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Sample Business Contracts

Rights Agreement - Open Market Inc. and BankBoston NA

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                               OPEN MARKET, INC.

                                      and

                                BANKBOSTON N.A.

                                  Rights Agent


                               __________________


                                Rights Agreement

                          Dated as of January 26, 1998
<PAGE>

                                 Table of Contents
                                 -----------------
<TABLE>
<CAPTION>
Section                                                                        Page
- -------                                                                        ----
 
<C>             <S>                                                             <C>
   Section 1.   Certain Definitions  . . . . . . . . . . . . . . . . . . . . . . 1
                                      
   Section 2.   Appointment of Rights Agent . . . . . . . . . . . . . . . . . .  6
             
   Section 3.   Issue of Rights Certificates  . . . . . . . . . . . . . . . . .  6
             
   Section 4.   Form of Rights Certificates . . . . . . . . . . . . . . . . . .  8
             
   Section 5.   Countersignature and Registration . . . . . . . . . . . . . . .  9
             
   Section 6.   Transfer, Split Up, Combination and Exchange of Rights
                Certificates; Mutilated, Destroyed, Lost or Stolen Rights
                Certificates. . . . . . . . . . . . . . . . . . . . . . . . . . 10

   Section 7.   Exercise of Rights; Purchase Price; Expiration Date
                of Rights . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

   Section 8.   Cancellation and Destruction of Rights Certificates . . . . . . 13

   Section 9.   Reservation and Availability of Capital Stock . . . . . . . . . 13

   Section 10.  Preferred Stock Record Date . . . . . . . . . . . . . . . . . . 15

   Section 11.  Adjustment of Purchase Price, Number and Kind of
                Shares or Number of Rights. . . . . . . . . . . . . . . . . . . 15

   Section 12.  Certificate of Adjusted Purchase Price or Number of Shares. . . 24

   Section 13.  Consolidation, Merger or Sale or Transfer of
                Assets or Earning Power . . . . . . . . . . . . . . . . . . . . 24

   Section 14.  Fractional Rights and Fractional Shares . . . . . . . . . . . . 27

   Section 15.  Rights of Action  . . . . . . . . . . . . . . . . . . . . . . . 28

   Section 16.  Agreement of Rights Holders . . . . . . . . . . . . . . . . . . 28

   Section 17.  Rights Certificate Holder Not Deemed a Stockholder. . . . . . . 29

   Section 18.  Concerning the Rights Agent . . . . . . . . . . . . . . . . . . 29

</TABLE>
<PAGE>

<TABLE>
<C>             <S>                                                             <C>
   Section 19.  Merger or Consolidation or Change of Name of
                Rights Agent. . . . . . . . . . . . . . . . . . . . . . . . . . 30

   Section 20.  Duties of Rights Agent. . . . . . . . . . . . . . . . . . . . . 31

   Section 21.  Change of Rights Agent. . . . . . . . . . . . . . . . . . . . . 33

   Section 22.  Issuance of New Rights Certificates . . . . . . . . . . . . . . 34

   Section 23.  Redemption and Termination. . . . . . . . . . . . . . . . . . . 34

   Section 24.  Exchange. . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

   Section 25.  Notice of Certain Events. . . . . . . . . . . . . . . . . . . . 37

   Section 26.  Notices . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

   Section 27.  Supplements and Amendments. . . . . . . . . . . . . . . . . . . 39

   Section 28.  Successors. . . . . . . . . . . . . . . . . . . . . . . . . . . 39

   Section 29.  Determinations and Actions by the Board of Directors, etc.. . . 40

   Section 30.  Benefits of this Agreement. . . . . . . . . . . . . . . . . . . 40

   Section 31.  Severability. . . . . . . . . . . . . . . . . . . . . . . . . . 40

   Section 32.  Governing Law . . . . . . . . . . . . . . . . . . . . . . . . . 40

   Section 33.  Counterparts. . . . . . . . . . . . . . . . . . . . . . . . . . 40

   Section 34.  Descriptive Headings. . . . . . . . . . . . . . . . . . . . . . 41

</TABLE>

Exhibit A - Certificate of Designations

Exhibit B - Form of Rights Certificate

Exhibit C - Form of Summary of Rights
<PAGE>


                                RIGHTS AGREEMENT

     RIGHTS AGREEMENT, dated as of January 26, 1998 (the "Agreement"), between
OPEN MARKET, INC., a Delaware corporation (the "Company"), and BankBoston N.A.,
a national banking association, as Rights Agent (the "Rights Agent").

                              W I T N E S S E T H
                              -------------------

     WHEREAS, as of January 26, 1998, the Board of Directors of the Company (the
"Board") authorized and declared a dividend of one right (a "Right") for each
share of Common Stock (as hereinafter defined) of the Company outstanding at the
close of business on February 12, 1998 (the "Record Date"), and authorized the
issuance of one Right (as such number may hereinafter be adjusted pursuant to
the provisions of Section 11(p) hereof) for each share of Common Stock of the
Company issued between the Record Date (whether originally issued or delivered
from the Company's treasury) and the earliest of the Distribution Date, the
Redemption Date or the Final Expiration Date, each Right initially representing
the right to purchase one one-thousandth of a share of Series A Junior
Participating Preferred Stock of the Company having the rights, powers and
preferences set forth in the form of Certificate of Designations attached hereto
as Exhibit A, upon the terms and subject to the conditions hereinafter set forth
(the "Rights");

     NOW, THEREFORE, in consideration of the premises and the mutual agreements
herein set forth, the parties hereby agree as follows:

     Section 1.  Certain Definitions.  For purposes of this Agreement, the
                 -------------------                                     
following terms have the meanings indicated:

     (a) "Acquiring Person" shall mean any Person who or which, together with
all Affiliates and Associates of such Person, shall be the Beneficial Owner of
18% or more of the shares of Common Stock then outstanding, but shall not
include (i) the Company, (ii) any Subsidiary of the Company, (iii) any employee
benefit plan of the Company or of any Subsidiary of the Company, or (iv) any
Person or entity organized, appointed or established by the Company for or
pursuant to the terms of any such plan.  Notwithstanding the foregoing, no
Person shall become an "Acquiring Person" as the result of an acquisition of
Common Stock by the Company which, by reducing the number of shares outstanding,
increases the proportionate number of shares beneficially owned by such Person
to 18% or more of the Common Stock of the Company then outstanding; provided,
                                                                    --------
however, that if a Person shall become the Beneficial Owner of 18% or more of
- -------                                                                     
the Common Stock of the Company then outstanding by reason of share purchases by
the Company and shall, after such share purchases by the Company, become the
Beneficial Owner of any additional Common Stock of the Company, then such Person
shall be deemed to be an

                                      -1-
<PAGE>

"Acquiring Person." Notwithstanding the foregoing, if the Board of Directors of
the Company determines in good faith that a Person who would otherwise be an
"Acquiring Person," as defined pursuant to the foregoing provisions of this
paragraph (a), has become such inadvertently, and such Person divests as
promptly as practicable a sufficient number of shares of Common Stock so that
such Person would no longer be an "Acquiring Person," as defined pursuant to the
foregoing provisions of this paragraph (a), then such Person shall not be deemed
to be an "Acquiring Person" for any purposes of this Agreement.

     (b) "Act" shall mean the Securities Act of 1933, as amended.

     (c) "Affiliate" and "Associate" shall have the respective meanings ascribed
to such terms in Rule 12b-2 of the General Rules and Regulations under the
Securities Exchange Act of 1934, as amended and in effect on the date of this
Agreement (the "Exchange Act").

     (d) A Person shall be deemed the "Beneficial Owner" of, and shall be deemed
to "beneficially own," any securities:

          (i) which such Person or any of such Person's Affiliates or
     Associates, beneficially owns, directly or indirectly, or which such person
     or any of such Person's Affiliates or Associates, directly or indirectly,
     has the right to acquire (whether such right is exercisable immediately or
     only after the passage of time) pursuant to any agreement, arrangement or
     understanding (other than customary agreements with and between
     underwriters and selling group members with respect to a bona fide public
     offering of securities), whether or not in writing, or upon the exercise of
     conversion rights, exchange rights, other rights, warrants or options, or
     otherwise; provided, however, that a Person shall not be deemed the
                --------                                               
     "Beneficial Owner" of, or to "beneficially own," (A) securities tendered
     pursuant to a tender or exchange offer made by such Person or any of such
     Person's Affiliates or Associates until such tendered securities are
     accepted for purchase or exchange, or (B) securities issuable upon exercise
     of Rights at any time prior to the occurrence of a Triggering Event, or (C)
     securities issuable upon exercise of Rights from and after the occurrence
     of a Triggering Event which Rights were acquired by such Person or any of
     such Person's Affiliates or Associates prior to the Distribution Date or
     pursuant to Section 3(a) or Section 22 hereof (the "Original Rights") or
     pursuant to Section 11(i) hereof in connection with an adjustment made with
     respect to any Original Rights;

          (ii) which such Person or any of such Person's Affiliates or
     Associates, directly or indirectly, has the right to vote or dispose of or
     has "beneficial ownership" of (as determined pursuant to Rule 13d-3 of the
     General Rules and Regulations under the Exchange Act, or any comparable or

                                      -2-
<PAGE>

     successor rule), including pursuant to any agreement, arrangement or
     understanding (other than customary agreements with and between
     underwriters and selling group members with respect to a bona fide public
     offering of securities), whether or not in writing; provided, however, that
                                                         --------              
     a Person shall not be deemed the "Beneficial Owner" of, or to "beneficially
     own," any security under this subparagraph (ii) as a result of an
     agreement, arrangement or understanding to vote such security if such
     agreement, arrangement or understanding:  (A) arises solely from a
     revocable proxy given in response to a public proxy or consent solicitation
     made pursuant to, and in accordance with, the applicable provisions of the
     General Rules and Regulations under the Exchange Act, and (B) is not also
     then reportable by such Person on Schedule 13D under the Exchange Act (or
     any comparable or successor report); or

          (iii) which are beneficially owned, directly or indirectly, by any
     other Person (or any Affiliate or Associate thereof) with which such Person
     (or any of such Person's Affiliates or Associates) has any agreement,
     arrangement or understanding (other than customary agreements with and
     between underwriters and selling group members with respect to a bona fide
     public offering of securities), whether or not in writing, for the purpose
     of acquiring, holding, voting (except pursuant to a revocable proxy as
     described in the proviso to subparagraph (ii) of this paragraph (d)) or
     disposing of any voting securities of the Company.

     Notwithstanding anything in this definition of Beneficial Ownership to the
contrary, the phrase "then outstanding," when used with reference to a Person's
Beneficial Ownership of securities of the Company, shall mean the number of such
securities then issued and outstanding together with the number of such
securities not then actually issued and outstanding which such Person would be
deemed to own beneficially hereunder.

     (e) "Business Day" shall mean any day other than a Saturday, Sunday or a
day on which banking institutions in the Commonwealth of Massachusetts are
authorized or obligated by law or executive order to close.

     (f) "Close of business" on any given date shall mean 5:00 P.M., Boston
time, on such date; provided, however, that if such date is not a Business Day
                    --------                                                 
it shall mean 5:00 P.M., Boston, Massachusetts time, on the next succeeding
Business Day.

     (g) "Common Stock" shall mean the common stock, $.001 par value, of the
Company, except that "Common Stock" when used with reference to any Person other
than the Company shall mean the capital stock of such Person with the greatest
voting power, or the equity securities or other equity interest having power to
control or direct the management, of such Person.

                                      -3-
<PAGE>

     (h) "Common stock equivalents" shall have the meaning set forth in Section
11(a)(iii) hereof.

     (i) "Continuing Director" shall mean (i) any member of the Board, while
such Person is a member of the Board, who is not an Acquiring Person, or an
Affiliate or Associate of an Acquiring Person, or a representative of an
Acquiring Person or of any such Affiliate or Associate, and was a member of the
Board prior to the date of this Agreement, or (ii) any Person who subsequently
becomes a member of the Board, while such Person is a member of the Board, who
is not an Acquiring Person, or an Affiliate or Associate of an Acquiring Person,
or a representative of an Acquiring Person or of any such Affiliate or
Associate, if such Person's nomination for election or election to the Board is
recommended or approved by a majority of the Continuing Directors.

     (j) "Current market price" shall have the meaning set forth in Section
11(d)(i) hereof.

     (k) "Current Value" shall have the meaning set forth in Section 11(a)(iii)
hereof.

     (l) "Distribution Date" shall have the meaning set forth in Section 3(a)
hereof.

     (m) "Exchange Act" shall have the meaning set forth in Section 1(c) hereof.

     (n) "Expiration Date" shall have the meaning set forth in Section 7(a)
hereof.

     (o) "Final Expiration Date" shall mean the close of business on January 26,
2008.

     (p) "Permitted Offer" shall mean a tender offer or an exchange offer for
all outstanding shares of Common Stock at a price and on terms determined by at
least a majority of the members of the Board of Directors who are not officers
of the Company and who are not representatives, nominees, Affiliates or
Associates of an Acquiring Person, after receiving advice from a nationally
recognized investment banking firm selected by the Board of Directors of the
Company, to be (a) at a price that is fair to stockholders (taking into account
all factors which such members of the board deem relevant including, without
limitation, prices which could reasonably be achieved if the Company or its
assets were sold on an orderly basis designed to realize maximum value) and (b)
otherwise in the best interests of the Company and its stockholders.

     (q) "Person" shall mean any individual, firm, corporation, partnership or
other entity.

                                      -4-
<PAGE>

     (r) "Preferred Stock" shall mean shares of Series A Junior Participating
Preferred Stock, $.10 par value, of the Company having the rights and
preferences set forth in the form of Certificate of Designations attached to
this Agreement as Exhibit A and, to the extent that there is not a sufficient
number of shares of Series A Junior Participating Preferred Stock authorized to
permit the full exercise of the Rights, any other series of Junior Series
Preferred Stock, $.10 par value, of the Company designated for such purpose
containing terms substantially similar to the terms of the Series A Junior
Participating Preferred Stock.

     (s) "Principal Party" shall have the meaning set forth in Section 13(b)
hereof.

     (t) "Purchase Price" shall have the meaning set forth in Section 4(a)
hereof.

     (u) "Record Date" shall have the meaning set forth in the WHEREAS clause at
the beginning of the Agreement.

     (v) "Redemption Date" shall have the meaning set forth in Section 7(a)
hereof.

     (w) "Redemption Price" shall have the meaning set forth in Section 23(a)
hereof.

     (x) "Rights" shall have the meaning set forth in the WHEREAS clause at the
beginning of the Agreement.

     (y) "Rights Certificates" shall have the meaning set forth in Section 3(a)
hereof.

     (z) "Section 11(a)(ii) Event" shall mean an acquisition of Common Stock
described in the first sentence of Section 11(a)(ii) hereof.

     (aa) "Section 11(a)(ii) Trigger Date" shall have the meaning set forth in
Section 11(a)(iii) hereof.

     (bb) "Section 13 Event" shall mean any event described in clauses (x), (y)
or (z) of Section 13(a) hereof.

     (cc) "Spread" shall have the meaning set forth in Section 11(a)(iii)
hereof.

     (dd) "Stock Acquisition Date" shall mean the first date of public
announcement (which, for purposes of this definition, shall include, without
limitation, a report filed pursuant to Section 13(d) under the Exchange Act) by
the Company or an Acquiring Person that an Acquiring Person has become such.

                                      -5-
<PAGE>

     (ee) "Subsidiary" shall mean, with reference to any Person, any corporation
of which an amount of voting securities sufficient to elect at least a majority
of the directors of such corporation is beneficially owned, directly or
indirectly, by such Person, or otherwise controlled by such Person.

     (ff) "Substitution Period" shall have the meaning set forth in Section
11(a)(iii) hereof.

     (gg) "Trading Day" shall have the meaning set forth in Section 11(d)(i)
hereof.

     (hh) "Triggering Event" shall mean any Section 11(a)(ii) Event or any
Section 13 Event.

     Section 2.  Appointment of Rights Agent.  The Company hereby appoints the
                 ---------------------------                                 
Rights Agent to act as agent for the Company and the holders of the Rights (who,
in accordance with Section 3 hereof, shall prior to the Distribution Date also
be the holders of the Common Stock) in accordance with the terms and conditions
hereof, and the Rights Agent hereby accepts such appointment.  The Company may
from time to time appoint such Co-Rights Agents as it may deem necessary or
desirable, upon ten (10) days' prior written notice to the Rights Agent.  The
Rights Agent shall have no duty to supervise, and in no event be liable for, the
acts, the acts or omissions of any such Co-Rights Agent.

     Section 3.  Issue of Rights Certificates.
                 ----------------------------

     (a) Until the earlier of (i) the close of business on the tenth day after
the Stock Acquisition Date (or, if the tenth day after the Stock Acquisition
Date occurs before the Record Date, the close of business on the Record Date),
or (ii) the close of business on the fifteenth Business Day (or such later date
as may be determined by action of the Board of Directors prior to such time as
any Person becomes an Acquiring Person) after the date that a tender or exchange
offer by any Person (other than the Company, any Subsidiary of the Company, any
employee benefit plan of the Company or of any Subsidiary of the Company, or any
Person or entity organized, appointed or established by the Company for or
pursuant to the terms of any such plan) is first published or sent or given
within the meaning of Rule 14d-2(a) of the General Rules and Regulations under
the Exchange Act, if upon consummation thereof, such Person would be the
Beneficial Owner of 18% or more of the shares of Common Stock then outstanding
(the earlier of (i) and (ii) being herein referred to as the "Distribution
Date"), (x) the Rights will be evidenced (subject to the provisions of paragraph
(b) of this Section 3) by the certificates for the Common Stock registered in
the names of the holders of the Common Stock (which certificates for Common
Stock shall be deemed also to be certificates for Rights) and not by separate
certificates, and (y) the Rights will be transferable only in connection with
the transfer of the underlying shares of Common Stock (including a transfer to
the Company).  As soon

                                      -6-

<PAGE>

as practicable after the Distribution Date, the Rights Agent will send by first-
class, insured, postage prepaid mail, to each record holder of the Common Stock
as of the close of business on the Distribution Date, at the address of such
holder shown on the records of the Company, one or more rights certificates, in
substantially the form of Exhibit B hereto (the "Rights Certificates"),
evidencing one Right for each share of Common Stock so held, subject to
adjustment as provided herein. In the event that an adjustment in the number of
Rights per share of Common Stock has been made pursuant to Section 11(p) hereof,
at the time of distribution of the Right Certificates, the Company shall make
the necessary and appropriate rounding adjustments (in accordance with Section
14(a) hereof) so that Rights Certificates representing only whole numbers of
Rights are distributed and cash is paid in lieu of any fractional Rights. As of
and after the Distribution Date, the Rights will be evidenced solely by such
Rights Certificates.

