<PAGE>

                                                                     Exhibit 4.1




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


                                NMT MEDICAL, INC.

                                       and

                    AMERICAN STOCK TRANSFER & TRUST COMPANY,

                                 as Rights Agent

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



                                Rights Agreement

                            Dated as of June 7, 1999


                   ----------------------------------------
<PAGE>

                                RIGHTS AGREEMENT


         RIGHTS AGREEMENT, dated as of June 7, 1999 (the "Agreement"), between
NMT Medical, Inc.(formerly Nitinol Medical Technologies, Inc.), a Delaware
corporation (the "Company"), and American Stock Transfer & Trust Company, a New
York company, as Rights Agent (the "Rights Agent").

                               W I T N E S S E T H

     WHEREAS, on May 26, 1999 the Board of Directors of the Company (the
"Board") authorized and declared a dividend distribution of one Right for each
share of Common Stock (as hereinafter defined) of the Company outstanding at the
close of business on June 10, 1999 (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 earlier of the Distribution Date or the
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 Designation 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
15% 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, (iv) any Person
organized, appointed or established by the Company for or pursuant to the terms
of any such plan or (v) an Exempted Person. Notwithstanding the foregoing, if
the Board 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 unless and until
such Person shall again become an "Acquiring Person."
<PAGE>

          (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, directly or indirectly, beneficially owns or 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
     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

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<PAGE>

     Regulations under the Exchange Act, and (B) is not 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.

     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)(l)(i) of the General Rules and Regulations
under the Exchange Act.

          (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 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.

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

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

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

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<PAGE>

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

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

          (m) "Exempted Person" shall mean Whitney Equity Partners, L.P., a
Delaware limited partnership, unless and until such time as such Person,
together with its Affiliates, directly or indirectly, becomes the Beneficial
Owner of more than 25% of the Common Stock then outstanding, in which case such
Person shall cease to be an Exempted Person.

          (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
June 9, 2009.

          (p) "Person" shall mean any individual, firm, corporation,
partnership, trust, association, limited liability company or other entity.

          (q) "Preferred Stock" shall mean shares of Series A Junior
Participating Preferred Stock, $.001 par value, of the Company having the rights
and preferences set forth in the form of Certificate of Designation 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 Preferred Stock,
$.001 par value, of the Company designated for such purpose containing terms
substantially similar to the terms of the Series A Junior Participating
Preferred Stock.

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

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

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

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

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

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<PAGE>

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

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

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

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

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

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

          (cc) "Stock Acquisition Date" shall mean the later of (i) 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 or (ii) the first date on which an executive officer of the Company
has actual knowledge that an Acquiring Person has become such.

          (dd) "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.

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

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

          (gg) "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

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<PAGE>

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 shall in no event be liable
for, the acts or omissions of any such co-Rights Agent.

     Section 3. Issuance of Rights.
                ------------------

          (a) Until the earlier of (i) the close of business on the tenth
Business Day (or such later date as may be determined by the Board) after the
Stock Acquisition Date (or, if the tenth Business 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 tenth Business Day (or such
later date as may be determined by the Board) 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 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 15% 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 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 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 Sections 11(i) and 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

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<PAGE>

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 upon the exercise, conversion or exchange
of securities, granted or 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 NMT Medical,
     Inc. (formerly Nitinol Medical Technologies, Inc., and hereinafter, the
     "Company") and American Stock Transfer & Trust Company (the "Rights Agent")
     dated as of June 7, 1999, as the same may be amended, restated or renewed
     from time to time (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, 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,
the transfer of any certificates representing shares of Common Stock in respect
of

                                       7
<PAGE>

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, Section 11(i)
or Section 22 hereof that represents Rights beneficially owned by persons known
to be: (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
(whether or not in writing) regarding the transferred Rights or (B) a transfer
which the Board has determined is part of a plan, arrangement or understanding
(whether or not in writing) 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:

                                       8
<PAGE>

     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, President or any Vice President, and by the
Treasurer or any Assistant Treasurer 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 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 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

                                       9
<PAGE>

Certificate or Certificates, entitling the registered holder to purchase a like
number of one one-thousandths 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 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
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-thousandths of a share (or other shares, securities, cash or other assets,
as the case may be) as to which such surrendered Rights are then exercisable,

                                       10
<PAGE>

at or prior to the earliest of (i) the Final Expiration Date, (ii) the time at
which the Rights are redeemed as provided in Section 23 hereof (the "Redemption
Date") or (iii) the time at which such Rights are exchanged as provided in
Section 24 hereof (the earliest of (i), (ii), and (iii) 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 $20.00
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-thousandths of a share of Preferred Stock to be
purchased and the Company hereby authorizes its transfer agent to comply with
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 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

                                       11
<PAGE>

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
(whether or not in writing) regarding the transferred Rights or (B) a transfer
which the Board has determined is part of a plan, arrangement or understanding
(whether or not in writing) that has as a primary purpose or effect 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 insure 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.

