of the Series A Preferred  Stock
                    or Alternative Series A Preferred Stock, as the case may be,
                    initially  issued  in the  Offer  remains  outstanding,  the
                    holders of such Series A Preferred Stock or such Alternative
                    Series A Preferred  Stock, as the case may be, issued in the
                    Offer  shall  be  entitled  to  designate   one  member  for
                    nomination  to the  Board  of  Directors  of  Hybridon  (the
                    "Designated  Director"),   provided  that  such  nominee  is
                    reasonably  acceptable to Hybridon.  The initial  Designated
                    Director  shall be Mr. Art Berry  (unless  the  holders of a
                    majority of the Series A Preferred  Stock or the Alternative
                    Series A Preferred  Stock, as the case may be, issued in the
                    Offer shall instruct  otherwise in the space provided in the
                    Amendment  to the Letter of  Transmittal,  in which case the
                    person  receiving  the  most  votes  shall  be  the  initial
                    Designated Director),  to hold office until his successor is
                    duly elected and qualified or until his earlier  resignation
                    or removal.

          (iv) Sections  1 and 2 of  Article  V of the  Exchange  Agreement  are
               hereby  amended  by  replacing  the  references  therein  to  the
               "Restructuring Trigger" with the following:

                    Restructuring  Trigger  (in  the  event  that  the  Original
                    Consideration  is issued  in the  Offer)  or  following  the
                    consummation  of Alternative  Equity  Offering (in the event
                    that the Alternative Consideration is issued in the Offer)

               and the  reference  therein to Series A Preferred  Stock shall be
               deemed to mean the  Alternative  Series A Preferred  Stock if the
               Alternative  Consideration is issued in exchange for the Notes as
               a result of the consummation of the Alternative Equity Offering.

          (v)  The reference to Series A Preferred Stock in Section 2 of Article
               V  of  the  Exchange  Agreement  shall  be  deemed  to  mean  the
               Alternative   Series  A  Preferred   Stock  if  the   Alternative
               Consideration  is issued in exchange for the Notes as a result of
               the consummation of the Alternative Equity Offering.


                                      - 2 -

<PAGE>

          (vi) Section  3 of  Article  V of the  Exchange  Agreement  is  hereby
               amended  by  inserting  the  following  sentence  after  the last
               sentence thereof:

                    Notwithstanding  anything to the contrary  contained in this
                    Section 3 of Article  V, in the event  that the  Alternative
                    Equity Offering is  consummated,  no Reset Warrants shall be
                    issued by Hybridon to the undersigned.

         (vii) In the event that the Alternative  Consideration  shall be issued
               in exchange for the Notes as a result of the  consummation of the
               Alternative Equity Offering, all references to Series A Preferred
               Stock contained in Article V, "Certain  Additional  Covenants and
               Representations  of Hybridon," of the Exchange Agreement shall be
               deemed to mean the Alternative Series A Preferred Stock.

        (viii) In the event that the Alternative Consideration shall be issued
               in exchange for the Notes as a result of the  consummation of the
               Alternative Equity Offering, all references to Series A Preferred
               Stock contained in Article VI of the Exchange  Agreement shall be
               deemed to mean the Alternative Series A Preferred Stock issued in
               the  Offer  as  part  of the  Alternative  Consideration  and any
               Alternative  Series A Preferred  Stock  declared  and issued as a
               dividend on such  Alternative  Series A Preferred Stock issued in
               the Offer.


                                      - 3 -

<PAGE>

         This Amendment will become effective and binding on the undersigned and
Hybridon at such time that  Hybridon  accepts for  exchange  any of the Exchange
Value of the Notes tendered by the undersigned.


                         PLEASE SIGN AND COMPLETE BELOW
        TO BE COMPLETED WHERE APPROPRIATE BY ALL HOLDERS TENDERING NOTES
                   (WHETHER OR NOT NOTES ARE BEING PHYSICALLY
                                    TENDERED)

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

ONLY REGISTERED NOTEHOLDER(S) SHOULD PROVIDE THIS INFORMATION AND SIGN
HERE. (BENEFICIAL OWNERS SHOULD COMPLETE THE INFORMATION REQUESTED ON,
AND SIGN, THE LAST PAGE HEREOF):

         I have read this  Amendment  to the  Exchange  Agreement  and Letter of
Transmittal and agree to be bound by the foregoing.