     (b) As promptly as practicable following the Record Date, the Company will
send a copy of a Summary of Rights to Purchase Preferred Stock, in substantially
the form attached hereto as Exhibit C, by first-class, postage prepaid mail, to
each record holder of the Common Stock as of the close of business on the Record
Date, at the address of such holder shown on the records of the Company.  With
respect to certificates for the Common Stock outstanding as of the close of
business on the Record Date, until the Distribution Date, the Rights will be
evidenced by such certificates for the Common Stock and the registered holders
of the Common Stock shall also be the registered holders of the associated
Rights.

     (c) Rights shall be issued (i) in respect of all shares of Common Stock
that are issued (either as an original issuance or from the Company's treasury)
after the Record Date but prior to the earlier of the Distribution Date or the
Expiration Date and (ii) in connection with the issuance or sale of Common Stock
following the Distribution Date and prior to the Expiration Date upon the
exercise of stock options or under any employee plan or arrangement, or upon the
exercise, conversion or exchange of securities issued by the Company prior to
the Distribution Date. Certificates representing such shares of Common Stock
(including, without limitation, certificates issued upon transfer or exchange of
Common Stock) shall also be deemed to be certificates for Rights, and shall bear
the following legend:

          This certificate also evidences and entitles the holder hereof to
     certain Rights as set forth in the Rights Agreement between Open Market,
     Inc. (the "Company") and BankBoston N.A. (the "Rights Agent") dated as of
     January 26, 1998 (the "Rights Agreement"), the terms of which are hereby
     incorporated herein by reference and a copy of which is on file at the
     principal offices of the Company.  Under certain circumstances, as set
     forth in the Rights Agreement, such Rights will be evidenced by separate
     certificates and will no longer be evidenced by this certificate.  The
     Company will mail to the holder of this certificate a copy of the Rights
     Agreement, as in effect on the date of mailing,

                                      -7-
<PAGE>

     without charge promptly after receipt of a written request therefor. Under
     certain circumstances set forth in the Rights Agreement, Rights issued to,
     or held by, any Person who is, was or becomes an Acquiring Person or any
     Affiliate or Associates thereof (as such terms are defined in the Rights
     Agreement), whether currently held by or on behalf of such Person or by any
     subsequent holder, may become null and void.

With respect to such certificates containing the foregoing legend, until the
earlier of (i) the Distribution Date or (ii) the Expiration Date, the Rights
associated with the Common Stock represented by such certificates shall be
evidenced by such certificates alone and registered holders of Common Stock
shall also be the registered holders of the associated Rights.

     (d) Until the earlier of the Distribution Date or the Expiration Date (as
such term is defined in Section 7 hereof), the transfer of any certificates
representing shares of Common Stock in respect of which Rights have been issued
shall also constitute the transfer of the Rights associated with such shares of
Common Stock.  In the event that the Company purchases or acquires any shares of
Common Stock after the Record Date but prior to the Distribution Date, any
Rights associated with such shares of Common Stock shall be deemed cancelled and
retired so that the Company shall not be entitled to exercise any Rights
associated with the shares of Common Stock which are no longer outstanding.

     Section 4.  Form of Rights Certificates.
                 ---------------------------

     (a) The Rights Certificates (and the forms of election to purchase,
certification and assignment to be printed on the reverse thereof) shall each be
substantially in the form set forth in Exhibit B hereto and may have such marks
of identification or designation and such legends, summaries or endorsements
printed thereon as the Company may deem appropriate and as are not inconsistent
with the provisions of this Agreement, or as may be required to comply with any
applicable law or with any rule or regulation made pursuant thereto or with any
rule or regulation of any stock exchange or over-the-counter market on which the
Rights may from time to time be listed, or to conform to usage.  Subject to the
provisions of Section 11 and Section 22 hereof, the Rights Certificates,
whenever distributed, shall entitle the holders thereof to purchase such number
of one one-thousandths of a share of Preferred Stock as shall be set forth
therein at the price set forth therein (such exercise price per one one-
thousandth of a share, the "Purchase Price"), but the amount and type of
securities purchasable upon the exercise of each Right and the Purchase Price
thereof shall be subject to adjustment as provided herein.

     (b) Any Rights Certificate issued pursuant to Section 3 or Section 22
hereof that represents Rights beneficially owned by persons known to be: (i) an
Acquiring Person or any Associate or Affiliate of an Acquiring Person, (ii) a
transferee of an

                                      -8-
<PAGE>

Acquiring Person (or of any such Associate or Affiliate) who becomes a
transferee after the Acquiring Person becomes such, or (iii) a transferee of an
Acquiring Person (or of any such Associate or Affiliate) who becomes a
transferee prior to or concurrently with the Acquiring Person becoming such and
receives such Rights pursuant to either (A) a transfer (whether or not for
consideration) from the Acquiring Person to holders of equity interests in such
Acquiring Person or to any Person with whom such Acquiring Person has any
continuing agreement, arrangement or understanding regarding the transferred
Rights or (B) a transfer which the Board of Directors of the Company has
determined is part of a plan, arrangement or understanding that has as a primary
purpose or effect avoidance of Section 7(e) hereof, and any Rights Certificate
issued pursuant to Section 6 or Section 11 hereof upon transfer, exchange,
replacement or adjustment of any other Rights Certificate referred to in this
sentence, shall contain (to the extent feasible) the following legend:

     The Rights represented by this Rights Certificate are or were beneficially
     owned by a Person who was or became an Acquiring Person or an Affiliate or
     Associate of an Acquiring Person (as such terms are defined in the Rights
     Agreement).  Accordingly, this Rights Certificate and the Rights
     represented hereby may become null and void in the circumstances specified
     in Section 7(e) of such Agreement.

     Section 5.  Countersignature and Registration.
                 ---------------------------------

     (a) The Rights Certificates shall be executed on behalf of the Company by
its Chairman of the Board, its Chief Executive Officer, its President or any
Vice President, either manually or by facsimile signature, and shall have
affixed thereto the Company's seal or a facsimile thereof, which shall be
attested by the Secretary or an Assistant Secretary of the Company, either
manually or by facsimile signature. The Rights Certificates shall be manually
countersigned by the Rights Agent and shall not be valid for any purpose unless
so countersigned.  In case any officer of the Company who shall have signed any
of the Rights Certificates shall cease to be such officer of the Company before
countersignature by the Rights Agent and issuance and delivery by the Company,
such Rights Certificates, nevertheless, may be countersigned by the Rights Agent
and issued and delivered by the Company with the same force and effect as though
the person who signed such Rights Certificates had not ceased to be such officer
of the Company; and any Rights Certificates may be signed on behalf of the
Company by any person who, at the actual date of the execution of such Rights
Certificate, shall be a proper officer of the Company to sign such Rights
Certificate, although at the date of the execution of this Rights Agreement any
such person was not such an officer.

     (b) Following the Distribution Date, the Rights Agent shall keep or cause
to be kept, at its office designated as the appropriate place for surrender of
Rights

                                      -9-
<PAGE>

Certificates upon exercise or transfer, books for registration and transfer of
the Rights Certificates issued hereunder. Such books shall show the names and
addresses of the respective holders of the Rights Certificates, the number of
Rights evidenced on its face by each of the Rights Certificates, the Certificate
number and the date of each of the Rights Certificates.

     Section 6.  Transfer, Split Up, Combination and Exchange of Rights
                 ------------------------------------------------------
Certificates; Mutilated, Destroyed, Lost or Stolen Rights Certificates.
- ----------------------------------------------------------------------

     (a) Subject to the provisions of Section 4(b), Section 7(e) and Section 14
hereof, at any time after the close of business on the Distribution Date, and at
or prior to the close of business on the earlier of the Redemption Date or the
Expiration Date, any Rights Certificate or Certificates (other than Rights
Certificates representing Rights that have become void pursuant to Section 7(e)
hereof or that have been exchanged pursuant to Section 24 hereof) may be
transferred, split up, combined or exchanged for another Rights Certificate or
Certificates, entitling the registered holder to purchase a like number of one
one-thousandth of a share of Preferred Stock (or, following a Triggering Event,
Common Stock, other securities, cash or other assets, as the case may be) as the
Rights Certificate or Certificates surrendered then entitled such holder (or
former holder in the case of a transfer) to purchase.  Any registered holder
desiring to transfer, split up, combine or exchange any Rights Certificate or
Certificates shall make such request in writing delivered to the Rights Agent,
and shall surrender the Rights Certificate or Certificates to be transferred,
split up, combined or exchanged, with the form of assignment and certificate
appropriately executed, at the office of the Rights Agent designated for such
purpose.  Neither the Rights Agent nor the Company shall be obligated to take
any action whatsoever with respect to the transfer of any such surrendered
Rights Certificate until the registered holder shall have completed and signed
the certificate contained in the form of assignment on the reverse side of such
Rights Certificate and shall have provided such additional evidence of the
identity of the Beneficial Owner (or former Beneficial Owner) or Affiliates or
Associates thereof as the Company shall reasonably request. Thereupon the Rights
Agent shall, subject to Section 4(b), Section 7(e) and Section 14 hereof,
countersign and deliver to the Person entitled thereto a Rights Certificate or
Rights Certificates, as the case may be, as so requested.  The Company may
require payment of a sum sufficient to cover any tax or governmental charge that
may be imposed in connection with any transfer, split up, combination or
exchange of Rights Certificates.

     (b) Upon receipt by the Company and the Rights Agent of evidence reasonably
satisfactory to them of the loss, theft, destruction or mutilation of a Rights
Certificate, and, in case of loss, theft or destruction, of indemnity or
security reasonably satisfactory to them, and reimbursement to the Company and
the Rights Agent of all reasonable expenses incidental thereto, and upon
surrender to the Rights Agent and cancellation of the Rights Certificate if
mutilated, the Company will

                                      -10-
<PAGE>

execute and deliver a new Rights Certificate of like tenor to the Rights Agent
for countersignature and delivery to the registered owner in lieu of the Rights
Certificate so lost, stolen, destroyed or mutilated.

     Section 7.  Exercise of Rights; Purchase Price; Expiration Date of Rights.
                 -------------------------------------------------------------

     (a) Subject to Section 7(e) hereof, the registered holder of any Rights
Certificate may exercise the Rights evidenced thereby (except as otherwise
provided herein including, without limitation, the restrictions on
exercisability set forth in Section 9(c), Section 11(a)(iii) and Section 23(a)
hereof) in whole or in part at any time after the Distribution Date upon
surrender of the Rights Certificate, with the form of election to purchase and
the certificate on the reverse side thereof duly executed, to the Rights Agent
at the office of the Rights Agent designated for such purpose, together with
payment of the aggregate Purchase Price with respect to the total number of one
one-thousandth of a share (or other securities, cash or other assets, as the
case may be) as to which such surrendered Rights are then exercisable, at or
prior to the earliest of (i) the Final Expiration Date, (ii) the time at which
the Rights expire as provided in Section 13(d) hereof, (iii) the time at which
the Rights are redeemed as provided in Section 23 hereof (the "Redemption
Date"), or (iv) the time at which such Rights are exchanged as provided in
Section 24 hereof (the earliest of (i), (ii), (iii) and (iv) being herein
referred to as the "Expiration Date").

     (b) The Purchase Price for each one one-thousandth of a share of Preferred
Stock pursuant to the exercise of a Right shall initially be $65.00, and shall
be subject to adjustment from time to time as provided in Sections 11 and 13(a)
hereof and shall be payable in, accordance with paragraph (c) below.

     (c) Upon receipt of a Rights Certificate representing exercisable Rights,
with the form of election to purchase and the certificate duly executed,
accompanied by payment, with respect to each Right so exercised, of the Purchase
Price per one one-thousandth of a share of Preferred Stock (or other shares,
securities, cash or other assets, as the case may be) to be purchased as set
forth below and an amount equal to any applicable transfer tax, the Rights Agent
shall, subject to Section 20(k) hereof, thereupon promptly (i) (A) requisition
from any transfer agent of the shares of Preferred Stock (or make available, if
the Rights Agent is the transfer agent for such shares) certificates for the
total number of one one-thousandth of a share of Preferred Stock to be purchased
and the Company hereby irrevocably authorizes its transfer agent to comply with
all such requests, or (B) if the Company shall have elected to deposit the total
number of shares of Preferred Stock issuable upon exercise of the Rights
hereunder with a depositary agent, requisition from the depositary agent
depositary receipts representing such number of one one-thousandths of a share
of Preferred Stock as are to be purchased (in which case certificates for the
shares of Preferred Stock represented by such receipts shall be deposited by the
transfer agent with the depositary agent) and the Company hereby directs the
depositary agent to

                                      -11-
<PAGE>

comply with such requests, (ii) requisition from the Company the amount of cash,
if any, to be paid in lieu of fractional shares in accordance with Section 14
hereof, (iii) after receipt of such certificates or depositary receipts, cause
the same to be delivered to or upon the order of the registered holder of such
Rights Certificate, registered in such name or names as may be designated by
such holder, and (iv) after receipt thereof, deliver such cash, if any, to or
upon the order of the registered holder of such Rights Certificate. The payment
of the Purchase Price (as such amount may be reduced pursuant to Section
11(a)(iii) hereof) may be made in cash or by certified bank check or money order
payable to the order of the Company. In the event that the Company is obligated
to issue other securities (including Common Stock) of the Company, pay cash
and/or distribute other property pursuant to Section 11(a) hereof, the Company
shall make all arrangements necessary so that such other securities, cash and/or
other property are available for distribution by the Rights Agent, if and when
appropriate.

     (d) In case the registered holder of any Rights Certificate shall exercise
less than all the Rights evidenced thereby, a new Rights Certificate evidencing
Rights equivalent to the Rights remaining unexercised shall be issued by the
Rights Agent and delivered to, or upon the order of, the registered holder of
such Rights Certificate, registered in such name or names as may be designated
by such holder, subject to the provisions of Section 14 hereof.

     (e) Notwithstanding anything in this Agreement to the contrary, from and
after the first occurrence of a Section 11(a) (ii) Event, any Rights
beneficially owned by (i) an Acquiring Person or an Associate or Affiliate of an
Acquiring Person, (ii) a transferee of an Acquiring Person (or of any such
Associate or Affiliate) who becomes a transferee after the Acquiring Person
becomes such, or (iii) a transferee of an Acquiring Person (or of any such
Associate or Affiliate) who becomes a transferee prior to or concurrently with
the Acquiring Person becoming such and receives such Rights pursuant to either
(A) a transfer (whether or not for consideration) from the Acquiring Person to
holders of equity interests in such Acquiring Person or to any Person with whom
the Acquiring Person has any continuing agreement, arrangement or understanding
regarding the transferred Rights or (B) a transfer which the Board of Directors
of the Company has determined is part of a plan, arrangement or understanding
that has as a primary purpose or effect the avoidance of this Section 7(e),
shall become null and void without any further action and no holder of such
Rights shall have any rights whatsoever with respect to such Rights, whether
under any provision of this Agreement or otherwise.  The Company shall use all
reasonable efforts to ensure that the provisions of this Section 7(e) and
Section 4(b) hereof are complied with, but shall have no liability to any holder
of Rights Certificates or other Person as a result of its failure to make any
determinations with respect to an Acquiring Person or its Affiliates, Associates
or transferees hereunder.

                                      -12-
<PAGE>

     (f) Notwithstanding anything in this Agreement to the contrary, neither the
Rights Agent nor the Company shall be obligated to undertake any action with
respect to a registered holder upon the occurrence of any purported transfer or
exercise as set forth in this Section 7 unless such registered holder shall have
(i) completed and signed the certificate following the form of assignment or
election to purchase set forth on the reverse side of the Rights Certificate
surrendered for such assignment or exercise, and (ii) provided such additional
evidence of the identity of the Beneficial Owner (or former Beneficial Owner) or
Affiliates or Associates thereof as the Company shall reasonably request.

     Section 8.  Cancellation and Destruction of Rights Certificates.  All
                 ---------------------------------------------------     
Rights Certificates surrendered for the purpose of exercise, transfer, split up,
combination or exchange shall, if surrendered to the Company or any of its
agents, be delivered to the Rights Agent for cancellation or in cancelled form,
or, if surrendered to the Rights Agent, shall be cancelled by it, and no Rights
Certificates shall be issued in lieu thereof except as expressly permitted by
any of the provisions of this Agreement. The Company shall deliver to the Rights
Agent for cancellation and retirement, and the Rights Agent shall so cancel and
retire, any other Rights Certificate purchased or acquired by the Company
otherwise than upon the exercise thereof.  The Rights Agent shall deliver all
cancelled Rights Certificates to the Company, or shall, at the written request
of the Company, destroy such cancelled Rights Certificates, and in such case
shall deliver a certificate of destruction thereof to the Company.

     Section 9.  Reservation and Availability of Capital Stock.
                 ---------------------------------------------

     (a) The Company covenants and agrees that it will cause to be reserved and
kept available out of its authorized and unissued shares of Preferred Stock
(and, following the occurrence of a Triggering Event, out of its authorized and
unissued shares of Common Stock and/or other securities or out of its authorized
and issued shares held in its treasury), the number of shares of Preferred Stock
(and, following the occurrence of a Triggering Event, Common Stock and/or other
securities) that, as provided in this Agreement including Section 11(a) (iii)
hereof, will be sufficient to permit the exercise in full of all outstanding
Rights.

     (b) So long as the shares of Preferred Stock (and, following the occurrence
of a Triggering Event, Common Stock and/or other securities) issuable and
deliverable upon the exercise of the Rights are eligible for listing on any
national securities exchange, the Company shall use its best efforts to cause,
from and after such time as the Rights become exercisable, all shares reserved
for such issuance to be listed on such exchange upon official notice of issuance
upon such exercise.