           (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

                                       12
<PAGE>

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 may be listed on any national
securities exchange or automated quotation system, 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 so listed 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 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

                                       13
<PAGE>

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-thousandths 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-thousandths 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-thousandths 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 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-thousandths 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)

                                       14
<PAGE>

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 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, alone or together with its Affiliates or Associates,
    becomes an Acquiring Person, 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 (subject to the last
    sentence of Section 23(a)), upon exercise thereof at the then current
    Purchase Price in accordance with the terms of this

                                       15
<PAGE>

    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-thousandths 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
    (1) 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, (1) 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 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 the foregoing, having an aggregate value
    equal to the Current Value, where such aggregate value has been
    determined by the Board based upon the advice of a nationally
    recognized investment banking firm selected by the Board; 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 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

                                       16
<PAGE>

    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 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, 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

                                       17
<PAGE>

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, 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 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

                                       18
<PAGE>

    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
    sale price, regular way, or, in case no such sale takes place on such
    day, the average of the closing bid and asked prices, regular way, in
    either case as reported in the principal consolidated transaction
    reporting system with respect to securities listed or admitted to
    trading on the principal national securities exchange on which the
    shares of Common Stock are listed or admitted to trading or, if the
    shares of Common Stock are not listed or admitted to trading on any
    national securities exchange, the last quoted price or, if not so
    quoted, the average of the high bid and the low asked prices in the
    over-the-counter market, as reported by The Nasdaq Stock Market, Inc.
    ("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. 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 shall be used. The term "Trading
    Day" shall mean a day on which Nasdaq or any 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 Nasdaq or 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, whose determination shall be described in a
    statement filed with the Rights Agent and shall be conclusive for all
    purposes.

        (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

                                       19
<PAGE>

     share as determined in good faith by the Board, 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 (1%) 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 hundred-thousandth of a share of Common Stock or other
security, 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 securities other than Preferred Stock,
thereafter the number of such other securities 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 securities; provided, however, that the Company shall
                                    --------  -------
not be liable for its inability to reserve and keep available for issuance upon
exercise of the Rights pursuant to Section 11(a)(ii) a number of shares of
Common Stock greater than the number then authorized by the Company's
Certificate of Incorporation but not outstanding or reserved for other purposes.

        (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-thousandths 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
ten-millionth) obtained by (i) multiplying

                                       20
<PAGE>

(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-thousandths 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 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-thousandths 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

                                       21
<PAGE>

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 such number of one one-thousandths of a share of fully paid and
nonassessable 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
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.

        (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

                                       22
<PAGE>

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.

    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.

                                       23
<PAGE>

    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, (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, 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 shall be equal
to the result obtained by (1) multiplying the then current Purchase Price by the
number of one one-thousandths of a share of Preferred Stock for which a Right is
exercisable immediately prior to the first 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-thousandths of a share
for which a Right was exercisable immediately prior to the first occurrence of a
Section 11(a)(ii) Event by the Purchase Price in effect immediately prior to
such first occurrence), and (2) dividing that product (which, following the
first 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 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, subject to clause (v) below, 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

                                       24
<PAGE>

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" 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

                                       25
<PAGE>

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).

    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 sale price, regular way, or, in case no such sale
takes place on such day, the average of the closing bid and asked prices,
regular way, in either case as reported in the principal consolidated
transaction reporting system with respect to securities listed or admitted to
trading on the principal national securities exchange on which the Rights are
listed or admitted to trading, or if the Rights are not listed or admitted to
trading on any national securities exchange, the last quoted price or, if not so
quoted, the average of the high bid and the low asked prices in the over-the-
counter market, as reported by Nasdaq or such other

                                       26
<PAGE>

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.
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
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.

