Document:

<PAGE>

                                   EXHIBIT 4.5

      Engagement Letter Dated December 20, 2001 Between the Registrant and
                            Sunrise Securities Corp.

<PAGE>

                                                               December 20, 2001

Matritech, Inc.
330 Nevada Street
Newton, MA 02460
Attn:  Stephen D. Chubb

Dear Mr. Chubb:

1.    This letter agreement (the "Agreement") confirms our understanding that
      Matritech, Inc. ("Company") has engaged Sunrise Securities Corp.
      ("Sunrise") to act as exclusive agent in connection with a best efforts
      private placement of a minimum of 2 million and a maximum of 5 million
      shares (but in no event, more than 19.9% of outstanding shares, inclusive
      of warrants and shares issued as fees for services) of common stock (the
      "Securities" or the "Shares") of the Company at $2.25 per share (the
      "Proposed Financing"), upon the terms, and subject to the conditions, set
      forth in this Agreement.

      The Proposed Financing will be made pursuant to the exemptions afforded by
      Section 4(2) of the Securities Act of 1933, as amended (the "Act") and
      Regulation D promulgated thereunder and applicable state securities laws.
      Our undertaking herein shall be subject to, among other things, the terms
      and conditions set forth in this Agreement, our due diligence
      investigation of the Company, the continuance of the Company without
      material adverse change, the absence of unfavorable market conditions in
      general and our continued satisfaction with the results of our ongoing
      review of the Company's business and affairs. It is understood that
      execution of this Agreement does not assure the successful completion of
      the Proposed Financing or any portion thereof.

2.    Our services will include: (i) assistance in the preparation of the
      Offering Materials described below; (ii) assistance in structuring the
      Proposed Financing and its terms; (iii) identifying and contacting
      selected qualified purchasers (the "Purchasers") of the Proposed Financing
      and furnishing them, on behalf of the Company, with copies of the Offering
      Materials; and (iv) negotiating under your guidance the financial aspects
      of the Proposed Financing.

3.    As compensation for the services to be provided by Sunrise hereunder, the
      Company agrees to pay to Sunrise a fee equal to 8% of the gross proceeds
      of the Proposed Financing payable in cash or shares, valued net of the
      commission, and three year warrants to purchase at $2.81 per share a
      number of shares equal to 10% of those sold in the Proposed Financing,
      payable to Sunrise at the closing of the Proposed Financing (the
      "Closing"). If the Proposed Financing is consummated by means of more than
      one Closing, Sunrise shall be entitled to the fees provided herein with
      respect to each such Closing. The Company shall reimburse Sunrise for all
      out-of-pocket expenses incurred by Sunrise in connection with its
      engagement hereunder, including reasonable fees and expenses of its
      counsel up to $20,000, whether or not a closing occurs.

4.    The Company acknowledges and agrees that Sunrise has been retained solely
      to provide the advice or services set forth in this Agreement. Sunrise
      shall act as an independent contractor, and any duties of Sunrise arising
      out of its engagement hereunder shall be owed solely to the Company. As
      Sunrise will be acting on your behalf in such capacity, it is our firm
      practice to be indemnified in connection with engagements of this type and
      the Company agrees to the indemnification agreement attached hereto as
      Exhibit A and the other obligations as set forth in paragraph 12 of this
      Agreement.

<PAGE>

5.    The Company will promptly and from time to time take such action as
      Sunrise may reasonably request to qualify the Securities as a private
      placement under the securities laws of the United States and of each of
      the states, as applicable, as Sunrise may reasonably request and to comply
      with such laws so as to permit such offers and sales.

6.    The Company will prepare and furnish a private placement memorandum
      (which, together with the appendices and exhibits thereto and any
      amendments or supplements thereto, is herein referred to as the "Offering
      Materials") relating to the Proposed Financing. The Company authorizes
      Sunrise to transmit the Offering Materials to prospective purchasers of
      the Proposed Financing, and represents and warrants that the information
      that it provides to be included in the Offering Materials, at all times
      through the Closing, will not contain any untrue statement of a material
      fact or omit to state any material fact required to be stated therein or
      necessary to make the statements contained therein, in light of the
      circumstances under which they were made, not misleading. The Company
      shall not transmit the Offering Materials to prospective purchasers
      without first consulting Sunrise. Sunrise will not make statements of
      material fact about the Company that are not contained in the offering
      materials or approved by the Company.

7.    The Company will also make available to Sunrise all financial and other
      information concerning its business and operations and the Proposed
      Financing which Sunrise reasonably requests and will provide access to
      their officers, directors, employees, independent accountants and legal
      counsel. Sunrise shall be entitled to rely without investigation upon all
      information that is available from public sources as well as all other
      information supplied to Sunrise by or on behalf of the Company or its
      other advisors and Sunrise shall not in any respect be responsible for the
      accuracy or completeness of, or have any obligation to verify, the same or
      to conduct any appraisal of assets. To the extent consistent with legal
      requirements and except as otherwise set forth in the Offering Materials,
      all information given to Sunrise by the Company, unless publicly available
      or otherwise available to Sunrise without restriction or breach of any
      confidentiality agreement ("Confidential Information"), will be held by
      Sunrise in confidence and will not be disclosed to anyone other than
      Sunrise's agents and advisors without the prior approval of the Company or
      used for any purpose other than those referred to in this Agreement;
      provided that nothing herein shall, in itself, prevent Sunrise from
      engaging in future transactions involving companies in a similar industry
      to the Company or, provided no Confidential Information is directly used
      in connection with such engagement, be deemed to violate any of the terms
      hereof.

8.    The parties acknowledge that it is their intention that the Proposed
      Financing shall be conducted so as to be exempt from the registration
      requirements of the Act. The Company has not taken, and will not take, any
      action, directly or indirectly, so as to cause the transactions
      contemplated by this Agreement to fail to be entitled to exemption under
      the Act. It is understood that investors in the Proposed Financing shall
      be "accredited investors" or fall within other categories sanctioned by
      Rule 506 of Regulation D under the Act. In effecting the Proposed
      Financing, the Company and Sunrise agree to comply in all material
      respects with applicable provisions of the Act and any regulations
      thereunder and any applicable state laws and requirements. The Company
      shall execute and/or deliver such other instruments, documents and
      agreements and take such other action as Sunrise may reasonably request in
      connection with the provision of its services hereunder and the
      consummation of the Proposed Financing, including without limitation,
      opinions of counsel to the effect that the placement of the Securities was
      exempt from registration under the Act and as to the accuracy of the
      Offering Materials. Additionally, if requested by Fidelity Investments or
      Mazama Capital as Investors in the Proposed Financial as a condition to
      Closing, the Company agrees that a registration statement on Form S-3
      covering the Securities, including Securities received by Sunrise or
      underlying its warrants, shall have been declared effective, and the
      Company will use its best efforts to keep such registration statement
      effective.

<PAGE>

9.    Any advice, written or oral, provided by Sunrise pursuant to this
      Agreement will be treated by the Company as confidential, will be solely
      for the information and assistance of the Company in connection with the
      Proposed Financing and may not be quoted, nor will any such advice or the
      name of Sunrise be referred to, in any report, document, release or other
      communication, whether written (including, without limitation, the
      Offering Materials) or oral, prepared, issued or transmitted by the
      Company or any affiliate, director, officer, employee, agent or
      representative of any thereof, without, in each instance, Sunrise 's prior
      written consent.

10.   This Agreement shall expire on March 31, 2002, provided that Matritech may
      terminate this Agreement, at any time after January 31, 2002 and prior to
      the Closing, on 10 business days written notice to Sunrise ("Early
      Termination") unless subscriptions from accredited investors for at least
      2 million shares have been received prior to January 31, 2002 and provided
      further that if Matritech rejects such subscriptions, then Matritech shall
      pay Sunrise its fees with respect thereto as if such subscriptions had
      been accepted and Sunrise will be entitled to prompt reimbursement from
      the Company of all its out-of-pocket expenses and fees as described above
      not to exceed $20,000. In addition, if at any time prior to 18 months
      after the Early Termination of this Agreement or 12 months after a
      termination other than an Early Termination, the Company consummates a
      financing transaction, including the Proposed Financing, with any party
      contacted regarding the Proposed Financing during the term of our
      engagement (and identified in writing for Matritech within 30 days after
      termination), Sunrise will be entitled to payment in full of the
      compensation described in the third paragraph of this Agreement, together
      with reimbursement from the Company of all its out-of-pocket expenses and
      fees as described above not to exceed $20,000. The indemnity and other
      provisions contained in Exhibit A and in paragraph 12 will also remain
      operative and in full force and effect regardless of any expiration or
      termination of this Agreement.

11.   This Agreement shall not give rise to any express or implied commitment by
      Sunrise to purchase or place any securities of the Company.

12.   The Company acknowledges that Sunrise is acting only as placement agent in
      the transactions contemplated by this engagement. The Company agrees to
      indemnify Sunrise, and its officers, directors, agents, employees and
      controlling persons in accordance with Exhibit A.

13.   This Agreement incorporates the entire understanding of the parties
      relating to the subject matter hereof. The benefits of this Agreement
      shall inure to the parties hereto, their respective successors and assigns
      and to the Indemnified Persons under Exhibit A and their respective
      successors and assigns, and the obligations and liabilities assumed in
      this Agreement shall be binding upon the parties hereto and their
      respective successors and assigns. Notwithstanding anything contained
      herein to the contrary, none of the parties hereto shall assign any of its
      obligations hereunder without the prior written consent of each of the
      other parties hereto.