     (c) The Company shall use its best efforts to (i) file, as soon as
practicable following the earliest date after the first occurrence of a Section
11(a)(ii) Event on which the consideration to be delivered by the Company upon
exercise of the Rights

                                      -13-
<PAGE>

has been determined in accordance with Section 11(a)(iii) hereof, or as soon as
is required by law following the Distribution Date, as the case may be, a
registration statement under the Act, with respect to the securities purchasable
upon exercise of the Rights on an appropriate form; (ii) cause such registration
statement to become effective as soon as practicable after such filing, and
(iii) cause such registration statement to remain effective (with a prospectus
at all times meeting the requirements of the Act) until the earlier of (A) the
date as of which the Rights are no longer exercisable for such securities, and
(B) the Expiration Date. The Company will also take such action as may be
appropriate under, or to ensure compliance with, the securities or "blue sky"
laws of the various states in connection with the exercisability of the Rights.
The Company may temporarily suspend, for a period of time not to exceed ninety
(90) days after the date set forth in clause (i) of the first sentence of this
Section 9(c), the exercisability of the Rights in order to prepare and file such
registration statement and permit it to become effective. Upon any such
suspension, the Company shall issue a public announcement stating that the
exercisability of the Rights has been temporarily suspended, as well as a public
announcement at such time as the suspension is no longer in effect.
Notwithstanding any provision of this Agreement to the contrary, the Rights
shall not be exercisable in any jurisdiction unless the requisite registration
or qualification in such jurisdiction shall have been effected or obtained.

     (d) The Company covenants and agrees that it will take all such action as
may be necessary to ensure that all one one-thousandths of a share of Preferred
Stock (and, following the occurrence of a Triggering Event, Common Stock and/or
other securities) delivered upon exercise of Rights shall, at the time of
delivery of the certificates for such shares (subject to payment of the Purchase
Price), be duly and validly authorized and issued and fully paid and
nonassessable.

     (e) The Company further covenants and agrees that it will pay when due and
payable any and all federal and state transfer taxes and charges that may be
payable in respect of the issuance or delivery of the Rights Certificates and of
any certificates for a number of one one-thousandth of a share of Preferred
Stock (or Common Stock and/or other securities, as the case may be) upon the
exercise of Rights.  The Company shall not, however, be required (i) to pay any
transfer tax that may be payable in respect of any transfer or delivery of
Rights Certificates to a Person other than, or the issuance or delivery of a
number of one one-thousandth of a share of Preferred Stock (or Common Stock
and/or other securities, as the case may be) in respect of a name other than
that of, the registered holder of the Rights Certificate evidencing Rights
surrendered for exercise or (ii) to issue or deliver any certificates for a
number of one one-thousandth of a share of Preferred Stock (or Common Stock
and/or other securities, as the case may be) in a name other than that of the
registered holder upon the exercise of any Rights until such tax shall have been
paid (any such tax being payable by the holder of such Rights Certificate at the
time

                                      -14-
<PAGE>

of surrender) or until it has been established to the Company's satisfaction
that no such tax is due.

     Section 10.  Preferred Stock Record Date.  Each Person in whose name any
                  ---------------------------                               
certificate for a number of one one-thousandth of a share of Preferred Stock (or
Common Stock and/or other securities, as the case may be) is issued upon the
exercise of Rights shall for all purposes be deemed to have become the holder of
record of such fractional shares of Preferred Stock (or Common Stock and/or
other securities, as the case may be) represented thereby on, and such
certificate shall be dated, the date upon which the Rights Certificate
evidencing such Rights was duly surrendered and payment of the Purchase Price
(and all applicable transfer taxes) was made; provided, however, that if the
                                              --------                     
date of such surrender and payment is a date upon which the Preferred Stock (or
Common Stock and/or other securities, as the case may be) transfer books of the
Company are closed, such Person shall be deemed to have become the record holder
of such shares (fractional or otherwise) on, and such certificate shall be
dated, the next succeeding Business Day on which the Preferred Stock (or Common
Stock and/or other securities, as the case may be) transfer books of the Company
are open.  Prior to the exercise of the Rights evidenced thereby, the holder of
a Rights Certificate, as such, shall not be entitled to any rights of a
stockholder of the Company with respect to securities for which the Rights shall
be exercisable, including, without limitation, the right to vote, to receive
dividends or other distributions or to exercise any preemptive rights, and shall
not be entitled to receive any notice of any proceedings of the Company, except
as provided herein.

     Section 11.  Adjustment of Purchase Price, Number and Kind of Shares or
                  ----------------------------------------------------------
Number of Rights.  The Purchase Price, the number and kind of shares covered by
- ----------------                                                              
each Right and the number of Rights outstanding are subject to adjustment from
time to time as provided in this Section 11.

          (a)(i) In the event the Company shall at any time after the date of
     this Agreement (A) declare a dividend on the Preferred Stock payable in
     shares of Preferred Stock, (B) subdivide the outstanding Preferred Stock,
     (C) combine the outstanding Preferred Stock into a smaller number of
     shares, or (D) issue any shares of its capital stock in a reclassification
     of the Preferred Stock (including any such reclassification in connection
     with a consolidation or merger in which the Company is the continuing or
     surviving corporation), except as otherwise provided in this Section 11(a)
     and Section 7(e) hereof, the Purchase Price in effect at the time of the
     record date for such dividend or of the effective date of such subdivision,
     combination or reclassification, and the number and kind of shares of
     Preferred Stock or capital stock, as the case may be, issuable on such
     date, shall be proportionately adjusted so that the holder of any Right
     exercised after such time shall be entitled to receive, upon payment of the
     Purchase Price then in effect, the aggregate number and kind of shares of

                                      -15-
<PAGE>

     Preferred Stock or capital stock, as the case may be, which, if such Right
     had been exercised immediately prior to such date and at a time when the
     Preferred Stock transfer books of the Company were open, he would have
     owned upon such exercise and been entitled to receive by virtue of such
     dividend, subdivision, combination or reclassification.  If an event occurs
     that would require an adjustment under both this Section 11(a)(i) and
     Section 11(a)(ii) hereof, the adjustment provided for in this Section
     11(a)(i) shall be in addition to, and shall be made prior to, any
     adjustment required pursuant to Section 11(a)(ii) hereof.

          (ii) Subject to Section 24 of this Agreement, in the event that any
     Person shall become an Acquiring Person, unless the event causing the 18%
     threshold to be crossed is a transaction set forth in Section 13(a) hereof,
     or is a Permitted Offer, then, promptly following the first occurrence of
     such event, proper provision shall be made so that each holder of a Right
     (except as provided below and in Section 7(e) hereof) shall thereafter have
     the right to receive, upon exercise thereof at the then current Purchase
     Price in accordance with the terms of this Agreement, in lieu of a number
     of one one-thousandths of a share of Preferred Stock, such number of shares
     of Common Stock of the Company that equals the result obtained by (x)
     multiplying the then current Purchase Price by the then number of one one-
     thousandth of a share of Preferred Stock for which a Right was exercisable
     immediately prior to the first occurrence of a Section 11(a)(ii) Event, and
     (y) dividing that product (which, following such first occurrence, shall
     thereafter be referred to as the "Purchase Price" for each Right and for
     all purposes of this Agreement) by 50% of the current market price
     (determined pursuant to Section 11(d) hereof) per share of Common Stock on
     the date of such first occurrence (such number of shares, the "Adjustment
     Shares").

          (iii) In the event that the number of shares of Common Stock that are
     authorized by the Company's certificate of incorporation but not
     outstanding or reserved for issuance for purposes other than upon exercise
     of the Rights are not sufficient to permit the exercise in full of the
     Rights in accordance with the foregoing subparagraph (ii) of this Section
     11(a), the Company shall: (A) determine the excess of (l) the value of the
     Adjustment Shares issuable upon the exercise of a Right (the "Current
     Value") over (2) the Purchase Price (such excess, the "Spread"), and (B)
     with respect to each Right, make adequate provision to substitute for the
     Adjustment Shares, upon payment of the applicable Purchase Price, (l) cash,
     (2) a reduction in the Purchase Price, (3) Common Stock or other equity
     securities of the Company (including, without limitation, shares, or units
     of shares, of preferred stock which the Board of Directors of the Company
     has deemed to have the same value as shares of Common Stock (such shares of
     preferred stock, "common stock equivalents")), (4) debt securities of the
     Company, (5) other assets, or (6) any combination of

                                      -16-
<PAGE>

     the foregoing, having an aggregate value equal to the Current Value, where
     such aggregate value has been determined by the Board of Directors of the
     Company based upon the advice of a nationally recognized investment banking
     firm selected by the Board of Directors of the Company; provided, however,
                                                             --------
     if the Company shall not have made adequate provision to deliver value
     pursuant to clause (B) above within thirty (30) days following the later of
     (x) the first occurrence of a Section 11(a)(ii) Event and (y) the date on
     which the Company's right of redemption pursuant to Section 23(a) expires
     (the later of (x) and (y) being referred to herein as the "Section
     11(a)(ii) Trigger Date"), then the Company shall be obligated to deliver,
     upon the surrender for exercise of a Right and without requiring payment of
     the Purchase Price, shares of Common Stock (to the extent available) and
     then, if necessary, cash, which shares and/or cash have an aggregate value
     equal to the Spread. If the Board of Directors of the Company shall
     determine in good faith that it is likely that sufficient additional shares
     of Common Stock could be authorized for issuance upon exercise in full of
     the Rights, the thirty (30) day period set forth above may be extended to
     the extent necessary, but not more than ninety (90) days after the Section
     11(a)(ii) Trigger Date, in order that the Company may seek shareholder
     approval for the authorization of such additional shares (such period, as
     it may be extended, the "Substitution Period"). To the extent that the
     Company determines that some action need be taken pursuant to the first
     and/or second sentences of this Section 11(a)(iii), the Company (x) shall
     provide, subject to Section 7(e) hereof, that such action shall apply
     uniformly to all outstanding Rights, and (y) may suspend the exercisability
     of the Rights until the expiration of the Substitution Period in order to
     seek any authorization of additional shares and/or to decide the
     appropriate form of distribution to be made pursuant to such first sentence
     and to determine the value thereof. In the event of any such suspension,
     the Company shall issue a public announcement stating that the
     exercisability of the Rights has been temporarily suspended, as well as a
     public announcement at such time as the suspension is no longer in effect.
     For purposes of this Section 11(a)(iii), the value of the Common Stock
     shall be the current market price (as determined pursuant to Section 11(d)
     hereof) per share of the Common Stock on the Section 11(a)(ii) Trigger Date
     and the value of any "common stock equivalent" shall be deemed to have the
     same value as the Common Stock on such date.

     (b) In case the Company shall fix a record date for the issuance of rights,
options or warrants to all holders of Preferred Stock entitling them to
subscribe for or purchase (for a period expiring within forty-five (45) calendar
days after such record date) Preferred Stock (or shares having the same rights,
privileges and preferences as the shares of Preferred Stock ("equivalent
preferred stock")) or securities convertible into Preferred Stock or equivalent
preferred stock at a price per share of Preferred Stock or per share of
equivalent preferred stock (or having a conversion price per share, if a
security convertible into Preferred Stock or equivalent preferred stock) less

                                      -17-
<PAGE>

than the current market price (as determined pursuant to Section 11(d) hereof)
per share of Preferred Stock on such record date, the Purchase Price to be in
effect after such record date shall be determined by multiplying the Purchase
Price in effect immediately prior to such record date by a fraction, the
numerator of which shall be the number of shares of Preferred Stock outstanding
on such record date, plus the number of shares of Preferred Stock which the
aggregate offering price of the total number of shares of Preferred Stock and/or
equivalent preferred stock so to be offered (and/or the aggregate initial
conversion price of the convertible securities so to be offered) would purchase
at such current market price, and the denominator of which shall be the number
of shares of Preferred Stock outstanding on such record date, plus the number of
additional shares of Preferred Stock and/or equivalent preferred stock to be
offered for subscription or purchase (or into which the convertible securities
so to be offered are initially convertible).  In case such subscription price
may be paid by delivery of consideration part or all of which may be in a form
other than cash, the value of such consideration shall be as determined in good
faith by the Board of Directors of the Company, whose determination shall be
described in a statement filed with the Rights Agent and shall be conclusive for
all purposes.  Shares of Preferred Stock owned by or held for the account of the
Company shall not be deemed outstanding for the purpose of any such computation.
Such adjustment shall be made successively whenever such a record date is fixed,
and in the event that such rights, options or warrants are not so issued, the
Purchase Price shall be adjusted to be the Purchase Price which would then be in
effect if such record date had not been fixed.

     (c) In case the Company shall fix a record date for a distribution to all
holders of Preferred Stock (including any such distribution made in connection
with a consolidation or merger in which the Company is the continuing
corporation) of evidences of indebtedness, cash (other than a regular quarterly
cash dividend out of the earnings or retained earnings of the Company), assets
(other than a dividend payable in Preferred Stock, but including any dividend
payable in stock other than Preferred Stock) or subscription rights or warrants
(excluding those referred to in Section 11(b) hereof), the Purchase Price to be
in effect after such record date shall be determined by multiplying the Purchase
Price in effect immediately prior to such record date by a fraction, the
numerator of which shall be the current market price (as determined pursuant to
Section 11(d) hereof) per share of Preferred Stock on such record date, less the
fair market value (as determined in good faith by the Board of Directors of the
Company, whose determination shall be described in a statement filed with the
Rights Agent and shall be conclusive for all purposes) of the portion of the
cash, assets or evidences of indebtedness so to be distributed or of such
subscription rights or warrants applicable to a share of Preferred Stock and the
denominator of which shall be such current market price (as determined pursuant
to Section 11(d) hereof) per share of Preferred Stock on such record date.  Such
adjustments shall be made successively whenever such a record date is fixed, and
in the event that such distribution is not so made, the Purchase Price shall be
adjusted

                                      -18-
<PAGE>

to be the Purchase Price which would have been in effect if such record date had
not been fixed.

          (d) (i) For the purpose of any computation hereunder, other than
     computations made pursuant to Section 11(a)(iii) hereof, the "current
     market price" per share of Common Stock on any date shall be deemed to be
     the average of the daily closing prices per share of such Common Stock for
     the thirty (30) consecutive Trading Days (as such term is hereinafter
     defined) immediately prior to such date, and for purposes of computations
     made pursuant to Section 11(a)(iii) hereof, the "current market price" per
     share of Common Stock on any date shall be deemed to be the average of the
     daily closing prices per share of such Common Stock for the ten (10)
     consecutive Trading Days immediately following such date; provided,
                                                               --------
     however, that in the event that the current market price per share of the
     Common Stock is determined during a period following the announcement by
     the issuer of such Common Stock of (A) a dividend or distribution on such
     Common Stock payable in shares of such Common Stock or securities
     convertible into shares of such Common Stock (other than the Rights), or
     (B) any subdivision, combination or reclassification of such Common Stock,
     and prior to the expiration of the requisite thirty (30) Trading Day or ten
     (10) Trading Day period, as set forth above, after the ex-dividend date for
     such dividend or distribution, or the record date for such subdivision,
     combination or reclassification, then, and in each such case, the "current
     market price" shall be properly adjusted to take into account ex-dividend
     trading.  The closing price for each day shall be the last quoted price or,
     if not so quoted, the average of the high bid and low asked prices in the
     over-the-counter market, as reported by the Nasdaq National Market
     ("Nasdaq") or such other system then in use, or, if on any such date the
     shares of Common Stock are not quoted by any such organization, the average
     of the closing bid and asked prices as furnished by a professional market
     maker making a market in the Common Stock selected by the Board of
     Directors of the Company.  If on any such date no market maker is making a
     market in the Common Stock, the fair value of such shares on such date as
     determined in good faith by the Board of Directors of the Company shall be
     used.  The term "Trading Day" shall mean a day on which the principal
     national securities exchange on which the shares of Common Stock are listed
     or admitted to trading is open for the transaction of business or, if the
     shares of Common Stock are not listed or admitted to trading on any
     national securities exchange, a Business Day.  If the Common Stock is not
     publicly held or not so listed or traded, "current market price" per share
     shall mean the fair value per share as determined in good faith by the
     Board of Directors of the Company, whose determination shall be described
     in a statement filed with the Rights Agent and shall be conclusive for all
     purposes.

                                      -19-
<PAGE>

          (ii) For the purpose of any computation hereunder, the "current market
     price" per share of Preferred Stock shall be determined in the same manner
     as set forth above for the Common Stock in clause (i) of this Section 11(d)
     (other than the last sentence thereof).  If the current market price per
     share of Preferred Stock cannot be determined in the manner provided above
     or if the Preferred Stock is not publicly held or listed or traded in a
     manner described in clause (i) of this Section 11(d), the "current market
     price" per share of Preferred Stock shall be conclusively deemed to be an
     amount equal to 1,000 (as such number may be appropriately adjusted for
     such events as stock splits, stock dividends and recapitalizations with
     respect to the Common Stock occurring after the date of this Agreement)
     multiplied by the current market price per share of the Common Stock.  If
     neither the Common Stock nor the Preferred Stock is publicly held or so
     listed or traded, "current market price" per share of the Preferred Stock
     shall mean the fair value per share as determined in good faith by the
     Board of Directors of the Company, whose determination shall be described
     in a statement filed with the Rights Agent and shall be conclusive for all
     purposes.  For all purposes of this Agreement, the "current market price"
     of one one-thousandth of a share of Preferred Stock shall be equal to the
     "current market price" of one share of Preferred Stock divided by 1,000.

     (e) Anything herein to the contrary notwithstanding, no adjustment in the
Purchase Price shall be required unless such adjustment would require an
increase or decrease of at least one percent (l%) in the Purchase Price;
                                                                       
provided, however, that any adjustments which by reason of this Section 11(e)
- --------                                                                    
are not required to be made shall be carried forward and taken into account in
any subsequent adjustment.  All calculations under this Section 11 shall be made
to the nearest cent or to the nearest ten-millionth of a share of Preferred
Stock, or one-hundred-thousandth of a share of Common Stock or other share, as
the case may be.  Notwithstanding the first sentence of this Section 11(e), any
adjustment required by this Section 11 shall be made no later than the earlier
of (i) three (3) years from the date of the transaction which mandates such
adjustment, or (ii) the Expiration Date.

     (f) If as a result of an adjustment made pursuant to Section 11(a)(ii) or
Section 13(a) hereof, the holder of any Right thereafter exercised shall become
entitled to receive any shares of capital stock other than Preferred Stock,
thereafter the number of such other shares so receivable upon exercise of any
Right and the Purchase Price thereof shall be subject to adjustment from time to
time in a manner and on terms as nearly equivalent as practicable to the
provisions with respect to the Preferred Stock contained in Sections 11(a), (b),
(c), (e), (g), (h), (i), (j), (k) and (m), and the provisions of Sections 7, 9,
10, 13 and 14 hereof with respect to the Preferred Stock shall apply on like
terms to any such other shares.