        (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

                                       27
<PAGE>

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;

        (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 prevent the issuance of any such order, decree or ruling and to have
any such order, decree or ruling lifted or otherwise overturned as soon as
possible.

                                       28
<PAGE>

    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-thousandths 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 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

                                       29
<PAGE>

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 countersignature 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.

    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

                                       30
<PAGE>

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 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

                                       31
<PAGE>

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; 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

                                       32
<PAGE>

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, 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 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

                                       33
<PAGE>

other case, if deemed necessary or appropriate by the Board, 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 may, at its option, at any time prior to the earlier of
(i) the close of business on the tenth Business Day (or such later date as may
be determined by the Board pursuant to clause (i) of the first sentence of
Section 3(a) with respect to the Distribution Date) 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 Business 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"). 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 in its sole discretion may establish. The Company
may, at its option, pay the Redemption Price in cash, shares of Common Stock
(based on the "current market price," as defined in Section 11(d)(i) hereof, of
the Common Stock at the time of redemption) or any other form of consideration,
or any combination of any of the foregoing, deemed appropriate by the Board.
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.

        (b) Immediately upon the action of the Board 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 shall 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 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
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.

                                       34
<PAGE>

        (c) In the event of a redemption of the Rights in accordance with this
Agreement, 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 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) 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 shall not be
empowered to effect such exchange at any time after any Person (other than the
Company, any Subsidiary of the Company, any employee benefit plan of the Company
or any such Subsidiary, or any entity holding Common Stock for or pursuant to
the terms of any such plan), together with all Affiliates and Associates of such
Person, becomes the Beneficial Owner of 50% or more of the shares of Common
Stock then outstanding.

        (b) Immediately upon the action of the Board 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 Rights which will be exchanged. Any partial exchange shall be effected
pro rata based on the number of Rights (other than

                                       35
<PAGE>

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 Designation
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 sale
or

                                       36
<PAGE>

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:

                     NMT Medical, Inc.
                     27 Wormwood Street
                     Boston, MA 02210
                     Attention: Secretary

                     with a copy to:

                     Hale and Dorr LLP
                     60 State Street
                     Boston, MA  02109
                     Attention:  Philip P. Rossetti, Esq.

                                       37
<PAGE>

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:

                 American Stock Transfer & Trust Company
                 40 Wall Street
                 New York, NY  10005
                 Attention:  Client Administration

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. Except as provided in the
                --------------------------
penultimate sentence of this Section 27, for so long as the Rights are then
redeemable, the Company may, in its sole and absolute discretion, and the Rights
Agent shall, if the Company so directs, supplement or amend any provision of
this Agreement in any respect without the approval of any holders of the Rights.
At any time when the Rights are no longer redeemable, except as provided in the
penultimate sentence of this Section 27, the Company may, by approval of a
majority of the members of the Board, and the Rights Agent shall, if the Company
so directs, supplement or amend this Agreement without the approval of any
holders of Rights in order (i) to cure any ambiguity or (ii) to correct or
supplement any provision contained herein which may be defective or inconsistent
with any other provisions herein, provided that no such supplement or amendment
                                  --------
shall adversely affect the interests of the holders of Rights as such (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 which changes the Redemption Price.
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.

                                       38
<PAGE>

    Section 29. Actions by the Board of Directors, etc. The Board 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; provided,
however, that notwithstanding anything in this Agreement to the contrary, if any
such term, provision, covenant or restriction is held by such court or authority
to be invalid, void or unenforceable and the Board determines in its good faith
judgment that severing the invalid, void or unenforceable language from this
Agreement would adversely affect the purpose or effect of this Agreement, the
right of redemption set forth in Section 23 hereof shall be reinstated and shall
not expire until the close of business on the tenth day following the date of
such determination by the Board.

    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 the State of Delaware applicable to
contracts made and to be performed entirely within the State of Delaware.

    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

                                       39
<PAGE>

original, and all such counterparts shall together constitute but one and the
same instrument.

    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.

                                       40
<PAGE>

        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:                                     NMT MEDICAL, INC.



