<PAGE>

                                                                    EXHIBIT 10.3
                                VALICERT, INC.

                               1998 STOCK PLAN

     1.  Purposes of the Plan. The purposes of this 1998 Stock Plan are to
         --------------------
attract and retain the best available personnel for positions of substantial
responsibility, to provide additional incentive to Employees and Consultants of
the Company and its Subsidiaries and to promote the success of the Company's
business.  Options granted under the Plan may be Incentive Stock Options (as
defined under Section 422 of the Code) or Nonstatutory Stock Options, as
determined by the Administrator at the time of grant of an option and subject to
the applicable provisions of Section 422 of the Code, as amended, and the
regulations promulgated thereunder.  Stock purchase rights may also be granted
under the Plan.

     2.  Definitions.  As used herein, the following definitions shall apply:
         -----------

         (a)  "Administrator" means the Board or any of its Committees
               -------------
appointed pursuant to Section 4 of the Plan.

         (b)  "Board" means the Board of Directors of the Company.
               -----

         (c)  "Change of Control" means (i) the acquisition of the Company by
               -----------------
another person or entity by means of any transaction or series of related
transactions (including, without limitation, any reorganization, merger or
consolidation, but excluding any merger effected exclusively for the purpose of
changing the domicile of the Company); or (ii) a sale of all or substantially
all of the assets of the Company, unless in the case of either (i) or (ii) the
Company's shareholders of record as constituted immediately prior to such
acquisition or sale will, immediately after such acquisition or sale (by virtue
of securities issued as consideration for the Company's acquisition or sale or
otherwise) hold at least 50% of the voting power of the surviving or acquiring
entity in approximately the same relative percentages after such acquisition or
sale as before such acquisition or sale.

         (d)  "Code" means the Internal Revenue Code of 1986, as amended.
               ----

         (e)  "Committee" means the Committee appointed by the Board of
               ---------
Directors in accordance with Section 4(a) or (b) of the Plan.


         (f)  "Common Stock" means the Common Stock of the Company.
               ------------

         (g)  "Company" means ValiCert, Inc., a Delaware corporation.
               -------

         (h)  "Consultant" means any person, including an advisor, who is
               ----------
engaged by the Company or any Parent or Subsidiary to render services and is
compensated for such services, and any director of the Company whether
compensated for such services or not.

         (i)  "Continuous Status as an Employee or Consultant" means the
               ----------------------------------------------
absence of any interruption or termination of service as an Employee or
Consultant. Continuous Status as an Employee or Consultant shall not be
considered interrupted in the case of: (i) sick leave; (ii) military leave;
(iii) any other leave of absence approved by the Administrator, provided that
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such leave is for a period of not more than 90 days, unless reemployment upon
the expiration of such leave is guaranteed by contract or statute, or unless
provided otherwise pursuant to Company policy adopted from time to time; or (iv)
transfers between locations of the Company or between the Company, its
Subsidiaries or their respective successors. For purposes of this Plan, a change
in status from an Employee to a Consultant or from a Consultant to an Employee
will not constitute an interruption of Continuous Status as an Employee or
Consultant.

         (j)  "Employee" means any person, including officers and directors,
               --------
employed by the Company or any Parent or Subsidiary of the Company, with the
status of employment determined based upon such minimum number of hours or
periods worked as shall be determined by the Administrator in its discretion,
subject to any requirements of the Code. The payment by the Company of a
director's fee to a director shall not be sufficient to constitute "employment"
of such director by the Company.

         (k)  "Exchange Act" means the Securities Exchange Act of 1934, as
               ------------
amended.

         (l)  "Fair Market Value" means, as of any date, the fair market value
               -----------------
of Stock determined as follows:

              (i)    If the Common Stock is listed on any established stock
exchange or a national market system including without limitation the National
Market of the National Association of Securities Dealers, Inc. Automated
Quotation ("Nasdaq") System, its Fair Market Value shall be the closing sales
            ------
price for such stock (or the closing bid, if no sales were reported), as quoted
on such system or exchange, or the exchange with the greatest volume of trading
in Common Stock, for the last market trading day prior to the time of
determination, as reported in The Wall Street Journal or such other source as
the Administrator deems reliable;

              (ii)   If the Common Stock is quoted on the Nasdaq System (but not
on the National Market thereof) or regularly quoted by a recognized securities
dealer but selling prices are not reported, its Fair Market Value shall be the
mean between the high bid and low asked prices for the Common Stock for the last
market trading day prior to the time of determination, as reported in The Wall
Street Journal or such other source as the Administrator deems reliable; or

              (iii)  In the absence of an established market for the Common
Stock, the Fair Market Value thereof shall be determined in good faith by the
Administrator.