                                      -20-
<PAGE>

     (g) All Rights originally issued by the Company subsequent to any
adjustment made to the Purchase Price hereunder shall evidence the right to
purchase, at the adjusted Purchase Price, the number of one one-thousandth of a
share of Preferred Stock purchasable from time to time hereunder upon exercise
of the Rights, all subject to further adjustment as provided herein.

     (h) Unless the Company shall have exercised its election as provided in
Section 11(i), upon each adjustment of the Purchase Price as a result of the
calculations made in Sections 11(b) and (c), each Right outstanding immediately
prior to the making of such adjustment shall thereafter evidence the right to
purchase, at the adjusted Purchase Price, that number of one one-thousandths of
a share of Preferred Stock (calculated to the nearest one-millionth) obtained by
(i) multiplying (x) the number of one one-thousandths of a share covered by a
Right immediately prior to this adjustment, by (y) the Purchase Price in effect
immediately prior to such adjustment of the Purchase Price, and (ii) dividing
the product so obtained by the Purchase Price in effect immediately after such
adjustment of the Purchase Price.

     (i) The Company may elect on or after the date of any adjustment of the
Purchase Price to adjust the number of Rights, in lieu of any adjustment in the
number of one one-thousandth of a share of Preferred Stock purchasable upon the
exercise of a Right.  Each of the Rights outstanding after the adjustment in the
number of Rights shall be exercisable for the number of one one-thousandths of a
share of Preferred Stock for which a Right was exercisable immediately prior to
such adjustment.  Each Right held of record prior to such adjustment of the
number of Rights shall become that number of Rights (calculated to the nearest
one-hundred-thousandth) obtained by dividing the Purchase Price in effect
immediately prior to adjustment of the Purchase Price by the Purchase Price in
effect immediately after adjustment of the Purchase Price.  The Company shall
make a public announcement of its election to adjust the number of Rights,
indicating the record date for the adjustment, and, if known at the time, the
amount of the adjustment to be made. This record date may be the date on which
the Purchase Price is adjusted or any day thereafter, but, if the Rights
Certificates have been issued, shall be at least ten (10) days later than the
date of the public announcement.  If Rights Certificates have been issued, upon
each adjustment of the number of Rights pursuant to this Section 11(i), the
Company shall, as promptly as practicable, cause to be distributed to holders of
record of Rights Certificates on such record date Rights Certificates
evidencing, subject to Section 14 hereof, the additional Rights to which such
holders shall be entitled as a result of such adjustment, or, at the option of
the Company, shall cause to be distributed to such holders of record in
substitution and replacement for the Rights Certificates held by such holders
prior to the date of adjustment, and upon surrender thereof, if required by the
Company, new Rights Certificates evidencing all the Rights to which such holders
shall be entitled after such adjustment.  Rights Certificates so to be
distributed shall be issued, executed and countersigned in the manner provided
for herein (and may bear, at the option of the Company, the

                                      -21-
<PAGE>

adjusted Purchase Price) and shall be registered in the names of the holders of
record of Rights Certificates on the record date specified in the public
announcement.

     (j) Irrespective of any adjustment or change in the Purchase Price or the
number of one one-thousandths of a share of Preferred Stock issuable upon the
exercise of the Rights, the Rights Certificates theretofore and thereafter
issued may continue to express the Purchase Price per one one-thousandth of a
share and the number of one one-thousandth of a share which were expressed in
the initial Rights Certificates issued hereunder.

     (k) Before taking any action that would cause an adjustment reducing the
Purchase Price below the then stated value, if any, of the number of one one-
thousandths of a share of Preferred Stock issuable upon exercise of the Rights,
the Company shall take any corporate action which may, in the opinion of its
counsel, be necessary in order that the Company may validly and legally issue
fully paid and nonassessable such number of one one-thousandths of a share of
Preferred Stock at such adjusted Purchase Price.

     (l) In any case in which this Section 11 shall require that an adjustment
in the Purchase Price be made effective as of a record date for a specified
event, the Company may elect to defer until the occurrence of such event the
issuance to the holder of any Right exercised after such record date the number
of one one-thousandths of a share of Preferred Stock and other capital stock or
securities of the Company, if any, issuable upon such exercise over and above
the number of one one-thousandths of a share of Preferred Stock and other
capital stock or securities of the Company, if any, issuable upon such exercise
on the basis of the Purchase Price in effect prior to such adjustment; provided,
                                                                       --------
however, that the Company shall deliver to such holder a due bill or other
appropriate instrument evidencing such holder's right to receive such additional
shares (fractional or otherwise) or securities upon the occurrence of the event
requiring such adjustment.

     (m) Anything in this Section 11 to the contrary notwithstanding, the
Company shall be entitled to make such reductions in the Purchase Price, in
addition to those adjustments expressly required by this Section 11, as and to
the extent that in their good faith judgment the Board of Directors of the
Company shall determine to be advisable in order that any (i) consolidation or
subdivision of the Preferred Stock, (ii) issuance wholly for cash of any shares
of Preferred Stock at less than the current market price, (iii) issuance wholly
for cash of shares of Preferred Stock or securities which by their terms are
convertible into or exchangeable for shares of Preferred Stock, (iv) stock
dividends or (v) issuance of rights, options or warrants referred to in this
Section 11, hereafter made by the Company to holders of its Preferred Stock
shall not be taxable to such stockholders.

                                      -22-
<PAGE>

     (n) The Company covenants and agrees that it shall not, at any time after
the Distribution Date, (i) consolidate with any other Person (other than a
Subsidiary of the Company in a transaction that complies with Section 11(o)
hereof), (ii) merge with or into any other Person (other than a Subsidiary of
the Company in a transaction which complies with Section 11(o) hereof), or (iii)
sell or transfer (or permit any Subsidiary to sell or transfer), in one
transaction, or a series of related transactions, assets or earning power
aggregating more than 50% of the assets or earning power of the Company and its
Subsidiaries (taken as a whole) to any other Person or Persons (other than the
Company and/or any of its Subsidiaries in one or more transactions each of which
complies with Section 11(o) hereof), if (x) at the time of or immediately after
such consolidation, merger or sale there are any rights, warrants or other
instruments or securities outstanding or agreements in effect that would
substantially diminish or otherwise eliminate the benefits intended to be
afforded by the Rights or (y) prior to, simultaneously with or immediately after
such consolidation, merger or sale, the shareholders of the Person who
constitutes, or would constitute, the "Principal Party" for purposes of Section
13(a) hereof shall have received a distribution of Rights previously owned by
such Person or any of its Affiliates and Associates.  The Company shall not
consummate any such consolidation, merger, sale or transfer unless prior thereto
the Company and such other Person shall have executed and delivered to the
Rights Agent a supplemental agreement evidencing compliance with this Section
11(n).

     (o) The Company covenants and agrees that, after the Distribution Date, it
will not, except as permitted by Section 23, Section 24 or Section 27 hereof,
take (or permit any Subsidiary to take) any action if at the time such action is
taken it is reasonably foreseeable that such action will diminish substantially
or otherwise eliminate the benefits intended to be afforded by the Rights.

     (p) Anything in this Agreement to the contrary notwithstanding, in the
event that the Company shall at any time after the Record Date and prior to the
Distribution Date (i) declare or pay any dividend on the outstanding shares of
Common Stock payable in shares of Common Stock, (ii) subdivide the outstanding
shares of Common Stock, or (iii) combine the outstanding shares of Common Stock
into a smaller number of shares, the number of Rights associated with each share
of Common Stock then outstanding, or issued or delivered thereafter but prior to
the Distribution Date, shall be proportionately adjusted so that the number of
Rights thereafter associated with each share of Common Stock following any such
event shall equal the result obtained by multiplying the number of Rights
associated with each share of Common Stock immediately prior to such event by a
fraction, the numerator of which shall be the number of shares of Common Stock
outstanding immediately prior to the occurrence of such event and the
denominator of which shall be the number of shares of Common Stock outstanding
immediately following the occurrence of such event.

                                      -23-
<PAGE>

     (q) The exercise of Rights under Section 11(a)(ii) shall only result in the
loss of rights under Section 11(a)(ii) to the extent so exercised and shall not
otherwise affect the rights represented by the Rights under this Rights
Agreement, including the rights represented by Section 13.

     Section 12.  Certificate of Adjusted Purchase Price or Number of Shares.
                  ---------------------------------------------------------- 
Whenever an adjustment is made as provided in Section 11 or Section 13 hereof,
the Company shall (a) promptly prepare a certificate setting forth such
adjustment and a brief statement of the facts accounting for such adjustment,
(b) promptly file with the Rights Agent, and with each transfer agent for the
Preferred Stock and the Common Stock, a copy of such certificate, and (c) mail a
brief summary thereof to each holder of a Rights Certificate (or, if prior to
the Distribution Date, to each holder of a certificate representing shares of
Common Stock) in accordance with Section 26 hereof.  The Rights Agent shall be
fully protected in relying on any such certificate and on any adjustment therein
contained and shall not be deemed to have knowledge of any adjustment unless and
until it shall have received such certificate.

     Section 13.  Consolidation, Merger or Sale or Transfer of Assets or Earning
                  --------------------------------------------------------------
Power.
- -----

     (a) In the event that, at any time after a Person has become an Acquiring
Person, directly or indirectly, (x) the Company shall consolidate with, or merge
with and into, any other Person (other than a Subsidiary of the Company in a
transaction that complies with Section 11(o) hereof), and the Company shall not
be the continuing or surviving corporation of such consolidation or merger, (y)
any Person (other than a Subsidiary of the Company in a transaction that
complies with Section 11(o) hereof) shall consolidate with, or merge with or
into, the Company, and the Company shall be the continuing or surviving
corporation of such consolidation or merger and, in connection with such
consolidation or merger, all or part of the outstanding shares of Common Stock
shall be changed into or exchanged for stock or other securities of any other
Person or cash or any other property, or (z) the Company shall sell or otherwise
transfer (or one or more of its Subsidiaries shall sell or otherwise transfer),
in one transaction or a series of related transactions, assets or earning power
aggregating more than 50% of the assets or earning power of the Company and its
Subsidiaries (taken as a whole) to any Person or Persons (other than the Company
or any Subsidiary of the Company in one or more transactions each of which
complies with Section 11(o) hereof), then, and in each such case and except as
contemplated by Section 13(d) hereof, proper provision shall be made so that:
(i) each holder of a Right, except as provided in Section 7(e) hereof, shall
thereafter have the right to receive, upon the exercise thereof at the then
current Purchase Price in accordance with the terms of this Agreement, such
number of validly authorized and issued, fully paid, non-assessable and freely
tradeable shares of Common Stock of the Principal Party (as such term is
hereinafter defined), not subject to any liens, encumbrances, rights of first
refusal or other adverse claims, as

                                      -24-
<PAGE>

shall be equal to the result obtained by (l) multiplying the then current
Purchase Price by the number of one one-thousandth of a share of Preferred Stock
for which a Right is exercisable immediately prior to the occurrence of a
Section 13 Event (or, if a Section 11(a)(ii) Event has occurred prior to the
first occurrence of a Section 13 Event, multiplying the number of such one one-
thousandth of a share for which a Right was exercisable immediately prior to the
occurrence of a Section 11(a)(ii) Event by the Purchase Price in effect
immediately prior to such occurrence), and dividing that product (which,
following the occurrence of a Section 13 Event, shall be referred to as the
"Purchase Price" for each Right and for all purposes of this Agreement) by (2)
50% of the current market price (determined pursuant to Section 11(d)(i) hereof)
per share of the Common Stock of such Principal Party on the date of
consummation of such Section 13 Event; (ii) such Principal Party shall
thereafter be liable for, and shall assume, by virtue of such Section 13 Event,
all the obligations and duties of the Company pursuant to this Agreement; (iii)
the term "Company" shall thereafter be deemed to refer to such Principal Party,
it being specifically intended that the provisions of Section 11 hereof shall
apply only to such Principal Party following the first occurrence of a Section
13 Event; (iv) such Principal Party shall take such steps (including, but not
limited to, the reservation of a sufficient number of shares of its Common
Stock) in connection with the consummation of any such transaction as may be
necessary to assure that the provisions hereof shall thereafter be applicable,
as nearly as reasonably may be, in relation to its shares of Common Stock
thereafter deliverable upon the exercise of the Rights; and (v) the provisions
of Section 11(a)(ii) hereof shall be of no effect following the first occurrence
of any Section 13 Event.

     (b)  "Principal Party" shall mean

          (i) in the case of any transaction described in clause (x) or (y) of
     the first sentence of Section 13(a), the Person that is the issuer of any
     securities into which shares of Common Stock of the Company are converted
     in such merger or consolidation, and if no securities are so issued, the
     Person that is the other party to such merger or consolidation; and

          (ii) in the case of any transaction described in clause (z) of the
     first sentence of Section 13(a), the Person that is the party receiving the
     greatest portion of the assets or earning power transferred pursuant to
     such transaction or transactions;

provided, however, that in any such case, (1) if the Common Stock of such Person
- --------                                                                       
is not at such time and has not been continuously over the preceding twelve (12)
month period registered under Section 12 of the Exchange Act, and such Person is
a direct or indirect Subsidiary of another Person the Common Stock of which is
and has been so registered, "Principal Party"

                                      -25-
<PAGE>

shall refer to such other Person; (2) in case such Person is a Subsidiary,
directly or indirectly, of more than one Person, the Common Stocks of two or
more of which are and have been so registered, "Principal Party" shall refer to
whichever of such Persons is the issuer of the Common Stock having the greatest
aggregate market value; and (3) in case such Person is owned, directly or
indirectly, by a joint venture formed by two or more Persons that are not owned,
directly or indirectly, by the same Person, the rules set forth in (1) and (2)
above shall apply to each of the chains of ownership having an interest in such
joint venture as if such party were a "Subsidiary" of both or all of such joint
ventures and the Principal Parties in each such chain shall bear the obligations
set forth in this Section 13 in the same ratio as their direct or indirect
interests in such Person bear to the total of such interests.

     (c) The Company shall not consummate any such consolidation, merger, sale
or transfer unless the Principal Party shall have a sufficient number of
authorized shares of its Common Stock which have not been issued or reserved for
issuance to permit the exercise in full of the Rights in accordance with this
Section 13 and unless prior thereto the Company and such Principal Party shall
have executed and delivered to the Rights Agent a supplemental agreement
providing for the terms set forth in paragraphs (a) and (b) of this Section 13
and further providing that, as soon as practicable after the date of any
consolidation, merger or sale of assets mentioned in paragraph (a) of this
Section 13, the Principal Party will

          (i) prepare and file a registration statement under the Act, with
     respect to the Rights and the securities purchasable upon exercise of the
     Rights on an appropriate form, and will use its best efforts to cause such
     registration statement to (A) become effective as soon as practicable after
     such filing and (B) remain effective (with a prospectus at all times
     meeting the requirements of the Act) until the Expiration Date;

          (ii) use its best efforts to qualify or register the Rights and the
     securities purchasable upon exercise of the Rights under the blue sky laws
     of such jurisdictions as may be necessary or appropriate; and

          (iii)  deliver to holders of the Rights historical financial
     statements for the Principal Party and each of its Affiliates that comply
     in all respects with the requirements for registration on Form 10 under the
     Exchange Act.

The provisions of this Section 13 shall similarly apply to successive mergers or
consolidations or sales or other transfers.  In the event that a Section 13
Event shall occur at any time after the occurrence of a Section 11(a)(ii) Event,
the Rights which have not theretofore been exercised shall thereafter become
exercisable in the manner described in Section 13(a).

     (d) Notwithstanding anything in this Agreement to the contrary, Section 13
shall not be applicable to a transaction described in subparagraphs (x) and (y)
of Section 13(a) if (i) such transaction is consummated with a Person or Persons
(or a

                                      -26-
<PAGE>

wholly-owned subsidiary of any such Person or Persons) who acquired shares of
Common Stock pursuant to a Permitted Offer, (ii) the price per share of Common
Stock paid in such transaction is not less than the price per share of Common
Stock paid to all holders of shares of Common Stock whose shares were purchased
pursuant to such Permitted Offer, and (iii) the form of consideration paid in
such transaction is the same as the form of consideration paid pursuant to such
Permitted Offer. Upon consummation of any such transaction contemplated by this
Section 13(d), all Rights hereunder shall expire.

     Section 14.  Fractional Rights and Fractional Shares.
                  ---------------------------------------

     (a) The Company shall not be required to issue fractions of Rights, except
prior to the Distribution Date as provided in Section 11(i) or (p) hereof, or to
distribute Rights Certificates that evidence fractional Rights.  In lieu of such
fractional Rights, there shall be paid to the registered holders of the Rights
Certificates with regard to which such fractional Rights would otherwise be
issuable, an amount in cash equal to the same fraction of the current market
value of a whole Right.  For purposes of this Section 14(a), the current market
value of a whole Right shall be the closing price of the Rights for the Trading
Day immediately prior to the date on which such fractional Rights would have
been otherwise issuable.  The closing price of the Rights for any day shall be
the last such quoted price or, if not so quoted, the average of the high bid and
low asked prices in the over-the-counter market, as reported by Nasdaq or such
other system then in use or, if on any such date the Rights are not quoted by
any such organization, the average of the closing bid and asked prices as
furnished by a professional market maker making a market in the Rights selected
by the Board of Directors of the Company.  If on any such date no such market
maker is making a market in the Rights the fair value of the Rights on such date
as determined in good faith by the Board of Directors of the Company shall be
used.

     (b) The Company shall not be required to issue fractions of shares of
Preferred Stock (other than fractions which are integral multiples of one one-
thousandth of a share of Preferred Stock) upon exercise of the Rights or to
distribute certificates that evidence fractional shares of Preferred Stock
(other than fractions which are integral multiples of one one-thousandth of a
share of Preferred Stock).  In lieu of fractional shares of Preferred Stock
(other than fractions which are integral multiples of one one-thousandth of a
share of Preferred Stock), the Company shall pay to the registered holders of
Rights Certificates at the time such Rights are exercised as herein provided an
amount in cash equal to the same fraction of the current market value of one
one-thousandth of a share of Preferred Stock.  For purposes of this Section
14(b), the current market value of one one-thousandth of a share of Preferred
Stock shall be one one-thousandth of the closing price of a share of Preferred
Stock (as determined pursuant to Section 11(d)(ii) hereof) for the Trading Day
immediately prior to the date of such exercise.