14.   All notices provided hereunder shall be given in writing and either
      delivered personally or by overnight courier service or sent by certified
      mail, return receipt requested, if to Sunrise, to Sunrise Securities
      Corp., 135 East 57th Street, New York, NY 10022, Attention: Nathan Low;
      with a copy to Mintz Levin Cohn Glovsky and Popeo, PC, 666 Third Avenue,
      25th Floor, New York, New York 10017, Attention: Kenneth R. Koch, and if
      to the Company, to Matritech, Inc.,330 Nevada Street, Newton,
      Massachusetts, Attention: Stephen D. Chubb with a copy to Testa, Hurwitz &
      Thibeault, LLP, 125 High Street, Boston, Massachusetts 02110, Attn: Rufus
      C. King. Any notice delivered personally shall be deemed given upon
      receipt; any notice given by overnight courier shall be deemed given on
      the next business day after delivery to the overnight courier; and any
      notice given by certified mail shall be deemed given upon the second
      business day after certification thereof.

<PAGE>

15.   The failure or neglect of either of the parties hereto to insist, in any
      one or more instances, upon the strict performance of any of the terms or
      conditions of this Agreement, or its waiver of strict performance of any
      of the terms or conditions of this Agreement, shall not be construed as a
      waiver or relinquishment in the future of such term or condition by such
      party, but the same shall continue in full force and effect. Any waiver
      must be in writing.

16.   This Agreement shall be governed by and construed in accordance with the
      laws of the State of New York applicable to agreements made and to be
      fully performed therein, without regard to conflicts of law principles.
      Each of the parties irrevocably submits to the exclusive jurisdiction of
      any court of the State of New York or the United States District Court for
      the Southern District of the State of New York for the purpose of any
      suit, action or other proceeding arising out of this Agreement, or any of
      the agreements or transactions contemplated hereby, and agrees that
      service of process in connection with any such suit, action or proceeding
      may be made in accordance with Section 14 hereof. The parties hereby
      expressly waive all rights to trial by jury in any suit, action or
      proceeding arising under this Agreement.

17.   This Agreement may not be modified or amended except in a writing duly
      executed by the parties hereto.

18.   At any time after the final closing of the Proposed Financing, Sunrise may
      place an announcement in such newspapers and publications as it may
      choose, stating that Sunrise has acted as exclusive financial advisor
      and/or placement agent in connection with the Proposed Financing.

19.   For the convenience of the parties, this Agreement may be executed in any
      number of counterparts, each of which shall be deemed to be an original
      instrument, but all of which taken together shall constitute one and the
      same agreement. Facsimile signatures shall be deemed to be original
      signatures for all purposes.

20.   After reviewing this Agreement, please confirm that the foregoing is in
      accordance with your understanding by signing and returning the duplicate
      of this letter attached hereto, whereupon it shall be our binding
      Agreement.

                                    Very truly yours,

                                    SUNRISE SECURITIES CORP.

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

Accepted and agreed to
this ___ day of December, 2001.

MATRITECH, INC.

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

<PAGE>

                                    EXHIBIT A

      This Exhibit A is entered into pursuant to, and is made a part of, the
attached Agreement among Sunrise and the Company. Capitalized terms used and not
defined in this Exhibit A shall have the meanings assigned them in the attached
Agreement.

      The Company agrees to indemnify and hold harmless Sunrise, its affiliates,
and each of its partners, directors, officers, consultants, employees, advisors,
representatives and controlling persons (each an "Indemnified Person") from and
against any claims, losses, damages, expenses or liabilities (collectively,
"Losses"), (subject to the limitations set forth below), incurred in connection
with investigating, preparing, defending, paying, settling or compromising any
action, claim or proceeding to which any Indemnified Person may become subject
and which is related to or arises out of the engagement set forth in the
Agreement or the transactions contemplated thereby. The Company will, however,
not be responsible to an Indemnified Person with respect to any Losses to the
extent that a court of competent jurisdiction shall have determined by a final
judgment not subject to further appeal that such Losses resulted substantially
from actions taken or omitted to be taken by such or any other Indemnified
Person due to the Indemnified Person's or any other Indemnified Person's gross
negligence or willful misconduct.

      The Company will reimburse each Indemnified Person for Losses as such
Losses are incurred or paid, notwithstanding the absence of judicial
determination as to the propriety or enforceability of the Company's obligation
to reimburse such Indemnified Person for such Losses and the possibility that
such payments might later be held by a court of competent jurisdiction to have
been improper. To the extent that any such reimbursement is so held to have been
improper, the Indemnified Person shall promptly return it to the Company
together with interest, compounded annually, equal to the prevailing prime rate
as published from time to time by The Wall Street Journal.

      If the indemnification provided for herein should be, for any reason
whatsoever, unenforceable, unavailable or otherwise insufficient to hold each
Indemnified Person harmless, the Company shall pay to or on behalf of each
Indemnified Person contributions for Losses so that the Indemnified Person
ultimately bears only a portion of such Losses as is appropriate (i) to reflect
the relative benefits received by such Indemnified Person on the one hand and
the Company on the other hand in connection with this engagement and any
transactions contemplated hereby or (ii) if the allocation on the basis set
forth in the immediately preceding clause (i) is not permitted by applicable
law, to reflect not only the relative benefits referred to in such clause (i)
but also the relative fault of the Indemnified Person and the Company as well as
any other relevant equitable considerations; provided, however, that in no event
shall the aggregate contribution of all Indemnified Persons to all Losses exceed
the amount of the fees actually received by Sunrise pursuant to the Agreement.
The respective relative benefits received by all Indemnified Persons and the
Company shall be deemed to be in the same proportion as the aggregate fee paid
to Sunrise pursuant to the Agreement bears to the total consideration paid or
contemplated to be paid to or received by the Company in connection with
transactions contemplated by the Agreement, whether or not such transactions are
consummated. The relative fault of each Indemnified Person and of the Company
shall be determined by reference to, among other things, whether the actions or
failures to act were by such Indemnified Person or the Company, and the parties'
relative intent, knowledge, access to information and opportunity to correct or
prevent such action or failure to act. Notwithstanding the foregoing, no
Indemnified Person shall have any obligation to investigate or verify the
information provided to Sunrise in connection with their providing financial
advisory services under the engagement letter, and the Company shall be liable
for any Losses related to or arising out of the use of such information that is
inaccurate for any reason.

<PAGE>

      The Company also agrees that no Indemnified Person shall have any
liability to the Company or its affiliates, directors, officers, employees,
Sunrise, consultants, advisors, representatives, control persons or
stockholders, directly or indirectly, related to or arising out of the Agreement
or any transactions contemplated thereby, in connection with claims by third
parties except Losses incurred by the Company to the extent a court of competent
jurisdiction shall have determined by a final judgment not subject to further
appeal that such Losses resulted primarily from actions taken or the failure to
take actions by such Indemnified Person due to such Indemnified Person's gross
negligence or willful misconduct. In no event, regardless of the legal theory
advanced, shall any Indemnified Person be liable for any consequential,
indirect, incidental or special damages of any nature. Sunrise likewise
indemnifies the Company in the event of gross negligence or willful misconduct
on the part of any Sunrise party, subject to the limit of the fees actually paid
to Sunrise hereunder. Sunrise will reimburse the Company for Losses related to
the foregoing as such Losses are paid, notwithstanding the absence of judicial
determination as to the propriety or enforceability of Sunrise's obligation to
reimburse the Company for such Losses and the possibility that such payments
might later be held by a court of competent jurisdiction to have been improper.
To the extent that any such reimbursement is so held to have been improper, the
Company shall promptly return it to Sunrise, together with interest, compounded
annually, equal to the prevailing prime rate as published from time to time by
The Wall Street Journal.

      In case any proceeding shall be instituted involving any Indemnified
Person, such Indemnified Person shall promptly notify the Company in writing.
The failure of an Indemnified Person to provide such prompt notice shall not
reduce such Indemnified Person's right to indemnification or contribution
hereunder to the extent that such failure does not materially prejudice the
ability to defend such proceeding. The Company shall retain counsel reasonably
satisfactory to Sunrise to represent the Indemnified Persons and any others the
Company may designate in such proceeding, shall have sole control of the defense
of any such proceeding and shall pay the fees and disbursements of such counsel
related to such proceeding. In any such proceeding, any Indemnified Person shall
have the right to retain its own counsel, but the fees and expenses of such
counsel shall be at the expense of such Indemnified Person, except to the extent
that (i) the Company and the Indemnified Person shall have mutually agreed to
the retention of such counsel at either the Company's expense, as applicable, or
(ii) the named parties to any such proceeding (including any impleaded parties)
include both the Company or any others the Company may designate and one or more
Indemnified Persons, and representation of the Indemnified Persons and such
other parties by the same counsel would be inappropriate due to actual or
potential differing interests between them. In any case in which one or more
Indemnified Persons are entitled to separate counsel due to such actual or
potential differing interests, the Company shall not be liable for the expenses
of more than one separate counsel, and such counsel shall be designated in
writing by Sunrise. The Company shall have sole control of any settlement of any
proceeding for which it is obligated to provide indemnification hereunder.
Notwithstanding the foregoing the Company shall not, without the prior written
consent of the Indemnified Person, effect any settlement of, or consent to the
entry of any judgment in connection with, any pending or threatened proceeding
in respect of which such Indemnified Person is or could have been a party and
indemnity or contribution could have been sought hereunder by such Indemnified
Person, unless such settlement or judgment includes an unconditional release of
such Indemnified Person from all liability on claims that are the subject matter
of the proceeding.

      Nothing in this Exhibit A shall affect Sunrise's potential liability to
the Company for any breach by Sunrise of the Agreement.

<PAGE>

      The obligations of the Company referred to above shall be in addition to
any rights that any Indemnified Person may otherwise have and shall inure to the
benefit of and be binding upon any successors, assigns, heirs and personal
representatives of any Indemnified Person or the Company.

                                                SUNRISE SECURITIES CORP.

                                            By: ________________________________

Agreed to and Accepted:

MATRITECH, INC.

By:_____________________________

Date:    December 20, 2001<PAGE>
                                                                     Exhibit 4.1

                             ASPEN TECHNOLOGY, INC.