          (m) "Incentive Stock Option" means an Option intended to qualify as an
               ----------------------
incentive stock option within the meaning of Section 422 of the Code, as
designated in the applicable written Option Agreement.

          (n) "Nonstatutory Stock Option" means an Option not intended to
               -------------------------
qualify as an Incentive Stock Option, as designated in the applicable written
Option Agreement.

          (o) "Option" means a stock option granted pursuant to the Plan.
               ------

                                      -2-
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          (p) "Option Agreement" means a written agreement between an Optionee
               ----------------
and the Company reflecting the terms of an Option granted under the Plan and
includes any documents attached to such Option Agreement, including, but not
limited to, a notice of stock option grant and a form of exercise notice.

          (q) "Optioned Stock" means the Common Stock subject to an Option or a
               --------------
Stock Purchase Right.

          (r) "Optionee" means an Employee or Consultant who receives an Option
               --------
or a Stock Purchase Right.

          (s) "Parent" means a "parent corporation," whether now or hereafter
               ------
existing, as defined in Section 424(e) of the Code, or any successor provision.

          (t) "Plan" means this 1998 Stock Plan.
               ----

          (u) "Reporting Person" means an officer, director, or greater than 10%
               ----------------
stockholder of the Company within the meaning of Rule 16a-2 under the Exchange
Act, who is required to file reports pursuant to Rule 16a-3 under the Exchange
Act.

          (v) "Restricted Stock" means shares of Common Stock acquired pursuant
               ----------------
to a grant of a Stock Purchase Right under Section 10.

          (w) "Restricted Stock Purchase Agreement" means a written agreement
               -----------------------------------
between a holder of a Stock Purchase Right and the Company reflecting the terms
of a Stock Purchase Right granted under the Plan and includes any documents
attached to such agreement.

          (x) "Rule 16b-3" means Rule 16b-3 promulgated under the Exchange Act,
               ----------
as the same may be amended from time to time, or any successor provision.

          (y) "Share" means a share of the Common Stock, as adjusted in
               -----
accordance with Section 12 of the Plan.

          (z) "Stock Exchange" means any stock exchange or consolidated stock
               --------------
price reporting system on which prices for the Common Stock are quoted at any
given time.

          (aa) "Stock Purchase Right" means the right to purchase Common Stock
                --------------------
pursuant to Section 10 below.

          (bb) "Subsidiary" means a "subsidiary corporation," whether now or
                ----------
hereafter existing, as defined in Section 424(f) of the Code, or any successor
provision.

     3.  Stock Subject to the Plan.  Subject to the provisions of Section 12 of
         -------------------------
the Plan, the maximum aggregate number of Shares that may be optioned and sold
under the Plan is 4,000,000 shares of Common Stock. The Shares may be
authorized, but unissued, or reacquired Common Stock. If an Option should expire
or become unexercisable for any reason without having been exercised in full,
the unpurchased Shares that were subject thereto shall, unless the Plan shall
have been terminated, become available for future grant under the Plan. In
addition,

                                      -3-
<PAGE>

any Shares of Common Stock which are retained by the Company upon exercise of an
Option or Stock Purchase Right in order to satisfy the exercise or purchase
price for such Option or Stock Purchase Right or any withholding taxes due with
respect to such exercise shall be treated as not issued and shall continue to be
available under the Plan. Shares repurchased by the Company pursuant to any
repurchase right which the Company may have shall not be available for future
grant under the Plan.

     4.  Administration of the Plan.
         --------------------------

          (a) Initial Plan Procedure. Prior to the date, if any, upon which the
              ----------------------
Company becomes subject to the Exchange Act, the Plan shall be administered by
the Board or a Committee appointed by the Board.

          (b) Plan Procedure After the Date, if any, Upon Which the Company
              -------------------------------------------------------------
Becomes Subject to the Exchange Act.
-----------------------------------

              (i)    Multiple Administrative Bodies.  If permitted by Rule
                     ------------------------------
16b-3, grants under the Plan may be made by different bodies with respect to
directors, non-director officers and Employees or Consultants who are not
Reporting Persons.