                                      -27-
<PAGE>

     (c) Following the occurrence of a Triggering Event, the Company shall not
be required to issue fractions of shares of Common Stock upon exercise of the
Rights or to distribute certificates which evidence fractional shares of Common
Stock.  In lieu of fractional shares of Common Stock, the Company shall pay to
the registered holders of Rights Certificates at the time such Rights are
exercised as herein provided an amount in cash equal to the same fraction of the
current market price of one (1) share of Common Stock (as determined pursuant to
Section 11(d)(i) hereof) for the Trading Day immediately prior to the date of
such exercise.

     (d) The holder of a Right by the acceptance of the Rights expressly waives
his right to receive any fractional Rights or any fractional shares upon
exercise of a Right, except as permitted by this Section 14.

     Section 15.  Rights of Action.  All rights of action in respect of this
                  ----------------                                         
Agreement, except the rights of action expressly given to the Rights Agent in
Section 18 hereof, are vested in the respective registered holders of the Rights
Certificates (and, prior to the Distribution Date, the registered holders of the
Common Stock); and any registered holder of any Rights Certificate (or, prior to
the Distribution Date, of the Common Stock), without the consent of the Rights
Agent or of the holder of any other Rights Certificate (or, prior to the
Distribution Date, of the Common Stock), may, in his own behalf and for his own
benefit, enforce, and may institute and maintain any suit, action or proceeding
against the Company to enforce, or otherwise act in respect of, his right to
exercise the Rights evidenced by such Rights Certificate in the manner provided
in such Rights Certificate and in this Agreement.  Without limiting the
foregoing or any remedies available to the holders of Rights, it is specifically
acknowledged that the holders of Rights would not have an adequate remedy at law
for any breach of this Agreement and shall be entitled to specific performance
of the obligations hereunder and injunctive relief against actual or threatened
violations of the obligations hereunder of any Person subject to this Agreement.

     Section 16.  Agreement of Rights Holders.  Every holder of a Right by
                  ---------------------------                            
accepting the same consents and agrees with the Company and the Rights Agent and
with every other holder of a Right that:

     (a) prior to the Distribution Date, the Rights will be transferable only in
connection with the transfer of Common Stock;

     (b) after the Distribution Date, the Rights Certificates are transferable
only on the registry books of the Rights Agent if surrendered at the office of
the Rights Agent designated for such purposes, duly endorsed or accompanied by a
proper instrument of transfer and with the appropriate forms and certificates
duly completed and fully executed;

                                      -28-
<PAGE>

     (c) subject to Section 6(a) and Section 7(f) hereof, the Company and the
Rights Agent may deem and treat the person in whose name a Rights Certificate
(or, prior to the Distribution Date, the associated Common Stock certificate) is
registered as the absolute owner thereof and of the Rights evidenced thereby
(notwithstanding any notations of ownership or writing on the Rights
Certificates or the associated Common Stock certificate made by anyone other
than the Company or the Rights Agent) for all purposes whatsoever, and neither
the Company nor the Rights Agent, subject to the last sentence of Section 7(e)
hereof, shall be required to be affected by any notice to the contrary; and

     (d) notwithstanding anything in this Agreement to the contrary, neither the
Company nor the Rights Agent shall have any liability to any holder of a Right
or other Person as a result of its inability to perform any of its obligations
under this Agreement by reason of any preliminary or permanent injunction or
other order, decree or ruling issued by a court of competent jurisdiction or by
a governmental, regulatory or administrative agency or commission, or any
statute, rule, regulation or executive order promulgated or enacted by any
governmental authority, prohibiting or otherwise restraining performance of such
obligation; provided, however, the Company must use its best efforts to have any
            --------                                                           
such order, decree or ruling lifted or otherwise overturned as soon as possible.

     Section 17.  Rights Certificate Holder Not Deemed a Stockholder.  No
                  --------------------------------------------------    
holder, as such, of any Rights Certificate shall be entitled to vote, receive
dividends or be deemed for any purpose the holder of the number of one one-
thousandth of a share of Preferred Stock or any other securities of the Company
which may at any time be issuable on the exercise of the Rights represented
thereby, nor shall anything contained herein or in any Rights Certificate be
construed to confer upon the holder of any Rights Certificate, as such, any of
the rights of a stockholder of the Company or any right to vote for the election
of directors or upon any matter submitted to stockholders at any meeting
thereof, or to give or withhold consent to any corporate action, or to receive
notice of meetings or other actions affecting stockholders (except as provided
in Section 25 hereof), or to receive dividends or subscription rights, or
otherwise, until the Right or Rights evidenced by such Rights Certificate shall
have been exercised in accordance with the provisions hereof.

     Section 18.  Concerning the Rights Agent.
                  ---------------------------

     (a) The Company agrees to pay to the Rights Agent reasonable compensation
for all services rendered by it hereunder and, from time to time, on demand of
the Rights Agent, its reasonable expenses and counsel fees and disbursements and
other disbursements incurred in the administration and execution of this
Agreement and the exercise and performance of its duties hereunder.  The Company
also agrees to indemnify the Rights Agent for, and to hold it harmless against,
any loss, liability or expense, incurred without gross negligence, bad faith or

                                      -29-
<PAGE>

willful misconduct on the part of the Rights Agent, for anything done or omitted
by the Rights Agent in connection with the acceptance and administration of this
Agreement, including the costs and expenses of defending against any claim of
liability in the premises.

     (b) The Rights Agent shall be protected and shall incur no liability for or
in respect of any action taken, suffered or omitted by it in connection with its
administration of this Agreement in reliance upon any Rights Certificate or
certificate for Common Stock or for other securities of the Company, instrument
of assignment or transfer, power of attorney, endorsement, affidavit, letter,
notice, direction, consent, certificate, statement, or other paper or document
believed by it to be genuine and to be signed, executed and, where necessary,
verified or acknowledged, by the proper Person or Persons, or otherwise upon the
advice of counsel as set forth in Section 20 hereof.

     Section 19.  Merger or Consolidation or Change of Name of Rights Agent.
                  ---------------------------------------------------------

     (a) Any corporation into which the Rights Agent or any successor Rights
Agent may be merged or with which it may be consolidated, or any corporation
resulting from any merger or consolidation to which the Rights Agent or any
successor Rights Agent shall be a party, or any corporation succeeding to the
corporate trust or stock transfer business of the Rights Agent or any successor
Rights Agent, shall be the successor to the Rights Agent under this Agreement
without the execution or filing of any paper or any further act on the part of
any of the parties hereto; provided, however, that such corporation would be
                           --------                                        
eligible for appointment as a successor Rights Agent under the provisions of
Section 21 hereof.  In case at the time such successor Rights Agent shall
succeed to the agency created by this Agreement, any of the Rights Certificates
shall have been countersigned but not delivered, any such successor Rights Agent
may adopt the counter- signature of a predecessor Rights Agent and deliver such
Rights Certificates so countersigned; and in case at that time any of the Rights
Certificates shall not have been countersigned, any successor Rights Agent may
countersign such Rights Certificates either in the name of the predecessor or in
the name of the successor Rights Agent; and in all such cases such Rights
Certificates shall have the full force provided in the Rights Certificates and
in this Agreement.

     (b) In case at any time the name of the Rights Agent shall be changed and
at such time any of the Rights Certificates shall have been countersigned but
not delivered, the Rights Agent may adopt the countersignature under its prior
name and deliver Rights Certificates so countersigned; and in case at that time
any of the Rights Certificates shall not have been countersigned, the Rights
Agent may countersign such Rights Certificates either in its prior name or in
its changed name; and in all such cases such Rights Certificates shall have the
full force provided in the Rights Certificates and in this Agreement.

                                      -30-
<PAGE>

     Section 20.  Duties of Rights Agent.  The Rights Agent undertakes the
                  ----------------------                                 
duties and obligations imposed by this Agreement upon the following terms and
conditions, by all of which the Company and the holders of Rights Certificates,
by their acceptance thereof, shall be bound:

     (a) The Rights Agent may consult with legal counsel (who may be legal
counsel for the Company), and the opinion of such counsel shall be full and
complete authorization and protection to the Rights Agent as to any action taken
or omitted by it in good faith and in accordance with such opinion.

     (b) Whenever in the performance of its duties under this Agreement the
Rights Agent shall deem it necessary or desirable that any fact or matter
(including, without limitation, the identity of any Acquiring Person and the
determination of "current market price") be proved or established by the Company
prior to taking or suffering any action hereunder, such fact or matter (unless
other evidence in respect thereof be herein specifically prescribed) may be
deemed to be conclusively proved and established by a certificate signed by the
Chairman of the Board, the President, any Vice President, the Treasurer, any
Assistant Treasurer, the Secretary or any Assistant Secretary of the Company and
delivered to the Rights Agent; and such certificate shall be full authorization
to the Rights Agent for any action taken or suffered in good faith by it under
the provisions of this Agreement in reliance upon such certificate.

     (c) The Rights Agent shall be liable hereunder only for its own gross
negligence, bad faith or willful misconduct.

     (d) The Rights Agent shall not be liable for or by reason of any of the
statements of fact or recitals contained in this Agreement or in the Rights
Certificates or be required to verify the same (except as to its
countersignature on such Rights Certificates), but all such statements and
recitals are and shall be deemed to have been made by the Company only.

     (e) The Rights Agent shall not be under any responsibility in respect of
the validity of this Agreement or the execution and delivery hereof (except the
due execution hereof by the Rights Agent) or in respect of the validity or
execution of any Rights Certificate (except its countersignature thereof); nor
shall it be responsible for any breach by the Company of any covenant or
condition contained in this Agreement or in any Rights Certificate; nor shall it
be responsible for any adjustment required under the provisions of Section 11,
Section 13 or Section 24 hereof or responsible for the manner, method or amount
of any such adjustment or the ascertaining of the existence of facts that would
require any such adjustment (except with respect to the exercise of Rights
evidenced by Rights Certificates after receipt of a certificate describing any
such adjustment, delivered pursuant to Section 12); nor shall it by any act
hereunder be deemed to make any representation or warranty as

                                      -31-
<PAGE>

to the authorization or reservation of any shares of Common Stock or Preferred
Stock to be issued pursuant to this Agreement or any Rights Certificate or as to
whether any shares of Common Stock or Preferred Stock will, when so issued, be
validly authorized and issued, fully paid and nonassessable.

     (f) The Company agrees that it will perform, execute, acknowledge and
deliver or cause to be performed, executed, acknowledged and delivered all such
further and other acts, instruments and assurances as may reasonably be required
by the Rights Agent for the carrying out or performing by the Rights Agent of
the provisions of this Agreement.

     (g) The Rights Agent is hereby authorized and directed to accept
instructions with respect to the performance of its duties hereunder from the
Chairman of the Board, the President, any Vice President, the Secretary, any
Assistant Secretary, the Treasurer or any Assistant Treasurer of the Company,
and to apply to such officers for advice or instructions in connection with its
duties, and it shall not be liable for any action taken or suffered to be taken
by it in good faith in accordance with instructions of any such officer.  Any
application by the Rights Agent for written instructions from the Company may,
at the option of the Rights Agent, set forth in writing any action proposed to
be taken or omitted by the Rights Agent with respect to its duties or
obligations under this Rights Agreement and the date on and/or after which such
action shall be taken or omitted and the Rights Agent shall not be liable for
any action taken or omitted in accordance with a proposal included in any such
application on or after the date specified therein (which date shall not be less
than five Business Days after the date any such officer actually receives such
application, unless any such officer shall have consented in writing to an
earlier date) unless, prior to taking or omitting any such action, the Rights
Agent has received written instructions in response to such application
specifying the action to be taken or omitted.

     (h) The Rights Agent and any stockholder, director, officer or employee of
the Rights Agent may buy, sell or deal in any of the Rights or other securities
of the Company or become pecuniarily interested in any transaction in which the
Company may be interested, or contract with or lend money to the Company or
otherwise act as fully and freely as though it were not Rights Agent under this
Agreement. Nothing herein shall preclude the Rights Agent from acting in any
other capacity for the Company or for any other legal entity.

     (i) The Rights Agent may execute and exercise any of the rights or powers
hereby vested in it or perform any duty hereunder either itself or by or through
its attorneys or agents, and the Rights Agent shall not be answerable or
accountable for any act, default, neglect or misconduct of any such attorneys or
agents or for any loss to the Company resulting from any such act, default,
neglect or misconduct;

                                      -32-
<PAGE>

provided, however, reasonable care was exercised in the selection and continued
- --------
employment thereof.

     (j) No provision of this Agreement shall require the Rights Agent to expend
or risk its own funds or otherwise incur any financial liability in the
performance of any of its duties hereunder or in the exercise of its rights if
there shall be reasonable grounds for believing that repayment of such funds or
adequate indemnification against such risk or liability is not reasonably
assured to it.

     (k) If, with respect to any Rights Certificate surrendered to the Rights
Agent for exercise or transfer, the certificate attached to the form of
assignment or form of election to purchase, as the case may be, has not been
completed, the Company and the Rights Agent will deem the beneficial owner of
the rights evidenced by such Rights Certificate to be an Acquiring Person or an
Affiliate or Associate thereof and such assignment or election to purchase will
not be honored.

     Section 21.  Change of Rights Agent.  The Rights Agent or any successor
                  ----------------------                                   
Rights Agent may resign and be discharged from its duties under this Agreement
upon thirty (30) days' notice in writing mailed to the Company, and to each
transfer agent of the Common Stock and Preferred Stock, by registered or
certified mail, and to the holders of the Rights Certificates by first-class
mail.  The Company may remove the Rights Agent or any successor Rights Agent
upon thirty (30) days' notice in writing, mailed to the Rights Agent or
successor Rights Agent, as the case may be, and to each transfer agent of the
Common Stock and Preferred Stock, by registered or certified mail, and to the
holders of the Rights Certificates by first-class mail.  If the Rights Agent
shall resign or be removed or shall otherwise become incapable of acting, the
Company shall appoint a successor to the Rights Agent.  If the Company shall
fail to make such appointment within a period of thirty (30) days after giving
notice of such removal or after it has been notified in writing of such
resignation or incapacity by the resigning or incapacitated Rights Agent or by
the holder of a Rights Certificate (who shall, with such notice, submit his
Rights Certificate for inspection by the Company), then any registered holder of
any Rights Certificate may apply to any court of competent jurisdiction for the
appointment of a new Rights Agent.  Any successor Rights Agent, whether
appointed by the Company or by such a court, shall be (a) a corporation
organized and doing business under the laws of the United States (or of any
state of the United States) in good standing, which is authorized under such
laws to exercise corporate trust or stock transfer powers and is subject to
supervision or examination by federal or state authority and which has at the
time of its appointment as Rights Agent a combined capital and surplus of at
least $50,000,000 or (b) an affiliate of a corporation described in clause (a)
of this sentence. After appointment, the successor Rights Agent shall be vested
with the same powers, rights, duties and responsibilities as if it had been
originally named as Rights Agent without further act or deed; but the
predecessor Rights Agent shall deliver and transfer to the successor Rights
Agent any property at the time held by it hereunder,

                                      -33-
<PAGE>

and execute and deliver any further assurance, conveyance, act or deed necessary
for the purpose. Not later than the effective date of any such appointment, the
Company shall file notice thereof in writing with the predecessor Rights Agent
and each transfer agent of the Common Stock and the Preferred Stock, and mail a
notice thereof in writing to the registered holders of the Rights Certificates.
Failure to give any notice provided for in this Section 21, however, or any
defect therein, shall not affect the legality or validity of the resignation or
removal of the Rights Agent or the appointment of the successor Rights Agent, as
the case may be.

     Section 22.  Issuance of New Rights Certificates.
                  -----------------------------------

Notwithstanding any of the provisions of this Agreement or of the Rights to the
contrary, the Company may, at its option, issue new Rights Certificates
evidencing Rights in such form as may be approved by its Board of Directors to
reflect any adjustment or change in the Purchase Price and the number or kind or
class of shares or other securities or property purchasable under the Rights
Certificates made in accordance with the provisions of this Agreement.  In
addition, in connection with the issuance or sale of shares of Common Stock
following the Distribution Date and prior to the redemption or expiration of the
Rights, the Company (a) shall, with respect to shares of Common Stock so issued
or sold pursuant to the exercise of stock options or under any employee plan or
arrangement, or upon the exercise, conversion or exchange of securities issued
by the Company prior to the Distribution Date, and (b) may, in any other case,
if deemed necessary or appropriate by the Board of Directors of the Company,
issue Rights Certificates representing the appropriate number of Rights in
connection with such issuance or sale; provided, however, that (i) no such
                                       --------                          
Rights Certificate shall be issued if, and to the extent that, the Company shall
be advised by counsel that such issuance would create a significant risk of
material adverse tax consequences to the Company or the Person to whom such
Rights Certificate would be issued, and (ii) no such Rights Certificate shall be
issued if, and to the extent that, appropriate adjustment shall otherwise have
been made in lieu of the issuance thereof.

     Section 23.  Redemption and Termination.
                  --------------------------

     (a) The Board of Directors of the Company may, at its option, at any time
prior to the earlier of (i) the close of business on the tenth day following the
Stock Acquisition Date (or, if the Stock Acquisition Date shall have occurred
prior to the Record Date, the close of business on the tenth day following the
Record Date), or (ii) the Final Expiration Date, redeem all but not less than
all the then outstanding Rights at a redemption price of $.001 per Right, as
such amount may be appropriately adjusted to reflect any stock split, stock
dividend or similar transaction occurring after the date hereof (such redemption
price being hereinafter referred to as the "Redemption Price") and the Company
may, at its option, pay the Redemption Price either in shares of Common Stock
(based on the "current market price," as defined in

                                      -34-
<PAGE>

Section 11(d)(i) hereof, of the shares of Common Stock at the time of
redemption) or cash; provided, however, that notwithstanding the foregoing if,
                     --------
following the occurrence of a Stock Acquisition Date and following the
expiration of the right of redemption set forth above in this Section 23(a),
either (i)(A) a Person who is an Acquiring Person shall have transferred or
otherwise disposed of a number of shares of Common Stock in one transaction or
series of transactions, not directly or indirectly involving the Company or any
of its Subsidiaries, such that such Person is thereafter a Beneficial Owner of
10% or less of the outstanding shares of Common Stock, and (B) there are no
other Persons, immediately following the occurrence of the event described in
clause (A), who are Acquiring Persons, and (C) there are at least two Continuing
Directors then in office and a majority of the Continuing Directors approve the
reinstatement of the right of redemption pursuant to this Section 23, or (ii)(A)
the Board approves the consolidation, merger or other combination of the Company
with or into, or the sale or other transfer (either by the Company or one or
more of its Subsidiaries), in one transaction or a series of related
transactions, of more than 50% of the assets or earning power of the Company and
its Subsidiaries (taken as a whole), to a Person other than the Acquiring Person
(or any Associate or Affiliate of such Acquiring Person) who caused the
occurrence of such Stock Acquisition Date, and (B) the Board of Directors of the
Company, as part of the approval of such an event described in the preceding
clause (ii)(A), approves the reinstatement of the right of redemption pursuant
to this Section 23, and (C) there are at least two Continuing Directors then in
office and a majority of the Continuing Directors so approve such reinstatement,
then, in either such case, the right of redemption shall be reinstated and
thereafter be subject to the provisions of this Section 23. Notwithstanding
anything contained in this Agreement to the contrary, the Rights shall not be
exercisable after the first occurrence of a Section 11(a)(ii) Event until such
time as the Company's right of redemption hereunder has expired (such right of
redemption hereunder being deemed to have expired notwithstanding the existence
of the possibility of the reinstatement thereof as provided above in this
Section 23(a)). Subject to the foregoing, the redemption of the Rights by the
Board may be made effective at such time, on such basis and with such conditions
as the Board of Directors in its sole discretion may establish.