         I hereby  certify that,  to the best of my  knowledge,  the Notes being
tendered are beneficially owned by: ____________________________________________
(if beneficially  owned by more than one person, I have indicated in parenthesis
the principal amount owned by each such person.)

         x___________________________________________________
         Signature(s) of Registered Noteholder(s) or Authorized Signatory

         ----------------------------------------------------
         Type or Print Name

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

         ----------------------------------------------------
         Type or Print Address(es)

         ----------------------------------------------------
         Capacity (Full Title)

         Dated:_______________, 1998

         Area Code and telephone No(s).:____________________________

         Tax Identification or Social Security No(s).:_________________________


         Must be signed by the registered  Noteholder(s)  exactly as the name(s)
appear(s) on the  certificate and by person(s)  authorized to become  registered
Noteholder(s) as evidenced by endorsements  and documents.  See Instruction 4 to
the Original  Letter of  Transmittal.  If  signature is by a trustee,  executor,
administrator,  guardian, attorney-in-fact,  officer of a corporation, agent, or
other  person  acting in a  fiduciary  or  representative  capacity,  please see
Instruction 4 to the Original Letter of Transmittal.


                                      - 4 -

<PAGE>

BENEFICIAL OWNER(S) OF THE NOTES BEING TENDERED (INCLUDING ANY REGISTERED
NOTEHOLDER(S) WHO ARE ALSO BENEFICIAL OWNER(S)) MUST CAREFULLY READ THE
FOLLOWING AND COMPLETE AND SIGN BELOW:

         I have read this  Amendment  to the  Exchange  Agreement  and Letter of
Transmittal  carefully and agree to be bound by each  covenant  contained in the
Original Letter of Transmittal, as amended by this Amendment.

         I  (hereinafter   referred  to  as  "Holder")  hereby  acknowledge  and
represent and warrant to Hybridon as follows:


     A. Investment Representations


         a. Investment Intent. The Holder recognizes that the tender of Notes in
exchange for Series A Preferred  Stock and Exchange  Warrants (in the event that
the  Original  Consideration  shall be issued in the  Offer) or the  Alternative
Series A Preferred  Stock and the  Alternative  Exchange  Warrants (in the event
that  the  Alternative  Consideration  shall be  issued  in the  Offer)  and the
Hybridon  Common  Stock  underlying  the  foregoing  securities  (the  foregoing
securities   are   hereinafter   collectively   referred  to  as  the  "Exchange
Securities")  involves a high degree of risk including,  but not limited to, the
following:  (i)  Hybridon  remains a  development  stage  business  with limited
operating history and requires substantial  additional funds; (ii) an investment
in Hybridon is highly speculative, and only investors who can afford the loss of
their entire  investment  should consider  tendering their Notes in exchange for
the  Exchange  Securities;  (iii) the  Holder may not be able to  liquidate  his
Exchange Securities received in the Offer; (iv)  transferability of the Exchange
Securities  received in the Offer is  extremely  limited;  (v) in the event of a
disposition of the Exchange  Securities  received in the Offer such Holder could
sustain the loss of his entire  investment  and (vi)  Hybridon  has not paid any
dividends  since  inception and does not  anticipate the payment of dividends on
the  Hybridon  Common Stock or the Series A Preferred  Stock or the  Alternative
Series A Preferred  Stock (except as required in the  applicable  Certificate of
Designation) in the foreseeable future.

         b. Lack of Liquidity.  The Holder confirms that he or it is able (i) to
bear the economic risk of this investment,  (ii) to hold the Exchange Securities
received in the Offer for an indefinite  period of time, and (iii)  presently to
afford a  complete  loss of the  investment;  and  represents  that he or it has
sufficient liquid assets so that the illiquidity associated with this investment
will not cause any undue financial  difficulties or affect such Holder's ability
to provide for his or its current  needs and possible  financial  contingencies,
and that his or its commitment to all  speculative  investments is reasonable in
relation  to his or its net worth and annual  income.  Furthermore,  each Holder
acknowledges  that the Series A  Preferred  Stock and the  Alternative  Series A
Preferred  Stock each  contains  certain  applicable  restrictions  on exercise,
voting,  conversion and certain other rights,  as more particularly set forth in
the applicable Certificate of Designation.

