HYBRIDON INC
10-Q, 1998-05-15
BIOLOGICAL PRODUCTS, (NO DIAGNOSTIC SUBSTANCES)
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                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM 10-Q

                        QUARTERLY REPORT UNDER SECTION 13
                 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934

                                     -------


      For the Quarter Ended: March 31, 1998 Commission File Number 0-27352

                                 Hybridon, Inc.
             (Exact name of registrant as specified in its charter)


                               Delaware 04-3072298
     (State or other jurisdiction of (I.R.S. Employer Identification Number)
                         organization or incorporation)

                               620 Memorial Drive
                               Cambridge, MA 02139
          (Address of principal executive offices, including zip code)


                                 (617) 528-7000
              (Registrant's telephone number, including area code)


Indicate by check mark  whether the  registrant  (1) has filed all reports to be
filed by Section 13 or 15(d) of the  Securities  Exchange Act of 1934 during the
preceding 12 months (or for such shorter period that the registrant was required
to file such reports),  and (2) has been subject to such filing requirements for
the past 90 days.

                                    YES X       NO
                                       --         --

Indicate the number of shares  outstanding  of each of the  issuer's  classes of
common stock, as of the latest practicable date.

                Common Stock, par value $.001 per share 5,061,650
              --------------------------------------- ------------
                     Class Outstanding as of April 30, 1998


<PAGE>


                                 HYBRIDON, INC.

                                    FORM 10-Q

                                      INDEX


PART I - FINANCIAL INFORMATION

ITEM 1 - FINANCIAL STATEMENTS

        CONSOLIDATED CONDENSED BALANCE SHEETS AS OF MARCH 31, 1998 AND
           DECEMBER 31, 1997.

        CONSOLIDATED  CONDENSED  STATEMENT  OF  OPERATIONS  FOR THE THREE MONTHS
           ENDED  MARCH  31,  1998  AND 1997 AND  CUMULATIVE  FROM MAY 25,  1989
           (INCEPTION) TO MARCH 31, 1998

        CONSOLIDATED  CONDENSED  STATEMENTS  OF CASH FLOWS FOR THE THREE  MONTHS
           ENDED  MARCH 31,  1998 AND 1997,  AND  CUMULATIVE  FROM MAY 25,  1989
           (INCEPTION) TO MARCH 31, 1998

        NOTES TO CONSOLIDATED CONDENSED FINANCIAL STATEMENTS


ITEM 2 - MANAGEMENT'S DISCUSSION AND ANALYSIS OF
           FINANCIAL CONDITION AND RESULTS OF OPERATIONS

PART II - OTHER INFORMATION

ITEM 2 - CHANGES IN SECURITIES

ITEM 6 - EXHIBITS AND REPORTS ON FORM 8-K

SIGNATURES


<PAGE>


                         HYBRIDON, INC. AND SUBSIDIARIES
                          (A DEVELOPMENT STAGE COMPANY)

                      CONSOLIDATED CONDENSED BALANCE SHEETS

                                   (UNAUDITED)

                                     ASSETS

<TABLE>
<CAPTION>

                                                                   MARCH 31,        December 31,
                                                                      1998              1997
<S>                                                             <C>               <C>        
CURRENT ASSETS:
  Cash and cash equivalents                                     $   439,214       $ 2,202,202
  Accounts receivable                                               521,887           529,702
  Prepaid expenses and other current assets                         706,869         1,005,825
                                                                -----------       -----------

        Total current assets                                      1,667,970         3,737,729
- --------                                                        -----------       -----------

PROPERTY AND EQUIPMENT, AT COST:
  Leasehold improvements                                         15,912,192        16,027,734
- --
  Laboratory equipment                                            6,172,583         6,770,402
  Equipment under capital leases                                  4,905,744         4,879,190
  Office equipment                                                1,935,959         1,947,818
  Furniture and fixtures                                            611,060           645,264
  Construction-in-progress                                           45,409            45,409
                                                                -----------
                                                                 29,582,947        30,315,817

  Less--Accumulated depreciation and amortization                 12,215,553        11,085,013
                                                                 -----------
                                                                 17,367,394        19,230,804
                                                                -----------
OTHER ASSETS:
  Restricted cash                                                   784,618         3,050,982
  Notes receivable from officers                                    250,100           247,250
  Deferred financing costs and other assets                       3,246,256         3,354,767
  Investment in real estate partnership                           5,450,000         5,450,000
                                                                -----------

                                                                  9,730,974        12,102,999

                                                                $28,766,338       $35,071,532



                        Liabilities and Stockholders' Equity (Deficit)

Current Liabilities:
  Current portion of long-term debt and capital lease obligations $ 5,723,036       $ 7,868,474
  Accounts payable                                                  7,572,385         8,051,817
  Accrued expenses                                                 12,663,288        11,917,298
                                                                  -----------
        Total current liabilities                                  25,958,709        27,837,589

LONG-TERM DEBT AND CAPITAL LEASE OBLIGATIONS, NET OF CURRENT        3,249,800         3,282,123
                                                                  -----------
PORTION
9% CONVERTIBLE SUBORDINATED NOTES PAYABLE                          50,000,000        50,000,000
                                                                  -----------
CONVERTIBLE SUBORDINATED NOTES PAYABLE                              4,800,000                 -
                                                                  -----------

STOCKHOLDERS' EQUITY(DEFICIT):
  Preferred stock, $.01 par value-
    Authorized--5,000,000 shares
    Issued and outstanding--None                                            -                 -
  Series A convertible preferred stock, $.01 par value-
    Authorized--5,000,000 shares
    Issued and outstanding--910,717 shares pro forma                        -                 -
  Common stock, $.001 par value-
    Authorized--100,000,000 shares
    Issued and outstanding-- 5,059,650 shares at March 31, 1998, and                      5,060
      December 31, 1997 and 11,659,650 shares pro forma                 5,060
  Additional paid-in capital                                      173,129,531       173,695,698
  Deficit accumulated during the development stage               (227,337,273)     (218,655,101)

  Deferred compensation                                            (1,039,489)       (1,093,837)
                                                                 ------------      ------------

        Total stockholders' equity(deficit)                       (55,242,171)      (46,048,180)
- --------                                                         ------------

                                                                  $28,766,338       $35,071,532


The  accompanying  notes are an integral  part of these  consolidated  condensed
financial statements.
</TABLE>


<PAGE>

                         HYBRIDON, INC. AND SUBSIDIARIES
                          (A DEVELOPMENT STAGE COMPANY)

                 CONSOLIDATED CONDENSED STATEMENTS OF OPERATIONS

                                   (UNAUDITED)
<TABLE>
<CAPTION>



                                                          Three Months Ended         Cumulative
                                                               March 31,            from May 25,
                                                                                        1989
                                                                                   (Inception) to
                                                                                      March 31,

                                                          1998             1997           1998
<S>                                                   <C>             <C>             <C>        
REVENUES:
  Research and development                            $     150,000   $593,900        $ 5,649,263
  Product revenue                                           825,069   348,154           3,782,106
  Interest income                                            17,845   117,412           3,238,584
  Royalty and other income                                        -             -         110,321
                                                      -------------   -----------     -----------

                                                            992,914     1,059,466      12,780,274
                                                      -------------   -----------     -----------

OPERATING EXPENSES:
  Research and development                                6,402,537    11,476,439     171,862,352
  General and administrative                              1,665,112     3,430,453      49,481,728
  Restructuring charge                                            -             -      11,020,000
  Interest                                                1,607,437       170,207       7,753,467
                                                      -------------   -----------     -----------

                                                          9,675,086    15,077,099     240,117,547
                                                      -------------   -----------     -----------

        Net loss                                      $  (8,682,172)  $(14,017,633)  (227,337,273)
                                                      =============   ============  =============

BASIC AND DILUTED NET LOSS PER COMMON SHARE          $    ( 1.72)     $   ( 2.78)
                                                      =============   ============
(Note 2)

SHARES USED IN COMPUTING BASIC AND DILUTED NET LOSS
PER COMMON SHARE (Note 2)                                 5,059,650    5,044,946 
                                                      =============   ============  =============


The accompanying notes are an integral part of these consolidated condensed financial statements
</TABLE>


<PAGE>

                         HYBRIDON, INC. AND SUBSIDIARIES
                          (A DEVELOPMENT STAGE COMPANY)

                 CONSOLIDATED CONDENSED STATEMENTS OF CASH FLOWS

                                   (UNAUDITED)
<TABLE>
<CAPTION>


                                                              THREE MONTHS ENDED           Cumulative
                                                                  MARCH 31,                   from
                                                                                          May 25,1989
                                                                                         (Inception) to
                                                                                           March 31,

                                                              1998            1997              1998
<S>                                                      <C>             <C>              <C>           
CASH FLOWS FROM OPERATING ACTIVITIES:
  Net loss                                               $  (8,682,172)  $  (14,017,633)  $(227,337,273)
  Adjustments to reconcile net loss to net cash used in
  operating activities-
    Depreciation and amortization                             1,130,540        1,227,137    12,316,994
    Loss on disposal of fixed assets                            359,424                -       359,424
    Issuance of common  stock for services rendered                   -          146,875       146,875
    Compensation on grant of stock options, warrants and         54,348          133,859     8,178,146
      restricted stock
    Amortization of discount on convertible promissory notes          -                -       690,157
      payable
    Amortization of deferred financing costs                    217,021          274,800       913,490
    Noncash interest on convertible promissory notes payable          -                -       260,799
    Write-down of assets related to restructuring                     -                -       600,000
    Changes in operating assets and liabilities-
      Accounts receivable                                         7,815        (163,984)      (521,887)
      Prepaid and other current assets                          298,956        (190,277)      (706,869)
      Notes receivable from officers                            (2,850)          (2,304)      (250,100)
      Amounts payable to related parties                              -                -      (200,000)
      Accounts payable and accrued expenses                     266,558        2,376,928    20,235,673
                                                         --------------  ---------------  -------------

           Net cash used in operating activities            (6,350,360)     (10,214,599)  (185,314,571)
                                                         --------------  ---------------  -------------

CASH FLOWS FROM INVESTING ACTIVITIES:
  Decrease (increase) in short-term investments                       -        3,785,146             -
  Purchases of property and equipment, net                            -      (3,831,655)   (29,312,465)
  Proceeds from sale of fixed assets                            400,000                -       400,000
  Investment in real estate partnership                               -                -    (5,450,000)
                                                         --------------  ---------------  -------------

           Net cash provided by (used in) investing             400,000         (46,509)   (34,362,465)
           activities                                    --------------  ---------------  -------------

CASH FLOWS FROM FINANCING ACTIVITIES:
  Proceeds from issuance of convertible preferred stock               -                -    96,584,154
  Proceeds from issuance of common stock related to stock             -           47,203     1,260,928
    options and restricted stock grants
  Proceeds from issuance of common stock related to stock             -                -     3,185,816
    warrants
  Net proceeds from issuance of common stock                          -                -    52,355,324
  Repurchase of common stock                                          -                -          (263)


<PAGE>

  Proceeds from notes payable                                         -                -     9,450,000
  Proceeds from issuance of convertible promissory notes      4,233,833                -    63,425,577
    payable
  Proceeds from long-term debt                                        -                -       662,107
  Payments on long-term debt and capital leases             (2,204,315)        (375,874)    (5,570,195)
  Proceeds from sale/leaseback                                                         -     4,001,018
  Decrease (increase)  in restricted cash and other assets    2,157,854          445,919    (1,981,277)
  (Increase) decrease in deferred financing costs                     -                -    (3,256,939)
           activities                                    --------------  ---------------  -------------

           Net cash provided by (used in) financing           4,187,372          117,248   220,116,250
           activities                                    --------------  ---------------  -------------

NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS        (1,762,988)     (10,143,860)       439,214

CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD                2,202,202       12,633,742             -
           activities                                    --------------  ---------------  -------------

CASH AND CASH EQUIVALENTS, END OF PERIOD                 $      439,214  $     2,489,882  $    439,214
                                                         ==============  ===============  =============

SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
  Cash paid for interest                                 $      358,680  $       170,207  $  3,989,130
                                                         ==============  ===============  ============
</TABLE>


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

<PAGE>

                         HYBRIDON, INC. AND SUBSIDIARIES
                          (A DEVELOPMENT STAGE COMPANY)

              NOTES TO CONSOLIDATED CONDENSED FINANCIAL STATEMENTS

                                   (UNAUDITED)




(1)   ORGANIZATION

      Hybridon,  Inc. (the Company) was incorporated in the State of Delaware on
      May 25, 1989.  The Company is engaged in the discovery and  development of
      novel  genetic  medicines  based  primarily on antisense  technology.  The
      Company is in the development stage. Since inception, the Company has been
      engaged primarily in research and development efforts,  development of its
      manufacturing   capabilities   and   organizational   efforts,   including
      recruiting of scientific and management  personnel and raising capital. To
      date,   the  Company   has  not   received   revenue   from  the  sale  of
      biopharmaceutical  products developed by it based on antisense technology.
      In order to  commercialize  its own  products,  the  Company  will need to
      address a number of technological challenges and comply with comprehensive
      regulatory  requirements.  Accordingly,  it is not possible to predict the
      amount of funds that will be required or the length of time that will pass
      before the Company receives  revenues from sales of any of these products.
      All  revenues  received  by the  Company  to date have been  derived  from
      collaboration  agreements,  interest on investment funds and revenues from
      the custom contract manufacturing of synthetic DNA and reagent products by
      the Company's Hybridon Specialty Products Division. As a result,  although
      the Company has begun to generate revenues from its contract manufacturing
      business,  the Company is dependent on the proceeds from  possible  future
      sales of equity  securities,  debt financings and research and development
      collaborations in order to fund future operations.