              (ii)   Administration With Respect to Reporting Persons.  With
                     ------------------------------------------------
respect to grants of Options or Stock Purchase Rights to Employees who are
Reporting Persons, such grants shall be made by (A) the Board if the Board may
make grants to Reporting Persons under the Plan in compliance with Rule 16b-3,
or (B) a Committee designated by the Board to make grants to Reporting Persons
under the Plan, which Committee shall be constituted in such a manner as to
permit grants under the Plan to comply with Rule 16b-3. Once appointed, such
Committee shall continue to serve in its designated capacity until otherwise
directed by the Board. From time to time the Board may increase the size of the
Committee and appoint additional members thereof, remove members (with or
without cause) and appoint new members in substitution therefor, fill vacancies,
however caused, and remove all members of the Committee and thereafter directly
make grants to Reporting Persons under the Plan, all to the extent permitted by
Rule 16b-3.

              (iii) Administration With Respect to Consultants and Other
                    ----------------------------------------------------
Employees.  With respect to grants of Options or Stock Purchase Rights to
---------
Employees or Consultants who are not Reporting Persons, the Plan shall be
administered by (A) the Board or (B) a Committee designated by the Board, which
Committee shall be constituted in such a manner as to satisfy the legal
requirements relating to the administration of Incentive Stock Option plans, if
any, of applicable corporate and securities laws, of the Code and of any
applicable Stock Exchange (the "Applicable Laws"). Once appointed, such
                                ---------------
Committee shall continue to serve in its designated capacity until otherwise
directed by the Board. From time to time the Board may increase the size of the
Committee and appoint additional members thereof, remove members (with or
without cause) and appoint new members in substitution therefor, fill vacancies,
however caused, and remove all members of the Committee and thereafter directly
administer the Plan, all to the extent permitted by the Applicable Laws.

                                      -4-
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          (c) Powers of the Administrator. Subject to the provisions of the Plan
              ---------------------------
and in the case of a Committee, the specific duties delegated by the Board to
such Committee, and subject to the approval of any relevant authorities,
including the approval, if required, of any Stock Exchange, the Administrator
shall have the authority, in its discretion:

              (i)    to determine the Fair Market Value of the Common Stock, in
accordance with Section 2(k) of the Plan;

              (ii)   to select the Consultants and Employees to whom Options and
Stock Purchase Rights or any combination thereof may from time to time be
granted hereunder;

              (iii)  to determine whether and to what extent Options and Stock
Purchase Rights or any combination thereof are granted hereunder;

              (iv)   to determine the number of shares of Common Stock to be
covered by each such award granted hereunder;

              (v)    to approve forms of agreement for use under the Plan;

              (vi)   to determine the terms and conditions, not inconsistent
with the terms of the Plan, of any award granted hereunder;

              (vii)  to determine whether and under what circumstances an Option
may be settled in cash under Section 9(f) instead of Common Stock;

              (viii) to reduce the exercise price of any Option to the then
current Fair Market Value if the Fair Market Value of the Common Stock covered
by such Option shall have declined since the date the Option was granted;

              (ix)   to determine the terms and restrictions applicable to Stock
Purchase Rights and the Restricted Stock purchased by exercising such Stock
Purchase Rights;

              (x)    to construe and interpret the terms of the Plan and awards
granted pursuant to the Plan; and

              (xi)   in order to fulfill the purposes of the Plan and without
amending the Plan, to modify grants of Options or Stock Purchase Rights to
participants who are foreign nationals or employed outside of the United States
in order to recognize differences in local law, tax policies or customs.

          (d) Effect of Administrator's Decision. All decisions, determinations
              ----------------------------------
and interpretations of the Administrator shall be final and binding on all
holders of Options or Stock Purchase Rights.

     5.  Eligibility
         -----------

          (a) Recipients of Grants. Nonstatutory Stock Options and Stock
              --------------------
Purchase Rights may be granted to Employees and Consultants. Incentive Stock
Options may be granted

                                      -5-
<PAGE>

only to Employees. An Employee or Consultant who has been granted an Option or
Stock Purchase Right may, if he or she is otherwise eligible, be granted
additional Options or Stock Purchase Rights.

          (b) Type of Option. Each Option shall be designated in the Option
              --------------
Agreement as either an Incentive Stock Option or a Nonstatutory Stock Option.
However, notwithstanding such designations, to the extent that the aggregate
Fair Market Value of Shares with respect to which Options designated as
Incentive Stock Options are exercisable for the first time by any Optionee
during any calendar year (under all plans of the Company or any Parent or
Subsidiary) exceeds $100,000, such excess Options shall be treated as
Nonstatutory Stock Options. For purposes of this Section 5(b), Incentive Stock
Options shall be taken into account in the order in which they were granted, and
the Fair Market Value of the Shares subject to an Incentive Stock Option shall
be determined as of the date of the grant of such Option.