         c.  Knowledge  and  Experience.   Such  Holder  has  prior   investment
experience, including investment in securities that are non-listed, unregistered
and are not  traded  on the  Nasdaq  National  or  SmallCap  Market,  nor on the
National  Association  of  Securities  Dealers,  Inc.'s (the  "NASD")  automated
quotation system, or such Holder has employed at its own expense the services of
an investment  advisor,  attorney  and/or  accountant to request  documents from
Hybridon  pursuant  to  Section  [e.]  hereof  and to read all of the  documents
furnished  or made  available  by Hybridon  to such  Holder and to evaluate  the
investment,  tax and  legal  merits  and the  consequences  and  risks of such a
transaction  on such  Holder's  behalf,  that such  Holder or such  professional
advisor has such knowledge and experience in financial and business matters that
such Holder or such professional advisor is capable of evaluating the merits and
risks of the prospective  investment and that such professional advisor, if any,
satisfies the conditions set out in Rule 501(h) under the Securities Act.

         d.  Holder  Capacity.  Either by reason of such  Holder's  business  or
financial  experience,  or the business or financial experience of such Holder's
professional advisors (who are unaffiliated with, and


                                      - 5 -

<PAGE>

who are not  compensated  by,  Hybridon or any affiliate or selling or placement
agent of  Hybridon,  directly or  indirectly),  such Holder has the  capacity to
protect  such  Holder's  own  interests  in  connection   with  the  transaction
contemplated hereby.

         e. Offer to  Exchange.  Such  Holder  hereby  acknowledges  receipt and
careful  review  of the Offer to  Exchange  of  Hybridon,  as  supplemented  and
amended,  and the annexes  and  exhibits  thereto,  all of which  constitute  an
integral part thereof, including,  without limitation, the information contained
in all material  concerning  Hybridon provided to the registered  holders of the
Notes in connection  with the Offer and hereby  represents  that such Holder has
been furnished by Hybridon with all  information  regarding  Hybridon which such
Holder or its representative has requested or desired to know, has been afforded
the  opportunity  to  ask  questions  of,  and to  receive  answers  from,  duly
authorized  officers or other  representatives of Hybridon  concerning the terms
and  conditions  of the Offer and the  Exchange  Securities  and the  affairs of
Hybridon and has received any  additional  information  which such Holder or its
representative has requested.

         f.  Reliance on  Information.  Such  Holder has relied  solely upon the
information provided by Hybridon in the Offer to Exchange in making the decision
to tender the Notes. To the extent necessary,  each Holder has retained,  at the
sole expense of such Holder, and relied upon,  appropriate  professional  advice
regarding the investment, tax and legal merits and consequences of the Offer and
its tender of Notes in exchange for the Exchange Securities.

         g. Registration. Such Holder hereby acknowledges that the Offer has not
been reviewed by the Securities and Exchange  Commission or any state regulatory
authority,  since  the Offer is  intended  to be  exempt  from the  registration
requirements of the Securities  Act. No Holder shall sell or otherwise  transfer
the  Exchange  Securities  unless  such  securities  are  registered  under  the
Securities Act or unless an exemption from such registration is available.

         h. Purchase for own Account.  Such Holder  understands that none of the
Exchange Securities have been registered under the Securities Act by reason of a
claimed  exemption under the provisions of the Securities Act which depends,  in
part, upon such Holder's investment intention.  In this connection,  such Holder
hereby  represents  that such Holder is tendering Notes in exchange for Exchange
Securities  for such Holder's own account,  for  investment  and not with a view
toward the resale or distribution to others,  or for resale in connection  with,
any  distribution or public offering (within the meaning of the Securities Act),
nor with any  present  intention  of  distributing  or selling the same and such
Holder has no  present  or  contemplated  agreement,  undertaking,  arrangement,
obligation or commitment providing for the disposition thereof.  Such Holder, if
an entity, was not formed for the purpose of acquiring the Notes or the Exchange
Securities.

         i.  Holding  Period.  Such Holder  understands  that there is no public
market for the preferred stock or warrants  included in the Exchange  Securities
and that no market is expected to develop for any such Exchange Securities. Such
Holder  understands  that even if a public  market  develops  for such  Exchange
Securities,  reliance  upon  Rule  144  under  the  Securities  Act for  resales
requires,  among other conditions, a one-year holding period prior to the resale
(in limited  amounts) of securities  acquired in a non-public  offering  without
having to satisfy the registration  requirements  under the Securities Act. Such
Holder shall hold Hybridon and its directors,  officers, employees,  controlling
persons and agents and their respective heirs,  representatives,  successors and
assigns harmless from, and shall indemnify them against, all liabilities,  costs
and expenses incurred by them as a result of (i) any  misrepresentation  made by
such Holder  contained in this Amendment,  (ii) any sale or distribution by such
Holder in violation of the Securities Act or any applicable  non-United  States,
state  securities or "blue sky" laws or (iii) any untrue  statement made by such
Holder.

         j.  Legends.  Such  Holder  consents  to the  placement  of one or more
restrictive  legends on any certificates  representing  the Exchange  Securities
required by applicable  securities laws. Such Holder is aware that Hybridon will
make a notation in its appropriate  records with respect to the  restrictions on
the transferability of such Exchange Securities.