      On  January  22,  1998,  the  Company  commenced  a  private  offering  of
      convertible  subordinated  notes  payable and warrants to purchase  common
      stock.  The Company had issued $4.8  million of such notes as of March 31,
      1998. On May 5, 1998, the Company  completed the private  offering raising
      total gross  proceeds of  approximately  $27.3 million for the issuance of
      approximately  10,195,000 shares of common stock,  including shares issued
      in lieu of cash fees to a placement  agent  unaffiliated  with the Company
      and its directors,  114,300 shares of Series A convertible preferred stock
      and warrants to purchase approximately 3,800,000 shares of common stock at
      $2.40  per  share,   including   warrants  issued  to  a  placement  agent
      unaffiliated  with the  Company  and its  directors.  The  gross  proceeds
      include the  conversion  of the $4.8 million of  convertible  subordinated
      notes  payable  outstanding  at  March  31,  1998  and the  conversion  of
      approximately  $6.7 million of accounts  payable,  capital lease and other
      obligations   outstanding  at  March  31,  1998.   The  Company   incurred
      approximately  $1.0  million  of out of  pocket  expenses  related  to the
      private  offering.  The compensation arrangement  with  Pillar,  a Company
      affiliated  with certain  directors  of the  Company,  with respect to the
      offshore  component of the private  offering  (Offshore  Offering) has not
      been  finalized by the Company's  Board of Directors.  However,  Pillar is
      expected to receive  fees  consisting  of (i) 9% of the gross  proceeds of
      such Offshore Offering and (ii) a non-accountable  expense allowance equal
      to 4% of such gross  proceeds.  Pillar  has  received  approximately  $1.6
      million pursuant to these  arrangements as of May 5, 1998.  Pillar is also
      expected to receive warrants to purchase approximately 1,112,000 shares of
      common stock at $2.40 per share.

      On  February  6, 1998,  the Company  commenced  an  exchange  offer to the
      holders of the 9% Notes to exchange the 9% Notes for Series A  convertible
      preferred stock and certain warrants of the


<PAGE>

                         HYBRIDON, INC. AND SUBSIDIARIES
                          (A DEVELOPMENT STAGE COMPANY)

              NOTES TO CONSOLIDATED CONDENSED FINANCIAL STATEMENTS

                                   (UNAUDITED)

                                   (CONTINUED)


      Company.  In the  exchange  offer,  each  $1,000 of  principal  amount and
      accrued but unpaid  interest on the 9% Notes may be exchanged,  upon terms
      and subject to the conditions  set forth in the Exchange Offer  documents,
      for 10 shares of Series A convertible  preferred stock,  stated value $100
      per share,  and warrants to purchase 25% of the number of shares of common
      stock  into which  such  Series A  convertible  preferred  stock  would be
      convertible.  On May 5, 1998, approximately $48.6 million principal amount
      of the 9% Notes and approximately $2,355,000 of accrued interest on the 9%
      Notes was  tendered  to the  Company  to be  exchanged  for  approximately
      510,000  shares of Series A  convertible  preferred  stock and warrants to
      purchase  approximately  3,000,000  shares  of  common  stock at $4.25 per
      share.

(2)   UNAUDITED INTERIM FINANCIAL STATEMENTS

      The unaudited  consolidated condensed financial statements included herein
      have been prepared by the Company,  without  audit,  pursuant to the rules
      and regulations of the Securities and Exchange  Commission and include, in
      the  opinion  of  management,  all  adjustments,   consisting  of  normal,
      recurring adjustments, necessary for a fair presentation of interim period
      results. Certain information and footnote disclosures normally included in
      financial  statements  prepared  in  accordance  with  generally  accepted
      accounting  principles  have been  condensed  or omitted  pursuant to such
      rules and regulations. The Company believes, however, that its disclosures
      are adequate to make the information presented not misleading. The results
      for the  interim  periods  presented  are not  necessarily  indicative  of
      results to be expected  for the full fiscal  year.  It is  suggested  that
      these  financial  statements  be  read in  conjunction  with  the  audited
      consolidated  financial  statements  and  notes  thereto  included  in the
      Company's Annual Report on Form 10-K for the year ended December 31, 1997,
      as filed with the Securities and Exchange Commission.

(3)   SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

      Net Loss per Common Share

      In February 1997, the Financial  Accounting  Standards Board (FASB) issued
      Statement of Financial  Accounting  Standards (SFAS) No. 128, Earnings per
      Share which  establishes  new standards  for  calculating  and  presenting
      earnings per share.  This standard is effective  for financial  statements
      for periods  ending after  December 15, 1997.  These  condensed  financial
      statements  have been  prepared and based on the new  standard.  Basic net
      loss per share is computed by dividing  net loss by the  weighted  average
      number of common shares  outstanding  during the period.  Diluted net loss
      per  share  for the  periods  presented  is the same as basic net loss per
      share as the inclusion of the potential common stock  equivalents would be
      antidilutive.

(4)   CASH EQUIVALENTS

      The Company  applies SFAS No. 115,  Accounting for Certain  Investments in
      Debt and Equity  Securities.  Under SFAS No. 115, debt securities that the
      Company has the positive intent and


<PAGE>

                         HYBRIDON, INC. AND SUBSIDIARIES
                          (A DEVELOPMENT STAGE COMPANY)

              NOTES TO CONSOLIDATED CONDENSED FINANCIAL STATEMENTS

                                   (UNAUDITED)

                                   (CONTINUED)


      ability  to hold to  maturity  are  recorded  at  amortized  cost  and are
      classified as held-to-maturity  securities.  These securities include cash
      equivalents and restricted cash. Cash equivalents have original maturities
      of less than three months. Cash and cash equivalents at March 31, 1998 and
      December 31, 1997
      consisted of the following:
<TABLE>
<CAPTION>

                                                        MARCH 31,        December 31,
                                                          1998               1997
<S>                                                 <C>                <C> 
        Cash and cash equivalents-
          Cash and money market funds               $         155,383  $       1,702,272
          Corporate bond                                      283,831            499,930
                                                    -----------------  -----------------

                                                    $         439,214  $       2,202,202
                                                    =================  =================


        Restricted cash-
          Certificates of deposit                   $               -  $       2,016,364
          Savings account                                     784,618          1,034,618
                                                    -----------------  -----------------

                                                    $         784,618  $       3,050,982
                                                    =================  =================

</TABLE>



(5)   9.0% CONVERTIBLE SUBORDINATED NOTES

      On April 2, 1997,  the  Company  issued  $50,000,000  of the 9% Notes.  As
      discussed in Note 1, on May 5, 1998  noteholders  holding $48.6 million of
      principal  value of the 9% Notes  tendered  such  notes and  approximately
      $2,355,000  of accrued  interest  in  exchange  for  Series A  convertible
      preferred  stock and warrants to purchase common stock. As of May 5, 1998,
      there was $1.4 million principal amount of 9% Notes outstanding. Under the
      terms of the 9% Notes, the Company must make semi-annual interest payments
      on the outstanding principal balance through the maturity date of April 1,
      2004.  If the  9%  Notes  are  converted  prior  to  April  1,  2000,  the
      Noteholders are entitled to receive accrued  interest from the date of the
      most recent interest payment through the conversion date. The 9% Notes are
      subordinate to substantially all of the Company's  existing  indebtedness.
      The 9% Notes are  convertible  at any time prior to the maturity date at a
      conversion price equal to $35.0625 per share,  subject to adjustment under
      certain circumstances, as defined.

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

<PAGE>

                         HYBRIDON, INC. AND SUBSIDIARIES
                          (A DEVELOPMENT STAGE COMPANY)

              NOTES TO CONSOLIDATED CONDENSED FINANCIAL STATEMENTS

                                   (UNAUDITED)

                                   (CONTINUED)


      through  March 31,  2003.  Upon a change of  control  of the  Company,  as
      defined,  the Company will be required to offer to repurchase the 9% Notes
      at 150% of the original issuance price.

(6)   NEW ACCOUNTING STANDARDS

      Effective  January 1, 1998,  the Company  adopted SFAS No. 130,  Reporting
      Comprehensive  Income.  SFAS No. 130 requires disclosure of all components
      of  comprehensive  income on an annual and  interim  basis.  Comprehensive
      income is defined as the change in equity of a business  enterprise during
      a period  from  transactions  and  other  events  and  circumstances  from
      non-owner  sources.  The Company's total  comprehensive loss for the three
      month  periods ended March 31, 1998 and 1997 were the same as reported net
      loss for those periods.

      In July 1997, the FASB issued SFAS No. 131,  Disclosures About Segments of
      an  Enterprise  and Related  Information.  SFAS No. 131  requires  certain
      financial and  supplementary  information to be disclosed on an annual and
      interim basis for each reportable  segment of an enterprise.  SFAS No. 131
      is effective for fiscal years  beginning  after December 15, 1997.  Unless
      impracticable,  companies  would  be  required  to  restate  prior  period
      information upon adoption.

      In March 1998,  the American  Institute of  Certified  Public  Accountants
      (AICPA) issued Statement of Position (SOP) 98-1,  Accounting for the Costs
      of Computer  Software  Developed or Obtained  for  Internal  Use. SOP 98-1
      requires  computer software costs associated with internal use software to
      be expensed as incurred until certain capitalization criteria are met. The
      Company  will  adopt SOP 98-1  prospectively  beginning  January  1, 1999.
      Adoption  of  this  statement  will  not  have a  material  impact  on the
      Company's consolidated financial position or results of operations.

      In April  1998,  the  AICPA  issued  SOP 98-5,  Reporting  on the Costs of
      Start-Up  Activities.  SOP  98-  5  requires  all  costs  associated  with
      pre-opening,  pre-operating and organization  activities to be expensed as
      incurred.  The  Company  will  adopt SOP 98-5  beginning  January 1, 1999.
      Adoption  of  this  Statement  will  not  have a  material  impact  on the
      Company's consolidated financial position or results of operations.

(7)   RESTRUCTURING

      Beginning in July 1997, the Company  implemented a  restructuring  plan to
      reduce  expenditures  on a phased  basis  over the  balance  of 1997 in an
      effort to conserve its cash resources. As part of this restructuring plan,
      in  addition  to  terminating  the  clinical  development  of GEM 91,  the
      Company's  first  generation  antisense drug for the treatment of AIDS and
      HIV  infection,   the  Company  reduced  or  suspended  selected  programs
      unrelated  to its  core  advanced  chemistry  antisense  drug  development
      programs, including its ribozyme program. In connection with the reduction
      in programs,  the Company has accrued termination fees related to research
      contracts and has incurred  restructuring charges related to programs that
      have been suspended or canceled. As part of the restructuring, all outside
      testing,  public  relations,   travel  and  entertainment  and  consulting
      arrangements   were  reviewed  and  where   appropriate   the  terms  were
      renegotiated, contracts canceled or the terms were

<PAGE>

                         HYBRIDON, INC. AND SUBSIDIARIES
                          (A DEVELOPMENT STAGE COMPANY)

              NOTES TO CONSOLIDATED CONDENSED FINANCIAL STATEMENTS

                                   (UNAUDITED)

                                   (CONTINUED)


      significantly  reduced. In addition, the Company terminated the employment
      of 84 employees at its  Cambridge  and Milford,  Massachusetts  facilities
      since  July of 1997 and  substantially  reduced  operations  at its Paris,
      France office and terminated 10 employees at that location in August 1997.
      In  connection  with  the  restructuring  the  Company  entered  into  two
      different subleasing arrangements.  The Company has subleased one facility
      in Cambridge,  Massachusetts, and a portion of its headquarters located at
      620  Memorial  Drive,  Cambridge,   Massachusetts.  The  Company  incurred
      expenses  relating  to these  subleases  for  broker  fees and  renovation
      expenses  incurred  in  preparing  the  Memorial  Drive  space for the new
      tenant.  In  addition,  the Company  accrued the  estimated  lease loss of
      subleasing 620 Memorial  Drive.  The Company  accrued the remaining  lease
      costs of its Paris, France office prior to terminating the lease effective
      March 31, 1998.

      The total  cash  impact of the  restructuring  amounted  to  approximately
      $5,165,000.  The total  cash paid as of March 31,  1998 was  approximately
      $2,394,000 and the remaining amount will be paid in 1998.


(8)   NOTE PAYABLE TO A BANK

      In December 1996,  the Company  entered into a five year  $7,500,000  note
      payable with a bank. The note contains  certain  financial  covenants that
      require  the Company to maintain  minimum  tangible  net worth and minimum
      liquidity and prohibits the payment of dividends.  On April 30, 1998,  the
      Company  received a waiver  from the bank for the  minimum  liquidity  and
      minimum tangible net worth  requirements.  The note is payable in 59 equal
      installments  of $62,500  commencing  on  February  1, 1997 with a balloon
      payment of $3,812,500,  due on January 1, 2002. If at specified  times the
      Company's  minimum  liquidity  is less than  $15,000,000,  $10,000,000  or
      $5,000,000,  the Company is required to pledge cash collateral to the bank
      equal to 25%, 50% or 100%,  respectively,  of the then outstanding balance
      under the note.  During 1997, the Company's  minimum  liquidity had fallen
      below $5,000,000 and the Company deposited  $1,758,542 as collateral under
      the cash pledge agreement.  During 1998, the bank withdrew the full amount
      of the restricted cash and applied it against the  outstanding  balance of
      the note.  In  connection  with the waiver  issued on April 30, 1998,  the
      minimum  liquidity  requirements were amended to provide that if as of the
      fifteenth  and last day of each  calendar  month the Company does not have
      minimum  liquidity of at least $8,000,000 or $4,000,000,  as defined,  the
      Company  will be required to  immediately  repay to the bank 35% and 100%,
      respectively,  of the then outstanding  balance.  Also, in connection with
      the note, the Company issued five year warrants to purchase  13,000 shares
      of common stock at an exercise  price of $34.49 per share.  These warrants
      were  fully  exercisable  at  December  31,  1997.  As of March 31,  1998,
      approximately   $5,125,000  was  outstanding   under  the  note  which  is
      classified  as a current  liability  in the  accompanying  March 31,  1998
      balance sheet.

<PAGE>

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

The Company is engaged in the discovery  and  development  of genetic  medicines
based on antisense technology. The Company commenced operations in February 1990
and since that time has been  engaged  primarily  in  research  and  development
efforts,  development  of  its  manufacturing  capabilities  and  organizational
efforts,  including  recruitment  of scientific and  management  personnel,  and
raising capital.  To date, the Company has not received revenue from the sale of
biopharmaceutical  products  developed by it. In order to commercialize  its own
products, the Company will need to address a number of technological  challenges
and comply with comprehensive  regulatory requirements.  Accordingly,  it is not
possible  to predict  the amount of funds that will be required or the length of
time that will pass before the Company  receives  revenues  from sales of any of
these products.  All revenues  received by the Company to date have been derived
from collaborative agreements,  interest on invested funds and revenues from the
custom  contract  manufacturing  of  synthetic  DNA and reagent  products by the
Company's HSP Division.