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

                           CERTIFICATE OF DESIGNATIONS
                                       OF
                     SERIES B-I CONVERTIBLE PREFERRED STOCK
                                       AND
                     SERIES B-II CONVERTIBLE PREFERRED STOCK

        (Pursuant to Section 151 of the Delaware General Corporation Law)

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

      Aspen Technology, Inc., a Delaware corporation (the "Corporation"), in
accordance with the provisions of Section 103 of the Delaware General
Corporation Law (the "DGCL") does hereby certify that, in accordance with
Section 141(c) of the DGCL, the following resolution was duly adopted by the
Board of Directors of the Corporation as of March 14, 2002:

      RESOLVED, that two series of Preferred Stock, Series B-I Convertible
Preferred Stock, par value $0.10 per share, and Series B-II Convertible
Preferred Stock, par value $0.10 per share, of the Corporation are hereby
created and the designation, number of shares, powers, preferences, rights,
qualifications, limitations and restrictions thereof (in addition to any
provisions set forth in the Certificate of Incorporation of the Corporation
which are applicable to the Preferred Stock of all classes and series) are as
follows:

                     SERIES B-I CONVERTIBLE PREFERRED STOCK
                                       AND
                     SERIES B-II CONVERTIBLE PREFERRED STOCK

      1. Designation, Amount, Par Value and Stated Value. The following two
series of preferred stock shall be designated as (i) the Corporation's Series
B-I Convertible Preferred Stock (the "SERIES B-I PREFERRED STOCK"), and the
number of shares so designated shall be 40,000, and (ii) the Corporation's
Series B-II Convertible Preferred Stock (the "SERIES B-II PREFERRED STOCK"), and
the number of shares so designated shall be 20,000. The Series B-I Preferred
Stock and Series B-II Preferred Stock are sometimes collectively referred to as
the "SERIES B PREFERRED STOCK." Each share of Series B Preferred Stock shall
have a par value of $0.10 per share and a stated value equal to $1,000 plus any
amount added to the Stated Value pursuant to Section 3(c) hereof or Section 2(f)
of the Registration Rights Agreement (the "STATED VALUE").

      2. Definitions. In addition to the terms defined elsewhere in this
Certificate of Designations, (a) the terms set forth in Exhibit A hereto have
the meanings indicated therein and (b) the following terms have the meanings
indicated:

            "CONVERSION PRICE" means the Initial Conversion Price as of the
      applicable Deemed Issue Date, as adjusted pursuant to Section 15 below.

            "DEEMED ISSUE DATE" means (i) February 6, 2002, with respect to the
      30,000 shares of Series B-I Preferred Stock originally issued on March 19,
      2002 in exchange for shares of the Series B-1 Convertible Preferred Stock
      of the Corporation, (ii) March 19, 2002, with respect to the 10,000 shares
      of Series B-I originally issued on such date, and (iii) February 28, 2002,
      with respect to the Series B-II Preferred Stock, in each case regardless
      of the number of transfers of any particular shares of such Series B
      Preferred Stock and regardless of the number of certificates that may be
      issued to evidence such Series B Preferred Stock.
<PAGE>
            "EQUITY CONDITIONS" means, with respect to a specified issuance of
      shares of Common Stock, that each of the following conditions is
      satisfied: (i) the number of authorized but unissued and otherwise
      unreserved shares of Common Stock is sufficient for such issuance; (ii)
      such shares of Common Stock are registered for resale by the Holders and
      may be sold by the Holders pursuant to an effective Underlying Shares
      Registration Statement, such shares may be sold without volume
      restrictions pursuant to Rule 144(k) under the Securities Act or all
      Underlying Shares owned by each Holder may be sold without volume
      restrictions pursuant to Rule 144 under the Securities Act; (iii) the
      Common Stock is listed or quoted (and is not suspended from trading) on an
      Eligible Market and such shares of Common Stock are approved for listing
      upon issuance; (iv) such issuance would be permitted in full without
      violating Section 16 hereof or the rules or regulations of any Trading
      Market; (v) no Bankruptcy Event has occurred; (vi) the Corporation is not
      in default with respect to any material obligation hereunder or under any
      other Transaction Document; and (vii) none of the following events have
      occurred and are continuing (A) an event constituting a Triggering Event
      or (B) an event that with the passage of time and without being cured
      would constitute a Triggering Event other than a pending, proposed or
      intended Change of Control.

            "HOLDER" means any holder of Series B Preferred Stock.

            "INITIAL CONVERSION PRICE" means (i) in the case of Series B-I
      Preferred Stock, $19.9703, and (ii) in the case of Series B-II Preferred
      Stock, $17.66.

            "INITIAL PURCHASE PRICE" means (i) in the case of Series B-I
      Preferred Stock, $17.75, and (ii) in the case of Series B-II Preferred
      Stock, $15.69.

            "JUNIOR SECURITIES" means the Common Stock and all other equity or
      equity equivalent securities of the Corporation, other than Series C
      Preferred Stock.

            "PURCHASE AGREEMENT" means the Amended and Restated Securities
      Purchase Agreement, dated March 19, 2002, among the Corporation and the
      original purchasers of the Series B Preferred Stock, as amended from time
      to time.

            "SERIES C PREFERRED STOCK" means the Series C preferred stock of the
      Corporation to be authorized and issued as contemplated by the Purchase
      Agreement.

      3. Dividends.

            (a) Holders shall be entitled to receive, out of funds legally
available therefor, and the Corporation shall pay, cumulative dividends on the
Series B Preferred Stock at the rate per share (as a percentage of the Stated
Value per share) of 4% per annum, payable quarterly in arrears commencing on
June 30, 2002 and thereafter on each March 31, June 30, September 30 and
December 31, except if such date is not a Trading Day, in which case such
dividend shall be payable on the next succeeding Trading Day (each, a "DIVIDEND
PAYMENT DATE"). Dividends on the Series B Preferred Stock shall be calculated on
the basis of a 365-day year, shall accrue daily commencing on the Deemed Issue
Date for the applicable shares of Series B Preferred Stock, and shall be deemed
to accrue from such date whether or not earned or declared and whether or not
there are profits, surplus or other funds of the Corporation legally available
for the payment of dividends.

            (b) Subject to the conditions and limitations set forth below, the
Corporation may pay required dividends (i) in cash or (ii) in Common Stock. The
Corporation must deliver written notice (the "DIVIDEND NOTICE") to the Holders
indicating the manner in which it intends to pay dividends at least ten Trading
Days prior to each Dividend Payment Date, but the Corporation may indicate in
any such notice that the election contained therein shall continue for
subsequent Dividend Payment Dates until revised.

                                       2
<PAGE>
Failure to timely provide such written notice shall be deemed an election by the
Corporation to pay the dividend in Common Stock, unless payment of dividends in
such manner is not permitted at the time of a dividend, in which case such
dividend shall be payable in cash. All dividends payable in respect of the
Series B Preferred Stock on any Dividend Payment Date must be paid in the same
manner.

            (c) Notwithstanding the foregoing, the Corporation may not pay
dividends by issuing Common Stock unless, at such time, the Equity Conditions
are satisfied with respect to such Common Stock dividend shares and all of the
Underlying Shares then issuable upon conversion in full of all outstanding
Series B Preferred Stock. If the Corporation is required to pay dividends in
cash on any Dividend Payment Date and does not timely make such payment, any
Holder may (but shall not be required to) treat such cash amount as if it had
been added to the Stated Value as of such Dividend Payment Date. If the
Corporation may not legally pay dividends on any Dividend Payment Date, such
amount shall be added to the Stated Value as of such Dividend Payment Date.

            (d) So long as any Series B Preferred Stock is outstanding, (i)
neither the Corporation nor any Subsidiary shall, directly or indirectly,
redeem, purchase or otherwise acquire any Junior Securities or set aside any
monies for such a redemption, purchase or other acquisition in excess of
$10,000,000 per calendar year, provided that the Corporation shall be entitled
to carry forward any amount not used in any calendar year to subsequent calendar
years, and (ii) the Corporation shall not pay or declare any dividend or make
any distribution on any Junior Securities, except pro rata stock dividends on
the Common Stock payable in additional shares of Common Stock and dividends due
and paid in the ordinary course on preferred stock of the Corporation, in each
case only at such times as the Corporation is in compliance with its payment and
other obligations hereunder.

            (e) In the event that the Corporation elects to pay dividends in
shares of Common Stock, the number of shares of Common Stock to be issued to
each Holder as such dividend shall be (i) determined by dividing the total
dividend then payable to such Holder by the Dividend Market Price (as defined
below) as of the applicable Dividend Payment Date, and rounding up to the
nearest whole share, and (ii) paid to such Holder in accordance with Section
3(f) below. The term "DIVIDEND MARKET PRICE" shall mean the average of the
Volume Weighted Average Prices of Common Stock for the five consecutive Trading
Days prior to the applicable Dividend Payment Date (not including such date).

            (f) In the event that any dividends are paid in Common Stock the
Corporation shall, on or before the third Trading Day following the payment date
of such dividend, (i) issue and deliver to such Holder a certificate, registered
in the name of the Holder or its designee, for the number of shares of Common
Stock to which the Holder shall be entitled or (ii) if and when the applicable
shares of Common Stock may be held in a balance account with The Depository
Trust Corporation through its Deposit Withdrawal Agent Commission System and
after the Holder has notified the Corporation that this clause (ii) shall apply,
credit the number of shares of Common Stock to which the Holder shall be
entitled to the Holder's or its designee's balance account with The Depository
Trust Corporation through its Deposit Withdrawal Agent Commission System.

      4. Registration of Series B Preferred Stock. The Corporation shall
register shares of the Series B Preferred Stock, upon records to be maintained
by the Corporation for that purpose (the "SERIES B PREFERRED STOCK REGISTER"),
in the name of the record Holders thereof from time to time. The Corporation may
deem and treat the registered Holder of shares of Series B Preferred Stock as
the absolute owner thereof for the purpose of any conversion hereof or any
distribution to such Holder, and for all other purposes, absent actual notice to
the contrary.