          (c) The Plan shall not confer upon the holder of any Option or Stock
Purchase Right any right with respect to continuation of employment or
consulting relationship with the Company, nor shall it interfere in any way with
such holder's right or the Company's right to terminate his or her employment or
consulting relationship at any time, with or without cause.

     6.   Term of Plan.  The Plan shall become effective upon the earlier to
          ------------
occur of its adoption by the Board of Directors or its approval by the
stockholders of the Company as described in Section 19 of the Plan. It shall
continue in effect for a term of ten years unless sooner terminated under
Section 15 of the Plan.

     7.   Term of Option.  The term of each Option shall be the term stated in
          --------------
the Option Agreement; provided, however, that the term shall be no more than ten
years from the date of grant thereof or such shorter term as may be provided in
the Option Agreement and provided further that, in the case of an Incentive
Stock Option granted to an Optionee who, at the time the Option is granted, owns
stock representing more than 10% of the total combined voting power of all
classes of stock of the Company or any Parent or Subsidiary, the term of the
Option shall be five years from the date of grant thereof or such shorter term
as may be provided in the Option Agreement.

     8.   Option Exercise Price and Consideration.
          ---------------------------------------

          (a) The per share exercise price for the Shares to be issued pursuant
to exercise of an Option shall be such price as is determined by the Board and
set forth in the applicable agreement, but shall be subject to the following:

              (i)    In the case of an Incentive Stock Option that is:

                     (A)  granted to an Employee who, at the time of the grant
of such Incentive Stock Option, owns stock representing more than 10% of the
total combined voting power of all classes of stock of the Company or any Parent
or Subsidiary, the per Share exercise price shall be no less than 110% of the
Fair Market Value per Share on the date of grant.

                     (B)  granted to any other Employee, the per Share exercise
price shall be no less than 100% of the Fair Market Value per Share on the date
of grant.

                                      -6-
<PAGE>

              (ii)   In the case of a Nonstatutory Stock Option that is:

                     (A)  granted to a person who, at the time of the grant of
such Option, owns stock representing more than 10% of the total combined voting
power of all classes of stock of the Company or any Parent or Subsidiary, the
per Share exercise price shall be no less than 110% of the Fair Market Value per
Share on the date of the grant.

                     (B)  granted to any person, the per Share exercise price
shall be no less than 85% of the Fair Market Value per Share on the date of
grant.

          (b) The consideration to be paid for the Shares to be issued upon
exercise of an Option, including the method of payment, shall be determined by
the Administrator (and, in the case of an Incentive Stock Option, shall be
determined at the time of grant) and may consist entirely of (1) cash, (2)
check, (3) promissory note (subject to the provisions of Section 153 of the
Delaware General Corporation Law), (4) other Shares that (x) in the case of
Shares acquired upon exercise of an Option, have been owned by the Optionee for
more than six months on the date of surrender or such other period as may be
required to avoid a charge to the Company's earnings, and (y) have a Fair Market
Value on the date of surrender equal to the aggregate exercise price of the
Shares as to which such Option shall be exercised, (5) authorization for the
Company to retain from the total number of Shares as to which the Option is
exercised that number of Shares having a Fair Market Value on the date of
exercise equal to the exercise price for the total number of Shares as to which
the Option is exercised, (6) delivery of a properly executed exercise notice
together with such other documentation as the Administrator and the broker, if
applicable, shall require to effect an exercise of the Option and delivery to
the Company of the sale or loan proceeds required to pay the exercise price and
any applicable income or employment taxes, (7) delivery of an irrevocable
subscription agreement for the Shares that irrevocably obligates the option
holder to take and pay for the Shares not more than twelve months after the date
of delivery of the subscription agreement, (8) any combination of the foregoing
methods of payment, or (9) such other consideration and method of payment for
the issuance of Shares to the extent permitted under the Applicable Laws. In
making its determination as to the type of consideration to accept, the
Administrator shall consider if acceptance of such consideration may be
reasonably expected to benefit the Company.

     9.   Exercise of Option.
          ------------------

          (a) Procedure for Exercise; Rights as a Stockholder. Any Option
              -----------------------------------------------
granted hereunder shall be exercisable at such times and under such conditions
as determined by the Administrator and reflected in the Option Agreement, which
may include vesting requirements and/or performance criteria with respect to the
Company and/or the Optionee; provided, however, that such Option shall become
exercisable at the rate of at least 20% per year over five years from the date
the Option is granted. In the event that any of the Shares issued upon exercise
of an Option should be subject to a right of repurchase in the Company's favor,
such repurchase right shall lapse at the rate of at least 20% per year over five
years from the date the Option is granted. Notwithstanding the above, in the
case of an Option granted to an officer, director or Consultant of the Company
or any Parent or Subsidiary of the Company, the Option may become fully
exercisable, and a repurchase right, if any, in favor of the Company shall
lapse, at any time or during any period established by the Administrator.