The Company has incurred cumulative losses from inception through March 31, 1998
of approximately $227.3 million. The Company implemented a restructuring plan in
the second half of 1997 which will significantly  reduce the Company's operating
expenses and cost  requirements in 1998 from 1997 levels.  However,  the Company
expects  that  its  research  and  development  expenses  will  continue  to  be
significant  in 1998 and future  years as it pursues  its core drug  development
programs and expects to continue to incur operating  losses and have significant
capital  requirements  that it  will  not be able  to  satisfy  with  internally
generated  funds.  The  Company  continues  to explore  opportunities  to reduce
operating  expenses in an effort to conserve its cash  resources.  The number of
employees has continued to decline,  through attrition,  resulting in a total of
66 full time employees as of May 5, 1998.

This Quarterly Report on Form 10-Q contains forward-looking statements. For this
purpose,  any statements  contained herein that are not statements of historical
fact may be  deemed  to be  forward-looking  statements.  Without  limiting  the
foregoing, the words "believes",  "anticipates",  "plans","expects",  "intends",
"may",  and other similar  expressions are intended to identify  forward-looking
statements.  There  are a number  of  important  factors  that  could  cause the
Company's  actual  results to differ  materially  from those  indicated  by such
forward-looking  statements.  These factors  include the matters set forth under
the heading "Item 7. Management's Discussion and Analysis of Financial Condition
and Results of Operations - Certain  Factors that May Affect Future  Results" in
the Company's  Annual  Report on Form 10-K for the year ended  December 31, 1997
(the "1997 10-K") which information is incorporated herein by reference.

RESULTS OF OPERATIONS

The Company had total  revenues of $993,000 and  $1,059,000  in the three months
ended  March  31,  1998 and  1997,  respectively.  Revenues  from  research  and
development  collaborations decreased from $594,000 in the first three months of
1997  to  $150,000  in  the  corresponding  1998  period  primarily  due  to the
termination of the Roche collaboration. Revenue from research and development in
the  first  three  months  of  1998  consists  of  revenue  from  the  Company's
collaboration  with Searle.  During the first  quarter of 1998 Searle  agreed to
extend their  collaboration with the Company until January 2000, and chose a new
target for which the  Company  has  conducted  early  proof-of-concept  studies.
Product revenue from HSP increased from $348,000 in the first quarter of 1997 to
$825,000  in the  first  quarter  of 1998 as a  result  of an  expansion  in the
customer base and increasing sales to existing  customers of Hybridon  Specialty
Products.  The  decline in  interest  income  during the 1998  quarter is mainly
attributable to lower cash and investments.

The decrease in research and development expenses to $6,403,000 during the first
quarter  of 1998 from  $11,476,000  in the first  quarter of 1997  reflects  the
Company's  restructuring  during the  second  half of 1997  which  included  the
termination of the clinical development of GEM 91 and the reduction or

<PAGE>

suspension  of  selected  programs  unrelated  to the  Company's  core  advanced
chemistry antisense drug development  program,  including the termination of its
ribozyme  program.  The  restructuring  resulted in  significant  reductions  in
employee-related expenses, clinical and outside testing,  consulting,  materials
and lab expenses.  The Company's  facility costs were also reduced by the income
received from subleasing its unutilized facilities.

General and administrative expenses decreased to $1,665,000 in the first quarter
of 1998 from  $3,430,000  in the  first  quarter  of 1997.  This  decrease  also
resulted primarily from the Company's restructuring program initiated during the
first half of 1997 and its effect on employee-related expenses,  consulting, and
net facilities costs.

The  increase in  interest  expense  during the first  quarter of 1998 is mainly
attributable to the 9% Convertible  Subordinated Notes due 2004 ("the 9% Notes")
issued in the second quarter of 1997. The Company's interest expense is expected
to  decrease  significantly  in the  future  as a result  of the  conversion  of
approximately  $48.6 million of the 9% Notes to Series A  Convertible  Preferred
Stock during the second quarter of 1998.

As a result of the above factors,  the Company incurred net losses of $8,682,000
and $14,018,000 during the first quarters of 1998 and 1997, respectively.

LIQUIDITY AND CAPITAL RESOURCES

During the three  months ended March 31, 1998,  the  Company's  net cash used in
operating  activities  amounted to  $6,350,000.  The  Company's  operating  cash
requirements  were funded primarily through the utilization of unrestricted cash
balances,  the proceeds from the Company's  private  placement  described in the
1997 10-K and the sale of equipment.  A portion of the Company's restricted cash
balance was utilized to reduce the related debt and capital lease obligations.

As of May 5, 1998, the Company had raised approximately $27.3 million in private
placement gross proceeds in 1998, including $6.7 million of which was applied to
reduce existing accounts payable and to satisfy lease and other obligations.  In
addition, approximately $48.6 million principal amount of its 9% Notes have been
tendered  to the Company to be  exchanged  for equity and  warrants  The Company
believes that these  transactions,  together  with the  committed  collaborative
research and  development  payments from Searle for 1998,  certain  research and
development   funding  expected  to  be  received  from  MethylGene,   Inc.  and
anticipated  product  sales by the  Company's  HSP  Division and margins on such
sales, will be adequate to fund the Company's capital requirements through 1998.
See "Item 1. Financial  Statements -- Notes to Consolidated  Condensed Financial
Statements" for a discussion of the Company's 1998 financing activities.

The Company  will be  required to raise  substantial  additional  funds  through
external sources,  including through  collaborative  relationships and public or
private  financings,  to support its operations beyond 1998. Except for research
and  development  funding from Searle (which is subject to early  termination in
certain  circumstances) and certain research and development funding expected to
be received from MethylGene,  Inc.,  Hybridon has no current external sources of
capital,  and, as  discussed  above,  expects no product  revenues  for at least
several years from sales of products that it is developing  (as opposed to sales
of DNA products and reagents  manufactured on a custom contract basis by the HSP
Division).

No assurance  can be given that  additional  funds will be available to fund the
Company's operations in future years, or, if available,  that such funds will be
available on acceptable  terms. If additional funds are raised by issuing equity
securities,   further  dilution  to  then  existing  stockholders  will  result.
Additionally,  the terms of any such additional  financing may adversely  affect
the holdings or rights of then existing stockholders.

If  adequate  funds are not  available,  the  Company may be required to further
curtail significantly one or more of its core drug development programs,  obtain
funds through arrangements with collaborative

<PAGE>

partners or others that may require the Company to relinquish  rights to certain
of its  technologies,  product  candidates  or products  which the Company would
otherwise  pursue  on its  own or  terminate  operations.

The Company's future capital requirements will depend on many factors, including
continued  scientific  progress in its research,  drug discovery and development
programs,  the  magnitude  of these  programs,  progress  with  preclinical  and
clinical trials,  sales of DNA products and reagents to third parties by the HSP
Division and the margins on such sales, the time and costs involved in obtaining
regulatory  approvals,  the costs involved in filing,  prosecuting and enforcing
patent claims,  competing technological and market developments,  the ability of
the Company to establish  and  maintain  collaborative  academic and  commercial
research, development and marketing relationships, the ability of the Company to
obtain  third-party  financing  for  leasehold  improvements  and other  capital
expenditures  and the  costs of  manufacturing  scale-up  and  commercialization
activities and arrangements.


<PAGE>

                                 HYBRIDON, INC.

                                     PART II

                                OTHER INFORMATION

                                     -------
                                 Items 1-5 None

Item 6.     Exhibits and Reports on Form 8-K


     (a)    Exhibits

            4.1    Certificate of Designation of Series A Convertible Preferred
                    Stock, par value $.01 per share, dated May 5, 1998.

            4.2    Form of 14% Note Due 2007

            4.3    Class A Warrant Agreement, dated May 5, 1998

            4.4    Class B Warrant Agreement, dated May 5, 1998

            4.5    Class C Warrant Agreement, dated May 5, 1998

            4.6    Class D Warrant Agreement, dated May 5, 1998

            11     Computation of Net Loss Per Common Share.

            27     Financial Data Schedule (EDGAR)

            99.1   First Amendment to Loan and Security Agreement between 
                   Hybridon, Inc. and Silicon Valley Bank.

     (b)    The  following  Current  Reports on Form 8-K were  filed  during the
            three months ended March 31, 1998:

            1.      On January 12, 1998, the Company filed a Current Report on
        Form 8-K dated  January  12,  1998,  reporting  that it had  commenced a
        consent  solicitation with respect to certain proposed amendments to the
        Indenture, dated as of March 26, 1997 (the "Original Indenture"), by and
        between  the  Company  and  State  Street  Bank and  Trust  Company,  as
        trustee(the  "Trustee"),  which  governs the  Company's  9%  Convertible
        Subordinated Notes due 2004 (the "9% Notes").

            2. On January 15, 1998,  the Company filed a Current  Report on Form
        8-K dated January 15, 1998,  reporting  that the Company and the Trustee
        had entered into a First Supplemental Indenture, dated as of January 13,
        1998, which amends the Original Indenture.

            3. On January 23, 1998,  the Company filed a Current  Report on Form
        8-K dated  January 22, 1998,  reporting,  among other  things,  that the
        Company had commenced a private  offering of units (the  "Units"),  each
        Unit  consisting  of  $100,000   principal  amount  of  Notes  due  2007
        ("Offering Notes") and certain warrants ("Warrants"), to


<PAGE>

        overseas investors in accordance with Regulations S under the Securities
        Act of 1933 (the "Overseas Offering").

            4. On February 2, 1998,  the Company filed a Current  Report on Form
        8-K dated  February 2, 1998 reporting that the Company had satisfied the
        20 Unit minimum offering threshold for the Overseas Offering.

            5. On February 24, 1998,  the Company filed a Current Report on Form
        8-K dated  February 24, 1998,  reporting the closing on February 9, 1998
        of  $2,348,000 of Offering  Notes and Warrants  pursuant to the terms of
        the Overseas Offering.

            6. On April 9, 1998,  the Company filed a Current Report on Form 8-K
        dated April 9, 1998  reporting the closing on March 27, 1998 of $200,000
        of Offering  Notes and  Warrants  pursuant to the terms of the  Overseas
        Offering.

            7. On April 27, 1998, the Company filed a Current Report on Form 8-K
        dated  April 27,  1998,  reporting  the  closing  on April  21,  1998 of
        $300,000 of  Offering  Notes and  Warrants  pursuant to the terms of the
        Overseas Offering.

            8. On April 28, 1998, the Company filed a Current Report on Form 8-K
        dated  April 28,  1998,  reporting  the  closing  on April  24,  1998 of
        $1,020,000 of Offering  Notes and Warrants  pursuant to the terms of the
        Overseas Offering.

            9. On May 8, 1998, the Company filed a Current Report on Form
        8-K dated May 8, 1998, reporting, inter alia, the closing on May 5, 1998
        of  approximately  6.6 million shares of Common Stock and 114,300 shares
        of Series A Convertible  Preferred  Stock and that  approximately  $48.6
        million principal amount of its 9% Notes were tendered to the Company to
        be exchanged for Series A Preferred Stock.

<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.


May 15, 1998                           /s/ E. Andrews Grinstead III
- ------------                           ----------------------------
Date                                   E. Andrews Grinstead, III
                                       Chairman, President and Chief Executive
                                       Officer (Principal Executive Officer)


May 15, 1998                           /s/ Robert G Andersen
- ------------                           ----------------------------
Date                                   Robert G. Andersen
                                       Treasurer (Principal Financial and
                                       Accounting Officer)


<PAGE>

                                 HYBRIDON, INC.

                                  EXHIBIT INDEX

                                     -------

4.1     Certificate of Designation of Series A Convertible Preferred Stock, 
        par value $.01 per share, dated May 5, 1998.

4.2     Form of 14% Note Due 2007

4.3     Class A Warrant Agreement, dated May 5, 1998

4.4     Class B Warrant Agreement, dated May 5, 1998

4.5     Class C Warrant Agreement, dated May 5, 1998

4.6     Class D Warrant Agreement, dated May 5, 1998

11      Computation of Net Loss Per Common Share.

27      Financial Data Schedule (EDGAR)

99.1    First Amendment to Loan and Security Agreement between Hybridon, Inc. 
        and Silicon Valley Bank.


<PAGE>

                                                                     EXHIBIT 4.1


                           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,  as
amended  (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 1,500,000  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  1,500,000.  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 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


<PAGE>

               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-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


<PAGE>

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.

               (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.

<PAGE>

               (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 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:


<PAGE>

                             (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.

                      (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.

<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 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;

<PAGE>

                      "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;

                      "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)

<PAGE>

               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 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

<PAGE>

                      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 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.

<PAGE>

                      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  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 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

<PAGE>

               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  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.

<PAGE>

                      (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).

                      (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

<PAGE>

               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 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

<PAGE>

               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  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

<PAGE>

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).

               (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

<PAGE>

Offering,  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]

<PAGE>

               IN WITNESS  WHEREOF,  E. Andrews  Grinstead,  III,  President and
Chief  Executive  Officer  of the  Corporation,  acting for and on behalf of the
Corporation, has hereunto subscribed his name this 5th day of May, 1998.





                                 HYBRIDON, INC.



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


<PAGE>


                                                                    EXHIBIT 99.1




                 FIRST AMENDMENT TO LOAN AND SECURITY AGREEMENT
                                     BETWEEN
                                 HYBRIDON, INC.
                                       AND
                               SILICON VALLEY BANK

        This First  Amendment  is made,  effective  as of the 30th day of March,
1998 to that certain Loan and Security  Agreement  dated as of December 31, 1996
as amended by consent letter agreement (the "Consent  Letter") dated January 15,
1998 (as  amended,  the "Loan  Agreement")  between  Hybridon,  Inc., a Delaware
corporation with a principal place of business at 620 Memorial Drive, Cambridge,
Massachusetts (the "Borrower") and Silicon Valley Bank (the "Bank"). Capitalized
terms used, but not defined in this Amendment  shall have the meanings  ascribed
to  them  in  the  Loan  Agreement  and  ancillary  documents,  instruments  and
agreements,  in the Consent  Letter and  ancillary  documents,  instruments  and
agreements, or if not so defined shall have the meanings ascribed to them in the
Uniform  Commercial  Code, or in the case of financial and accounting  terms, in
accordance with generally accepted accounting principles.