      5. Registration of Transfers. The Corporation shall register the transfer
of any shares of Series B Preferred Stock in the Series B Preferred Stock
Register, upon surrender of certificates evidencing such shares to the
Corporation at its address specified herein. Upon any such registration or
transfer, a new

                                       3
<PAGE>
certificate evidencing the shares of Series B Preferred Stock so transferred
shall be issued to the transferee and a new certificate evidencing the remaining
portion of the shares not so transferred, if any, shall be issued to the
transferring Holder.

      6. Liquidation.

            (a) In the event of any liquidation, dissolution or winding up of
the Corporation, either voluntary or involuntary (a "LIQUIDATION EVENT"), the
Holders of Series B Preferred Stock shall be entitled to receive, prior and in
preference to any distribution of any of the assets or surplus funds of the
Corporation to the holders of Junior Securities by reason of their ownership
thereof, an amount per share in cash equal to the Stated Value for each share of
Series B Preferred Stock then held by them (as adjusted for any stock splits,
stock dividends, stock combinations and similar transactions with respect to the
Series B Preferred Stock), plus all accrued but unpaid dividends on such Series
B Preferred Stock as of the date of such event (the "SERIES B STOCK LIQUIDATION
PREFERENCE"). If, upon the occurrence of a Liquidation Event, the assets and
funds thus distributed among the Holders of the Series B Preferred Stock shall
be insufficient to permit the payment to such Holders of the full Series B Stock
Liquidation Preference, then the entire assets and funds of the Corporation
legally available for distribution shall be distributed ratably among the
Holders of the Series B Preferred Stock in proportion to the aggregate Series B
Stock Liquidation Preference that would otherwise be payable to each of such
Holders.

            (b) In the event of a Liquidation Event, following completion of the
distributions required by the first sentence of paragraph (a) of this Section 6,
if assets or surplus funds remain in the Corporation, the holders of the Common
Stock shall share ratably in all remaining assets of the Corporation, based on
the number of shares of Common Stock then outstanding.

            (c) The Corporation shall mail written notice of any Liquidation
Event to each record Holder not less than 20 Trading Days prior to the payment
date or effective date thereof.

      7. Conversion.

            (a) Conversion at Option of Holder. At the option of any Holder, any
Series B Preferred Stock held by such Holder may be converted into Common Stock
based on the applicable Conversion Price then in effect for such series of
Series B Preferred Stock. A Holder may convert Series B Preferred Stock into
Common Stock pursuant to this paragraph at any time and from time to time after
the applicable Deemed Issue Date, by delivering to the Corporation a Conversion
Notice, in the form attached hereto as Exhibit B, appropriately completed and
duly signed, and the date any such Conversion Notice is delivered to the
Corporation (as determined in accordance with the notice provisions hereof) is a
"CONVERSION DATE."

            (b) Conversion at Option of Corporation. If, at any time after the
Effective Date, the Closing Price on each of 20 consecutive Trading Days (a
"QUALIFYING PERIOD") exceeds 135% of the applicable Conversion Price for a
series of Series B Preferred Stock (each, a "THRESHOLD PRICE"), the Corporation
may require the Holders to convert the shares of such series into Common Stock
based on the applicable Conversion Price. The Corporation may require a
conversion pursuant to this paragraph by delivering irrevocable written notice
of such election to the Holders, and the fifth Trading Day after the date any
such notice is delivered to the Holders (as determined in accordance with the
notice provisions hereof) will be the "CONVERSION DATE" for such required
conversion. Notwithstanding the foregoing, (i) if the Corporation has publicly
announced a pending, proposed or intended Change of Control and the Qualifying
Period includes any Trading Days on or after the date of such public
announcement, then to the extent that a Holder has not had the ability to sell
all or a portion of the Underlying Shares pursuant to Rule 144 under the
Securities Act or an effective Underlying Share Registration Statement for at
least 20 Trading Days after the date of the public announcement of such Change
of Control, the Conversion Date

                                       4
<PAGE>
with respect to those shares of Series B Preferred Stock that are convertible
into the portion of the Underlying Shares that are not so saleable shall be
deferred until the date on which such Underlying Shares shall have been so
saleable for a period of 20 Trading Days from the date of such public
announcement (and if no such period of 20 Trading Days occurs prior to the
Change of Control with respect to any such Underlying Shares then the notice of
conversion applicable to those shares of Series B Preferred Stock convertible
into such Underlying Shares shall be void) and (ii) the Corporation may not
require any conversion under this paragraph (and any notice thereof will be
void), unless from the beginning of such period of 20 consecutive Trading Days
through the Conversion Date, (A) the Equity Conditions are satisfied with
respect to all of the Underlying Shares then issuable upon conversion in full of
all outstanding Series B Preferred Stock, and (B) the Closing Price equals or
exceeds the applicable Threshold Price.

      8. Mechanics of Conversion.

            (a) The number of Underlying Shares issuable upon any conversion of
shares of either series of Series B Preferred Stock hereunder shall equal (i)
the Stated Value of such share of Series B Preferred Stock to be converted,
divided by the applicable Conversion Price on the Conversion Date, plus (ii) the
amount of any accrued but unpaid dividends on such share of Series B Preferred
Stock through the Conversion Date, divided by the applicable Conversion Price on
the Conversion Date.

            (b) Upon conversion of any Series B Preferred Stock, the Corporation
shall promptly (but in no event later than three Trading Days after the
Conversion Date) issue or cause to be issued and cause to be delivered to or
upon the written order of the Holder and in such name or names as the Holder may
designate a certificate for the Underlying Shares issuable upon such conversion,
free of restrictive legends unless such Underlying Shares are not then freely
transferable without volume restrictions pursuant to Rule 144(k) under the
Securities Act. The Holder, or any Person so designated by the Holder to receive
Underlying Shares, shall be deemed to have become holder of record of such
Underlying Shares as of the Conversion Date. If and when such Underlying Shares
may be freely transferred pursuant to Rule 144 under the Securities Act or
pursuant to an effective Underlying Shares Registration Statement, the
Corporation shall use its best efforts to deliver Underlying Shares hereunder
electronically through the Depository Trust Corporation or another established
clearing corporation performing similar functions, and shall issue such
Underlying Shares in the same manner as dividend payment shares are issued
pursuant to Section 3(f) above.

            (c) A Holder shall not be required to deliver the original
certificate(s) evidencing the Series B Preferred Stock being converted in order
to effect a conversion of such Series B Preferred Stock. Execution and delivery
of the Conversion Notice shall have the same effect as cancellation of the
original certificate(s) and issuance of a new certificate evidencing the
remaining shares of Series B Preferred Stock. Upon surrender of a certificate
following one or more partial conversions, the Corporation shall promptly
deliver to the Holder a new certificate representing the remaining shares of
Series B Preferred Stock.

            (d) The Corporation's obligations to issue and deliver Underlying
Shares upon conversion of Series B Preferred Stock in accordance with the terms
hereof are absolute and unconditional, irrespective of any action or inaction by
any Holder to enforce the same, any waiver or consent with respect to any
provision hereof, the recovery of any judgment against any Person or any action
to enforce the same, or any setoff, counterclaim, recoupment, limitation or
termination, or any breach or alleged breach by any Holder or any other Person
of any obligation to the Corporation or any violation or alleged violation of
law by any Holder or any other Person, and irrespective of any other
circumstance which might otherwise limit such obligation of the Corporation to
any Holder in connection with the issuance of such Underlying Shares.

                                       5
<PAGE>
      9. Redemption Rights.

            (a) Holders' Redemption Rights.

                  (i) Subject to the provisions of Section 9(a)(iii) below, if,
      at any time on or after August 7, 2003, in the case of the Series B-I
      Preferred Stock, and August 28, 2003, in the case of the Series B-II
      Preferred Stock (either such date being referred to as an "Initial
      Redemption Date"), the average of the Closing Prices for 20 consecutive
      Trading Days immediately preceding the applicable Initial Redemption Date
      or any date thereafter is below the applicable Conversion Price of such
      series of Series B Preferred Stock, the Holder of such Series B Preferred
      Stock, upon 15 Trading Days' advance notice (the "REDEMPTION NOTICE") to
      the Corporation, shall have the right to request the Corporation to redeem
      that number of shares of Series B Preferred Stock held by such Holders as
      is set forth in the Redemption Notice at a per share price (the
      "REDEMPTION PRICE") equal to the Stated Value of such shares of Series B
      Preferred Stock to be redeemed plus all accrued but unpaid dividends
      thereon to the date of payment.

                  (ii) Notwithstanding anything to the contrary in Section
      9(a)(i), the Holders of the Series B Preferred Stock (x) may not deliver a
      Redemption Notice with respect to a particular series of Series B
      Preferred Stock until after the applicable Initial Redemption Date, (y)
      may not deliver a Redemption Notice covering in aggregate more than
      $20,000,000 of Stated Value, with respect to the Series B-I Preferred
      Stock, until after February 7, 2004, and $10,000,000 of Stated Value, with
      respect to the Series B-II Preferred Stock, until after February 28, 2004,
      and (z) may deliver a Redemption Notice with respect to a particular
      series of Series B Preferred Stock after February 7, 2004 or February 28,
      2004, as applicable, irrespective of whether the average of the Closing
      Prices for the 20 consecutive Trading Days is below the applicable
      Conversion Price of such series of Series B Preferred Stock and without
      limit as to Stated Value.