                                      - 6 -

<PAGE>

         k. Financial Review.  Such Holder understands that Hybridon will review
this Amendment and is hereby given authority by the  undersigned  Holder to call
such  Holder's  bank or place of  employment  or otherwise  review the financial
standing of such Holder;  and it is further  agreed that  Hybridon  reserves the
unrestricted  right,  without further  documentation or agreement on the part of
such Holder, to reject or limit any tender of Notes.

         l. Residence of Holder.  Such Holder hereby represents that the address
of such Holder furnished set forth below is such Holder's principal residence if
such  Holder is an  individual  or its  principal  business  address  if it is a
corporation or other entity.

         m. NASD.  Such Holder  acknowledges  that if he or she is a  registered
representative  of an NASD member firm, he or she must give such firm the notice
required  by the  NASD's  Rules  of Fair  Practice,  receipt  of  which  must be
acknowledged by such firm in the appropriate space provided below.

         n.  Securities  Laws.  Such Holder  acknowledges  that at such time, if
ever,  as the  Exchange  Securities  are  registered,  sales  of  such  Exchange
Securities  will be subject to  applicable  United  States and state  securities
Laws.

         o. Beneficial Owner.  Such Holder,  whose name appears on the signature
line below, is the beneficial owner of the Notes being tendered, and will be the
beneficial owner of the Exchange  Securities that such Holder acquires  pursuant
to the Offer.

         p. Accredited Investor. Such Holder represents that it has indicated in
Section B below  whether or not it is an  "accredited  investor" as such term is
defined in Rule 501 of Regulation D.

         q. Reliance on Representation  and Warranties.  Such Holder understands
that the Exchange  Securities  are being offered and sold to the  undersigned in
reliance on specific  exemptions  from the  registration  requirements of United
States Federal and state  securities  laws and that Hybridon is relying upon the
truth   and   accuracy   of   the   representations,   warranties,   agreements,
acknowledgments  and understandings of the undersigned set forth herein in order
to determine the  applicability  of such  exemptions and the  suitability of the
undersigned to acquire the Exchange Securities pursuant to the Offer.


     B. Confidential Questionnaire


         a. The  undersigned  represents  and warrants  that he, she or it comes
within one category marked below, and that for any category  marked,  he, she or
it has  truthfully  set forth where  applicable the factual basis or reason that
he, she or it comes within that  category.  ALL  INFORMATION IN RESPONSE TO THIS
SECTION WILL BE KEPT STRICTLY  CONFIDENTIAL.  The undersigned  agrees to furnish
any additional information which Hybridon deems necessary in order to verify the
answers set forth below.

Category  A:____  The  undersigned  is an individual  (not a partnership,
                  corporation,  etc.) whose  individual net worth,  or joint net
                  worth with his or her spouse, presently exceeds $1,000,000.

                                            Explanation.   In  calculating   net
                                            worth  you  may  include  equity  in
                                            personal  property  and real estate,
                                            including your principal  residence,
                                            cash, short-term investments,  stock
                                            and  securities.  Equity in personal
                                            property  and real estate  should be
                                            based  on the fair  market  value of
                                            such  property  less debt secured by
                                            such property.

Category B:____   The  undersigned  is an individual  (not a partnership,
                  corporation,  etc.) who had an individual  income in excess of
                  $200,000 in each of the two most recent years, or joint income
                  with his or her spouse in excess of  $300,000 in each of those
                  years (in each


                                      - 7 -

<PAGE>

                  case  including  foreign  income,  tax exempt  income and full
                  amount of capital gains and losses but excluding any income of
                  other family members and any unrealized capital  appreciation)
                  and has a reasonable  expectation  of reaching the same income
                  level in the current year.

Category C:____   The   undersigned  is  a  director   or  executive  officer of
                  Hybridon.