                                    RECITALS

        Pursuant to the Loan Agreement and on the terms and conditions set forth
therein, on December 31, 1996, the Bank made a secured term loan to the Borrower
in the original face amount of $7,500,000  (the  "Loan").  In connection  with a
planned  offering of Units of  investment  in the  Borrower in January 1998 (the
"Original  Offering"),  the Borrower  requested that the Bank waive or amend the
application of certain covenants  contained in the original Loan Agreement,  the
Negative Pledge Agreement and certain other and ancillary documents, instruments
and agreements executed and delivered in connection with the Loan Agreement. The
Bank and the Borrower  executed the Consent Letter to  memorialize  such waivers
and  amendments.  The  Borrower has advised the Bank that it wishes to amend the
Original Offering (subject to the occurrence of certain conditions  described in
EXHIBIT A hereto) to  provide,  among  other  things,  for the  issuance  in the
Amended Offering of common stock, warrants and Series A Preferred Stock only and
not for Senior  Subordinated  Notes.  The Borrower has  requested  that the Bank
consent to the  amendment of the Original  Offering on the terms and  conditions
set forth in Exhibit A, annexed hereto (the "Amended  Offering"),  that the Bank
waive certain covenant defaults in the Loan Agreement and that the Bank agree to
amend certain other  provisions of the Loan Agreement to accommodate the Amended
Offering.  The term  "Offering" as used in the Loan Agreement  shall include the
Amended  Offering or any other equity  offering or corporate  collaboration  not
involving indebtedness of the Borrower.

        The Bank is willing to consent to the amendment of the  Offering,  waive
certain  covenant  defaults  in the  Loan  Agreement  and  amend  certain  other
provisions of the Loan Agreement to accommodate the Amended  Offering,  but only
upon the terms and conditions set forth in this Amendment.

                                    AGREEMENT

        In  consideration  of  the  foregoing,   and  of  the  undertakings  and
obligations of the Borrower and the Bank set forth herein and for other good and
valuable   consideration,   receipt   and   sufficiency   of  which  are  hereby
acknowledged, the Borrower and Bank agree as follows:

<PAGE>

     1.   The  Borrower  shall pay to the Bank on the date of this  Amendment in
          good and immediately  collectible  funds a waiver fee in the amount of
          $35,000.

     2.   The last sentence of Section 6 of the Consent Letter is hereby amended
          to  provide  that  the  Borrower  shall  pay  to the  Bank  a  monthly
          Administrative  Fee in the  amount  of $5,000  which  shall be due and
          payable in good and immediately collectible funds, on the fifteenth of
          each month (or if not a business  day, on the next business day) until
          the earlier of : (i) full and final  payment of the Loan,  or (ii) the
          receipt by the  Borrower of net  proceeds in the  Offering of at least
          $30,000,000.

     3.   The Borrower  acknowledges and agrees that the outstanding  balance of
          principal  and  interest  on the Loan as of March  31,  1998 is as set
          forth in  Schedule  3 hereto,  and that the  Borrower  has no claim or
          offset which would preclude payment of the full amount of the Loan.

     4.   The Borrower's  Obligations to the Bank under the Loan  Agreement,  as
          amended by the Consent Letter and hereby,  are expressly  ratified and
          confirmed by the Borrower hereby.  The Borrower  ratifies and confirms
          all of the  representations  and  warranties  made  by it in the  Loan
          Agreement,  except as expressly disclosed to the Bank, and confirms to
          the Bank that it is in compliance  with the  covenants and  agreements
          contained  in the Loan  Agreement  except for its  failure to maintain
          compliance  with the  covenants  waived  in  Sections  7 and 8 of this
          Amendment,  and except for its failure to comply with Section  6.10(c)
          of the Loan Agreement, to the extent that such failure is nevertheless
          in compliance with the Intellectual  Property Security  Agreement (the
          "IP Security Agreement")  delivered by the Borrower in connection with
          the Consent  Letter (it being  agreed that the  provisions  of Section
          6.10(c) shall be deemed superseded by the analogous  provisions of the
          IP Security Agreement).  To the extent possible,  this Amendment shall
          be  construed  to be  consistent  with  the  provisions  of  the  Loan
          Agreement  and  Consent  Letter;  however,  to  the  extent  that  the
          provisions of this Amendment expressly conflict with or contradict the
          provisions of the Consent Letter or the Loan Agreement, the provisions
          of this Amendment shall be deemed to control.

     5.   The  effective  rate of interest to be charged to the  Borrower on the
          Loan (the "Effective  Rate") shall continue to be the sum of the Prime
          Rate plus Five (5%)  percent  per annum.  Provided  that there has not
          occurred and is not continuing an Event of Default, the Effective Rate
          will be reduced  (i) to the Prime Rate plus  Three  (3%)  percent  per
          annum as of the first  business  day of the  month  after the month in
          which less than Fifteen  (15%) percent of the  Borrower's  outstanding
          accounts payable are over ninety (90) days past due, (ii) to the Prime
          Rate plus Two (2%)  percent per annum as of the first  business day of
          the month after the month in which less than Ten (10%)  percent of the
          Borrower's outstanding accounts payable are over ninety (90) days past
          due, and (iii) to the Prime Rate plus One (1%) percent per annum as of
          the first business day of the month after the month in which less than
          Five(5%)  percent of the Borrower's  outstanding  accounts payable are
          over ninety (90) days past due. The Borrower  shall not be entitled to
          elect a Libor Rate Loan under the Loan  Agreement  without the written
          consent of the Bank which may be withheld in its sole discretion.  For
          purposes of  computing  the above  percentages  of  accounts  payable,
          credit balances shall be ignored.

     6.   The following  additional  reporting  requirements of the Borrower are
          hereby added to Section 6.3 of the Loan Agreement as  subsections  (g)
          and (h) thereof:

            "(g) the Borrower  shall report to the Bank on the fifteenth  (15th)
            and on the last  business day of each month (or on the next business
            day if either is not a business  day) the total of its book  balance
            of cash(including cash equivalents and marketable  securities),  and
            (h) the


<PAGE>

            Borrower  shall  provide to the Bank on or before  thirty  (30) days
            after the end of each fiscal  quarter a listing of all  Intellectual
            Property owned by it and of all Intellectual  Property  abandoned or
            proposed to be abandoned by it within the next thirty (30) days, and
            will fully  cooperate  with the Bank in, at the  Bank's  discretion,
            amending the Intellectual Property Security Agreement granted to the
            Bank or in filing a new  Intellectual  Property  Security  Agreement
            covering  new  Intellectual  Property  in  which  the  Borrower  has
            acquired any rights."

     7.   The Bank hereby  waives  compliance  by the Borrower  with the Minimum
          Tangible  Net Worth  covenant  established  in Section 6.8 of the Loan
          Agreement for the quarters ended December 31, 1997 and March 31, 1998.
          The Bank's agreement to waive this covenant as of the quarter ends set
          forth in the preceding  sentence does not  constitute any agreement by
          the Bank to waive such covenant other than for the quarters indicated,
          or any other  covenant  at any time,  and  shall not be  construed  to
          create a course of dealing with respect to such  covenant or any other
          covenant.  The Bank also  waives  the  requirement  of an  unqualified
          opinion on the Borrower's 1997 fiscal financial statements which would
          otherwise  be  required   pursuant  to  Section  6.3(b)  of  the  Loan
          Agreement.

     8.   The Bank hereby  waives  compliance  by the Borrower  with the Minimum
          Liquidity  covenant  established  in Section 6.9 of the Loan Agreement
          with respect to Borrower's  Minimum  Liquidity at March 31, 1998.  The
          Bank's  agreement  to waive this  covenant for the period set forth in
          the preceding  sentence does not  constitute any agreement by the Bank
          to waive such  covenant  other than for the period  indicated,  or any
          other  covenant at any time,  and shall not be  construed  to create a
          course of dealing with respect to such covenant or any other covenant.
          The Minimum Liquidity covenant (as revised hereinafter) shall again be
          applicable to the Borrower in respect to Borrower's  Minimum Liquidity
          at April 30, 1998 and all testing dates thereafter.

     9.   Section 6.9 of the Loan  Agreement  and the Consent  Letter are hereby
          amended to provide that "Minimum  Liquidity" shall mean the sum of (i)
          Borrower's  book  balance  of cash  (including  cash  equivalents  and
          marketable securities,  but exclusive of the CRLP Withhold), plus (ii)
          50% of  Borrower's  Accounts  Receivable,  plus  (iii)  the sum of all
          Minimum Liquidity Payments made by the Borrower, including the payment
          in the amount of  $1,762,825.00  made by the Borrower in January 1998.
          "Minimum  Liquidity  Payments"  shall mean all prepayments of the Loan
          made by the  Borrower  as a result of  Borrower's  failure to meet the
          "Minimum Liquidity" required to be maintained by the Borrower pursuant
          to  Section  6.9 of  the  Loan  Agreement.  Section  6.9  of the  Loan
          Agreement is hereby amended further to provide that,  commencing April
          30, 1998,  compliance  with the Minimum  Liquidity  covenant  shall be
          tested as of the fifteenth (15th) and as of the last day of each month
          (or on the next  business  day if either is not a business  day),  and
          that if the Borrower fails to maintain Minimum  Liquidity at either of
          such dates,  the  Borrower  must prepay the Loan by an amount equal to
          the  applicable  percentage  (based on the  actual  Minimum  Liquidity
          reported)  set forth in Section 6.9. Such payment shall be made on the
          next business day.


     10.  At least fifty (50%) of the net  proceeds of the  Offering and Amended
          Offering will be deposited in the  Borrower's  demand deposit or other
          deposit  accounts  with  the  Bank,  and at least  fifty  (50%) of the
          Borrower's present unencumbered cash will be maintained with the Bank,
          all such funds to be used in the Borrower's  discretion subject to the
          covenants in the Loan Agreement.

     11.  A new  paragraph is hereby added to Section 7.1 of the Loan  Agreement
          to provide  that,  provided  that there is not a  continuing  Event of
          Default,  Fifty  (50%)  percent  of  the  net  cash  proceeds  of  any
          dispositions  of assets of the  Borrower  permitted by the Bank (other
          than sales of inventory


<PAGE>

          and  licensing  of  Intellectual  Property in the  ordinary  course of
          Borrower's business and sales of assets permitted by the Bank with net
          cash proceeds of less than $5,000 in any  instance,  or $25,000 in any
          fiscal  quarter  )shall be applied as a  prepayment  against  the most
          remote payments due under the Loan, and that the remaining Fifty (50%)
          percent of such net proceeds may be used in the Borrower's discretion,
          subject to the covenants in the Loan  Agreement.  After and during the
          continuance of an Event of Default, all such payments shall be applied
          against the most remote  payments due under the Loan.  With respect to
          Borrower's  interest in CRLP,  provided that there is not a continuing
          Event of Default,  Fifty (50%) percent of such net proceeds (estimated
          to be $3.4  Million)  shall  be used by the  Borrower  to pay past due
          accounts  payable,  with the CRLP  Withhold to be  deposited in a time
          deposit with the Bank and pledged to the Bank as security for the Loan
          until  the  earlier  of the time  that (i)  Borrower  has  raised  net
          proceeds of at least  $10,000,000 in net proceeds in the Offering,  or
          (ii) the Termination Date, at which time,  provided that there has not
          occurred and is not  continuing an Event of Default,  such amount will
          be released to the Borrower to pay past due accounts  payable,  except
          if the  Borrower  has not raised net  proceeds of  $10,000,000  in the
          Offering by the Termination  Date or if there is a continuing Event of
          Default at the time that the  Borrower has raised  $10,000,000  in the
          Offering,  the CRLP Withhold  shall be applied by the Bank to the most
          remote  payments  due under the Loan.  The Bank  agrees to release its
          security interest in the Borrower's  interest in CRLP to accommodate a
          sale in accordance with this paragraph.

     12.  The Bank  hereby  consents  to, and  waives any Event of Default  that
          would  otherwise  arise  as a  result  of,  the  consummation  of  the
          "Alternative   Equity   Offering"   described   in   Schedule  A  (the
          "Alternative  Equity  Offering"),  including without  limitation,  the
          compensation  to be paid  to  Pillar  Investments,  Ltd.  referred  to
          therein.  The Bank  acknowledges  that the Amended  Offering  does not
          constitute a termination  or  abandonment of the Offering for purposes
          of the Loan  Agreement,  Consent Letter,  Intercreditor  Agreement and
          this Amendment.

     13.  Section 12.1 is revised to read as follows:

          "12.1 Assignments/Participations. This Agreement shall be binding upon
          and  shall  inure to the  benefit  of  Borrower  and  Bank  and  their
          respective  successors  and assigns;  PROVIDED  THAT  Borrower may not
          assign or transfer any rights or obligations  hereunder without Bank's
          prior written consent.  Bank may at any time pledge all or any portion
          of its rights under this Agreement to any of the Federal Reserve Banks
          organized  under Section 4 of the Federal  Reserve Act. No such pledge
          or  enforcement  thereof shall  release the Bank from its  obligations
          under this Agreement. Bank shall also have the right from time to time
          without  consent of the  Borrower  to assign all or any portion of its
          rights  hereunder to one or more banks or financial  institutions  (an
          "Assignee")  and  Borrower  agrees to execute  such  documents as Bank
          shall require to effect such assignment.  In addition,  at the request
          of the Bank and such Assignee,  the Borrower shall execute and deliver
          one or  more  new  promissory  notes  in  replacement  of,  but not in
          discharge of, the liability  evidenced by the promissory  note held by
          the Bank prior to such  assignment and shall reflect the amount of the
          respective  commitments and loans held by such Assignee and Bank after
          giving effect to such  assignment.  Upon the execution and delivery of
          appropriate   assignment    documentation,    amendments   and   other
          documentation required by the Bank in connection with such assignment,
          and the payment by the  Assignee of the  purchase  price  agreed to by
          Bank and such Assignee, such Assignee shall become a party to the Loan
          Agreement  and shall have all of the rights  and  obligations  of Bank
          hereunder  and under all  related  documents  to the extent  that such
          rights and obligations  have been assigned by the Bank pursuant to the
          assignment  documentation between the Bank and such Assignee, and Bank
          shall be released from its future obligations hereunder and thereunder
          to a corresponding extent."