                  (iii) Within three Trading Days of receipt of a Redemption
      Notice, the Corporation will deliver written notice to each Holder of the
      applicable series of Series B Preferred Stock (the "CORPORATION NOTICE"),
      confirming pursuant to the Redemption Notice the aggregate amount of such
      Series B Preferred Stock being redeemed, the Redemption Date (as defined
      below) and the applicable Redemption Prices. Notwithstanding the aggregate
      shares set forth in the Redemption Notice, each Holder of such series of
      Series B Preferred Stock shall have the right to elect to have all or any
      number of shares of the applicable series of Series B Preferred Stock held
      by such Holder redeemed on the Redemption Date at the applicable
      Redemption Price by notifying the Corporation within five Trading Days of
      receipt of the Corporation Notice of its election to do so, and specifying
      the number of shares as to which such election is made. In the event that
      the aggregate number of shares of Series B Preferred Stock to be redeemed
      on such Redemption Date exceeds the aggregate limitations set forth in
      Section 9(a)(ii), the number of shares to be redeemed from each Holder
      shall be reduced pro rata based upon the aggregate number of shares of the
      applicable series of Series B Preferred Stock held by each Holder
      requesting redemption.

                  (iv) The Redemption Notice will specify the effective date of
      the redemption, which must be a Trading Day at least 15 Trading Days after
      the date such notice is delivered (the "REDEMPTION DATE"), and the entire
      Redemption Price may be paid at the Corporation's option in cash, in
      Common Stock or in Series C Preferred Stock. The Corporation must deliver
      written notice to the Holders indicating the manner in which it intends to
      pay the Redemption Price at least three Trading Days after receipt of the
      Redemption Notice. Failure to timely provide such written notice shall be
      deemed an election by the Corporation to make the payment in Common Stock.
      Notwithstanding the foregoing, the Corporation (a) may not pay the
      Redemption Price by issuing Common Stock unless, at such time, the Equity
      Conditions are satisfied with respect to such

                                       6
<PAGE>
      Common Stock and (b) may not pay the Redemption Price by issuing Series C
      Preferred Stock unless, at such time, the Equity Conditions are not
      satisfied.

                  (v) Upon receipt of payment of the Redemption Price, each
      Holder will deliver the original certificate(s) evidencing the Series B
      Preferred Stock so redeemed to the Corporation, unless such Holder is
      awaiting receipt of a new certificate evidencing such shares from the
      Corporation pursuant to another provision hereof. At any time on or prior
      to the Redemption Date, the Holders may convert any or all of the shares
      of Series B Preferred Stock, and the Corporation shall honor any such
      conversions in accordance with the terms hereof.

                  (vi) In the event that the Corporation elects to pay the
      Redemption Price in shares of Common Stock, the number of shares of Common
      Stock to be issued to each Holder as payment of the Redemption Price shall
      be determined by dividing the total Redemption Price then payable to such
      Holder by the Redemption Market Price (as defined below) as of the
      applicable Redemption Date, and rounding up to the nearest whole share.
      Such shares shall be issued to such Holder in the same manner as dividend
      payment shares are issued pursuant to Section 3(f) above. The term
      "REDEMPTION MARKET PRICE" shall mean the average of the Volume Weighted
      Average Prices of Common Stock for the ten consecutive Trading Days prior
      to the applicable Redemption Date (not including such date).

                  (vii) In the event that the Corporation elects to pay the
      Redemption Price in shares of Series C Preferred Stock, the number of
      shares of Series C Preferred Stock to be issued to each Holder in payment
      of the Redemption Price shall be determined by dividing the total
      Redemption Price then payable to such Holder with respect to all of such
      Holder's shares of Series B Preferred Stock by $10,000 (the initial stated
      value per share of the Series C Preferred Stock) and rounding downward to
      the nearest whole number of shares of Series C Preferred Stock. In
      addition, the Corporation shall pay to Holder in cash the amount, if any,
      by which the Redemption Price payable to such Holder exceeds the aggregate
      stated value of the Series C Preferred Stock issued pursuant to the
      preceding sentence. If the total Redemption Price payable to a Holder is
      less than $10,000, then the Corporation shall pay such amount to such
      Holder entirely in cash.

            (b) Mandatory Redemption. On February 7, 2009 (the "MANDATORY
REDEMPTION DATE"), the Corporation shall redeem all of the then outstanding
Series B Preferred Stock at a price equal to 100% of the Stated Value of such
shares of Series B Preferred Stock plus all accrued but unpaid dividends thereon
to the date of payment in cash, Common Stock or Series C Preferred Stock (or a
combination thereof) at the election of the Corporation. The Corporation must
deliver written notice to the Holders indicating the manner in which it intends
to pay the Redemption Price at least 20 Trading Days prior to the Mandatory
Redemption Date. Failure to timely provide such written notice shall be deemed
an election by the Corporation to make the payment in Common Stock.
Notwithstanding the foregoing, the Corporation (i) may not pay the Redemption
Price by issuing Common Stock unless, at such time, the Equity Conditions are
satisfied with respect to such Common Stock and (ii) may not pay the Redemption
Price by issuing Series C Preferred Stock unless, at such time, the Equity
Conditions are not satisfied. Upon receipt of payment of the Redemption Price,
each Holder will deliver the original certificate(s) evidencing the Series B
Preferred Stock so redeemed to the Corporation, unless such Holder is awaiting
receipt of a new certificate evidencing such shares from the Corporation
pursuant to another provision hereof. In the event that the Corporation elects
to pay the Redemption Price in shares of Common Stock or Series C Preferred
Stock, the number of such shares shall be determined in the manner described in
Section 9(a)(vi) or (vii), as the case may be. At any time on or prior to the
Mandatory Redemption Date, the Holders may convert any or all of the shares of
Series B Preferred Stock, and the Corporation shall honor any such conversions
in accordance with the terms hereof.

                                       7
<PAGE>
      10. Triggering Events. At any time or times following the occurrence of a
Triggering Event (other than a Change of Control), each Holder shall have the
option to elect, by notice to the Corporation (an "EVENT NOTICE"), to require
the Corporation to repurchase all or any portion of (i) the Series B Preferred
Stock then held by such Holder, at a price per share equal to the greater of (A)
115% of the Stated Value plus all accrued but unpaid dividends thereon through
the date of payment, or (B) the Event Equity Value of the Underlying Shares
issuable upon conversion of such Series B Preferred Stock (including such
accrued but unpaid dividends thereon), and (ii) any Underlying Shares issued to
such Holder upon conversion of Series B Preferred Stock, at a price per share
equal to the Event Equity Value of such Underlying Shares. The aggregate amount
payable pursuant to the preceding sentence is referred to as the "EVENT PRICE."
The Corporation shall pay the aggregate Event Price to each Holder in cash or
Series C Preferred Stock (or a combination thereof), at the election of the
Corporation, by no later than the third Trading Day following the date of
delivery of the Event Notice, and upon receipt thereof such Holder shall deliver
original certificates evidencing the shares of Series B Preferred Stock and
Underlying Shares so repurchased to the Corporation (to the extent such
certificates have been delivered to the Holder). In the event that the
Corporation elects to pay the Redemption Price in shares of Series C Preferred
Stock, the number of such shares shall be determined in the manner described in
Section 9(a)(vii).

      11. Voting Rights. Except as otherwise provided herein or as required by
applicable law, the Holders of the Series B Preferred Stock shall be entitled to
vote on all matters on which holders of Common Stock are entitled to vote,
including, without limitation, the election of directors. For such purposes,
each Holder shall be entitled to a number of votes in respect of the shares of
Series B Preferred Stock owned by it equal to the number of shares of Common
Stock into which such shares of Series B Preferred Stock are convertible as of
the record date for the determination of stockholders entitled to vote on such
matter, or if no record date is established, at the date such vote is taken or
any written consent of stockholders is solicited. Except as otherwise provided
herein, in any relevant agreement or as required by applicable law, the holders
of the Series B Preferred Stock and Common Stock, respectively, shall vote
together as a single class on all matters submitted to a vote or consent of
stockholders; provided that so long as any shares of Series B Preferred Stock
are outstanding, the Corporation shall not, without the affirmative vote of the
Holders of a majority of the shares of Series B Preferred Stock then
outstanding, (a) alter or change adversely the powers, preferences or rights
given to the Series B Preferred Stock or alter or amend this Certificate of
Designations (whether by merger, reorganization, consolidation or otherwise),
(b) authorize or create any class of stock ranking as to dividends or
distribution of assets upon a Liquidation Event or Change of Control senior to
the Series B Preferred Stock, (c) amend its certificate of incorporation or
bylaws so as to affect adversely any rights of the Holders (whether by merger,
reorganization, consolidation or otherwise), (d) increase the authorized number
of shares of Series B Preferred Stock, or (e) enter into any agreement with
respect to the foregoing.

      12. Charges, Taxes and Expenses. Issuance of certificates for shares of
Series B Preferred Stock and for Underlying Shares issued on conversion of (or
otherwise in respect of) the Series B Preferred Stock shall be made without
charge to the Holders for any issue or transfer tax, withholding tax, transfer
agent fee or other incidental tax or expense in respect of the issuance of such
certificates, all of which taxes and expenses shall be paid by the Corporation;
provided, however, that the Corporation shall not be required to pay any tax
that may be payable in respect of any transfer involved in the registration of
any certificates for Common Stock or Series B Preferred Stock in a name other
than that of the Holder. The Holder shall be responsible for all other tax
liability that may arise as a result of holding or transferring the Series B
Preferred Stock or receiving Underlying Shares in respect of the Series B
Preferred Stock.

      13. Replacement Certificates. If any certificate evidencing Series B
Preferred Stock or Underlying Shares is mutilated, lost, stolen or destroyed,
the Corporation shall issue or cause to be issued in exchange and substitution
for and upon cancellation hereof, or in lieu of and substitution for such

                                       8
<PAGE>
certificate, a new certificate, but only upon receipt of evidence reasonably
satisfactory to the Corporation of such loss, theft or destruction and customary
and reasonable indemnity, if requested. Applicants for a new certificate under
such circumstances shall also comply with such other reasonable regulations and
procedures and pay such other reasonable third-party costs as the Corporation
may prescribe.