                                      -7-
<PAGE>

     An Option may not be exercised for a fraction of a Share.

     An Option shall be deemed to be exercised when written notice of such
exercise has been given to the Company in accordance with the terms of the
Option by the person entitled to exercise the Option and the Company has
received full payment for the Shares with respect to which the Option is
exercised.  Full payment may, as authorized by the Board, consist of any
consideration and method of payment allowable under Section 8(b) of the Plan.
Until the issuance (as evidenced by the appropriate entry on the books of the
Company or of a duly authorized transfer agent of the Company) of the stock
certificate evidencing such Shares, no right to vote or receive dividends or any
other rights as a stockholder shall exist with respect to the Optioned Stock,
notwithstanding the exercise of the Option.  The Company shall issue (or cause
to be issued) such stock certificate promptly upon exercise of the Option.  No
adjustment will be made for a dividend or other right for which the record date
is prior to the date the stock certificate is issued, except as provided in
Section 12 of the Plan.

     Exercise of an Option in any manner shall result in a decrease in the
number of Shares that thereafter may be available, both for purposes of the Plan
and for sale under the Option, by the number of Shares as to which the Option is
exercised.

          (b) Termination of Employment or Consulting Relationship. Subject to
              ----------------------------------------------------
Section 9(c) below, in the event of termination of an Optionee's Continuous
Status as an Employee or Consultant with the Company, such Optionee may, but
only within three months (or such other period of time not less than 30 days as
is determined by the Administrator, with such determination in the case of an
Incentive Stock Option being made at the time of grant of the Option and not
exceeding three months) after the date of such termination (but in no event
later than the expiration date of the term of such Option as set forth in the
Option Agreement), exercise his or her Option to the extent that the Optionee
was entitled to exercise it at the date of such termination. To the extent that
the Optionee was not entitled to exercise the Option at the date of such
termination, or if the Optionee does not exercise such Option to the extent so
entitled within the time specified herein, the Option shall terminate. No
termination shall be deemed to occur and this Section 9(b) shall not apply if
(i) the Optionee is a Consultant who becomes an Employee, or (ii) the Optionee
is an Employee who becomes a Consultant.

          (c) Disability of Optionee.
              ----------------------

              (i)    Notwithstanding Section 9(b) above, in the event of
termination of an Optionee's Continuous Status as an Employee or Consultant as a
result of his or her total and permanent disability (within the meaning of
Section 22(e)(3) of the Code), such Optionee may, but only within twelve months
from the date of such termination (but in no event later than the expiration
date of the term of such Option as set forth in the Option Agreement), exercise
the Option to the extent otherwise entitled to exercise it at the date of such
termination. To the extent that the Optionee was not entitled to exercise the
Option at the date of termination, or if the Optionee does not exercise such
Option to the extent so entitled within the time specified herein, the Option
shall terminate.

              (ii)   In the event of termination of an Optionee's Continuous
Status as an Employee or Consultant as a result of a disability which does not
fall within the meaning of

                                      -8-
<PAGE>

total and permanent disability (as set forth in Section 22(e)(3) of the Code),
such Optionee may, but only within six months from the date of such termination
(but in no event later than the expiration date of the term of such Option as
set forth in the Option Agreement), exercise the Option to the extent otherwise
entitled to exercise it at the date of such termination. However, to the extent
that such Optionee fails to exercise an Option which is an Incentive Stock
Option (within the meaning of Section 422 of the Code) within three months of
the date of such termination, the Option will not qualify for Incentive Stock
Option treatment under the Code. To the extent that the Optionee was not
entitled to exercise the Option at the date of termination, or if the Optionee
does not exercise such Option to the extent so entitled within six months from
the date of termination, the Option shall terminate.

          (d) Death of Optionee. In the event of the death of an Optionee during
              -----------------
the period of Continuous Status as an Employee or Consultant since the date of
grant of the Option, or within 30 days following termination of the Optionee's
Continuous Status as an Employee or Consultant, the Option may be exercised, at
any time within six months following the date of death (but in no event later
than the expiration date of the term of such Option as set forth in the Option
Agreement), by such Optionee's estate or by a person who acquired the rights to
exercise the Option by bequest or inheritance, but only to the extent of the
right to exercise that had accrued at the date of death or, if earlier, the date
of termination of the Optionee's Continuous Status as an Employee or Consultant.
To the extent that the Optionee was not entitled to exercise the Option at the
date of death or termination, as the case may be, or if the Optionee does not
exercise such Option to the extent so entitled within the time specified herein,
the Option shall terminate.