<PAGE>

     14.  Section  1 of the  Consent  letter  is hereby  amended  to change  the
          reference to the sum of $35,000,000 in clause i) thereof to the sum of
          $30,000,000.  The Bank  acknowledges that the Offset Right shall be as
          set  forth in the  Intercreditor  Agreement  notwithstanding  that the
          Amended Offering may be pursued in lieu of the Original Offering.

     15.  The Bank  hereby  consents  to the  deferral  by the  Borrower  of the
          Deferred  Payments  referred  to in Section 9 of the  Consent  Letter,
          notwithstanding   that  the  conditions  precedent  to  such  deferral
          referred to in Section 9 may not have been satisfied.

     16.  The Borrower  further  acknowledge  that all reasonable  out-of-pocket
          costs  and  expenses  of the  Bank  in  connection  with  negotiation,
          documentation  and   administration   of  this  Amendment,   including
          reasonable fees of attorneys  engaged to represent the Bank,  shall be
          borne by the Borrower.

     17.  The Borrower  acknowledges  and  confirms  that to the extent that the
          Borrower  may have any claims,  offsets,  counterclaims,  or defenses,
          asserted or unasserted, the Borrower, for itself, and on behalf of its
          successors,   assigns,  parents,  subsidiaries,   agents,  affiliates,
          predecessors,  employees, officers, directors, executors and heirs, as
          applicable  (collectively,  the  "Borrower  Affiliates")  releases and
          forever discharges the Bank, its subsidiaries,  affiliates, employees,
          officers,  directors, agents, successors and assigns, both present and
          former  (collectively,  the "Bank Affiliates") of and from any and all
          manner  of  claims,  offsets,  counterclaims,   defenses,  action  and
          actions,  cause and causes of  action,  suits,  debts,  controversies,
          damages,  judgments,  executions, and demands whatsoever,  asserted or
          unasserted,  in law or in equity,  which  against  the Bank and/or the
          Bank  Affiliates,  they or the  Borrower  Affiliates  ever  had to and
          including  the date  hereof,  upon or by reason of any matter,  cause,
          causes or thing whatsoever,  in connection with the Loan and/or any of
          the  transactions   and  matters  related  thereto,   except  for  the
          obligations of the Bank in such documents,  instruments and agreements
          to be performed after the date of this  Amendment.  The Borrower shall
          indemnify,  defend  and hold the Bank  harmless  of and from any claim
          brought or  threatened  against the Bank by the  Borrower or any other
          person (as well as from  attorneys'  fees and  expenses in  connection
          therewith)  on account of the Loan  Agreement,  the Note,  the Consent
          Letter,   the  Intellectual   Property  Security   Agreement,   Pledge
          Agreement,  Intercreditor  Agreement,  this  Amendment,  and any other
          document,  instrument or agreement  given in connection  with the Loan
          and any of the transactions and matters related thereto (each of which
          may be  defended,  compromised,  settled  or  pursued by the Bank with
          counsel of the Bank's election reasonably  acceptable to the Borrower,
          but at the expense of the Borrower),  except in the case of the Bank's
          failure to comply with its  obligations  hereunder or thereunder,  its
          gross negligence or willful misconduct.

     18.  This  Amendment  represents the entire  agreement  between the parties
          with  respect  to the  modifications  contained  herein,  and shall be
          construed  in  accordance  with  the  laws  of  the   Commonwealth  of
          Massachusetts as an agreement under seal. The Borrower has voluntarily
          entered into this Amendment without coercion or duress of any kind and
          has been or has had the opportunity to have been  represented by legal
          counsel of their choosing.

<PAGE>

        WITNESS OUR hands and seals on this 30th day of March, 1998.

                                    HYBRIDON, INC.

                                         By: /s/ F. Andrews Grinstead, III
                                             -----------------------------

                                    SILICON VALLEY BANK

                                    By:  /s/ Judy Sanchez
                                         ----------------
                                    Judy Sanchez, Senior Vice President


<PAGE>

                                                                     EXHIBIT 4.2



THE TERMS OF THIS NOTE ARE SUBJECT TO THE TERMS OF A UNIT PURCHASE AGREEMENT,  A
COPY OF WHICH IS AVAILABLE FROM HYBRIDON,  INC. (THE "COMPANY").  THE SECURITIES
REPRESENTED  BY THIS  NOTE 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.

THIS NOTE MAY NOT BE OFFERED OR SOLD IN THE UNITED STATES OR TO A U.S. PERSON OR
FOR THE  ACCOUNT OR  BENEFIT OF A U.S.  PERSON  PRIOR TO THE  EXPIRATION  OF THE
RESTRICTED  PERIOD (AS DEFINED IN THE  PURCHASE  AGREEMENT),  AND NO TRANSFER OR
EXCHANGE  OF  THIS  NOTE  MAY BE MADE  UNTIL  AFTER  THE  LATER  OF THE  DATE OF
EXPIRATION  OF THE  RESTRICTED  PERIOD  AND  THE  DATE  ON  WHICH  THE  REQUIRED
CERTIFICATION RELATING TO SUCH INTEREST HAS BEEN PROVIDED IN ACCORDANCE WITH THE
TERMS OF THE PURCHASE AGREEMENT.




                                 HYBRIDON, INC.

                                                                          No.___
                                  NOTE DUE 2007

$---------
                                                          [DATE OF ISSUANCE]

        Hybridon,  Inc.,  a Delaware  corporation,  (the  "Company"),  for value
received, hereby promises to pay to ___________________________  (the "Holder"),
or  registered  assigns,  the  principal  sum set forth above,  with accrued but
unpaid interest  thereon at a rate equal to fourteen percent (14%) per annum, on
December 31, 2007 (the "Maturity Date"); provided, however, that if the offering
(the "Unit Offering") of units ("Units")  consisting of Notes (as defined below)
and Warrants is  terminated  before the Mandatory  Conversion  Event (as defined
below) has occurred,  then the interest  rate will increase to eighteen  percent
(18%)  per  annum,  effective  as of the date  the  Additional  Warrants  become
exercisable.  Payment  shall be made at such place as  designated by the Company
upon surrender of this Note, and shall be in such coin or currency of the United
States  of  America  as at the time of  payment  shall be legal  tender  for the
payment of public and private debts. This Note is one of a duly authorized issue
of Hybridon,  Inc. Notes due 2007  (individually a "Note" and  collectively  the
"Notes") in an aggregate original principal

<PAGE>

amount of up to  $68,750,000  plus any Notes issued in lieu of cash  interest on
Notes,  issued pursuant to a Unit Purchase Agreement which is available from the
Company (the "Purchase  Agreement") and similar  agreements.  The Notes shall be
senior in right of payment to the Company's 9%  Convertible  Subordinated  Notes
Due  2004  (the "9%  Notes")  to the  extent  provided  in a First  Supplemental
Indenture,  dated as of January 13, 1998, to an Indenture, dated as of March 26,
1997,  pursuant  to  which  such 9%  Notes  were  issued.  The  Notes  shall  be
subordinated in right of payment to all existing and future Senior  Indebtedness
of the Company.  The Notes are secured by certain assets of the Company pursuant
to the Purchase Agreement on a subordinated basis. Capitalized terms used herein
without  definition  have the  respective  meanings  specified  therefor  in the
Purchase Agreement.

SECTION 7.         INTEREST.

               The Company will pay interest semi-annually in arrears on April 1
and October 1 of each year (each an "Interest Payment Date"), or if any such day
is not a Business  Day, on the next  succeeding  Business Day to the  registered
Holder  hereof as of the  preceding  March 15 or September  15 (each,  a "Record
Date").  Interest on this Note will accrue from the most recent Interest Payment
Date to which interest has been paid or, if no interest has been paid,  from the
date of its  issuance  set forth  above;  provided  that if there is no existing
Default in the payment of interest,  and if this Note is authenticated between a
Record Date,  and the next  succeeding  Interest  Payment Date,  interest  shall
accrue from such next succeeding Interest Payment Date; provided,  further, that
the first  Interest  Payment Date shall be April 1, 1998 or, if interest is paid
in cash, October 1, 1998. The Company may, with respect to each Interest Payment
Date, at its option and in its sole  discretion,  in lieu of payment of interest
on the Notes in cash, issue additional Notes ("Interest  Notes") in an aggregate
principal  amount  equal  to the  amount  of  interest  not paid in cash on such
Interest Payment Date. Each issuance of Interest Notes in lieu of the payment of
cash  interest  on the  Notes  shall  be  made  pro  rata  with  respect  to the
outstanding  Notes;  provided,  however,  that the Company may at its option pay
cash in lieu of issuing  Interest Notes in any denomination of less than $1,000.
Interest  will be computed on the basis of a 360-day  year  comprised  of twelve
30-day months.

SECTION 8.         PREPAYMENT.

               This Note (including  interest  accrued on the principal  hereof)
may be prepaid by the Company, at any time without penalty or premium.

SECTION 9.     MANDATORY CONVERSION

               (a)  Mandatory  Conversion.  Upon the  occurrence  of a Mandatory
Conversion Event (as hereinafter defined),  and not before such occurrence under
any   circumstances,   the  Notes  and  all  accrued   interest   thereon  shall
automatically  convert into the number of shares of Series B Preferred  Stock of
the Company in  substantially  the form  attached to the  Purchase  Agreement as
Exhibit C (the  "Conversion  Securities")  equal to the  Conversion  Amount  (as
defined below) divided by the then current  Conversion Price (as defined below).
The "Conversion  Amount" shall be the Liquidation Amount (as defined below). The
"Liquidation  Amount"  shall be the  aggregate  principal  amount  of,  plus any
accrued but unpaid interest on,

<PAGE>

the Notes held by such Holder.  The "Conversion  Price" shall initially be $100,
subject to adjustment as provided below, representing an initial conversion rate
(subject to  adjustment)  of 10 shares of  Conversion  Securities  per $1,000 of
Conversion Amount (the "Conversion Rate").

               A "Mandatory  Conversion Event" shall be deemed to have occurred,
effective immediately, when all of the following shall have occurred:

               (i) the holders of  $40,000,000  or more in  aggregate  principal
amount of the 9%  Convertible  Subordinated  Notes  due 2004 (the  "Subordinated
Notes")  issued  pursuant to the Indenture  between the Company and State Street
Bank  and  Trust  Company,  as  Trustee,   dated  as  of  March  26,  1997  (the
"Indenture"),  irrevocably  exchange such Subordinated Notes and all accrued but
unpaid interest thereon for Series A Preferred Stock of the Company and warrants
to purchase Common Stock of the Company; and

               (ii) the Company has received proceeds in the Unit Offering,  net
of cash fees, commissions and expenses, equal to or exceeding $20,000,000 in the
aggregate.

               (b) Conversion  Procedures.  Such  conversion  shall be deemed to
have been made automatically, irrevocably and immediately upon the occurrence of
a Mandatory  Conversion Event and, upon such Mandatory  Conversion Event,  Notes
shall no longer be deemed  outstanding  and all  rights  whatsoever  in  respect
thereof (including the right to receive interest thereon) shall terminate except
as provided in the following sentence.  The Company shall deliver to each Holder
certificates  evidencing  the number of full shares of Conversion  Securities to
which such person shall be entitled as provided in Subsection  3(a),  subject to
Section 4 hereof.

               (c) [Reserved]

               (d) Reservation of Shares; Transfer Taxes; Etc. The Company shall
at all times  reserve and keep  available,  out of its  authorized  and unissued
shares of  Conversion  Securities,  solely  for the  purpose  of  effecting  the
conversion of the Notes, such number of shares of its Conversion Securities free
of  preemptive  rights as shall be  sufficient  to effect the  conversion of all
Notes from time to time outstanding. The Company 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  Conversion  Securities  if at any time the
number  of  shares  of  Conversion  Securities  not  outstanding  shall  not  be
sufficient to permit the conversion of all the then-outstanding Notes.

               The  Company  shall pay any and all issue or other  taxes  (other
than  income  taxes)  that may be payable in respect of any issue or delivery of
shares of Conversion  Securities  on conversion of the Notes.  The Company 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 Conversion  Securities  (or other
securities  or assets) in a name other than that in which the Notes 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 Company the amount of such tax
or has established,  to the satisfaction of the Company,  that such tax has been
paid.

               (e) Other  Changes in Conversion  Rate.  The Company from time to
time may  increase the  Conversion  Rate by any amount for any period of time if
the period is at least 20


<PAGE>

days  and if the  increase  is  irrevocable  during  the  period.  Whenever  the
Conversion Rate is so increased,  the Company shall mail to the holder of record
of this  Note 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 Company may make such  increases in the  Conversion  Rate, in
addition  to those  required  or  allowed  by this  paragraph  (e),  as shall be
determined  by it, as evidenced by a resolution of the Board of Directors of the
Company, 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.

SECTION 10.        FRACTIONAL SHARES.

               The Company shall not be required to issue fractions of shares of
Conversion  Securities or other capital stock of the Company upon  conversion of
any Notes.  If any  fraction of a share would be issuable on  conversion  of any
Notes (aggregating,  for this purpose,  all Notes held by a record holder),  the
number of shares of  Conversion  Securities  issuable  shall be  rounded  to the
nearest whole share, with .5 of a share rounded upward.

SECTION 11.        EVENTS OF DEFAULT DEFINED.