      14. Reservation of Underlying Shares. The Corporation covenants that it
shall at all times reserve and keep available out of the aggregate of its
authorized but unissued and otherwise unreserved Common Stock, solely for the
purpose of enabling it to issue the Underlying Shares as required hereunder (i)
a sufficient number of authorized but unissued and otherwise unreserved shares
of Common Stock available to issue Underlying Shares upon any conversion of
Shares or, if the number of shares so reserved is insufficient to make available
a sufficient number of authorized but unissued and otherwise unreserved shares
of Common Stock for such issuance within 60 days after the occurrence of such
deficiency, and (ii) at least 6,401,394 authorized but unissued and otherwise
unreserved shares of Common Stock (as adjusted for any stock splits, stock
combinations or similar events) less any shares of Common Stock issued upon
conversion of the Shares, as dividends on the Shares, upon exercise of the
Warrants or upon a redemption of the Shares. The Corporation covenants that all
Underlying Shares so issuable and deliverable shall, upon issuance in accordance
with the terms hereof, be duly and validly authorized, issued and fully paid and
nonassessable.

      15. Certain Adjustments. The Conversion Price is subject to adjustment
from time to time as set forth in this Section 15.

            (a) Stock Dividends and Splits. If the Corporation, at any time
while Series B Preferred Stock is outstanding, (i) pays a stock dividend on its
Common Stock or otherwise makes a distribution on any class of capital stock
that is payable in shares of Common Stock (other than regular dividends on the
Series B Preferred Stock), (ii) subdivides outstanding shares of Common Stock
into a larger number of shares, or (iii) combines outstanding shares of Common
Stock into a smaller number of shares, then in each such case the applicable
Conversion Price for each series of Series B Preferred Stock shall be multiplied
by a fraction of which the numerator shall be the number of shares of Common
Stock outstanding immediately before such event and of which the denominator
shall be the number of shares of Common Stock outstanding immediately after such
event. Any adjustment made pursuant to clause (i) of this paragraph shall become
effective immediately after the record date for the determination of
stockholders entitled to receive such dividend or distribution, and any
adjustment pursuant to clause (ii) or (iii) of this paragraph shall become
effective immediately after the effective date of such subdivision or
combination.

            (b) Pro Rata Distributions. If the Corporation, at any time while
Series B Preferred Stock is outstanding, distributes to all holders of Common
Stock (i) evidences of its indebtedness, (ii) any security (other than a
distribution of Common Stock covered by the preceding paragraph), (iii) rights
or warrants to subscribe for or purchase any security, or (iv) any other asset
other than cash paid as a dividend (in each case, "DISTRIBUTED PROPERTY"), then,
at the request of any Holder delivered before the ninetieth day after the record
date fixed for determination of stockholders entitled to receive such
distribution, the Corporation will deliver to such Holder, within five Trading
Days after such request (or, if later, on the effective date of such
distribution), the Distributed Property that such Holder would have been
entitled to receive in respect of the Underlying Shares for which such Holder's
Series B Preferred Stock could have been converted immediately prior to such
record date. If such Distributed Property is not delivered to a Holder pursuant
to the preceding sentence, then upon any conversion of Series B Preferred Stock
that occurs after such record date, such Holder shall be entitled to receive, in
addition to the Underlying Shares otherwise issuable upon such conversion, the
Distributed Property that such Holder would have been entitled to receive in
respect of such number of Underlying Shares had the Holder been the record
holder of such Underlying Shares immediately prior to such record date.

                                       9
<PAGE>
            (c) Certain Transactions.

                  (i) If, at any time while Series B Preferred Stock is
      outstanding, the Corporation proposes to enter into a transaction that
      would constitute a Change of Control, the Corporation shall mail written
      notice of the proposed Change of Control transaction to each record Holder
      not less than 20 Trading Days prior to the effective date thereof. Each
      Holder shall have the right to receive on the date of the consummation of
      such Change of Control, at its option, either (A) for each Underlying
      Share that would have been issuable upon such conversion of the shares of
      Series B Preferred Stock upon the effective time of such Change of
      Control, the same kind and amount of securities, cash or property as it
      would have been entitled to receive upon the occurrence of such Change of
      Control if it had been, immediately prior to such Change of Control, the
      holder of one share of Common Stock or (B) for each share of Series B
      Preferred Stock, cash in an amount equal to 115% of the Stated Value plus
      all accrued but unpaid dividends thereon through the date of payment. If
      holders of Common Stock are given any choice as to the securities, cash or
      property to be received in a Change of Control transaction, then each
      Holder shall be given the same choice as to the consideration it receives
      pursuant to clause (A) above. Each Holder shall make the election of which
      consideration it has elected to receive at least three Trading Days prior
      to the effective date of a Change of Control. Failure of any Holder to
      timely provide written notice of its election shall be deemed an election
      by such Holder to receive the consideration specified in clause (B) above.
      Notwithstanding the foregoing, if a Holder elects to receive cash pursuant
      to clause (B) of the preceding sentence or is deemed to have so elected,
      the Corporation may elect instead to have such successor to the
      Corporation or surviving entity in the Change of Control issue to the
      Holder a new series of Preferred Stock with a stated value equal to 115%
      of the Stated Value of the Series B Preferred Stock, plus all accrued but
      unpaid dividends thereon, and consistent with terms substantially
      equivalent to the terms of the Series B-I Preferred Stock or Series B-II
      Preferred Stock, as the case may be, held by such Holder and evidencing
      the Holder's right to convert such Preferred Stock into the consideration
      described in clause (A) of this subparagraph (i). To the extent the
      Corporation elects to have the successor to the Corporation or the
      surviving entity issue a new series of Preferred Stock, the terms of any
      agreement pursuant to which a Change of Control is effected shall include
      terms requiring any such successor or surviving entity to comply with the
      provisions substantially equivalent to the provisions of this paragraph
      (c) and providing that the Series B Preferred Stock (or any such
      replacement security) will be similarly adjusted upon any subsequent
      transaction analogous to a Change of Control.

                  (ii) Any recapitalization, reorganization, reclassification,
      consolidation, merger, sale of all or substantially all of the
      Corporation's assets to another Person or other transaction which is
      effected in such a way that holders of Common Stock are entitled to
      receive (either directly or upon subsequent liquidation) stock, securities
      or assets with respect to or in exchange for Common Stock is referred to
      herein as "ORGANIC CHANGE." Prior to the consummation of any (A) sale of
      all or substantially all of the Corporation's assets to an acquiring
      Person or (B) other Organic Change following which the Corporation is not
      a surviving entity, other than in each case an Organic Change that is a
      Change of Control (which shall be subject to Section 15(c)(i)), the
      Corporation will secure from the Person purchasing such assets or the
      successor, or, if applicable, the parent of the successor, resulting from
      such Organic Change (in each case, the "ACQUIRING ENTITY") a written
      agreement (in form and substance reasonably satisfactory to the holders of
      at least a majority of the shares of Series B Preferred Stock then
      outstanding) to deliver to each holder of Series B Preferred Stock in
      exchange for such shares, a security of the Acquiring Entity evidenced by
      a written instrument substantially similar in form and substance to such
      Series B Preferred Stock, including, without limitation, having a stated
      value and liquidation preference equal to the Stated Value and the Series
      B Stock Liquidation Preference of the Series B Preferred Stock held by
      such holder, and

                                       10
<PAGE>
      reasonably satisfactory to the holders of at least a majority of the
      Series B Preferred Stock then outstanding.

            (d) Subsequent Equity Sales.

                  (i) If, at any time while any shares of either series of
      Series B Preferred Stock are outstanding, the Corporation or any
      Subsidiary issues additional shares of Common Stock or rights, warrants,
      options or other securities or debt convertible, exercisable or
      exchangeable for shares of Common Stock or otherwise entitling any Person
      to acquire shares of Common Stock (collectively, "COMMON STOCK
      EQUIVALENTS") at an effective net price to the Corporation per share of
      Common Stock (the "EFFECTIVE PRICE") less than the lesser of (A) the
      Initial Purchase Price for a series of Series B Preferred Stock or (B)
      then-applicable Conversion Price for a series of Series B Preferred Stock,
      then the applicable Conversion Price for such series of Series B Preferred
      Stock shall be reduced to equal the Effective Price. For purposes of this
      paragraph, in connection with any issuance of any Common Stock
      Equivalents, (A) the maximum number of shares of Common Stock potentially
      issuable at any time upon conversion, exercise or exchange of such Common
      Stock Equivalents (the "DEEMED NUMBER") shall be deemed to be outstanding
      upon issuance of such Common Stock Equivalents, (B) the Effective Price
      applicable to such Common Stock shall equal the minimum dollar value of
      consideration payable to the Corporation to purchase such Common Stock
      Equivalents and to convert, exercise or exchange them into Common Stock
      (net of any discounts, fees, commissions and other expenses), divided by
      the Deemed Number, (C) no further adjustment shall be made to the
      Conversion Price upon the actual issuance of Common Stock upon conversion,
      exercise or exchange of such Common Stock Equivalents, and (D) upon the
      expiration or termination of any Common Stock Equivalent that does not
      result in the issuance of any Common Stock or additional Common Stock
      Equivalent, any adjustment that has been made under this paragraph (d) in
      respect of the issuance of such Common Stock Equivalent shall be
      readjusted as if such Common Stock Equivalent had not been issued (but
      shall in no event affect previously converted stock).

                  (ii) If, at any time while Series B Preferred Stock is
      outstanding, the Corporation or any Subsidiary issues Common Stock
      Equivalents with an Effective Price or a number of underlying shares that
      floats or resets or otherwise varies or is subject to adjustment based
      (directly or indirectly) on market prices of the Common Stock (a "FLOATING
      PRICE SECURITY"), then for purposes of applying the preceding paragraph in
      connection with any subsequent conversion, the Effective Price will be
      determined separately on each Conversion Date and will be deemed to equal
      the lowest Effective Price at which any holder of such Floating Price
      Security is entitled to acquire Common Stock on such Conversion Date
      (regardless of whether any such holder actually acquires any shares on
      such date).