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

Attest:                                     AMERICAN STOCK TRANSFER & TRUST
                                            COMPANY, RIGHTS AGENT



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

                                      41
<PAGE>

                                                                       Exhibit A

                                NMT MEDICAL, INC.
                           CERTIFICATE OF DESIGNATION

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

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

RESOLVED:         That pursuant to the authority granted to and vested in the
                  Board of Directors (hereinafter called the "Board of
                  Directors" or the "Board") of NMT Medical, Inc. (formerly
                  Nitinol Medical Technologies, Inc., and hereinafter called the
                  "Corporation") in accordance with the provisions of the Second
                  Amended and Restated Certificate of Incorporation, as amended
                  (the "Certificate of Incorporation"), the Board of Directors
                  hereby creates a series of Preferred Stock, $.001 par value
                  per share (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 50,000. Such number of shares may be increased or
decreased by resolution of the Board prior to issuance; 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 $.001
per share (the "Common Stock"), of the Corporation, and of any other junior
stock, shall be entitled to receive, when, as and if declared by the Board out
of funds of the Corporation legally available for the payment of dividends,
quarterly dividends payable in cash on the last day of each fiscal quarter of
the Corporation 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


                                      A-1
<PAGE>

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) $10 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 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 $10 per share on the
Series A Preferred Stock shall nevertheless be payable on such subsequent
Quarterly Dividend Payment Date.


                                      A-2
<PAGE>

    (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 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 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

                                      A-3
<PAGE>

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 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 the
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. Such 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, 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.

        (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
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.


                                      A-4
<PAGE>

        (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;

        (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


                                      A-5
<PAGE>

        (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) to all holders of
such shares upon such terms as the Board, 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 Designation
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 $1000 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 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


                                      A-6
<PAGE>

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 6 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 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


                                      A-7
<PAGE>

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. At such time as any shares of Series A Preferred
                ---------
Stock are outstanding, the Certificate of Incorporation, as amended, 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.


                                      A-8
<PAGE>

                                                                       Exhibit B
                                                                       ---------

                          [Form of Rights Certificate]


Certificate No. R-                                       ______ Rights

NOT EXERCISABLE AFTER JUNE 9, 2009 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/

                               NMT MEDICAL, INC.

                              Rights Certificate

    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 June 7, 1999 (the "Rights Agreement"), between NMT
Medical, Inc. (formerly Nitinol Medical Technologies, Inc.), a Delaware
corporation (the "Company"), and American Stock Transfer & Trust Company (the
"Rights Agent"), to purchase from the Company after the Distribution Date (as
such term is defined in the Rights Agreement) and at any time prior to 5:00 p.m.
(Boston time) on June 9, 2009 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, $.001 par value per share, at a purchase
price of $20.00 in cash per one one-thousandth of a share (the "Purchase
Price"), upon presentation and surrender of

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

/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

                                      B-1
<PAGE>

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 June 10, 1999, 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 evidencing Rights entitling the holder to purchase a like
aggregate number of one


                       Front Side of Rights Certificate

                                      B-2
<PAGE>

one-thousandths 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.

    Subject to the provisions of the Rights Agreement, the Company may, at its
option, at any time after a Section 11(a)(ii) Event, 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

                                      B-3
<PAGE>

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

Dated as of ______________________


ATTEST:                                     NMT MEDICAL, INC.



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


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

                                            Title:
                                                  -----------------------------
                                                  Treasurer/Assistant Treasurer


COUNTERSIGNED:

AMERICAN STOCK TRANSFER &
TRUST COMPANY



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





                       Front Side of Rights Certificate

                                      B-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: ________________



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



Signature Guaranteed:

                                  Certificate


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

Dated: ______________


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

Signature Guaranteed:


                      Reverse Side of Rights Certificate

                                      B-5
<PAGE>

                                     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

                                      B-6
<PAGE>

                          FORM OF ELECTION TO PURCHASE

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

To:      American Stock Transfer & Trust Company

    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: ______________
                                                              _________________
                                                              Signature

Signature Guaranteed:


                      Reverse Side of Rights Certificate

                                      B-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: _______________

                                                 _____________________________
                                                 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

                                      B-8
<PAGE>

                                                                       Exhibit C
                                                                       ---------


                              SUMMARY OF RIGHTS TO
                            PURCHASE PREFERRED STOCK

    On May 26, 1999, the Board of Directors of NMT Medical, Inc. (formerly
Nitinol Medical Technologies, Inc., and hereinafter, the "Company"), declared a
dividend of one Right for each outstanding share of the Company's Common Stock
to stockholders of record at the close of business on June 10, 1999 (the "Record
Date"). Each Right entitles the registered holder to purchase from the Company
one one-thousandth of a share of Series A Junior Participating Preferred Stock,
$.001 par value per share (the "Preferred Stock"), at a Purchase Price of $20.00
in cash, subject to adjustment. The description and terms of the Rights are set
forth in a Rights Agreement dated as of June 7, 1999 (the "Rights Agreement")
between the Company and American Stock Transfer & Trust Company.