          (e) Rule 16b-3. Options granted to Reporting Persons shall comply with
              ----------
Rule 16b-3 and shall contain such additional conditions or restrictions as may
be required thereunder to qualify for the maximum exemption for Plan
transactions.

     10.  Stock Purchase Rights.
          ---------------------

          (a) Rights to Purchase. Stock Purchase Rights may be issued either
              ------------------
alone, in addition to, or in tandem with other awards granted under the Plan
and/or cash awards made outside of the Plan. After the Administrator determines
that it will offer Stock Purchase Rights under the Plan, it shall advise the
offeree in writing of the terms, conditions and restrictions related to the
offer, including the number of Shares that such person shall be entitled to
purchase, the price to be paid (which price shall not be less than 85% of the
Fair Market Value of the Shares as of the date of the offer, or, in the case of
a person owning stock representing more than 10% of the total combined voting
power of all classes of stock of the Company or any Parent or Subsidiary, the
price shall not be less than 100% of the Fair Market Value of the Shares as of
the date of the offer), and the time within which such person must accept such
offer, which shall in no event exceed 30 days from the date upon which the
Administrator made the determination to grant the Stock Purchase Right. The
offer shall be accepted by execution of a Restricted Stock Purchase Agreement in
the form determined by the Administrator.

          (b) Repurchase Option. Unless the Administrator determines otherwise,
              -----------------
the Restricted Stock Purchase Agreement shall grant the Company a repurchase
option exercisable upon the voluntary or involuntary termination of the
purchaser's employment with the Company

                                      -9-
<PAGE>

for any reason (including death or disability). The purchase price for Shares
repurchased pursuant to the Restricted Stock Purchase Agreement shall be the
original purchase price paid by the purchaser and may be paid by cancellation of
any indebtedness of the purchaser to the Company. The repurchase option shall
lapse at such rate as the Administrator may determine; provided, however, that
with respect to an Optionee who is not an officer, director or Consultant of the
Company or of any Parent or Subsidiary of the Company, it shall lapse at a
minimum rate of 20% per year.

          (c) Other Provisions. The Restricted Stock Purchase Agreement shall
              ----------------
contain such other terms, provisions and conditions not inconsistent with the
Plan as may be determined by the Administrator in its sole discretion. In
addition, the provisions of Restricted Stock Purchase Agreements need not be the
same with respect to each purchaser.

          (d) Rights as a Stockholder. Once the Stock Purchase Right is
              -----------------------
exercised, the purchaser shall have the rights equivalent to those of a
stockholder, and shall be a stockholder when his or her purchase is entered upon
the records of the duly authorized transfer agent of the Company. No adjustment
will be made for a dividend or other right for which the record date is prior to
the date the Stock Purchase Right is exercised, except as provided in Section 12
of the Plan.

     11.  Stock Withholding to Satisfy Withholding Tax Obligations.  At the
          --------------------------------------------------------
discretion of the Administrator, Optionees may satisfy withholding obligations
as provided in this paragraph.  When an Optionee incurs tax liability in
connection with an Option or Stock Purchase Right, which tax liability is
subject to tax withholding under applicable tax laws, and the Optionee is
obligated to pay the Company an amount required to be withheld under applicable
tax laws, the Optionee may satisfy the withholding tax obligation by one or some
combination of the following methods: (a) by cash or check payment, (b) out of
the Optionee's current compensation, (c) if permitted by the Administrator, in
its discretion, by surrendering to the Company Shares that (i) in the case of
Shares previously acquired from the Company, have been owned by the Optionee for
more than six months on the date of surrender, and (ii) have a fair market value
on the date of surrender equal to or less than the Optionee's marginal tax rate
times the ordinary income recognized, or (d) by electing to have the Company
withhold from the Shares to be issued upon exercise of the Option, or the Shares
to be issued in connection with the Stock Purchase Right, if any, that number of
Shares having a Fair Market Value equal to the amount required to be withheld.
For this purpose, the fair market value of the Shares to be withheld shall be
determined on the date that the amount of tax to be withheld is to be determined
(the "Tax Date").
      --------

     Any surrender by a Reporting Person of previously owned Shares to satisfy
tax withholding obligations arising upon exercise of this Option must comply
with the applicable provisions of Rule 16b-3.