Category D:____   The  undersigned is a bank; a savings and loan  association;
                  insurance company; registered investment company; registered
                  business  development   company;   licensed  small  business
                  investment company ("SBIC"); or employee benefit plan within
                  the  meaning  of  Title  1  of  Employee  Retirement  Income
                  Security Act of 1974,  as amended (the  "ERISA") and (a) the
                  investment  decision  is made by a plan  fiduciary  which is
                  either  a bank,  savings  and  loan  association,  insurance
                  company or registered invest- ment advisor,  or (b) the plan
                  has  total  assets  in  excess  of  $5,000,000  or is a self
                  directed  plan  with  investment  decisions  made  solely by
                  persons that are accredited investors.
                 
Category E:____   The  undersigned   is   a    private   business   development
                  company as defined in  section  202(a)(22)  of the  Investment
                  Advisors Act of 1940.

Category F:____   The  undersigned   is  either  a  corporation,  partnership,
                  business trust, or non-profit  organization within the meaning
                  of Section  501(c)(3) of the Internal  Revenue  Code,  in each
                  case not formed for the  specific  purpose  of  acquiring  the
                  Notes or the  Exchange  Securities,  and with total  assets in
                  excess of $5,000,000.

Category G:____   The  undersigned   is  a  trust  with  total  assets in excess
                  of  $5,000,000,   not  formed  for  the  specific  purpose  of
                  acquiring  the  Notes or the  Exchange  Securities,  where its
                  investment decisions are directed by a "sophisticated  person"
                  as defined in Regulation  506(b)(2)(ii)  under the  Securities
                  Act.

Category H:____   The undersigned  is  an  entity  (other  than  a  trust),  all
                  the equity owners of which are "accredited  investors"  within
                  one or more of the  above  categories.  If  relying  upon this
                  category  alone,  each  such  equity  owner  must  complete  a
                  separate copy of this Amendment.

Category I:____   The undersigned is not within any of the categories above and 
                  is therefore not an accredited investor.

The undersigned agrees that the undersigned will notify Hybridon  immediately in
the event that the  representations and warranties in this Amendment shall cease
to be true, accurate and complete.

                  b. NASD Affiliation.

Are you affiliated or associated with an NASD member firm (please check one):

Yes _________              No __________

If Yes, please describe:

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


                                      - 8 -

<PAGE>

*If Holder is a Registered  Representative  with an NASD member  firm,  have the
following acknowledgment signed by the appropriate party:

         The  undersigned  NASD member firm  acknowledges  receipt of the notice
         required  by  Article  3,  Sections  28(a) and (b) of the Rules of Fair
         Practice.

         ---------------------------------
         Name of NASD Member Firm

         By: ______________________________
                  Authorized Officer

         Date: ____________________________

                  c.  Reliance  on  Confidential  Investor  Questionnaire.   The
undersigned  is  informed  of the  significance  to  Hybridon  of the  foregoing
representations   and  answers  contained  in  the  Confidential   Questionnaire
contained  above and such answers have been provided under the  assumption  that
Hybridon will rely on them in the Offer.


         I hereby certify that the record owner of the Notes  beneficially owned
         by the undersigned is

         ----------------------------------------------------------------------.


         x___________________________________________________
         Signature(s) of Beneficial Owner(s) or Authorized Signatory

         ----------------------------------------------------
         Type or Print Name

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

         ----------------------------------------------------
         Type or Print Address(es)

         ----------------------------------------------------
         Capacity (Full Title)

         Dated:_______________, 1998

         Area Code and telephone No(s).:____________________________

         Tax Identification or Social Security No(s).:__________________________


         See Instruction 4 to the Original  Letter of Transmittal.  If signature
is by a trustee, executor, administrator, guardian, attorney-in-fact, officer of
a corporation,  agent,  or other person acting in a fiduciary or  representative
capacity, please see Instruction 4 to the Original Letter of Transmittal.

         [ ] I do not wish to appoint  Mr. Art Barry as the  initial  Designated
         Director (see clause (iii) above). I wish to appoint _________________.
         (Please check the box only if you agree with this statement).


                                      - 9 -



                                 EXHIBIT 9(g)(3)

                    CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS



         As   independent   public   accountants,   we  hereby  consent  to  the
incorporation  by reference in this Schedule  13E-4 of our report dated February
21, 1997 (except with respect to the matter discussed in Note 1, as to which the
date is March 26,  1997)  included  in  Hybridon's  Form 10-K for the year ended
December 31, 1996,  and to all  references to our Firm included in this Schedule
13E-4.


                                                  /s/ ARTHUR ANDERSEN LLP
                                                  -----------------------

Boston, Massachusetts
March 27, 1998




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