  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 business days (or such
later date as may be determined by the Board of Directors of the Company)
following the later of (a) the first date of 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 15% or more
of the outstanding shares of Common Stock (or, in the case of Whitney Equity
Partners, L.P. and its affiliates, more than 25% of the outstanding shares of
Common Stock) or (b) the first date on which an executive officer of the Company
has actual knowledge that an Acquiring Person has become such (the "Stock
Acquisition Date"), or (ii) 10 business days (or such later date as may be
determined by the Board of Directors of the Company) following the commencement
of a tender offer or exchange offer that would result in a person or group
beneficially owning 15% or more of such outstanding shares of Common Stock.
Until the Distribution Date (or earlier redemption or expiration of the rights),
(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 the Record Date will contain a notation
incorporating the Rights Agreement by reference and (iii) the surrender for
transfer of any certificates for Common Stock outstanding, even without such
notation, 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
upon the close of business on June 9, 2009 (the "Final Expiration Date") unless
earlier redeemed or exchanged as described below. As soon as practicable after
the

                                      C-1
<PAGE>

Distribution Date, separate 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.

  In the event that any Person becomes an Acquiring Person then, promptly
following the first occurrence of such event, each holder of a Right (except as
provided below and in Section 7(e) of the Rights Agreement) shall thereafter
have the right to receive, upon exercise, that number of shares of Common Stock
of the Company (or, in certain circumstances, cash, property or other securities
of the Company) which equals the exercise price of the Right divided by 50% of
the current market price (as defined in the Rights Agreement) per share of
Common Stock at the date of the occurrence of such event. However, Rights are
not exercisable following such event until such time as the Rights are no longer
redeemable by the Company as described 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
summarized in this paragraph is referred to as a "Section 11(a)(ii) Event."

  In the event that, at any time after any Person becomes an Acquiring
Person, (i) the Company is consolidated with, or merged with and into, another
entity and the Company is not the surviving entity of such consolidation or
merger or if the Company is the surviving entity, but shares of its outstanding
Common Stock are changed or exchanged for stock or securities (of any other
person) or cash or any other property, 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
50% of the current market price of such common stock at the date of the
occurrence of the event. The events summarized in this paragraph are referred to
as "Section 13 Events." A Section 11(a)(ii) Event and Section 13 Events are
collectively referred to as "Triggering Events."

  At any time after the occurrence of a Section 11(a)(ii) Event, subject to
certain conditions, 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


                                      C-2
<PAGE>

preferred stock having equivalent rights, preferences and privileges), per Right
(subject to adjustment).

  The Purchase Price payable, and the number of units 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 then-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 periodic cash dividends paid out of earnings or
retained earnings) 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 the Common Stock occurring, in
any such case, prior to the Distribution Date.

  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.

  Preferred Stock purchasable upon exercise of the Rights will not be
redeemable. Each share of Preferred Stock will be entitled to receive, when, as
and if declared by the Board of Directors, a minimum preferential quarterly
dividend payment of $10 per share or, if greater, 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 liquidation payment of $1,000 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. 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.

  At any time prior to the earlier of (i) the tenth Business Day (or such
later date as may be determined by the Board of Directors of the Company) after
the Stock

                                      C-3
<PAGE>

Acquisition Date, or (ii) the Final Expiration Date, the Company may redeem the
Rights in whole, but not in part, at a price of $.001 per Right (the "Redemption
Price"), 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 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.

  Subject to certain exceptions, any of the provisions of the Rights
Agreement may be amended by the Board of Directors of the Company prior to such
time as the Rights are no longer redeemable.

  A copy of the Rights Agreement will be filed with the Securities and
Exchange Commission as an Exhibit to the Company's Current Report on Form 8-K. A
copy of the Rights Agreement is available free of charge from the Company. This
summary description of the Rights does not purport to be complete and is
qualified in its entirety by reference to the Rights Agreement, which is
incorporated herein by reference.


                                      C-4