     All elections by an Optionee to have Shares withheld to satisfy tax
withholding obligations shall be made in writing in a form acceptable to the
Administrator and shall be subject to the following restrictions:

          (a) the election must be made on or prior to the applicable Tax Date;

                                      -10-
<PAGE>

          (b) once made, the election shall be irrevocable as to the particular
Shares of the Option or Stock Purchase Right as to which the election is made;
and

          (c) all elections shall be subject to the consent or disapproval of
the Administrator.

     In the event the election to have Shares withheld is made by an Optionee
and the Tax Date is deferred under Section 83 of the Code because no election is
filed under Section 83(b) of the Code, the Optionee shall receive the full
number of Shares with respect to which the Option or Stock Purchase Right is
exercised but such Optionee shall be unconditionally obligated to tender back to
the Company the proper number of Shares on the Tax Date.

     12.  Adjustments Upon Changes in Capitalization, Merger or Certain Other
          -------------------------------------------------------------------
Transactions.
------------

          (a) Changes in Capitalization. Subject to any required action by the
              -------------------------
stockholders of the Company, the number of shares of Common Stock covered by
each outstanding Option or Stock Purchase Right, and the number of shares of
Common Stock that have been authorized for issuance under the Plan but as to
which no Options or Stock Purchase Rights have yet been granted or that have
been returned to the Plan upon cancellation or expiration of an Option or Stock
Purchase Right, as well as the price per share of Common Stock covered by each
such outstanding Option or Stock Purchase Right, shall be proportionately
adjusted for any increase or decrease in the number of issued shares of Common
Stock resulting from a stock split, reverse stock split, stock dividend,
combination, recapitalization or reclassification of the Common Stock, or any
other increase or decrease in the number of issued shares of Common Stock
effected without receipt of consideration by the Company; provided, however,
that conversion of any convertible securities of the Company shall not be deemed
to have been "effected without receipt of consideration." Such adjustment shall
be made by the Board, whose determination in that respect shall be final,
binding and conclusive. Except as expressly provided herein, no issuance by the
Company of shares of stock of any class, or securities convertible into shares
of stock of any class, shall affect, and no adjustment by reason thereof shall
be made with respect to, the number or price of shares of Common Stock subject
to an Option or Stock Purchase Right.

          (b) Dissolution or Liquidation. In the event of the proposed
              --------------------------
dissolution or liquidation of the Company, the Board shall notify the Optionee
at least 15 days prior to such proposed action. To the extent it has not been
previously exercised, the Option or Stock Purchase Right will terminate
immediately prior to the consummation of such proposed action.

          (c) Merger or Sale of Assets.
              ------------------------

              (i)  Assumption of Options and Stock Purchase Rights.  In the
                   -----------------------------------------------
event of a proposed sale of all or substantially all of the Company's assets or
a merger of the Company with or into another corporation where the successor
corporation issues its securities to the Company's stockholders, each
outstanding Option or Stock Purchase Right shall be assumed or an equivalent
option or right shall be substituted by such successor corporation or a parent
or subsidiary of such successor corporation, unless the successor corporation
does not agree to

                                      -11-
<PAGE>

assume the Option or Stock Purchase Right or to substitute an equivalent option
or right, in which case such Option or Stock Purchase Right shall terminate upon
the consummation of the merger or sale of assets. For purposes of this Section
12(c), an Option or a Stock Purchase Right shall be considered assumed, without
limitation, if, at the time of issuance of the stock or other consideration upon
such merger or sale of assets, each holder of an Option or a Stock Purchase
Right would be entitled to receive upon exercise of the Option or Stock Purchase
Right the same number and kind of shares of stock or the same amount of
property, cash or securities as such holder would have been entitled to receive
upon the occurrence of such transaction if the holder had been, immediately
prior to such transaction, the holder of the number of Shares of Common Stock
covered by the Option or the Stock Purchase Right at such time (after giving
effect to any adjustments in the number of Shares covered by the Option or Stock
Purchase Right as provided for in this Section 12).

              (ii)   Acceleration of Vesting.  The Administrator shall have the
                     -----------------------
right to provide for the acceleration of vesting of Option and Purchase Rights
upon a Change of Control and to determine the terms of such acceleration, if
any.

          (d) Certain Distributions. In the event of any distribution to the
              ---------------------
Company's stockholders of securities of any other entity or other assets (other
than dividends payable in cash or stock of the Company) without receipt of
consideration by the Company, the Administrator may, in its discretion,
appropriately adjust the price per share of Common Stock covered by each
outstanding Option or Stock Purchase Right to reflect the effect of such
distribution.