                  (iii) Notwithstanding the foregoing, no adjustment will be
      made under this paragraph (d) in respect of the issuance of Excluded
      Stock.

            (e) Calculations. All calculations under this Section 15 shall be
made to the nearest cent or the nearest 1/100th of a share, as applicable. The
number of shares of Common Stock outstanding at any given time shall not include
shares owned or held by or for the account of the Corporation, and the
disposition of any such shares shall be considered an issue or sale of Common
Stock.

            (f) Notice of Adjustments. Upon the occurrence of each adjustment
pursuant to this Section 15, the Corporation at its expense will promptly
compute such adjustment in accordance with the terms hereof and prepare a
certificate describing in reasonable detail such adjustment and the transactions
giving rise thereto, including all facts upon which such adjustment is based.
Upon written request, the

                                       11
<PAGE>
Corporation will promptly deliver a copy of each such certificate to each Holder
and to the Corporation's Transfer Agent.

            (g) Notice of Corporate Events. If the Corporation (i) declares a
dividend or any other distribution of cash, securities or other property in
respect of its Common Stock, including without limitation any granting of rights
or warrants to subscribe for or purchase any capital stock of the Corporation or
any Subsidiary, (ii) authorizes or approves, enters into any agreement
contemplating or solicits stockholder approval for any Fundamental Transaction
or (iii) authorizes the voluntary dissolution, liquidation or winding up of the
affairs of the Corporation, then the Corporation shall deliver to each Holder a
notice describing the material terms and conditions of such transaction, at
least 20 calendar days prior to the applicable record or effective date on which
a Person would need to hold Common Stock in order to participate in or vote with
respect to such transaction, and the Corporation will take all steps reasonably
necessary in order to insure that each Holder is given the practical opportunity
to convert its Series B Preferred Stock prior to such time so as to participate
in or vote with respect to such transaction; provided, however, that the failure
to deliver such notice or any defect therein shall not affect the validity of
the corporate action required to be described in such notice.

      16. Limitation on Conversion.

            (a) Notwithstanding anything to the contrary contained herein, the
number of shares of Common Stock that may be acquired by any Holder upon any
conversion of Series B Preferred Stock (or otherwise in respect of the Series B
Preferred Stock) shall be limited to the extent necessary to insure that,
following such conversion (or other issuance), the total number of shares of
Common Stock then beneficially owned by such Holder and its Affiliates and any
other Persons whose beneficial ownership of Common Stock would be aggregated
with the Holder's for purposes of Section 13(d) of the Exchange Act, does not
exceed 4.999% (the "MAXIMUM PERCENTAGE") of the total number of issued and
outstanding shares of Common Stock (including for such purpose the shares of
Common Stock issuable upon such conversion). For such purposes, beneficial
ownership shall be determined in accordance with Section 13(d) of the Exchange
Act and the rules and regulations promulgated thereunder. Each delivery of a
Conversion Notice by a Holder will constitute a representation by such Holder
that it has evaluated the limitation set forth in this paragraph and determined
that issuance of the full number of Underlying Shares requested in such
Conversion Notice is permitted under this paragraph. By written notice to the
Corporation, any Holder may waive the provisions of this Section or increase or
decrease the Maximum Percentage to any other percentage specified in such
notice, but (i) any such waiver or increase will not be effective until the 61st
day after such notice is delivered to the Corporation, and (ii) any such waiver
or increase or decrease will apply only to such Holder and not to any other
Holder and (iii) any such waiver or increase shall not be effective to the
extent such waiver or increase would cause the Corporation to violate the Nasdaq
Stockholder Approval Rule.

            (b) For purposes of this Section 16, in determining the number of
outstanding shares of Common Stock, a Holder may rely on the number of
outstanding shares of Common Stock as reflected in (1) the Corporation's most
recent Form 10-Q, Form 10-K or other public filing with the Commission, as the
case may be, (2) a more recent public announcement by the Corporation, or (3)
any other notice by the Corporation or its transfer agent setting forth the
number of shares of Common Stock outstanding. Upon the written request of any
Holder, the Corporation shall promptly, but in no even later than one Trading
Day following the receipt of such notice, confirm in writing to any such Holder
the number of shares of Common Stock then outstanding.

      17. Fractional Shares. The Corporation shall not be required to issue or
cause to be issued fractional Underlying Shares on conversion of Series B
Preferred Stock. If any fraction of an Underlying

                                       12
<PAGE>
Share would, except for the provisions of this Section, be issuable upon
conversion of Series B Preferred Stock, the number of Underlying Shares to be
issued will be rounded up to the nearest whole share.

      18. Notices. Any and all notices or other communications or deliveries
hereunder (including without limitation any Conversion Notice) shall be in
writing and shall be deemed given and effective on the earliest of (i) the date
of transmission, if such notice or communication is delivered via facsimile at
the facsimile number specified in this Section prior to 5:30 p.m. (New York City
time) on a Trading Day, (ii) the next Trading Day after the date of
transmission, if such notice or communication is delivered via facsimile at the
facsimile number specified in this Section on a day that is not a Trading Day or
later than 5:30 p.m. (New York City time) on any Trading Day, (iii) the Trading
Day following the date of mailing, if sent by nationally recognized overnight
courier service, or (iv) upon actual receipt by the party to whom such notice is
required to be given. The addresses for such communications shall be (i) if to
the Corporation, to Ten Canal Park, Cambridge, Massachusetts 02141, facsimile:
(617) 949-1722, Attention: Chief Executive Officer and General Counsel, or (ii)
if to a Holder, to the address or facsimile number appearing on the
Corporation's stockholder records or such other address or facsimile number as
such Holder may provide to the Corporation in accordance with this Section.

      19. Miscellaneous.

            (a) The headings herein are for convenience only, do not constitute
a part of this Certificate of Designations and shall not be deemed to limit or
affect any of the provisions hereof.

            (b) Any of the rights of the Holders of Series B Preferred Stock set
forth herein may be waived by the affirmative vote of the Holders of a majority
of the shares of Series B Preferred Stock then outstanding. No waiver of any
default with respect to any provision, condition or requirement of this
Certificate of Designations shall be deemed to be a continuing waiver in the
future or a waiver of any subsequent default or a waiver of any other provision,
condition or requirement hereof, nor shall any delay or omission of either party
to exercise any right hereunder in any manner impair the exercise of any such
right.

                                      * * *

                                       13
<PAGE>
      IN WITNESS WHEREOF, Aspen Technology, Inc. has caused this Certificate of
Designations to be duly executed as of March 19, 2002.

                                        ASPEN TECHNOLOGY, INC.

                                        By: /s/ Lisa W. Zappala
                                            ------------------------------------
                                            Lisa W. Zappala
                                            Senior Vice President and
                                              Chief Financial Officer

                                       14
<PAGE>
                                                                       EXHIBIT A

                             ADDITIONAL DEFINITIONS

      "AFFILIATE" means any Person that, directly or indirectly through one or
more intermediaries, controls or is controlled by or is under common control
with a Person, as such terms are used in and construed under Rule 144. With
respect to a Purchaser, any investment fund or managed account that is managed
on a discretionary basis by the same investment manager as such Purchaser will
be deemed to be an Affiliate of such Purchaser.

      "BANKRUPTCY EVENT" means any of the following events: (a) the Corporation
or any Material Subsidiary commences a case or other proceeding under any
bankruptcy, reorganization, arrangement, adjustment of debt, relief of debtors,
dissolution, insolvency or liquidation or similar law of any jurisdiction
relating to the Corporation or any Material Subsidiary thereof; (b) there is
commenced against the Corporation or any Material Subsidiary any such case or
proceeding that is not dismissed within 60 days after commencement; (c) the
Corporation or any Material Subsidiary is adjudicated insolvent or bankrupt or
any order of relief or other order approving any such case or proceeding is
entered; (d) the Corporation or any Material Subsidiary suffers any appointment
of any custodian or the like for it or any substantial part of its property that
is not discharged or stayed within 60 days; (e) the Corporation or any Material
Subsidiary makes a general assignment for the benefit of creditors; (f) the
Corporation or any Material Subsidiary fails to pay, or states in writing that
it is unable to pay or is unable to pay, its debts generally as they become due;
or (g) the Corporation or any Subsidiary, by any act or failure to act,
expressly indicates its consent to, approval of or acquiescence in any of the
foregoing or takes any corporate or other action that effects any of the
foregoing.

      "CHANGE OF CONTROL" means the occurrence of any of the following in one or
a series of related transactions: (i) an acquisition after the date hereof by an
individual or legal entity or "group" (as described in Rule 13d-5(b)(1) under
the Exchange Act) of a majority of the voting rights or equity interests in the
Corporation; (ii) a replacement of more than one-half of the members of the
Corporation's Board of Directors that is not approved by those individuals who
are members of the Board of Directors on the Deemed Issue Date (or other
directors previously approved by such individuals); (iii) a merger or
consolidation of the Corporation or a sale of all or substantially all of the
assets of the Corporation in one or a series of related transactions, unless
following such transaction or series of transactions, the holders of the
Corporation's securities prior to the first such transaction continue to hold,
directly or indirectly, at least a majority of the voting rights and equity
interests in the surviving entity or acquirer of such assets; (iv) a
recapitalization, reorganization or other transaction involving the Corporation
that constitutes or results in a transfer of a majority of the voting rights or
equity interests in the Corporation to Persons other than holders of the
Corporation's voting equity securities prior to such transaction; or (v)
consummation of a "Rule 13e-3 transaction" as defined in Rule 13e-3 under the
Exchange Act with respect to the Corporation other than a Rule 13e-3 transaction
in which no Holder's interest in the Corporation has been adversely changed or
diluted in any material manner.