               The  following  shall  each  constitute  an  "Event  of  Default"
hereunder:

               (a) the  failure  of the  Company  to  make  any  payment  of (i)
principal of this Note when due and payable and such failure shall  continue for
five (5) or more days and (ii)  interest  on this Note when due and  payable and
such failure  shall  continue for thirty (30) or more days,  whether or not such
payment  is  prohibited  by the  subordination  provisions  of this  Note or the
Purchase Agreement;

               (b) the failure of the Company to observe or perform any covenant
in this Note or in the Purchase Agreement, and such failure shall have continued
unremedied  for a period of sixty (60) days after written  notice as provided in
the last paragraph of this Section 5;

               (c) a default occurs (after giving effect to any applicable grace
periods  or any  extension  of any  maturity  date) in the  payment  when due of
principal of, or an acceleration  of, any indebtedness for money borrowed by the
Company or any of its  Subsidiaries  (other than an Unrestricted  Subsidiary (as
defined  below) which is not a Significant  Subsidiary  and provided there is no
recourse  against  the  Company  or any other  Subsidiary  with  respect  to the
obligations of such Unrestricted Subsidiary arising as a result of such default)
in excess of $2 million,  individually or in the aggregate, if such indebtedness
is not discharged,  or such  acceleration is not annulled,  within 30 days after
written notice as provided in the last paragraph of this Section 5;

               (d) the Company or any of its Significant Subsidiaries,  pursuant
to or within the meaning of any Bankruptcy Law:

                    (i) commences a voluntary case,

<PAGE>

                    (ii) consents to the entry of an order for relief against it
               in an involuntary case,

                    (iii)  consents to the  appointment  of a Custodian of it or
               for all or substantially all of its property,  and such Custodian
               is not discharged within 30 days,

                    (iv)  makes a  general  assignment  for the  benefit  of its
               creditors, or

                    (v) admits in writing that it is generally unable to pay its
               debts as the same become due;

               (e) a court of competent  jurisdiction enters and order or decree
under any Bankruptcy Law that:

                    (i) is  for  relief  in any  involuntary  case  against  the
               Company or any Significant Subsidiary,

                    (ii) appoints a Custodian of the Company or any  Significant
               Subsidiary or for all or substantially all of the property of the
               Company or any Significant Subsidiary, or

                    (iii)  orders  the   liquidation   of  the  Company  or  any
               Significant  Subsidiary,  and, in each case,  the order or decree
               remains unstayed and in effect for 60 consecutive days.

               The term  "Bankruptcy Law" means Title 11 of the U.S. Code or any
similar  federal,  foreign  or state  law for the  relief of  debtors.  The term
"Custodian"  means any  receiver,  trustee,  assignee,  liquidator,  examiner or
similar official under any Bankruptcy Law. The term "Significant Subsidiary" has
the same meaning as  significant  subsidiary  has under  Regulation SX under the
Securities Act as in effect on the date hereof.  "Unrestricted Subsidiary" means
any Subsidiary of the Company which (i) is not wholly-owned by the Company, (ii)
is  designated  as an  Unrestricted  Subsidiary by the Board of Directors of the
Company  and  (iii)  at the  time  of any  investment  by the  Company  in  such
Subsidiary,  in the aggregate  holds or comprises less than 20% of the Company's
assets  as  shown  on the  Company's  consolidated  balance  sheet  prepared  in
accordance with generally accepted accounting principles consistently applied as
at the time of such investment.

               A Default  under  Subsection  (b) of this Section 5 (other than a
Default under Section 8.14 of the Purchase Agreement,  which Default shall be an
Event of Default  with the notice but without the passage of time  specified  in
Subsection  (b) of this Section 5) or Subsection (c) of this Section 5 shall not
be an Event of  Default  until  (i) the  holders  of at least  25% in  aggregate
principal amount of the Notes then  outstanding  shall have notified the Company
of the Default and (ii) the Company  shall have failed to cure the Default under
such  Subsection  (b) within 60 days  after  receipt of the notice or under such
Subsection  (c) within 10 days after  receipt of the notice,  respectively.  Any
such notice must specify the Default,  demand that it be remedied and state that
the notice is a "Notice of Default."

SECTION 12.    REMEDIES UPON EVENT OF DEFAULT.

<PAGE>

               (a) If an  Event of  Default  (other  than an  Event  of  Default
specified in Subsections (d) and (e) of Section 5) occurs and is continuing, the
Holders  of at  least  25% in  aggregate  principal  amount  of the  Notes  then
outstanding  (by notice to the Company and the Secured  Party),  may declare the
unpaid principal of and accrued interest on all the Notes then outstanding to be
due and payable. Upon any such declaration,  such principal and accrued interest
shall  be due and  payable  immediately.  If an Event of  Default  specified  in
Subsection  (d) or (e) of  Section 5 occurs,  such an amount  shall  ipso  facto
become and be immediately  due and payable  without any declaration or other act
on the part of any Holder.  The Holders of at least fifty  percent (50%) or more
in  aggregate  principal  amount of the Notes then  outstanding  may  rescind an
acceleration  and its  consequences if (a) the Company has paid a sum sufficient
to pay (i) all  overdue  interest  on all Notes  then  outstanding  and (ii) the
principal of the Notes then outstanding  which have become due otherwise than by
such declaration of acceleration and accrued interest thereon at a rate borne by
the Notes and (b) the rescission  would not conflict with any judgment or decree
and if all  existing  Events  of  Default  have  been  cured  or  waived  except
nonpayment  of  principal  or  interest  that has become  due solely  because of
acceleration.  No such rescission shall effect any subsequent  Default or impair
any right consequent thereto.

               (b) The  Holders  of at  least  fifty  percent  (50%)  or more in
aggregate  principal  amount of the Notes then outstanding may waive an existing
Default or Event of Default and its  consequences.  Upon any such  waiver,  such
Default shall cease to exist and any Event of Default arising therefrom shall be
deemed  to have  been  cured for  every  purpose  of this Note and the  Purchase
Agreement; but no such waiver shall extend to any subsequent or other Default or
impair any right consequent thereon.

               (c) If the  Company  defaults  in a payment  of  interest  on the
Notes, the Company shall pay defaulted interest (plus interest on such defaulted
interest,  to the extent  lawful,  at the rate borne by this Note) in any lawful
manner. The Company shall pay the defaulted interest to the Holders of the Notes
on a special  record date.  The Company  shall fix or cause to be fixed any such
special record date and payment date,  which specified  record date shall not be
less than 10 days prior to the payment  date for such  defaulted  interest,  and
shall  promptly  mail or cause to be mailed to each  Holder a notice that states
the special record date,  the payment date and the amount of defaulted  interest
to be paid.

               (d) No remedy  herein  conferred  upon the Holder of this Note is
intended  to be  exclusive  of any other  remedy and each and every such  remedy
shall be  cumulative  and  shall be in  addition  to every  other  remedy  given
hereunder  or now or  hereafter  existing  at law or in equity or by  statute or
otherwise.

               (e) In any suit for the  enforcement of any right or remedy under
this Note or the Purchase  Agreement,  a court in its discretion may require the
filing by any party  litigant in the suit of an  undertaking to pay the costs of
the suit, and the court in its discretion may assess reasonable costs, including
reasonable  attorneys' fees,  against any party litigant in the suit, having due
regard to the merits and good faith of the claims or defenses  made by the party
litigant.  This Subsection 6(e) does not apply to a suit by Holders of more than
10% in aggregate

<PAGE>

principal amount of the then  outstanding  Notes or any suit for the enforcement
of the mandatory conversion right set forth in Section 3.

SECTION 13.    NOTE REGISTER.

               (a) The Company  shall keep at its principal  executive  office a
register  (herein  sometimes  referred  to as the  "Note  Register"),  in which,
subject to such reasonable  regulations as it may prescribe,  but at its expense
(other  than  transfer  taxes,  if  any),  the  Company  shall  provide  for the
registration and transfer of this Note.

               (b)  Whenever  this Note shall be  surrendered  at the  principal
executive  office of the Company  for  transfer or  exchange,  accompanied  by a
written  instrument of transfer in form  reasonably  satisfactory to the Company
duly executed by the Holder  hereof or his attorney duly  authorized in writing,
and,  subject to compliance with applicable  securities  laws, the Company shall
execute  and  deliver  in  exchange  therefor  a new  Note or  Notes,  as may be
requested by such Holder,  in the same  aggregate  unpaid  principal  amount and
payable  on the  same  date as the  principal  amount  of the  Note or  Notes so
surrendered;  each such new Note shall be dated as of the date to which interest
has been paid on the unpaid principal amount of the Note or Notes so surrendered
and shall be in such  principal  amount and  registered in such name or names as
such Holder may designate in writing.

               (c)  Upon   receipt  by  the  Company  of   evidence   reasonably
satisfactory  to it of the loss,  theft,  destruction or mutilation of this Note
and of indemnity  reasonably  satisfactory to it, and upon  reimbursement to the
Company of all reasonable expenses  incidental  thereto,  and upon surrender and
cancellation  of this Note (in case of  mutilation)  the  Company  will make and
deliver  in lieu of this  Note a new Note of like  tenor  and  unpaid  principal
amount  and dated as of the date to which  interest  has been paid on the unpaid
principal  amount  of this  Note in lieu of  which  such  new  Note is made  and
delivered.

SECTION 14.    MISCELLANEOUS.

               (a) Amendments and Waivers. The holders of at least fifty percent
(50%) or more in principal  amount of outstanding  Notes or the Secured Party on
behalf  of the  holders  of the  Notes may  waive or  otherwise  consent  to the
amendment  of any of the  provisions  hereof,  provided  that no such  waiver or
amendment may reduce the principal  amount of or interest on any of the Notes or
change the stated  maturity of the principal or reduce the percentage of holders
of Notes  necessary to waive or amend the  provisions of this Note,  without the
consent of each holder of any Note affected thereby.

               (b)   Restrictions  on   Transferability.   In  addition  to  the
restrictions set forth in the Purchase Agreement,  the securities represented by
this Note have been acquired for investment and have not been  registered  under
the Securities Act of 1933, as amended,  or the securities  laws of any state or
other jurisdiction.  Without such registration, such securities may not be sold,
pledged,  hypothecated or otherwise  transferred,  except pursuant to exemptions
from the  Securities  Act of 1933, as amended,  and the  securities  laws of any
state or other jurisdiction.

<PAGE>

               (c) Forbearance from Suit. No holder of Notes shall institute any
suit or proceeding  for the  enforcement of the payment of principal or interest
unless the holders of at least 25% in principal amount of all of the outstanding
Notes join in such suit or proceeding.

               (d) No Recourse Against Others. No directors,  officer, employee,
incorporator  or stockholder of the Company,  as such,  shall have any liability
for any  obligations of the Company under this Note,  the Purchase  Agreement or
for any claim  based on, in respect  of, or by reason of,  such  obligations  or
their  creation.  The  Holder of this Note by  accepting  this Note  waives  and
releases  all  such   liability.   The  waiver  and  release  are  part  of  the
consideration for the issuance of this Note.

               (e) Subordination.  The Holder by accepting this Note agrees that
the payment (by set-off or  otherwise) of principal of and interest on the Notes
is subordinated in right of payment, to the extent and in the manner provided in
Section  9 of the  Purchase  Agreement,  to the  prior  payment  in  full of all
obligations  in  respect  of  Senior   Indebtedness  of  the  Company,   whether
outstanding on the date of the Purchase Agreement or thereafter incurred.

               (f) Denominations. This Note is issuable in minimum denominations
of  $1,000  and  integral  multiples  of $1,000  in  excess  thereof,  except as
otherwise provided in Section 1 hereof.

               (g) Governing  Law. This Note shall be governed by, and construed
in accordance with, the laws of the State of New York, excluding the body of law
relating to conflict of laws. Notwithstanding anything to the contrary contained
herein, in no event may the effective rate of interest  collected or received by
the Holder exceed that which may be charged, collected or received by the Holder
under applicable law.

               (h)  Interpretation.  If any term or provision of this Note shall
be held invalid,  illegal or unenforceable,  the validity of all other terms and
provisions hereof shall in no way be affected thereby.

               (i) Successors  and Assigns.  This Note shall be binding upon the
Company  and its  successors  and  assigns and shall inure to the benefit of the
Holder and its successors and registered assigns.

               (j) Notices. All notices, requests, consents and demands shall be
made in writing and shall be mailed  postage  prepaid,  or delivered by hand, to
the Company or to the Holder  thereof at their  respective  addresses  set forth
below or to such other address as may be furnished in writing to the other party
hereto:

               If to the Holder:    At the address shown on Schedule A attached 
                                    hereto

               If to the Company:   Hybridon, Inc.
                                    620 Memorial Drive
                                    Cambridge, Massachusetts 02139
                                    Attention:   E. Andrews Grinstead, III

<PAGE>

               (k)  Saturdays,  Sundays,  Holidays.  If any date that may at any
time be  specified  in this  Note as a date for the  making  of any  payment  of
principal or interest under this Note shall fall on Saturday, Sunday or on a day
which in New York or Massachusetts or California shall be a legal holiday,  then
the date for the making of that payment shall be the next  subsequent  day which
is not a Saturday, Sunday or legal holiday.

               (l)  Purchase  Agreement.  This  Note  is  subject  to the  terms
contained in the Purchase  Agreement and the  registered  Holder of this Note is
entitled  to the  benefits of such  Purchase  Agreement  to the extent  provided
therein and may, in addition to any rights hereunder,  enforce the agreements of
the Company  contained therein and exercise the remedies provided for thereby or
otherwise available in respect thereof.

               (m) No Adverse Interpretation of Other Agreements.  This Note and
the Purchase  Agreement may not be used to interpret  another  note,  indenture,
loan or debt agreement of the Company or a Subsidiary. Any such note, indenture,
loan or debt  agreement  may not be used to interpret  this Note or the Purchase
Agreement.

<PAGE>

        IN WITNESS  WHEREOF,  this Note has been  executed and  delivered on the
date first above written by the duly authorized representative of the Company.


                                          HYBRIDON, INC.


                                          By:
                                             ------------------------

                                               Name:
                                               Title:


<PAGE>

                                   SCHEDULE A



Name of Holder                              Address of Holder
- --------------                              -----------------

<PAGE>

                                                                     EXHIBIT 4.3

                                   FORM OF WARRANT AGREEMENT

                AGREEMENT, dated as of this fifth day of May, 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:


<PAGE>

               (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 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

<PAGE>

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]

               (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.

<PAGE>

               (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.

               (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

<PAGE>

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 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

<PAGE>

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)).

               (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

<PAGE>

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 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

<PAGE>

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 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.

<PAGE>

               (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  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;


<PAGE>

                   "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;

                   "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  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;


<PAGE>

                   "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:

                   (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


<PAGE>

        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  convertible  preferred  stock was  issued (or as a
result of any subsequent modification to the terms


<PAGE>

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


<PAGE>

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.

               (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


<PAGE>

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 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 t convertible into or
exchangeable  for Common Stock or carrying the right to purchase  Common t Stock
or any securities so convertible or exchangeable. t

               (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


<PAGE>

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  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.