     13.  Non-Transferability of Options and Stock Purchase Rights.  Options and
          --------------------------------------------------------
Stock Purchase Rights may not be sold, pledged, assigned, hypothecated,
transferred, or disposed of in any manner other than by will or by the laws of
descent or distribution and may be exercised or purchased during the lifetime of
the Optionee or the holder of Stock Purchase Rights only by the Optionee or the
holder of Stock Purchase Rights.

     14.  Time of Granting Options and Stock Purchase Rights.  The date of
          --------------------------------------------------
grant of an Option or Stock Purchase Right shall, for all purposes, be the date
on which the Administrator makes the determination granting such Option or Stock
Purchase Right, or such other date as is determined by the Board; provided,
however, that in the case of any Incentive Stock Option, the grant date shall be
the later of the date on which the Administrator makes the determination
granting such Incentive Stock Option or the date of commencement of the
Optionee's employment relationship with the Company. Notice of the determination
shall be given to each Employee or Consultant to whom an Option or Stock
Purchase Right is so granted within a reasonable time after the date of such
grant.

     15.  Amendment and Termination of the Plan.
          -------------------------------------

          (a) Authority to Amend or Terminate. The Board may at any time amend,
alter, suspend or discontinue the Plan, but no amendment, alteration, suspension
or discontinuation shall be made that would impair the rights of any Optionee
under any grant theretofore made, without his or her consent. In addition, to
the extent necessary and desirable to comply with Rule 16b-3 or with Section 422
of the Code (or any other applicable law or

                                      -12-
<PAGE>

regulation, including the requirements of any Stock Exchange), the Company shall
obtain stockholder approval of any Plan amendment in such a manner and to such a
degree as required.

          (b) Effect of Amendment or Termination. No amendment or termination of
              ----------------------------------
the Plan shall adversely affect Options already granted, unless mutually agreed
otherwise between the Optionee and the Board, which agreement must be in writing
and signed by the Optionee and the Company.

     16.  Conditions Upon Issuance of Shares.  Shares shall not be issued
          ----------------------------------
pursuant to the exercise of an Option or Stock Purchase Right unless the
exercise of such Option or Stock Purchase Right and the issuance and delivery of
such Shares pursuant thereto shall comply with all relevant provisions of law,
including, without limitation, the Securities Act of 1933, as amended, the
Exchange Act, the rules and regulations promulgated thereunder, and the
requirements of any Stock Exchange.

     As a condition to the exercise of an Option, the Company may require the
person exercising such Option to represent and warrant at the time of any such
exercise that the Shares are being purchased only for investment and without any
present intention to sell or distribute such Shares if, in the opinion of
counsel for the Company, such a representation is required by law.

     17.  Reservation of Shares.  The Company, during the term of this Plan,
          ---------------------
will at all times reserve and keep available such number of Shares as shall be
sufficient to satisfy the requirements of the Plan. The inability of the Company
to obtain authority from any regulatory body having jurisdiction, which
authority is deemed by the Company's counsel to be necessary to the lawful
issuance and sale of any Shares hereunder, shall relieve the Company of any
liability in respect of the failure to issue or sell such Shares as to which
such requisite authority shall not have been obtained.

     18.  Agreements.  Options and Stock Purchase Rights shall be evidenced by
          ----------
written Option Agreements and Restricted Stock Purchase Agreements,
respectively, in such form(s) as the Administrator shall approve from time to
time.

     19.  Stockholder Approval.  Continuance of the Plan shall be subject to
          --------------------
approval by the stockholders of the Company within twelve months before or after
the date the Plan is adopted. Such stockholder approval shall be obtained in the
degree and manner required under applicable state and federal law and the rules
of any Stock Exchange upon which the Common Stock is listed. All Options and
Stock Purchase Rights issued under the Plan shall become void in the event such
approval is not obtained.

     20.  Information and Documents to Optionees and Purchasers.  The Company
          -----------------------------------------------------
shall provide financial statements at least annually to each Optionee and to
each individual who acquired Shares pursuant to the Plan, during the period such
Optionee or purchaser has one or more Options or Stock Purchase Rights
outstanding, and in the case of an individual who acquired Shares pursuant to
the Plan, during the period such individual owns such Shares. The Company shall
not be required to provide such information if the issuance of Options or Stock
Purchase Rights under the Plan is limited to key employees whose duties in
connection with the

                                      -13-
<PAGE>

Company assure their access to equivalent information. In addition, at the time
of issuance of any securities under the Plan, the Company shall provide to the
Optionee or the purchaser a copy of the Plan and any agreement(s) pursuant to
which securities granted under the Plan are issued.

                                      -14-