     (b) Immediately upon the action of the Board of Directors of the Company
ordering the redemption of the Rights, evidence of which shall have been filed
with the Rights Agent and without any further action and without any notice, the
right to exercise the Rights will terminate and the only right thereafter of the
holders of Rights shall be to receive the Redemption Price for each Right so
held.  Promptly after the action of the Board of Directors ordering the
redemption of the Rights, the Company shall give notice of such redemption to
the Rights Agent and the holders of the then outstanding Rights by mailing such
notice to all such holders at each holder's last address as it appears upon the
registry books of the Rights Agent or, prior to the Distribution Date, on the
registry books of the Transfer Agent for the Common Stock.  Any notice which is
mailed in the manner herein provided shall be

                                      -35-
<PAGE>

deemed given, whether or not the holder receives the notice. Each such notice of
redemption will state the method by which the payment of the Redemption Price
will be made.

     (c) The Company may, at its option, discharge all of its obligations with
respect to the Rights by (i) issuing a press release announcing the manner of
redemption of the Rights in accordance with this Agreement and (ii) mailing
payment of the Redemption Price to the registered holders of the Rights at their
last addresses as they appear on the registry books of the Rights Agent or,
prior to the Distribution Date, on the registry books of the Transfer Agent of
the Common Shares, and upon such action, all outstanding Rights and Right
Certificates shall be null and void without any further action by the Company.

     Section 24.  Exchange.
                  --------

     (a) The Board of Directors of the Company may, at its option, at any time
after a Section 11(a)(ii) Event, exchange all or part of the then outstanding
and exercisable Rights (which (i) shall not include Rights that have become void
pursuant to the provisions of Section 7(e) hereof, and (ii) shall include,
without limitation, any Rights issued after the Distribution Date in connection
with the exercise of options pursuant to the Company's employee benefit plans,
where such option is exercised for securities of the Company or surrendered for
cash) for shares of Common Stock at an exchange ratio of one share of Common
Stock per Right, appropriately adjusted to reflect any stock split, stock
dividend or similar transaction occurring after the date hereof (such exchange
ratio being hereinafter referred to as the "Exchange Ratio"). Notwithstanding
the foregoing, the Board of Directors may effect such an exchange only if there
are at least two Continuing Directors then in office and a majority of such
Continuing Directors concur with such exchange.

     (b) Immediately upon the action of the Board of Directors of the Company
ordering the exchange of any Rights pursuant to subsection (a) of this Section
24, evidence of which shall have been filed with the Rights Agent, and without
any further action and without any notice, the right to exercise such Rights
shall terminate and the only right thereafter of a holder of such Rights shall
be to receive that number of shares of Common Stock equal to the number of such
Rights held by such holder multiplied by the Exchange Ratio.  The Company shall
promptly give public notice of any such exchange; provided, however, that the
                                                  --------                  
failure to give, or any defect in, such notice shall not affect the validity of
such exchange.  The Company promptly shall mail a notice of any such exchange to
all of the holders of such Rights at their last addresses as they appear upon
the registry books of the Rights Agent.  Any notice which is mailed in the
manner herein provided shall be deemed given, whether or not the holder receives
the notice.  Each such notice of exchange shall state the method by which the
exchange of shares of Common Stock for Rights will be effected and, in the event
of any partial exchange, the number of

                                      -36-
<PAGE>

Rights which will be exchanged. Any partial exchange shall be effected pro rata
based on the number of Rights (other than Rights which have become void pursuant
to the provisions of Section 7(e) hereof) held by each holder of Rights.

     (c) In any exchange pursuant to this Section 24, the Company, at its
option, may substitute Preferred Stock (or equivalent preferred stock, as such
term is defined in Section 11(b) hereof) for shares of Common Stock exchangeable
for Rights, at the initial rate of one one-thousandth of a share of Preferred
Stock (or equivalent preferred stock) for each share of Common Stock, as
appropriately adjusted to reflect adjustments in the voting rights of the
Preferred Stock pursuant to Section 3(A) of the Certificate of Designations
attached hereto as Exhibit A, so that the fraction of a share of Preferred Stock
(or equivalent preferred stock) delivered in lieu of each share of Common Stock
shall have the same voting rights as one share of Common Stock.

     (d) In the event that there shall not be sufficient shares of Common Stock
or Preferred Stock issued but not outstanding or authorized but unissued to
permit any exchange of Rights as contemplated in accordance with this Section
24, the Company shall take all such action as may be necessary to authorize
additional shares of Common Stock or Preferred Stock for issuance upon exchange
of the Rights.

     (e) The Company shall not be required to issue fractions of shares of
Common Stock or to distribute certificates which evidence fractional shares of
Common Stock.  In lieu of such fractional shares of Common Stock, there shall be
paid to the registered holders of the Right Certificates with regard to which
such fractional shares of Common Stock would otherwise be issuable, an amount in
cash equal to the same fraction of the current market value of a whole share of
Common Stock.  For the purposes of this subsection (e), the current market value
of a whole share of Common Stock shall be the closing price per share of Common
Stock (as determined pursuant to the second sentence of Section 11(d)(i) hereof)
for the Trading Day immediately prior to the date of exchange pursuant to this
Section 24.

     Section 25.  Notice of Certain Events.
                  ------------------------

     (a) In case the Company shall propose, at any time after the Distribution
Date, (i) to pay any dividend payable in stock of any class to the holders of
Preferred Stock or to make any other distribution to the holders of Preferred
Stock (other than a regular quarterly cash dividend out of earnings or retained
earnings of the Company), or (ii) to offer to the holders of Preferred Stock
rights or warrants to subscribe for or to purchase any additional shares of
Preferred Stock or shares of stock of any class or any other securities, rights
or options, or (iii) to effect any reclassification of its Preferred Stock
(other than a reclassification involving only the subdivision of outstanding
shares of Preferred Stock), or (iv) to effect any consolidation or merger into
or with any other Person (other than a Subsidiary of the Company in a
transaction which complies with Section 11(o) hereof), or to effect any

                                      -37-
<PAGE>

sale or other transfer (or to permit one or more of its Subsidiaries to effect
any sale or other transfer), in one transaction or a series of related
transactions, of more than 50% of the assets or earning power of the Company and
its Subsidiaries (taken as a whole) to any other Person or Persons (other than
the Company and/or any of its Subsidiaries in one or more transactions each of
which complies with Section 11(o) hereof), or (v) to effect the liquidation,
dissolution or winding up of the Company, then, in each such case, the Company
shall give to each holder of a Rights Certificate, to the extent feasible and in
accordance with Section 26 hereof, a notice of such proposed action, which shall
specify the record date for the purposes of such stock dividend, distribution of
rights or warrants, or the date on which such reclassification, consolidation,
merger, sale, transfer, liquidation, dissolution, or winding up is to take place
and the date of participation therein by the holders of the shares of Preferred
Stock, if any such date is to be fixed, and such notice shall be so given in the
case of any action covered by clause (i) or (ii) above at least twenty (20) days
prior to the record date for determining holders of the shares of Preferred
Stock for purposes of such action, and in the case of any such other action, at
least twenty (20) days prior to the date of the taking of such proposed action
or the date of participation therein by the holders of the shares of Preferred
Stock whichever shall be the earlier.

     (b) In case a Section 11(a) (ii) Event shall occur, then, in any such case,
(i) the Company shall as soon as practicable thereafter give to each holder of a
Rights Certificate, to the extent feasible and in accordance with Section 26
hereof, a notice of the occurrence of such event, which shall specify the event
and the consequences of the event to holders of Rights under Section 11(a)(ii)
hereof, and (ii) all references in the preceding paragraph to Preferred Stock
shall be deemed thereafter to refer also to Common Stock and/or, if appropriate,
other securities.

     Section 26.  Notices.  Notices or demands authorized by this Agreement to
                  -------                                                    
be given or made by the Rights Agent or by the holder of any Rights Certificate
to or on the Company shall be sufficiently given or made if sent by first-class
mail, postage prepaid, addressed (until another address is filed in writing with
the Rights Agent) as follows:

          Open Market, Inc.
          245 First Street
          Cambridge, MA  02142
          Attention:  Corporate Secretary

Subject to the provisions of Section 21, any notice or demand authorized by this
Agreement to be given or made by the Company or by the holder of any Rights
Certificate to or on the Rights Agent shall be sufficiently given or made if
sent by first-class mail, postage prepaid, addressed (until another address is
filed in writing with the Company) as follows:

                                      -38-
<PAGE>

          BankBoston N.A.
          c/o Boston EquiServe Limited Partnership
          150 Royall Street,  Mail Stop 450262
          Canton, MA  02021


Notices or demands authorized by this Agreement to be given or made by the
Company or the Rights Agent to the holder of any Rights Certificate (or, if
prior to the Distribution Date, to the holder of certificates representing
shares of Common Stock) shall be sufficiently given or made if sent by first-
class mail, postage prepaid, addressed to such holder at the address of such
holder as shown on the registry books of the Company.

     Section 27.  Supplements and Amendments.  Prior to the Stock Acquisition
                  --------------------------                                
Date and subject to the penultimate sentence of this Section 27, the Company and
the Rights Agent shall, if the Company so directs, supplement or amend any
provision of this Agreement without the approval of any holders of certificates
representing shares of Common Stock.  From and after the Stock Acquisition Date
and subject to the penultimate sentence of this Section 27, the Company and the
Rights Agent shall, if the Company so directs, supplement or amend this
Agreement without the approval of any holders of Rights Certificates in order
(i) to cure any ambiguity, (ii) to correct or supplement any provision contained
herein which may be defective or inconsistent with any other provisions herein,
or (iii) to change or supplement the provisions hereunder in any manner which
the Company may deem necessary or desirable and which shall not adversely affect
the interests of the holders of Rights Certificates (other than an Acquiring
Person or an Affiliate or Associate of an Acquiring Person). Upon the delivery
of a certificate from an appropriate officer of the Company which states that
the proposed supplement or amendment is in compliance with the terms of this
Section 27, the Rights Agent shall execute such supplement or amendment.
Notwithstanding anything contained in this Agreement to the contrary, no
supplement or amendment shall be made (i) which changes the Redemption Price or
(ii) at any time prior to such time as any Person first becomes an Acquiring
Person lowers the thresholds set forth in Sections 1(a) and/or 3(a) hereof from
18% to less than, in either case, the greater of (x) the sum of .001% and the
largest percentage of the outstanding shares of Common Stock then known by the
Company to be beneficially owned by any Person or (y) 10%.   Prior to the
Distribution Date, the interests of the holders of Rights shall be deemed
coincident with the interests of the holders of Common Stock.

     Section 28.  Successors.  All the covenants and provisions of this
                  ----------                                          
Agreement by or for the benefit of the Company or the Rights Agent shall bind
and inure to the benefit of their respective successors and assigns hereunder.

                                      -39-
<PAGE>

     Section 29.  Determinations and Actions by the Board of Directors, etc.
                  --------------------------------------------------------- 
For all purposes of this Agreement, any calculation of the number of shares of
Common Stock outstanding at any particular time, including for purposes of
determining the particular percentage of such outstanding shares of Common Stock
of which any Person is the Beneficial Owner, shall be made in accordance with
the last sentence of Rule 13d-3(d)(1)(i) of the General Rules and Regulations
under the Exchange Act. The Board of Directors of the Company shall have the
exclusive power and authority to administer this Agreement and to exercise all
rights and powers specifically granted to the Board or to the Company, or as may
be necessary or advisable in the administration of this Agreement, including,
without limitation, the right and power to (i) interpret the provisions of this
Agreement, and (ii) make all determinations deemed necessary or advisable for
the administration of this Agreement (including a determination to redeem or not
redeem the Rights or to amend this Agreement).  All such actions, calculations,
interpretations and determinations (including, for purposes of clause (y) below,
all omissions with respect to the foregoing) which are done or made by the Board
in good faith, shall (x) be final, conclusive and binding on the Company, the
Rights Agent, the holders of the Rights and all other parties, and (y) not
subject the Board to any liability to the holders of the Rights.

     Section 30.  Benefits of this Agreement.  Nothing in this Agreement shall
                  --------------------------                                 
be construed to give to any Person other than the Company, the Rights Agent and
the registered holders of the Rights Certificates (and, prior to the
Distribution Date, registered holders of the Common Stock) any legal or
equitable right, remedy or claim under this Agreement; but this Agreement shall
be for the sole and exclusive benefit of the Company, the Rights Agent and the
registered holders of the Rights Certificates (and, prior to the Distribution
Date, registered holders of the Common Stock).

     Section 31.  Severability.  If any term, provision, covenant or restriction
                  ------------                                                 
of this Agreement is held by a court of competent jurisdiction or other
authority to be invalid, void or unenforceable, the remainder of the terms,
provisions, covenants and restrictions of this Agreement shall remain in full
force and effect and shall in no way be affected, impaired or invalidated.

     Section 32.  Governing Law.  This Agreement, each Right and each Rights
                  -------------                                            
Certificate issued hereunder shall be deemed to be a contract made under the
laws of the State of Delaware and for all purposes shall be governed by and
construed in accordance with the laws of such State applicable to contracts made
and to be performed entirely within such State.

     Section 33.  Counterparts.  This Agreement may be executed in any number of
                  ------------                                                 
counterparts and each of such counterparts shall for all purposes be deemed to
be an original, and all such counterparts shall together constitute but one and
the same instrument.

                                      -40-
<PAGE>

     Section 34.  Descriptive Headings.  Descriptive headings of the several
                  --------------------                                     
Sections of this Agreement are inserted for convenience only and shall not
control or affect the meaning or construction of any of the provisions hereof.

     IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed and their respective corporate seals to be hereunto affixed and
attested, all as of the day and year first above written.

Attest:                             OPEN MARKET, INC.


By: /s/ Eric Pyenson                By: /s/ Regina O. Sommer
   -------------------------           ---------------------------
   Name:  Eric Pyenson                 Name:  Regina O. Sommer
   Title: Legal Counsel                Title: SVP & CFO


Attest:                             BankBoston N.A.


By: /s/ Norris L. Richardson        By: /s/ Carol Mulvey-Eori
   ---------------------------         ----------------------------
   Name:  Norris L. Richardson         Name:  Carol Mulvey-Eori
   Title: Account Manager              Title: Administration Manager

                                      -41-
<PAGE>

                                                                       Exhibit A

                          CERTIFICATE OF DESIGNATIONS

                                       of

                               OPEN MARKET, INC.

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


                         ______________________________



     Open Market, Inc., a corporation organized and existing under the General
Corporation Law of the State of Delaware (hereinafter called the "Corporation"),
hereby certifies that the following resolution was adopted by the Board of
Directors of the Corporation as required by Section 151 of the General
Corporation Law at a meeting duly called and held on January 23, 1998:

     RESOLVED, that pursuant to the authority granted to and vested in the Board
of Directors of this Corporation (hereinafter called the "Board of Directors" or
the "Board") in accordance with the provisions of the Certificate of
Incorporation, the Board of Directors hereby creates a series of Preferred
Stock, $.10 par value (the "Preferred Stock"), of the Corporation and hereby
states the designation and number of shares, and fixes the relative rights,
preferences and limitations thereof as follows:

     Series A Junior Participating Preferred Stock:

     Section 1.  Designation and Amount.  The shares of such series shall be
                 ----------------------                                    
designated as "Series A Junior Participating Preferred Stock" (the "Series A
Preferred Stock") and the number of shares constituting the Series A Preferred
Stock shall be 40,000.  Such number of shares may be increased or decreased by
resolution of the Board of Directors; provided, that no decrease shall reduce
                                      --------                              
the number of shares of Series A Preferred Stock to a number less than the
number of shares then outstanding plus the number of shares reserved for
issuance upon the exercise of outstanding options, rights or warrants or upon
the conversion of any outstanding securities issued by the Corporation
convertible into Series A Preferred Stock.

     Section 2.  Dividends and Distributions.
                 ---------------------------

          (A) Subject to the rights of the holders of any shares of any series
of Preferred Stock (or any similar stock) ranking prior and superior to the
Series A Preferred Stock with respect to dividends, the holders of shares of
Series A Preferred Stock, in preference to the holders of Common Stock, par
value $.01 per share (the "Common Stock"), of the Corporation, and of any other
junior stock, shall
<PAGE>

be entitled to receive, when, as and if declared by the Board of Directors out
of funds of the Corporation legally available for the payment of dividends,
quarterly dividends payable in cash on March 31, June 30, September 30 and
December 31 in each year (each such date being referred to herein as a
"Quarterly Dividend Payment Date"), commencing on the first Quarterly Dividend
Payment Date after the first issuance of a share or fraction of a share of
Series A Preferred Stock, in an amount per share (rounded to the nearest cent)
equal to the greater of (a) $100 or (b) subject to the provision for adjustment
hereinafter set forth, 1,000 times the aggregate per share amount of all cash
dividends, and 1,000 times the aggregate per share amount (payable in kind) of
all non-cash dividends or other distributions, other than a dividend payable in
shares of Common Stock or a subdivision of the outstanding shares of Common
Stock (by reclassification or otherwise), declared on the Common Stock since the
immediately preceding Quarterly Dividend Payment Date or, with respect to the
first Quarterly Dividend Payment Date, since the first issuance of any share or
fraction of a share of Series A Preferred Stock. In the event the Corporation
shall at any time declare or pay any dividend on the Common Stock payable in
shares of Common Stock, or effect a subdivision, combination or consolidation of
the outstanding shares of Common Stock (by reclassification or otherwise than by
payment of a dividend in shares of Common Stock) into a greater or lesser number
of shares of Common Stock, then in each such case the amount to which holders of
shares of Series A Preferred Stock were entitled immediately prior to such event
under clause (b) of the preceding sentence shall be adjusted by multiplying such
amount by a fraction, the numerator of which is the number of shares of Common
Stock outstanding immediately after such event and the denominator of which is
the number of shares of Common Stock that were outstanding immediately prior to
such event. In the event the Corporation shall at any time declare or pay any
dividend on the Series A Preferred Stock payable in shares of Series A Preferred
Stock, or effect a subdivision, combination or consolidation of the outstanding
shares of Series A Preferred Stock (by reclassification or otherwise than by
payment of a dividend in shares of Series A Preferred Stock) into a greater or
lesser number of shares of Series A Preferred Stock, then in each such case the
amount to which holders of shares of Series A Preferred Stock were entitled
immediately prior to such event under clause (b) of the first sentence of this
Section 2(A) shall be adjusted by multiplying such amount by a fraction, the
numerator of which is the number of shares of Series A Preferred Stock that were
outstanding immediately prior to such event and the denominator of which is the
number of shares of Series A Preferred Stock outstanding immediately after such
event.