<PAGE>

               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  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

<PAGE>

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 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

<PAGE>

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 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

<PAGE>

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.

               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.

<PAGE>

               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.

<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:  /s/ E. Andrews Grinstead
                                 -----------------------------
                            Authorized Officer



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


                            By: /s/ Lynore Le Conche
                                 -----------------------------
                               Authorized Officer

<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. AWA _______________ Class A Warrants

                             VOID AFTER MAY 4, 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 May 5, 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.

<PAGE>

               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
May 5, 1998, by and among the Company and the Warrant Agent.

               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 May
4, 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,

<PAGE>

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.

               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


<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.

<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

<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.

<PAGE>

                                                                     EXHIBIT 4.4


                            FORM OF WARRANT AGREEMENT

               AGREEMENT,  dated as of this fifth day of May, 1998, by and among
HYBRIDON,  INC., a Delaware  corporation  ("Company"),  CHASEMELLON  SHAREHOLDER
SERVICES,  L.L.C.,  a New Jersey  limited  liability  company,  as warrant agent
("Warrant Agent"), and PILLAR INVESTMENTS LTD. (the "Placement Agent")..

                               W I T N E S S E T H

               WHEREAS, the Alternative Equity Closing Conditions referred to in
Supplement  and  Amendment  No. 2 dated April 1, 1998 (the  "Amendment")  to the
Confidential  Term Sheet of the Company  dated  January 15, 1998 (the  "Original
Term Sheet") have been satisfied;

               WHEREAS,  each Class B 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 B
Warrants,  the issuance of certificates  representing the Class B Warrants,  the
exercise of the Class B 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 B Warrants and the certificates representing the Class B
Warrants and the respective  rights and  obligations  thereunder of the Company,
the holders of  certificates  representing  the Class B 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 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


<PAGE>

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 B Warrant,  the
date on which  the  Warrant  Agent  shall  have  received  both (a) the  Warrant
Certificate  representing  such  Class B  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
B Warrant,  the  Alternative  Equity  Financing  Closing Date (as defined in the
Amendment).

               (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)  "Purchase  Price"  shall  mean  120% of  $2.00,  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]

               (k) "Registered Holder" shall mean, as to any Class B Warrant and
as of any particular date, the person in whose name the certificate representing
the Class B 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

<PAGE>

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)    [Reserved]

               (p)  "Warrant  Expiration  Date"  shall mean 5:00 P.M.  (New York
time) on the day prior to the fifth  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 B Warrant  initially  shall  entitle  the  Registered
Holder of the Warrant Certificate  representing such Class B 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 B Warrants issued pursuant hereto will  immediately
be  detachable  and  separately  transferable  from the  shares of Common  Stock
included in the Alternative Equity Units (as defined in the Amendment).

               (c)  Within  five  business  days  after the  Alternative  Equity
Financing Closing Date, Warrant Certificates  representing the number of Class B
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.

<PAGE>

               (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 B 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 B  Warrants  represented  by any  Warrant
Certificate, to evidence any unexercised Class B 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 B 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 B 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  B  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 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

<PAGE>

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 B 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 B 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 B 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 B Warrant and shall notify the Company in writing of the
exercise of the Class B 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 B  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 B Warrant and  clearance of the funds  received,  the Warrant  Agent shall
promptly  remit the  payment  received  for the Class B  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 B Warrants,  such  number of shares of Common  Stock as
shall then be issuable  upon the exercise of all  outstanding  Class B Warrants.
The Company  covenants  that all shares of Common  Stock which shall be issuable
upon exercise of the Class B 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)).

         (b)  The  Registered  Holders  of  Class  B  Warrants  shall  have  the
registration  rights  provided  in  the  Unit  Purchase  Agreement  attached  as
Supplemental  Exhibit  D to the  Amendment.  The Class B  Warrants  shall not be
exercisable in any state where such exercise would be unlawful.

<PAGE>

               (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 B Warrants,  or the issuance or
delivery of any shares upon exercise of the Class B 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
B 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 B
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 B
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 B 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 B 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 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.

<PAGE>

               (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 B 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 B
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 B 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 B 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 B Warrants outstanding,  in lieu
of the adjustment in the number of shares of Common Stock  purchasable  upon the
exercise  of each  Class B Warrant  as  herein  provided,  so that each  Class B
Warrant  outstanding after such adjustment shall represent the right to purchase
one share of Common  Stock.  Each Class B Warrant  held of record  prior to such
adjustment of the number of Class B Warrants shall become that number of Class B
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 of which shall be the Purchase Price in effect  immediately
after such adjustment. Upon each adjustment of the

<PAGE>

number of Class B 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 B 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 B 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 B 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 admitted

<PAGE>

               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 a 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 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;

                      "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

<PAGE>

               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 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 B 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 B 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

<PAGE>

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:

                      (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

<PAGE>

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
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 B 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 B 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 B 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

<PAGE>

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.

               (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 Company's  Certificate of Designation (the
"Series A Certificate of  Designation")  for the Series A Convertible  Preferred
Stock,  par  value  $.01  per  share  (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

<PAGE>

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 B 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
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 B Warrants  exercised  after such record date and before the
occurrence  of such event the  additional  shares of Common Stock  issuable upon
such exercise by

<PAGE>

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  Term Sheet or any options or warrants  described  in the  Amendment in
respect of the Alternative  Equity  Financing (as defined in the Amendment),  in
each case issued to (or to the  designee  of) any  placement  agent or financial
advisor,  (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  exchange  for the  Company's  9%  Convertible
Subordinated  Notes due 2004 (the "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 Term Sheet 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
Series A Certificate of Designation.

               (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 B 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 B  Warrants.  If more  than one  certificate
evidencing Class B 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  B  Warrants  so
surrendered.  Instead  of any  fractional  share of  Common  Stock  which  would
otherwise  be  issuable  upon  exercise  of such  aggregate  number  of  Class B
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 B Warrants shall, as such, be entitled to vote or to receive  dividends or
be deemed the holder of

<PAGE>

Common  Stock that may at any time be  issuable  upon  exercise  of such Class B
Warrants for any purpose  whatsoever,  nor shall  anything  contained  herein be
construed  to confer  upon the holder of Class B 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 B
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 B
Warrants, and any Registered Holder of a Class B Warrant, without consent of the
Warrant  Agent or of the holder of any other  Class B Warrant,  may,  in his own
behalf  and for his own  benefit,  enforce  against  the  Company  his  right to
exercise  his Class B 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 B  Warrant,  by his  acceptance  thereof,  consents  and  agrees  with the
Company, the Warrant Agent and every other holder of any Class B Warrant that:

               (a) The Class B 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 B 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 B 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 B Warrant or Class B 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 B 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,

<PAGE>

relationship,  agency  or  trust  for or  with  any of the  holders  of  Warrant
Certificates or beneficial  owners of Class B 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 B Warrants  represented
thereby or of any  securities or other  property  delivered upon exercise of any
Class B Warrant or whether any stock issued upon exercise of any Class B 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 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

<PAGE>

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 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 B 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 B Warrants
which are to be governed by this Agreement  resulting from a subsequent offering
of Company  securities which includes Class B Warrants having the same terms and
conditions as the Class B 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

<PAGE>

writing of the Registered Holders of Warrant Certificates representing more than
50% of the Class B Warrants then  outstanding;  and provided,  further,  that no
change in the number or nature of the securities  purchasable  upon the exercise
of any Class B 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 B 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;  and, if to
Pillar, at Pillar  Investments  Ltd., 28 Avenue de Messine 75008 Paris,  France,
Attention: Youssef El Zein..

               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 B  Warrants  shall be  entitled  to
exercise  such  Class B 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 Placement Agent, 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 B Warrants or
such  earlier  date upon  which  all Class B  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.

<PAGE>

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

<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:  /s/ E. Andrews Grinstead, III
                                  -----------------------------
                                  Authorized Officer



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


                             By:  /s/ Lynore Le Conche
                                  -----------------------------
                                  Authorized Officer


                             PILLAR INVESTMENTS LTD.


                             By:  /s/ Youssef El-Zein
                                  -----------------------------
                                  Authorized Officer

<PAGE>

                                    EXHIBIT A

                  [FORM OF FACE OF CLASS B 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.

THIS WARRANT AND THE  SECURITIES  UNDERLYING  THIS WARRANT MAY NOT BE OFFERED OR
SOLD IN THE UNITED STATES OR TO A U.S. PERSON OR FOR THE ACCOUNT OR BENEFIT OF A
U.S. PERSON PRIOR TO THE EXPIRATION OF THE RESTRICTED  PERIOD (AS DEFINED IN THE
UNIT  PURCHASE  AGREEMENT,  DATED  AS OF  APRIL  1,  1998  (THE  "UNIT  PURCHASE
AGREEMENT"),  A COPY OF WHICH IS AVAILABLE FROM THE COMPANY), AND NO TRANSFER OR
EXCHANGE OF THIS WARRANT AND THE SECURITIES  UNDERLYING THIS WARRANT MAY BE MADE
UNTIL AFTER THE LATER OF THE DATE OF EXPIRATION OF THE RESTRICTED PERIOD AND THE
DATE ON WHICH THE  REQUIRED  CERTIFICATION  RELATING TO SUCH  INTEREST  HAS BEEN
PROVIDED IN ACCORDANCE  WITH THE TERMS OF THE UNIT PURCHASE  AGREEMENT.  HEDGING
TRANSACTIONS  INVOLVING THIS WARRANT AND THE SECURITIES  UNDERLYING THIS WARRANT
MAY NOT BE CONDUCTED UNLESS IN COMPLIANCE WITH THE SECURITIES ACT.

No. AWB _______________ Class B Warrants

                             VOID AFTER MAY 4, 2003

                    CLASS B WARRANT CERTIFICATE FOR PURCHASE
                                 OF COMMON STOCK

                                 HYBRIDON, INC.

        This certifies that FOR VALUE RECEIVED
- --------------------------------------------------------------------------------

____________________________  or registered assigns (the "Registered Holder") is
the owner

<PAGE>

of the number of Class B Warrants  ("Class B Warrants")  specified  above.  Each
Class B 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 May 5, 1998, 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 B 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
May 5, 1998, by and among the Company and the Warrant Agent.

               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 B 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 B 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 B 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 B Warrant.

               The term  "Expiration  Date" shall mean 5:00 P.M. (New York time)
on May 4, 2003, or such earlier date as the Class B 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 B Warrants,  the Company shall have the right to extend the
Expiration Date.

               The Class B 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 B Warrants,

<PAGE>

each of such new  Warrant  Certificates  to  represent  such  number  of Class B
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 B  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 B 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  B  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.

               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.,

<PAGE>

as Warrant Agent



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

<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 B Warrants


        The undersigned  Registered Holder hereby irrevocably elects to exercise
_________  Class B Warrants  represented  by this  Warrant  Certificate,  and to
purchase the securities issuable upon the exercise of such Class B 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 B  Warrants  shall not be all the Class B  Warrants
evidenced by this Warrant  Certificate,  that a new Warrant  Certificate for the
balance of such Class B Warrants be registered in the name of, and delivered to,
the Registered Holder at the address stated below.

<PAGE>

The  undersigned  represents that the exercise of the within Class B 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


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

<PAGE>

                                   ASSIGNMENT

                     To Be Executed by the Registered Holder
                       in Order to Assign Class B 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 B  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.

<PAGE>

                                                                     EXHIBIT 4.5


                                   FORM OF WARRANT AGREEMENT

               AGREEMENT,  dated as of this fifth day of May, 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, each Registered Holder (as defined below) has executed a
Subscription Agreement (the "Subscription Agreement") which has been accepted by
the Company, and the Closing Date (as defined in the Subscription Agreement) has
occurred.

               WHEREAS,  each Class C 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 C
Warrants,  the issuance of certificates  representing the Class C Warrants,  the
exercise of the Class C 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 C Warrants and the certificates representing the Class C
Warrants and the respective  rights and  obligations  thereunder of the Company,
the holders of  certificates  representing  the Class C 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 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

<PAGE>

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 C Warrant,  the
date on which  the  Warrant  Agent  shall  have  received  both (a) the  Warrant
Certificate  representing  such  Class C  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
C Warrant, the Closing Date (as defined in the Subscription Agreement).

               (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)  "Purchase  Price"  shall  mean  120% of  $2.00,  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]

               (k) "Registered Holder" shall mean, as to any Class C Warrant and
as of any particular date, the person in whose name the certificate representing
the Class C 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

<PAGE>

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)    [Reserved]

               (p)  "Warrant  Expiration  Date"  shall mean 5:00 P.M.  (New York
time) on the day prior to the fifth  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 C Warrant  initially  shall  entitle  the  Registered
Holder of the Warrant Certificate  representing such Class C 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 C Warrants issued pursuant hereto will  immediately
be  detachable  and  separately  transferable  from the  shares of Common  Stock
included in the Alternative Equity Units (as defined in the Amendment).

               (c) Within five  business  days after the Closing  Date,  Warrant
Certificates  representing  the number of Class C Warrants to be issued pursuant
to the Offering (as defined in the Subscription  Agreement) 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.

<PAGE>

               (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 C 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 C  Warrants  represented  by any  Warrant
Certificate, to evidence any unexercised Class C 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 C 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 C 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  C  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 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

<PAGE>

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 C 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 C 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 C 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 C Warrant and shall notify the Company in writing of the
exercise of the Class C 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 C  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 C Warrant and  clearance of the funds  received,  the Warrant  Agent shall
promptly  remit the  payment  received  for the Class C  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 C Warrants,  such  number of shares of Common  Stock as
shall then be issuable  upon the exercise of all  outstanding  Class C Warrants.
The Company  covenants  that all shares of Common  Stock which shall be issuable
upon exercise of the Class C 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)).