      "CLOSING PRICE" means, for any date, the price determined by the first of
the following clauses that applies: (a) if the Common Stock is then listed or
quoted on an Eligible Market or any other national securities exchange, the last
closing price per share of the Common Stock for such date (or the nearest
preceding date) on the primary Eligible Market or exchange on which the Common
Stock is then listed or quoted; (b) if prices for the Common Stock are then
quoted on the OTC Bulletin Board, the average of the highest closing bid price
and the lowest closing ask price per share of the Common Stock for such date (or
the nearest preceding date) so quoted; (c) if prices for the Common Stock are
then reported in the "Pink Sheets" published by the National Quotation Bureau
Incorporated (or a similar organization or agency succeeding to its functions of
reporting prices), the most recent bid price per share of the Common

                                       15
<PAGE>
Stock so reported; or (d) in all other cases, the fair market value of a share
of Common Stock as determined by an independent appraiser selected in good faith
by a majority-in-interest of the Purchasers and the Corporation.

      "COMMISSION" means the Securities and Exchange Commission.

      "COMMON STOCK" means the common stock of the Corporation, par value $0.10
per share.

      "EFFECTIVE DATE" means the date that an Underlying Shares Registration
Statement is declared effective by the Commission.

      "ELIGIBLE MARKET" means the New York Stock Exchange, the American Stock
Exchange, the Nasdaq National Market or the Nasdaq SmallCap Market.

      "EVENT EQUITY VALUE" means 115% of the average of the Closing Prices for
the five Trading Days preceding the date of delivery of the notice requiring
payment of the Event Equity Value, provided that if the Corporation does not
make such required payment (together with any other payments, expenses and
liquidated damages then due and payable under the Transaction Documents) when
due or, in the event the Corporation disputes in good faith the occurrence of
the Triggering Event pursuant to which such notice relates, does not instead
deposit such required payment (together with such other payments, expenses and
liquidated damages then due) in escrow with an independent third-party escrow
agent within five Trading Days of the date such required payment is due, then
the Event Equity Value shall be 115% of the greater of (a) the average of the
Closing Prices for the five Trading Days preceding the date of delivery of the
notice requiring payment of the Event Equity Value and (b) the average of the
Closing Prices for the five Trading Days preceding the date on which such
required payment (together with such other payments, expenses and liquidated
damages) is paid in full.

      "EXCHANGE ACT" means the Securities Exchange Act of 1934, as amended.

      "EXCLUDED STOCK" means any shares of Common Stock issued or issuable: (A)
upon exercise, conversion or exchange of any Common Stock Equivalents described
in Schedule 3.1(g) to the Purchase Agreement (provided that such exercise or
conversion occurs in accordance with the terms thereof, without amendment or
modification, and that the applicable exercise or conversion price or ratio is
described in such schedule); (B) to officers, directors, employees or
consultants of the Corporation pursuant to a stock option plan, employee stock
purchase plan or other equity incentive plan approved by the Board of Directors
of the Corporation; (C) pursuant to as part of a bona fide firm commitment
underwritten public offering with a nationally recognized underwriter (including
any "at the market offering," as defined in Rule 415(a)(4) under the Securities
Act, only if such offering does not constitute an "equity line" and generates
aggregate gross proceeds of at least $50 million); (D) in connection with any
transaction with a strategic investor, vendor, lessor, customer, supplier,
marketing partner, developer or integrator or any similar arrangement, in each
case the primary purpose of which is not to raise equity capital; (E) in
connection with a transaction involving a merger or acquisition of an entity,
business or assets (not principally for the purpose of obtaining cash); or (F)
in connection with any other transaction for consideration other than cash up to
108,166 shares of Common Stock in the aggregate (as adjusted for stock splits,
stock combinations and similar events).

      "MATERIAL SUBSIDIARY" means any significant subsidiary, as defined in Rule
1-02(w) of Regulation S-X promulgated by the Commission, of the Corporation.

      "PERSON" means an individual or corporation, partnership, trust,
incorporated or unincorporated association, joint venture, limited liability
Corporation, joint stock Corporation, government (or an agency or subdivision
thereof) or other entity of any kind.

                                       16
<PAGE>
      "PURCHASER" has the meaning set forth in the Purchase Agreement.

      "REGISTRATION RIGHTS AGREEMENT" means the Amended and Restated
Registration Rights Agreement, dated as of March 19, 2002 among the Corporation
and the Purchasers, as amended from time to time.

      "REQUIRED EFFECTIVENESS DATE" means the date on which an Underlying Shares
Registration Statement is required to become effective pursuant to the
Registration Rights Agreement.

      "RULE 144" means Rule 144 promulgated by the Commission pursuant to the
Securities Act, as such Rule may be amended from time to time, or any similar
rule or regulation hereafter adopted by the Commission having substantially the
same effect as such Rule.

      "SECURITIES" means the Shares, the Warrants and the Underlying Shares.

      "SECURITIES ACT" means the Securities Act of 1933, as amended.

      "SHARES" means, collectively, the shares of Series B-I Preferred Stock and
Series B-II Preferred Stock.

      "SUBSIDIARY" means any subsidiary, as defined in Rule 1-02(x) of
Regulation S-X promulgated by the Commission, of the Corporation.

      "TRADING DAY" means (a) any day on which the Common Stock is listed or
quoted and traded on its primary Trading Market or (b) if the Common Stock is
not then listed or quoted and traded on any Eligible Market, then a day on which
trading occurs on the New York Stock Exchange (or any successor thereto).

      "TRADING MARKET" means the Nasdaq National Market or any other Eligible
Market on which the Common Stock is then listed or quoted.

      "TRANSACTION DOCUMENTS" means the Purchase Agreement, the Registration
Rights Agreement, this Certificate of Designations and the Warrants.

      "TRIGGERING EVENT" means any of the following events: (a) immediately
prior to any Bankruptcy Event; (b) the Common Stock is not listed or quoted, or
is suspended from trading, on an Eligible Market for a period of five
consecutive Trading Days or ten aggregate Trading Days in any 365-day period;
(c) the Corporation fails for any reason to deliver a certificate evidencing any
Securities to a Purchaser within ten Trading Days after delivery of such
certificate is required pursuant to any Transaction Document or the exercise or
conversion rights of the Holders pursuant to the Transaction Documents are
otherwise suspended for any reason; (d) the Corporation fails to have available
both (i) a sufficient number of authorized but unissued and otherwise unreserved
shares of Common Stock available to issue Underlying Shares upon any exercise of
the Warrants or any conversion of Shares and does not make available a
sufficient number of authorized but unissued and otherwise unreserved shares of
Common Stock for such issuance within 60 days after the occurrence of such
deficiency and (ii) at least 6,401,394 authorized but unissued and otherwise
unreserved shares of Common Stock (as adjusted for any stock splits, stock
combinations or similar events), less reductions reasonably agreed to by the
Purchasers to reflect shares of Common Stock issued upon conversion of the
Shares (and, therefore, reduced aggregate dividend payments), as dividends on
the Shares, upon exercise of the Warrants or upon a redemption of the Shares;
(e) at any time after the Required Effectiveness Date, any Common Stock issuable
pursuant to the Transaction Documents is not listed on an Eligible Market; (f)
any other Event (as defined in the Registration Rights Agreement) occurs and
remains uncured for 60 days; (g) the Corporation fails to

                                       17
<PAGE>
make any cash payment required under the Transaction Documents and such failure
is not cured within five days after notice of such default is first given to the
Corporation by a Purchaser; (h) the Corporation defaults in the timely
performance of any other obligation under the Transaction Documents and such
default continues uncured for a period of 20 days after the date on which notice
of such default is first given to the Corporation by a Purchaser (it being
understood that no prior notice need be given in the case of a default that
cannot reasonably be cured within 20 days), or (i) any Change of Control event.

      "UNDERLYING SHARES" means the shares of Common Stock issuable upon
conversion of, or in redemption of, the Shares, as payment of dividends on the
Shares and upon exercise of the Warrants, and any securities issued in exchange
for, or upon conversion or in respect of, such shares.

      "UNDERLYING SHARES REGISTRATION STATEMENT" means a registration statement
meeting the requirements set forth in the Registration Rights Agreement and
covering the resale of the Underlying Shares by the Purchasers.

      "VOLUME WEIGHTED AVERAGE PRICE" means, with respect to a Trading Day, the
average of the daily volume weighted average trading price (the total dollar
amount traded on each day divided by trading volume for such day) of the Common
Stock for the regular Trading Day session as reported at 4:15 p.m. (New York
time) as reported by Bloomberg, LP function key HP by using W to calculate the
daily weighted average.

      "WARRANTS" means the Common Stock purchase warrants, as amended from time
to time, issued pursuant to the Purchase Agreement.

                                       18
<PAGE>
                                                                       EXHIBIT B

                            FORM OF CONVERSION NOTICE

(To be executed by the registered Holder
  in order to convert shares of Series B Preferred Stock)

      The undersigned hereby elects to convert the number of shares of Series B
Preferred Stock indicated below into shares of Common Stock of Aspen Technology,
Inc., a Delaware corporation, according to the conditions hereof, as of the date
written below.

                  Series of Series B Preferred Stock to be
                  converted (check):                           _____ Series B-I
                                                               _____ Series B-II

                  ______________________________________________________________
                  Date to effect conversion

                  ______________________________________________________________
                  Number and series of shares of Series B Preferred Stock owned
                  prior to conversion

                  ______________________________________________________________
                  Number and series of shares of Series B Preferred Stock to be
                  converted

                  ______________________________________________________________
                  Stated Value of shares of Series B Preferred Stock to be
                  converted (including $_______________ of dividends added under
                  Section 2(f) of the Registration Rights Agreement)

                  ______________________________________________________________
                  Number of shares of Common Stock to be issued

                  ______________________________________________________________
                  Applicable Conversion Price

                  ______________________________________________________________
                  Number and series of shares of Series B Preferred Stock
                  subsequent to conversion

                  ______________________________________________________________
                  Name of Holder

                  By:___________________________________________________________
                     Name:______________________________________________________
                     Title:_____________________________________________________

                                       19

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00035-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00035-of-00352.parquet"}]]