          (B) The Corporation shall declare a dividend or distribution on the
Series A Preferred Stock as provided in paragraph (A) of this Section
immediately after it declares a dividend or distribution on the Common Stock
(other than a dividend payable in shares of Common Stock) and the Corporation
shall pay such dividend or distribution on the Series A Preferred Stock before
the dividend or distribution declared on the Common Stock is paid or set apart;
provided that, in the
<PAGE>

event no dividend or distribution shall have been declared on the Common Stock
during the period between any Quarterly Dividend Payment Date and the next
subsequent Quarterly Dividend Payment Date, a dividend of $100 per share on the
Series A Preferred Stock shall nevertheless be payable on such subsequent
Quarterly Dividend Payment Date.

          (C) Dividends shall begin to accrue and be cumulative on outstanding
shares of Series A Preferred Stock from the Quarterly Dividend Payment Date next
preceding the date of issue of such shares, unless the date of issue of such
shares is prior to the record date for the first Quarterly Dividend Payment
Date, in which case dividends on such shares shall begin to accrue from the date
of issue of such shares, or unless the date of issue is a Quarterly Dividend
Payment Date or is a date after the record date for the determination of holders
of shares of Series A Preferred Stock entitled to receive a quarterly dividend
and before such Quarterly Dividend Payment Date, in either of which events such
dividends shall begin to accrue and be cumulative from such Quarterly Dividend
Payment Date.  Accrued but unpaid dividends shall not bear interest.  Dividends
paid on the shares of Series A Preferred Stock in an amount less than the total
amount of such dividends at the time accrued and payable on such shares shall be
allocated pro rata on a share-by-share basis among all such shares at the time
outstanding.  The Board of Directors may fix a record date for the determination
of holders of shares of Series A Preferred Stock entitled to receive payment of
a dividend or distribution declared thereon, which record date shall be not more
than 60 days prior to the date fixed for the payment thereof.

     Section 3.  Voting Rights.  The holders of shares of Series A Preferred
                 -------------                                             
Stock shall have the following voting rights:

          (A) Subject to the provision for adjustment hereinafter set forth,
each share of Series A Preferred Stock shall entitle the holder thereof to 1,000
votes on all matters submitted to a vote of the stockholders of the Corporation.
In the event the Corporation shall at any time declare or pay any dividend on
the Common Stock payable in shares of Common Stock, or effect a subdivision,
combination or consolidation of the outstanding shares of Common Stock (by
reclassification or otherwise than by payment of a dividend in shares of Common
Stock) into a greater or lesser number of shares of Common Stock, then in each
such case the number of votes per share to which holders of shares of Series A
Preferred Stock were entitled immediately prior to such event shall be adjusted
by multiplying such number by a fraction, the numerator of which is the number
of shares of Common Stock outstanding immediately after such event and the
denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.  In the event the Corporation shall
at any time declare or pay any dividend on the Series A Preferred Stock payable
in shares of Series A Preferred Stock, or effect a subdivision, combination or
consolidation of the outstanding shares
<PAGE>

of Series A Preferred Stock (by reclassification or otherwise than by payment of
a dividend in shares of Series A Preferred Stock) into a greater or lesser
number of shares of Series A Preferred Stock, then in each such case the number
of votes per share to which holders of shares of Series A Preferred Stock were
entitled immediately prior to such event shall be adjusted by multiplying such
amount by a fraction, the numerator of which is the number of shares of Series A
Preferred Stock that were outstanding immediately prior to such event and the
denominator of which is the number of shares of Series A Preferred Stock
outstanding immediately after such event.

          (B) Except as otherwise provided herein, in the Certificate of
Incorporation or by law, the holders of shares of Series A Preferred Stock and
the holders of shares of Common Stock and any other capital stock of the
Corporation having general voting rights shall vote together as one class on all
matters submitted to a vote of stockholders of the Corporation.

          (C)(i) If at any time dividends on any Series A Preferred Stock shall
be in arrears in an amount equal to six quarterly dividends thereon, the holders
of the Series A Preferred Stock, voting as a separate series from all other
series of Preferred Stock and classes of capital stock, shall be entitled to
elect two members of the Board of Directors in addition to any Directors elected
by any other series, class or classes of securities and the authorized number of
Directors will automatically be increased by two.  Promptly thereafter, the
Board of Directors of this Corporation shall, as soon as may be practicable,
call a special meeting of holders of Series A Preferred Stock for the purpose of
electing such members of the Board of Directors. Said special meeting shall in
any event be held within 45 days of the occurrence of such arrearage.

          (ii) During any period when the holders of Series A Preferred Stock,
voting as a separate series, shall be entitled and shall have exercised their
right to elect two Directors, then and during such time as such right continues
(a) the then authorized number of Directors shall be increased by two, and the
holders of Series A Preferred Stock, voting as a separate series, shall be
entitled to elect the additional Directors so provided for, and (b) each such
additional Director shall not be a member of any existing class of the Board of
Directors, but shall serve until the next annual meeting of stockholders for the
election of Directors, or until his successor shall be elected and shall
qualify, or until his right to hold such office terminates pursuant to the
provisions of this Section 3(C).

          (iii)          A Director elected pursuant to the terms hereof may be
removed with or without cause by the holders of Series A Preferred Stock
entitled to vote in an election of such Director.
<PAGE>

          (iv) If, during any interval between annual meetings of stockholders
for the election of Directors and while the holders of Series A Preferred Stock
shall be entitled to elect two Directors, there is no such Director in office by
reason of resignation, death or removal, then, promptly thereafter, the Board of
Directors shall call a special meeting of the holders of Series A Preferred
Stock for the purpose of filling such vacancy and such vacancy shall be filled
at such special meeting.  Such special meeting shall in any event be held within
45 days of the occurrence of such vacancy.

          (v) At such time as the arrearage is fully cured, and all dividends
accumulated and unpaid on any shares of Series A Preferred Stock outstanding are
paid, and, in addition thereto, at least one regular dividend has been paid
subsequent to curing such arrearage, the term of office of any Director elected
pursuant to this Section 3(C), or his successor, shall automatically terminate,
and the authorized number of Directors shall automatically decrease by two, the
rights of the holders of the shares of the Series A Preferred Stock to vote as
provided in this Section 3(C) shall cease, subject to renewal from time to time
upon the same terms and conditions, and the holders of shares of the Series A
Preferred Stock shall have only the limited voting rights elsewhere herein set
forth.

          (D) Except as set forth herein, or as otherwise provided by law,
holders of Series A Preferred Stock shall have no special voting rights and
their consent shall not be required (except to the extent they are entitled to
vote with holders of Common Stock as set forth herein) for taking any corporate
action.

     Section 4.  Certain Restrictions.
                 --------------------

          (A) Whenever quarterly dividends or other dividends or distributions
payable on the Series A Preferred Stock as provided in Section 2 are in arrears,
thereafter and until all accrued and unpaid dividends and distributions, whether
or not declared, on shares of Series A Preferred Stock outstanding shall have
been paid in full, the Corporation shall not:

               (i) declare or pay dividends, or make any other distributions, on
     any shares of stock ranking junior (either as to dividends or upon
     liquidation, dissolution or winding up) to the Series A Preferred Stock;

               (ii) declare or pay dividends, or make any other distributions,
     on any shares of stock ranking on a parity (either as to dividends or upon
     liquidation, dissolution or winding up) with the Series A Preferred Stock,
     except dividends paid ratably on the Series A Preferred Stock and all such
     parity stock on which dividends are payable or in arrears in proportion to
     the total amounts to which the holders of all such shares are then
     entitled;
<PAGE>

               (iii)  redeem or purchase or otherwise acquire for consideration
     shares of any stock ranking junior (either as to dividends or upon
     liquidation, dissolution or winding up) to the Series A Preferred Stock,
     provided that the Corporation may at any time redeem, purchase or otherwise
     acquire shares of any such junior stock in exchange for shares of any stock
     of the Corporation ranking junior (either as to dividends or upon
     dissolution, liquidation or winding up) to the Series A Preferred Stock; or

               (iv) redeem or purchase or otherwise acquire for consideration
     any shares of Series A Preferred Stock, or any shares of stock ranking on a
     parity with the Series A Preferred Stock, except in accordance with a
     purchase offer made in writing or by publication (as determined by the
     Board of Directors) to all holders of such shares upon such terms as the
     Board of Directors, after consideration of the respective annual dividend
     rates and other relative rights and preferences of the respective series
     and classes, shall determine in good faith will result in fair and
     equitable treatment among the respective series or classes.

          (B) The Corporation shall not permit any subsidiary of the Corporation
to purchase or otherwise acquire for consideration any shares of stock of the
Corporation unless the Corporation could, under paragraph (A) of this Section 4,
purchase or otherwise acquire such shares at such time and in such manner.

     Section 5.  Reacquired Shares.  Any shares of Series A Preferred Stock
                 -----------------                                        
purchased or otherwise acquired by the Corporation in any manner whatsoever
shall be retired and cancelled promptly after the acquisition thereof.  All such
shares shall upon their cancellation become authorized but unissued shares of
Preferred Stock and may be reissued as part of a new series of Preferred Stock
subject to the conditions and restrictions on issuance set forth herein, in the
Certificate of Incorporation, or in any other Certificate of Designations
creating a series of Preferred Stock or any similar stock or as otherwise
required by law.

     Section 6.  Liquidation, Dissolution or Winding Up.
                 --------------------------------------

          (A) Upon any liquidation, dissolution or winding up of the
Corporation, no distribution shall be made (1) to the holders of shares of stock
ranking junior (either as to dividends or upon liquidation, dissolution or
winding up) to the Series A Preferred Stock unless, prior thereto, the holders
of shares of Series A Preferred Stock shall have received $100 per share, plus
an amount equal to accrued and unpaid dividends and distributions thereon,
whether or not declared, to the date of such payment, provided that the holders
of shares of Series A Preferred Stock shall be entitled to receive an aggregate
amount per share, subject to the provision for adjustment hereinafter set forth,
equal to 1,000 times the aggregate amount to be distributed per share to holders
of shares of Common Stock, or (2) to the holders of
<PAGE>

shares of stock ranking on a parity (either as to dividends or upon liquidation,
dissolution or winding up) with the Series A Preferred Stock, except
distributions made ratably on the Series A Preferred Stock and all such parity
stock in proportion to the total amounts to which the holders of all such shares
are entitled upon such liquidation, dissolution or winding up.

          (B) Neither the consolidation, merger or other business combination of
the Corporation with or into any other corporation nor the sale, lease, exchange
or conveyance of all or any part of the property, assets or business of the
Corporation shall be deemed to be a liquidation, dissolution or winding up of
the Corporation for purposes of this Section 6.

          (C) In the event the Corporation shall at any time declare or pay any
dividend on the Common Stock payable in shares of Common Stock, or effect a
subdivision, combination or consolidation of the outstanding shares of Common
Stock (by reclassification or otherwise than by payment of a dividend in shares
of Common Stock) into a greater or lesser number of shares of Common Stock, then
in each such case the aggregate amount to which holders of shares of Series A
Preferred Stock were entitled immediately prior to such event under the proviso
in clause (1) of paragraph (A) of this Section 6 shall be adjusted by
multiplying such amount by a fraction the numerator of which is the number of
shares of Common Stock outstanding immediately after such event and the
denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.  In the event the Corporation shall
at any time declare or pay any dividend on the Series A Preferred Stock payable
in shares of Series A Preferred Stock, or effect a subdivision, combination or
consolidation of the outstanding shares of Series A Preferred Stock (by
reclassification or otherwise than by payment of a dividend in shares of Series
A Preferred Stock) into a greater or lesser number of shares of Series A
Preferred Stock, then in each such case the aggregate amount to which holders of
shares of Series A Preferred Stock were entitled immediately prior to such event
under the proviso in clause (1) of paragraph (A) of this Section 4 shall be
adjusted by multiplying such amount by a fraction, the numerator of which is the
number of shares of Series A Preferred Stock that were outstanding immediately
prior to such event and the denominator of which is the number of shares of
Series A Preferred Stock outstanding immediately after such event.

     Section 7.  Consolidation, Merger, etc.  Notwithstanding anything to the
                 ---------------------------                                
contrary contained herein, in case the Corporation shall enter into any
consolidation, merger, combination or other transaction in which the shares of
Common Stock are exchanged for or changed into other stock or securities, cash
and/or any other property, then in any such case each share of Series A
Preferred Stock shall at the same time be similarly exchanged or changed into an
amount per share, subject to the provision for adjustment hereinafter set forth,
equal to 1,000 times the aggregate amount of stock, securities, cash and/or any
other property (payable in kind), as the
<PAGE>

case may be, into which or for which each share of Common Stock is changed or
exchanged. In the event the Corporation shall at any time declare or pay any
dividend on the Common Stock payable in shares of Common Stock, or effect a
subdivision, combination or consolidation of the outstanding shares of Common
Stock (by reclassification or otherwise than by payment of a dividend in shares
of Common Stock) into a greater or lesser number of shares of Common Stock, then
in each such case the amount set forth in the preceding sentence with respect to
the exchange or change of shares of Series A Preferred Stock shall be adjusted
by multiplying such amount by a fraction, the numerator of which is the number
of shares of Common Stock outstanding immediately after such event and the
denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event. In the event the Corporation shall
at any time declare or pay any dividend on the Series A Preferred Stock payable
in shares of Series A Preferred Stock, or effect a subdivision, combination or
consolidation of the outstanding shares of Series A Preferred Stock (by
reclassification or otherwise than by payment of a dividend in shares of Series
A Preferred Stock) into a greater or lesser number of shares of Series A
Preferred Stock, then in each such case the amount set forth in the first
sentence of this Section 7 with respect to the exchange or change of shares of
Series A Preferred Stock shall be adjusted by multiplying such amount by a
fraction, the numerator of which is the number of shares of Series A Preferred
Stock that were outstanding immediately prior to such event and the denominator
of which is the number of shares of Series A Preferred Stock outstanding
immediately after such event.

     Section 8.  No Redemption.  The shares of Series A Preferred Stock shall
                 -------------                                              
not be redeemable.

     Section 9.  Rank.  The Series A Preferred Stock shall rank, with respect to
                 ----                                                          
the payment of dividends and the distribution of assets, junior to all series of
any other class of the Preferred Stock issued either before or after the
issuance of the Series A Preferred Stock, unless the terms of any such series
shall provide otherwise.

     Section 10.  Amendment.  The Certificate of Incorporation of the
                  ---------                                         
Corporation shall not be amended in any manner which would materially alter or
change the powers, preferences or special rights of the Series A Preferred Stock
so as to affect them adversely without the affirmative vote of the holders of at
least two-thirds of the outstanding shares of Series A Preferred Stock, voting
together as a single class.

     Section 11.  Fractional Shares.  Series A Preferred Stock may be issued in
                  -----------------                                           
fractions of a share which shall entitle the holder, in proportion to such
holder's fractional shares, to exercise voting rights, receive dividends,
participate in distributions and have the benefit of all other rights of holders
of Series A Preferred Stock.
<PAGE>

     IN WITNESS WHEREOF, this Certificate of Designations is executed on behalf
of the Corporation by its Chairman of the Board and Chief Executive Officer this
23rd day of January, 1998.


                                    OPEN MARKET, INC.

                                    /s/ Gary B. Eichhorn
                                    ------------------------------------
                                    Gary B. Eichhorn
                                    President and Chief Executive Officer
<PAGE>

                                                             Exhibit B

                         [Form of Rights Certificate]


Certificate No. R-                                                Rights
                                                      -----------

NOT EXERCISABLE AFTER ____________, 2008 OR EARLIER IF REDEEMED OR EXCHANGED BY
THE COMPANY.  THE RIGHTS ARE SUBJECT TO REDEMPTION AT $.001 PER RIGHT AND TO
EXCHANGE ON THE TERMS SET FORTH IN THE RIGHTS AGREEMENT.  UNDER CERTAIN
CIRCUMSTANCES, RIGHTS BENEFICIALLY OWNED BY AN ACQUIRING PERSON (AS SUCH TERM IS
DEFINED IN THE RIGHTS AGREEMENT) AND ANY SUBSEQUENT HOLDER OF SUCH RIGHTS MAY
BECOME NULL AND VOID.  [THE RIGHTS REPRESENTED BY THIS RIGHTS CERTIFICATE ARE OR
WERE BENEFICIALLY OWNED BY A PERSON WHO WAS OR BECAME AN ACQUIRING PERSON OR AN
AFFILIATE OR ASSOCIATE OF AN ACQUIRING PERSON (AS SUCH TERMS ARE DEFINED IN THE
RIGHTS AGREEMENT).  ACCORDINGLY, THIS RIGHTS CERTIFICATE AND THE RIGHTS
REPRESENTED HEREBY MAY BECOME NULL AND VOID IN THE CIRCUMSTANCES SPECIFIED IN
SECTION 7(e) OF SUCH AGREEMENT.]/1/


                              Rights Certificate

                               OPEN MARKET, INC.