         (b)  The  Registered  Holders  of  Class  C  Warrants  shall  have  the
registration rights provided in the Subscription Agreement. The Class C 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

<PAGE>

the issuance of Class C Warrants, or the issuance or delivery of any shares upon
exercise  of the Class C  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 C  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 C
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 C
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 C 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 C 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 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

<PAGE>

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 C 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 C
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 C 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 C 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 C Warrants outstanding,  in lieu
of the adjustment in the number of shares of Common Stock  purchasable  upon the
exercise  of each  Class C Warrant  as  herein  provided,  so that each  Class C
Warrant  outstanding after such adjustment shall represent the right to purchase
one share of Common  Stock.  Each Class C Warrant  held of record  prior to such
adjustment of the number of Class C Warrants shall become that number of Class C
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 of which shall be the Purchase Price in effect  immediately
after such  adjustment.  Upon each  adjustment of the number of Class C 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

<PAGE>

of such adjustment Warrant Certificates  evidencing,  subject to Section 10, the
number of additional  Class C 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 C 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 C 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  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

<PAGE>

               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 a 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 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;

                      "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  dissolution   of,  such  Person  (or  equivalent
               thereof) over interests of any other class of interests

<PAGE>

               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 C 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 C 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

<PAGE>

convertible or exchangeable  securities,  the Purchase Price shall be reduced by
multiplying the Purchase Price in effect immediately prior to such earliest date
by:

                      (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

<PAGE>

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  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 C 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 C 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 C 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

<PAGE>

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.

               (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 Company's  Certificate of Designation (the
"Series A Certificate of  Designation")  for the Series A Convertible  Preferred
Stock,  par  value  $.01  per  share  (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

<PAGE>

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 C 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
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 C 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

<PAGE>

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 to the  extent  that no  adjustment  to the
Purchase  Price would be  required  under the warrant  agreements  entered  into
pursuant  to  the  Common  Stock  Offering  (as  such  term  is  defined  in the
Subscription Agreement).

               (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 C 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 C  Warrants.  If more  than one  certificate
evidencing Class C 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  C  Warrants  so
surrendered.  Instead  of any  fractional  share of  Common  Stock  which  would
otherwise  be  issuable  upon  exercise  of such  aggregate  number  of  Class C
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 C 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 C Warrants for any purpose whatsoever, nor shall anything
contained herein be construed to confer upon the holder of Class C 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 C
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 C
Warrants, and any Registered Holder of a Class C Warrant, without consent of the
Warrant  Agent or of the holder of any other  Class C Warrant,  may,  in his own
behalf  and for his own  benefit,  enforce  against  the  Company  his  right to
exercise  his Class C Warrants for the purchase of shares of Common Stock in the
manner provided in the Warrant Certificate and this Agreement.

<PAGE>

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

               (a) The Class C 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 C 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 C 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 C Warrant or Class C 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 C 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 C 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 C
Warrants  represented  thereby or of any securities or other property  delivered
upon  exercise of any Class C Warrant or whether any stock issued upon  exercise
of any Class C 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 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

<PAGE>

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 and delivered by the resigning Warrant
Agent. Not later than the effective date of any such appointment, the

<PAGE>

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 C 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 C Warrants
which are to be governed by this Agreement  resulting from a subsequent offering
of Company  securities which includes Class C Warrants having the same terms and
conditions as the Class C 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 C Warrants then  outstanding;  and provided,  further,  that no
change in the number or nature of the securities  purchasable  upon the exercise
of any Class C 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 C 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;  and if to the Warrant
Agent, at its Corporate Office, Attention:
Relationship Manager.

<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 C  Warrants  shall be  entitled  to
exercise  such  Class C 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 Placement Agent, 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 C Warrants or
such  earlier  date upon  which  all Class C  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.

<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:  /s/ E. Andrews Grinstead, III
                                   -----------------------------
                              Authorized Officer



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


                               By: /s/ Lynore Le Conche
                                   -----------------------------
                               Authorized Officer

<PAGE>

                                    EXHIBIT A

                 [FORM OF FACE OF CLASS C 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. AWC _______________ Class C Warrants

                             VOID AFTER MAY 4, 2003

                    CLASS C 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 C  Warrants  ("Class  C  Warrants")  specified
above. Each Class C 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 May 5, 1998, 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.

<PAGE>

               This  Warrant  Certificate  and each Class C 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
May 5, 1998, by and among the Company and the Warrant Agent.

               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 C 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 C 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 C 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 C Warrant.

               The term  "Expiration  Date" shall mean 5:00 P.M. (New York time)
on May 4, 2003, or such earlier date as the Class C 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 C Warrants,  the Company shall have the right to extend the
Expiration Date.

               The Class C 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 C  Warrants,  each of such  new  Warrant
Certificates to represent such number of Class C 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 C
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 C Warrants held
by such Registered Holder,

<PAGE>

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  C  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.

               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

<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 C Warrants


        The undersigned  Registered Holder hereby irrevocably elects to exercise
_________  Class C Warrants  represented  by this  Warrant  Certificate,  and to
purchase the securities issuable upon the exercise of such Class C 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 C  Warrants  shall not be all the Class C  Warrants
evidenced by this Warrant  Certificate,  that a new Warrant  Certificate for the
balance of such Class C Warrants be registered in the name of, and delivered to,
the Registered Holder at the address stated below.

<PAGE>

The  undersigned  represents that the exercise of the within Class C 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


<PAGE>

                                   ASSIGNMENT

                     To Be Executed by the Registered Holder
                       in Order to Assign Class C 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 C  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.

<PAGE>


                                                                     EXHIBIT 4.6

                            FORM OF WARRANT AGREEMENT

         AGREEMENT,  dated  as of this  fifth  day of May,  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 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,  the  Company  has  sold,  pursuant  to  several  subscription
agreements  (each, a  "Subscription  Agreement")  units  consisting of shares of
Series A  Preferred  Stock and Class D Warrants  to be issued  pursuant  to this
Agreement ("Units");

         WHEREAS,  each Class D 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  D
Warrants,  the issuance of certificates  representing the Class D Warrants,  the
exercise of the Class D 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 D Warrants and the certificates representing the Class D
Warrants and the respective  rights and  obligations  thereunder of the Company,
the holders of  certificates  representing  the Class D 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:



<PAGE>


         (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 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 D Warrant,  the date on
which the Warrant  Agent shall have  received  both (a) the Warrant  Certificate
representing  such Class D 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 D
Warrant,  the date which is 12 months after the closing date of the  Alternative
Equity Offering (as such term is defined in the Amendment).

         (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 1.2  multiplied  by the per share  price of Common  Stock sold by the
Company  in  connection  with  the  Alternative  Equity  Offering,   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]


<PAGE>


         (k) "Registered Holder" shall mean, as to any Class D Warrant and as of
any particular  date, the person in whose name the certificate  representing the
Class D 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  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.

         (p) 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 D Warrant  initially shall entitle the Registered Holder of
the Warrant Certificate  representing such Class D 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 D  Warrants  included  in the Units will  immediately  be
detachable  and  separately  transferable  from the shares of Series A Preferred
Stock included in the Units.

         (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 D  Warrants  to be  issued  pursuant  to the
Subscription Agreements shall be executed by the Company and delivered to the


<PAGE>


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 D 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 D  Warrants  represented  by any  Warrant  Certificate,  to
evidence any  unexercised  Class D 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 D 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 D 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 D 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  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,


<PAGE>

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 D 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 D 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 D 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 D Warrant and shall notify the Company in writing of the
exercise of the Class D 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 D  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 D Warrant and  clearance of the funds  received,  the Warrant  Agent shall
promptly  remit the  payment  received  for the Class D  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 D Warrants,  such  number of shares of Common  Stock as
shall then be issuable  upon the exercise of all  outstanding  Class D Warrants.
The Company  covenants  that all shares of Common  Stock which shall be issuable
upon exercise of the Class D 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)).

         (b)  The  Registered  Holders  of  Class  D  Warrants  shall  have  the
registration rights provided in the Subscription Agreement. The Class D Warrants
shall not be exercisable in any state where such exercise would be unlawful.


<PAGE>


         (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 D Warrants,  or the issuance or
delivery of any shares upon exercise of the Class D 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
D 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 D 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 D 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 D 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 D 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 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.


<PAGE>

         (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 D 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 D
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 D 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 D 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 D Warrants outstanding,  in lieu of the
adjustment in the number of shares of Common Stock purchasable upon the exercise
of each  Class D  Warrant  as  herein  provided,  so that  each  Class D Warrant
outstanding  after such  adjustment  shall  represent  the right to purchase one
share of  Common  Stock.  Each  Class D  Warrant  held of  record  prior to such
adjustment of the number of Class D Warrants shall become that number of Class D
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 of which shall be the Purchase Price in effect  immediately
after such  adjustment.  Upon each  adjustment of the number of Class D 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 D Warrants to which such Holder shall be entitled as
a result of such adjustment or, at the option of the


<PAGE>

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 D 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 D
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 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


<PAGE>


          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 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;

               "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 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;


<PAGE>

               "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 D 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 D 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:

               (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


<PAGE>

          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
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


<PAGE>

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 D 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 D 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 D 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.

         (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


<PAGE>

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 D 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  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


<PAGE>

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 D 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  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
D 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 D Warrants. If more than one certificate evidencing Class
D 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 D Warrants so surrendered. Instead of any
fractional share of Common Stock


<PAGE>

which would  otherwise be issuable  upon  exercise of such  aggregate  number of
Class D 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
D 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 D  Warrants  for  any  purpose  whatsoever,  nor  shall  anything
contained herein be construed to confer upon the holder of Class D 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 D
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 D
Warrants, and any Registered Holder of a Class D Warrant, without consent of the
Warrant  Agent or of the holder of any other  Class D Warrant,  may,  in his own
behalf  and for his own  benefit,  enforce  against  the  Company  his  right to
exercise  his Class D 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 D
Warrant,  by his acceptance thereof,  consents and agrees with the Company,  the
Warrant Agent and every other holder of any Class D Warrant that:

         (a) The Class D 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 D 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 D 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 D Warrant  or Class D  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


<PAGE>

and  retired.  The Warrant  Agent shall also cancel the Warrant  Certificate  or
Warrant  Certificates  following  exercise of any or all of the Class D 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 D 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 D
Warrants  represented  thereby or of any securities or other property  delivered
upon  exercise of any Class D Warrant or whether any stock issued upon  exercise
of any Class D 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 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.


<PAGE>

         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 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 D 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 D Warrants
which are to be governed by this Agreement  resulting from a subsequent offering
of Company  securities which includes Class D Warrants having the same terms and
conditions as the Class D 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


<PAGE>

with the consent in writing of the  Registered  Holders of Warrant  Certificates
representing  more  than  50% of the  Class D  Warrants  then  outstanding;  and
provided,  further,  that no  change in the  number or nature of the  securities
purchasable  upon the  exercise of any Class D 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 D 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.

         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 D Warrants  shall be entitled to exercise such
Class D 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 D Warrants  or such
earlier  date upon which all Class D 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.


<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:  /s/ E. Andrews Grinstead, III
                                            -----------------------------
                                            Authorized Officer



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


                                       By: /s/ Lynore Le Conche
                                           ---------------------
                                           Authorized Officer


<PAGE>

                                    EXHIBIT A

                  [FORM OF FACE OF CLASS D 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. AWD _______________ Class D Warrants

                             VOID AFTER MAY 4, 2003

                    CLASS D 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 D Warrants ("Class D Warrants")  specified above. Each Class
D  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 May 5, 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 D 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
May 5, 1998, by and among the Company and the Warrant Agent.

         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 D 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.


<PAGE>


         Each Class D 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 D 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 D Warrants.

         The term "Expiration  Date" shall mean 5:00 P.M. (New York time) on May
4, 2003, or such earlier date as the Class D 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 D Warrants,  the Company shall have the right to extend the
Expiration Date.

         The Class D 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 D Warrants,  each of such new Warrant  Certificates to
represent  such  number  of Class D  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 D
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 D 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  D  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.

         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.


<PAGE>

                                            HYBRIDON, INC.


Dated:                                      By:_______________________________

                                            By:_______________________________

                                                               [seal]



Countersigned:

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



By:  ______________________________
     Authorized Officer


<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 D Warrants


         The undersigned Registered Holder hereby irrevocably elects to exercise
_________  Class D Warrants  represented  by this  Warrant  Certificate,  and to
purchase the securities issuable upon the exercise of such Class D 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 D  Warrants  shall not be all the Class D  Warrants
evidenced by this Warrant  Certificate,  that a new Warrant  Certificate for the
balance of such Class D Warrants be registered in the name of, and delivered to,
the Registered Holder at the address stated below.


<PAGE>

The  undersigned  represents that the exercise of the within Class D 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


                                            ____________________________


<PAGE>


                                   ASSIGNMENT

                     To Be Executed by the Registered Holder
                       in Order to Assign Class D 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 D  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.




<TABLE> <S> <C>

<ARTICLE>                     5
<LEGEND>
                       HYBRIDON, INC. AND SUBSIDIARIES
                          (A DEVELOPMENT STAGE COMPANY)
</LEGEND>
       
<S>                             <C>
<PERIOD-TYPE>                   3-MOS
<FISCAL-YEAR-END>                               MAR-31-1998
<PERIOD-START>                                  JAN-01-1998
<PERIOD-END>                                    MAR-31-1998
<CASH>                                              439,214
<SECURITIES>                                              0
<RECEIVABLES>                                       521,887
<ALLOWANCES>                                              0
<INVENTORY>                                               0
<CURRENT-ASSETS>                                  1,667,970
<PP&E>                                           29,582,947
<DEPRECIATION>                                   12,215,553
<TOTAL-ASSETS>                                   28,766,338
<CURRENT-LIABILITIES>                            25,958,709
<BONDS>                                          58,049,800
                                 5,060
                                               0
<COMMON>                                                  0
<OTHER-SE>                                      (55,247,231)
<TOTAL-LIABILITY-AND-EQUITY>                     28,766,338
<SALES>                                             825,069
<TOTAL-REVENUES>                                    992,914
<CGS>                                                     0
<TOTAL-COSTS>                                             0
<OTHER-EXPENSES>                                  8,067,649
<LOSS-PROVISION>                                          0
<INTEREST-EXPENSE>                                1,607,437
<INCOME-PRETAX>                                  (8,682,172)
<INCOME-TAX>                                              0
<INCOME-CONTINUING>                              (8,682,172)
<DISCONTINUED>                                            0
<EXTRAORDINARY>                                           0
<CHANGES>                                                 0
<NET-INCOME>                                     (8,682,172)
<EPS-PRIMARY>                                         (1.72)
<EPS-DILUTED>                                         (1.72)
        


</TABLE>


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