     This certifies that _____________________, or registered assigns, is the
registered owner of the number of Rights set forth above, each of which entitles
the owner thereof, subject to the terms, provisions and conditions of the Rights
Agreement, dated as of January 26, 1998 (the "Rights Agreement"), between Open
Market, Inc., a Delaware corporation (the "Company"), and BankBoston N.A., a
national banking association (the "Rights Agent"), to purchase from the Company
after the Distribution Date (as such term is defined on the Rights Agreement)
and at any time prior to 5:00 P.M. (Boston time) on January 26, 2008 at the
office of the Rights Agent designated for such purpose, or its successors as
Rights Agent, one one-thousandth of a fully paid, non-assessable share of Series
A Junior Participating Preferred Stock (the "Preferred Stock") of the Company,
$.10 par value per share, at a purchase price of $65 in cash per one one-
thousandth of a share (the "Purchase Price"), upon presentation and

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

     /1/The portion of the legend in brackets shall be inserted only if
applicable and shall replace the preceding sentence.

                       Front Side of Rights Certificate
<PAGE>

surrender of this Rights Certificate with the Form of Election to Purchase and
related Certificate duly executed. The number of Rights evidenced by this Rights
Certificate (and the number of one one-thousandth of a share of Preferred Stock
which may be purchased upon exercise hereof) set forth above, and the Purchase
Price set forth above, are the number and Purchase Price as of the close of
business on February 12, 1998, based on the Preferred Stock as constituted at
such date. Capitalized terms used herein and not otherwise defined herein shall
have the meanings ascribed to such terms in the Rights Agreement.

     Upon the occurrence of a Section 11(a)(ii) Event, if the Rights evidenced
by this Rights Certificate are beneficially owned by (i) an Acquiring Person or
an Affiliate or Associate of any such Acquiring Person (as such terms are
defined in the Rights Agreement), (ii) a transferee of any such Acquiring
Person, Associate or Affiliate who becomes a transferee after the Acquiring
Person becomes an Acquiring Person, or (iii) under certain circumstances
specified in the Rights Agreement, a transferee of a person who, concurrently
with or after such transfer, became an Acquiring Person, or an Affiliate or
Associate of an Acquiring Person, such Rights shall become null and void and no
holder hereof shall have any right with respect to such Rights from and after
the occurrence of such Section 11(a)(ii) Event.

     As provided in the Rights Agreement, the Purchase Price and the number and
kind of shares of Preferred Stock or other securities which may be purchased
upon the exercise of the Rights evidenced by this Rights Certificate are subject
to modification and adjustment upon the happening of certain events, including
Section 11(a)(ii) Events.

     This Rights Certificate is subject to all of the terms, provisions and
conditions of the Rights Agreement, which terms, provisions and conditions are
hereby incorporated herein by reference and made a part hereof and to which
Rights Agreement reference is hereby made for a full description of the rights,
limitations of rights, obligations, duties and immunities hereunder of the
Rights Agent, the Company and the holders of the Rights Certificates, which
limitations of rights include the temporary suspension of the exercisability of
such Rights under the specific circumstances set forth in the Rights Agreement.

     Copies of the Rights Agreement are on file at the principal offices of the
Company and are available upon written request to the Company.

     This Rights Certificate, with or without other Rights Certificates, upon
surrender at the office of the Rights Agent designated for such purpose, with
the Form of Election and Certificate set forth on the reverse side duly
executed, may be exchanged for another Rights Certificate or Rights Certificates
of like tenor and date

                       Front Side of Rights Certificate

                                      -2-
<PAGE>

evidencing Rights entitling the holder to purchase a like aggregate number of
one one-thousandth of a share of Preferred Stock as the Rights evidenced by the
Rights Certificate or Rights Certificates surrendered shall have entitled such
holder to purchase. If this Rights Certificate shall be exercised in part, the
holder shall be entitled to receive upon surrender hereof another Rights
Certificate or Rights Certificates for the number of whole Rights not exercised.

     Subject to the provisions of the Rights Agreement, the Rights evidenced by
this Certificate may be redeemed by the Company at its option at a redemption
price of $.001 per Right at any time prior to the earlier of the close of
business on (i) the tenth day following the Stock Acquisition Date (as such time
period may be extended pursuant to the Rights Agreement), and (ii) the Final
Expiration Date.

     Subject to the provisions of the Rights Agreement, the Company may, at its
option, at any time after a Section 11(a)(ii) Event, subject to the approval of
a majority of the Continuing Directors, exchange all or part of the Rights
evidenced by this Certificate for shares of the Company's Common Stock or for
Preferred Stock (or shares of a class or series of the Company's preferred stock
having the same rights, privileges and preferences as the Preferred Stock).

     No fractional shares of Preferred Stock will be issued upon the exercise of
any Right or Rights evidenced hereby (other than fractions which are integral
multiples of one one-thousandth of a share of Preferred Stock, which may, at the
election of the Company, be evidenced by depositary receipts), but in lieu
thereof a cash payment will be made, as provided in the Rights Agreement.

     No holder of this Rights Certificate, as such, shall be entitled to vote or
receive dividends or be deemed for any purpose the holder of shares of Preferred
Stock or of any other securities of the Company which may at any time be
issuable on the exercise hereof, nor shall anything contained in the Rights
Agreement or herein be construed to confer upon the holder hereof, as such, any
of the rights of a stockholder of the Company or any right to vote for the
election of directors or upon any matter submitted to stockholders at any
meeting thereof, or to give or withhold consent to any corporate action, or to
receive notice of meetings or other actions affecting stockholders (except as
provided in the Rights Agreement), or to receive dividends or subscription
rights, or otherwise, until the Right or Rights evidenced by this Rights
Certificate shall have been exercised as provided in the Rights Agreement.

     This Rights Certificate shall not be valid or obligatory for any purpose
until it shall have been countersigned by the Rights Agent.


                       Front Side of Rights Certificate

                                      -3-
<PAGE>

     WITNESS the facsimile signature of the proper officers of the Company and
its corporate seal.

Dated as of _____________, 199_


ATTEST:                            OPEN MARKET, INC.


                                   By:
- ------------------------------        ---------------------------
Secretary
                                   Title:    
                                         ------------------------

COUNTERSIGNED:

BankBoston N.A.


By:
   ---------------------------
   Authorized Signature







                       Front Side of Rights Certificate

                                      -4-
<PAGE>

                 [Form of Reverse Side of Rights Certificate]

                              FORM OF ASSIGNMENT
                              ------------------

               (To be executed by the registered holder if such
              holder desires to transfer the Rights Certificate.)




FOR VALUE RECEIVED ____________________________________________ hereby sells,
assigns and transfers unto __________________________________________________
_____________________________________________________________________________
                 (Please print name and address of transferee)

________________________________________________________________________ this
Rights Certificate, together with all right, title and interest therein, and
does hereby irrevocably constitute and appoint _________________________
Attorney, to transfer the within Rights Certificate on the books of the within-
named Company, with full power of substitution.




Dated:                       , 19
       ----------------------    --

                                             --------------------------------
                                             Signature

Signature Guaranteed:

                                  Certificate
                                  -----------


     The undersigned hereby certifies that the Rights evidenced by this Rights
Certificate are not being beneficially owned by an Acquiring Person or an
Affiliate or Associate thereof (as such terms are defined pursuant to the Rights
Agreement).



                      Reverse Side of Rights Certificate

                                      -5-
<PAGE>

Dated:                   , 19 
      -------------------    --
                                         ------------------------------
                                         Signature

Signature Guaranteed:



                                     NOTICE
                                     ------

     The signature to the foregoing Assignment and Certificate must correspond
to the name as written upon the face of this Rights Certificate in every
particular, without alteration or enlargement or any change whatsoever,



                       Reverse Side of Rights Certificate

                                      -6-
<PAGE>

                          FORM OF ELECTION TO PURCHASE
                          ----------------------------

                 (To be executed if holder desires to exercise
                 Rights represented by the Rights Certificate.)

To:  BankBoston, N.A.

     The undersigned hereby irrevocably elects to exercise _____________ Rights
represented by this Rights Certificate to purchase the shares of Preferred Stock
issuable upon the exercise of the Rights (or such other securities of the
Company or of any other person which may be issuable upon the exercise of the
Rights) and requests that certificates for such shares be issued in the name of
and delivered to:

Please insert social security
or other identifying number 
                             ---------------------------------------------------

- --------------------------------------------------------------------------------
                        (Please print name and address)

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

     If such number of Rights shall not be all the Rights evidenced by this
Rights Certificate, a new Rights Certificate for the balance of such Rights
shall be registered in the name of and delivered to:

Please insert social security
or other identifying number ----------------------------------------------------

- --------------------------------------------------------------------------------
                        (Please print name and address)

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


Dated:                    , 19 
      --------------------    --
                                          ---------------------------------
                                          Signature                       

Signature Guaranteed:

                       Reverse Side of Rights Certificate

                                      -7-
<PAGE>

                                  Certificate
                                  -----------

     The undersigned hereby certifies by checking the appropriate boxes that:

     (1) the Rights evidenced by this Rights Certificate [ ] are [ ] are not
being exercised by or on behalf of a Person who is or was an Acquiring Person or
an Affiliate or Associate thereof (as such terms are defined pursuant to the
Rights Agreement);

     (2) after due inquiry and to the best knowledge of the undersigned, the
undersigned [_] did [_] did not acquire the Rights evidenced by this Rights
Certificate from any Person who is, was or became an Acquiring Person or an
Affiliate or Associate thereof.



Dated:                          , 19 
      --------------------------    --
                                         ------------------------------
                                         Signature

Signature Guaranteed:


                                     NOTICE
                                     ------


     The signature to the foregoing Election to Purchase and Certificate must
correspond to the name as written upon the face of this Rights Certificate in
every particular, without alteration or enlargement or any change whatsoever.



                       Reverse Side of Rights Certificate

                                      -8-
<PAGE>

                                                                    Exhibit C


                         SUMMARY OF RIGHTS TO PURCHASE
                                PREFERRED STOCK


     As of January 26, 1998 the Board of Directors of Open Market, Inc. (the
"Company") declared a dividend distribution of one Right for each outstanding
share of the Company's Common Stock to stockholders of record at the close of
business on February 12, 1998.  Each Right entitles the registered holder to
purchase from the Company one one-thousandth of a share of Series A Junior
Participating Preferred Stock, $.10 par value (the "Preferred Stock") at a
Purchase Price of $65.00 in cash, subject to adjustment.  The description and
terms of the Rights are set forth in a Rights Agreement (the "Rights Agreement")
between the Company and BankBoston N.A., as Rights Agent.

     Initially, the Rights will be attached to all Common Stock certificates
representing shares then outstanding, and no separate Rights Certificates will
be distributed.  The Rights will separate from the Common Stock and a
Distribution Date will occur upon the earlier of (i) 10 days following a public
announcement that a person or group of affiliated or associated persons (an
"Acquiring Person") has acquired, or obtained the right to acquire, beneficial
ownership of 18% or more of the outstanding shares of Common Stock (the "Stock
Acquisition Date"), or (ii) 15 business days following the commencement of a
tender offer or exchange offer that would result in a person or group
beneficially owning 18% or more of such outstanding shares of Common Stock.
Until the Distribution Date, (i) the Rights will be evidenced by the Common
Stock certificates and will be transferred with and only with such Common Stock
certificates, (ii) new Common Stock certificates issued after February 12, 1998
will contain a notation incorporating the Rights Agreement by reference and
(iii) the surrender for transfer of any certificates for Common Stock
outstanding will also constitute the transfer of the Rights associated with the
Common Stock represented by such certificate.

     The Rights are not exercisable until the Distribution Date and will expire
at the close of business on January 26, 2008 unless earlier redeemed or
exchanged by the Company as described below.

     As soon as practicable after the Distribution Date, Rights Certificates
will be mailed to holders of record of the Common Stock as of the close of
business on the Distribution Date and, thereafter, the separate Rights
Certificates alone will represent the Rights.  Except as otherwise determined by
the Board of Directors, and except for shares of Common Stock issued upon
exercise, conversion or exchange of then outstanding options, convertible or
exchangeable securities or other contingent obligations to issue shares, only
shares of Common Stock issued prior to the Distribution Date will be issued with
Rights.
<PAGE>

     In the event that a Person becomes the beneficial owner of 18% or more of
the then outstanding shares of Common Stock, except pursuant to an offer for all
outstanding shares of Common Stock which the independent directors determine to
be fair to, and otherwise in the best interests of, stockholders, each holder of
a Right will thereafter have the right to receive, upon exercise, that number of
shares of Common Stock (or, in certain circumstances, cash, property or other
securities of the Company) which equals the exercise price of the Right divided
by one-half of the current market price (as defined in the Rights Agreement) of
the Common Stock at the date of the occurrence of the event.  However, Rights
are not exercisable following the event set forth above until such time as the
Rights are no longer redeemable by the Company as set forth below.
Notwithstanding any of the foregoing, following the occurrence of such event,
all Rights that are, or (under certain circumstances specified in the Rights
Agreement) were, beneficially owned by any Acquiring Person will be null and
void.  The event set forth in this paragraph is referred to as a "Section
11(a)(ii) Event."

     For example, at an exercise price of $65 per Right, each Right not owned by
an Acquiring Person (or by certain related parties) following an event set forth
in the preceding paragraph would entitle its holder to purchase for $65 such
number of shares of Common Stock (or other consideration, as noted above) as
equals $65 divided by one-half of the current market price (as defined in the
Rights Agreement) of the Common Stock.  Assuming that the Common Stock had a per
share value of $13 at such time, the holder of each valid Right would be
entitled to purchase 10 shares of Common Stock for $65.

     In the event that, at any time after any person has become an Acquiring
Person, (i) the Company is acquired in a merger or other business combination
transaction in which the Company is not the surviving corporation or its Common
Stock is changed or exchanged (other than a merger which follows an offer
determined by the independent directors to be fair as described in the first
sentence of the second preceding paragraph), or (ii) 50% or more of the
Company's assets or earning power is sold or transferred, each holder of a Right
(except Rights which previously have been voided as set forth above) shall
thereafter have the right to receive, upon exercise, that number of shares of
common stock of the acquiring company which equals the exercise price of the
Right divided by one-half of the current market price of such common stock at
the date of the occurrence of the event.

     For example, at an exercise price of $65 per Right, each Right following an
event set forth in the preceding paragraph would entitle its holder to purchase
for $65 such number of shares of common stock of the acquiring company as equals
$65 divided by one-half of the current market price (as defined in the Rights
Agreement) of such common stock.  Assuming that such common stock had a per
share value of $13 at such time, the holder of each valid Right would be
entitled to purchase 10 shares of common stock of the acquiring company for $65.
<PAGE>

     At any time after the occurrence of a Section 11(a)(ii) Event, and subject
to the concurrence of a majority of the Continuing Directors (as defined in the
Rights Agreement), the Board of Directors of the Company may exchange the Rights
(other than Rights owned by such Acquiring Person which have become void), in
whole or in part, at an exchange ratio of one share of Common Stock, or one one-
thousandth of a share of Preferred Stock (or of a share of a class or series of
the Company's preferred stock having equivalent rights, preferences and
privileges), per Right (subject to adjustment).

     The Purchase Price payable, and the number of shares of Preferred Stock or
other securities or property issuable, upon exercise of the Rights are subject
to adjustment from time to time to prevent dilution (i) in the event of a stock
dividend on, or a subdivision, combination or reclassification of, the Preferred
Stock, (ii) if holders of the Preferred Stock are granted certain rights or
warrants to subscribe for Preferred Stock or convertible securities at less than
the current market price of the Preferred Stock, or (iii) upon the distribution
to holders of the Preferred Stock of evidences of indebtedness or assets
(excluding regular quarterly cash dividends) or of subscription rights or
warrants (other than those referred to above).

     The number of Rights associated with each share of Common Stock is also
subject to adjustment in the event of a stock split of the Common Stock or a
stock dividend on the Common Stock payable in Common Stock or subdivisions,
consolidations or combinations of Common Stock occurring, in any such case,
prior to the Distribution Date.

     Preferred Stock purchasable upon exercise of the Rights will not be
redeemable.  Each share of Preferred Stock will be entitled to a minimum
preferential quarterly dividend payment of $100 per share and will be entitled
to an aggregate dividend of 1,000 times the dividend declared per share of
Common Stock.  In the event of liquidation, the holders of the Preferred Stock
will be entitled to a minimum preferential liquidating payment of $100 per share
and will be entitled to an aggregate payment of 1,000 times the payment made per
share of Common Stock. Each share of Preferred Stock will have 1,000 votes,
voting together with the Common Stock.  Finally, in the event of any merger,
consolidation or other transaction in which Common Stock is changed or
exchanged, each share of Preferred Stock will be entitled to receive 1,000 times
the amount received per share of Common Stock.  These rights are protected by
customary antidilution provisions.

     Because of the nature of the Preferred Stock's dividend, liquidation and
voting rights, the value of one one-thousandth of a share of Preferred Stock
purchasable upon exercise of each Right should approximate the value of one
share of Common Stock.
<PAGE>

     With certain exceptions, no adjustment in the Purchase Price will be
required until cumulative adjustments amount to at least 1% of the Purchase
Price.  No fractional shares of Preferred Stock (other than fractions which are
integral multiples of one one-thousandth of a share of Preferred Stock) will be
issued and, in lieu thereof, an adjustment in cash will be made based on the
market price of the Preferred Stock on the last trading date prior to the date
of exercise.

     At any time until ten days following the Stock Acquisition Date, the
Company may redeem the Rights in whole, but not in part, at a price of $.001 per
Right (payable in cash or stock).  Immediately upon the action of the Board of
Directors ordering redemption of the Rights, the Rights will terminate and the
only right of the holders of Rights will be to receive the $.001 redemption
price.  The Rights may also be redeemable following certain other circumstances
specified in the Rights Agreement.

     Until a Right is exercised, the holder thereof, as such, will have no
rights as a stockholder of the Company, including, without limitation, the right
to vote or to receive dividends.  While the distribution of the Rights will not
be taxable to stockholders or to the Company, stockholders may, depending upon
the circumstances, recognize taxable income in the event that the Rights become
exercisable for Common Stock (or other consideration) of the Company or for
common stock of the acquiring company as set forth above.

     Prior to the Distribution Date, the terms of the Rights are subject to
amendment by the Board of Directors without the consent of the holders of the
Rights, except that the redemption price of the Rights is not subject to
amendment. After the Distribution Date, only limited terms of the Rights are
subject to amendment by the Board.

     A copy of the Rights Agreement has been filed with the Securities and
Exchange Commission as an Exhibit to a Registration Statement on Form 8-A dated
January 26, 1998.  A copy of the Rights Agreement is available free of charge
from the Company. This summary description of the Rights Agreement does not
purport to be complete and is qualified in its entirety by reference to the
Rights Agreement, which is incorporated herein by reference.