<PAGE>

                                                                    EXHIBIT 10.4

                          IDENIX PHARMACEUTICALS, INC.

                            2005 STOCK INCENTIVE PLAN

1. Purpose

      The purpose of this 2005 Stock Incentive Plan (the "Plan") of Idenix
Pharmaceuticals, Inc., a Delaware corporation (the "Company"), is to advance the
interests of the Company's stockholders by enhancing the Company's ability to
attract, retain and motivate persons who are expected to make important
contributions to the Company and by providing such persons with equity ownership
opportunities and performance-based incentives that are intended to align their
interests with those of the Company's stockholders. Except where the context
otherwise requires, the term "Company" shall include any of the Company's
present or future parent or subsidiary corporations as defined in Sections
424(e) or (f) of the Internal Revenue Code of 1986, as amended, and any
regulations promulgated thereunder (the "Code") and any other business venture
(including, without limitation, joint venture or limited liability company) in
which the Company has a controlling interest, as determined by the Board of
Directors of the Company (the "Board").

2. Eligibility

      All of the Company's employees, officers, directors, consultants and
advisors are eligible to receive options, stock appreciation rights, restricted
stock, restricted stock units and other stock-based awards (each, an "Award")
under the Plan. Each person who receives an Award under the Plan is deemed a
"Participant".

3. Administration and Delegation

      (a) Administration by Board of Directors. The Plan will be administered by
the Board. The Board shall have authority to grant Awards and to adopt, amend
and repeal such administrative rules, guidelines and practices relating to the
Plan as it shall deem advisable. The Board may correct any defect, supply any
omission or reconcile any inconsistency in the Plan or any Award in the manner
and to the extent it shall deem expedient to carry the Plan into effect and it
shall be the sole and final judge of such expediency. All decisions by the Board
shall be made in the Board's sole discretion and shall be final and binding on
all persons having or claiming any interest in the Plan or in any Award. No
director or person acting pursuant to the authority delegated by the Board shall
be liable for any action or determination relating to or under the Plan made in
good faith.

      (b) Appointment of Committees. To the extent permitted by applicable law,
the Board may delegate any or all of its powers under the Plan to one or more
committees or subcommittees of the Board (a "Committee"). All references in the
Plan to the "Board" shall mean the Board or a Committee of the Board or the
officers referred to in Section 3(c) to the extent that the Board's powers or
authority under the Plan have been delegated to such Committee or officers.

      (c) Delegation to Officers. To the extent permitted by applicable law, the
Board may delegate to one or more officers of the Company the power to grant
Awards to non-officer employees or officers of the Company or any of its present
or future subsidiary corporations and to exercise such other powers under the
Plan as the Board may determine, provided that the Board shall fix the terms of
the Awards to

<PAGE>

be granted by such officers (including the exercise price of such Awards, which
may include a formula by which the exercise price will be determined) and the
maximum number of shares subject to Awards that the officers may grant; provided
further, however, that no officer shall be authorized to grant Awards to any
"executive officer" of the Company (as defined by Rule 3b-7 under the Securities
Exchange Act of 1934, as amended (the "Exchange Act")) or to any "officer" of
the Company (as defined by Rule 16a-1 under the Exchange Act).

4. Stock Available for Awards

      (a) Number of Shares. Subject to adjustment under Section 9, Awards may be
made under the Plan for up to 2,200,000 shares of common stock, $.001 par value
per share, of the Company (the "Common Stock") plus the number of shares
previously authorized for issuance under the Company's 2004 Stock Incentive
Plan: (i) which are not subject to outstanding options on June 7, 2005; or (ii)
which become available for future Award grants as a result of the subsequent
forfeiture, lapse or expiration of options granted pursuant to the 2004 Stock
Incentive Plan and outstanding as of June 7, 2005. If any Award expires or is
terminated, surrendered or canceled without having been fully exercised or is
forfeited in whole or in part (including as the result of shares of Common Stock
subject to such Award being repurchased by the Company at the original issuance
price pursuant to a contractual repurchase right) or results in any Common Stock
not being issued, the unused Common Stock covered by such Award shall again be
available for the grant of Awards under the Plan. Further, shares of Common
Stock tendered to the Company by a Participant to exercise an Award shall be
added to the number of shares of Common Stock available for the grant of Awards
under the Plan. However, in the case of Incentive Stock Options (as hereinafter
defined), the foregoing provisions shall be subject to any limitations under the
Code. Shares issued under the Plan may consist in whole or in part of authorized
but unissued shares or treasury shares.

      (b) Section 162(m) Per-Participant Limit. The maximum number of shares of
Common Stock with respect to which Awards may be granted to any Participant
under the Plan shall be 500,000 per calendar year. For purposes of the foregoing
limit, the combination of an Option in tandem with an SAR (as each is hereafter
defined) shall be treated as a single Award. The per-Participant limit described
in this Section 4(b) shall be construed and applied consistently with Section
162(m) of the Code or any successor provision thereto, and the regulations
thereunder ("Section 162(m)").

5. Stock Options

      (a) General. The Board may grant options to purchase Common Stock (each,
an "Option") and determine the number of shares of Common Stock to be covered by
each Option, the exercise price of each Option and the conditions and
limitations applicable to the exercise of each Option, including conditions
relating to applicable federal or state securities laws, as it considers
necessary or advisable. An Option which is not intended to be an Incentive Stock
Option (as hereinafter defined) shall be designated a "Nonstatutory Stock
Option".

      (b) Incentive Stock Options. An Option that the Board intends to be an
"incentive stock option" as defined in Section 422 of the Code (an "Incentive
Stock Option") shall only be granted to employees of the of Company, any of the
of Company's present or future parent or subsidiary corporations as defined in
Sections 424(e) or (f) of the Code, and any other entities the employees of
which are eligible to receive Incentive Stock Options under the Code, and shall
be subject to and shall be construed consistently with the requirements of
Section 422 of the Code. The Company shall have no liability to a Participant,
or any

                                       2

<PAGE>

other party, if an Option (or any part thereof) that is intended to be an
Incentive Stock Option is not an Incentive Stock Option or for any action taken
by the Board pursuant to Section 10(f), including without limitation the
conversion of an Incentive Stock Option to a Nonstatutory Stock Option.

      (c) Exercise Price. The Board shall establish the exercise price of each
Option provided however that the exercise price shall not be less than 100% of
the Fair Market Value (as hereinafter defined) per share of Common Stock on the
date of grant. The exercise price shall be specified in the applicable option
agreement.

      (d) Limitation on Repricing. Unless such action is approved by the
Company's stockholders: (1) no outstanding Option granted under the Plan may be
amended to provide an exercise price per share that is lower than the
then-current exercise price per share of such outstanding Option (other than
adjustments pursuant to Section 9) and (2) the Board may not cancel any
outstanding Option and grant in substitution therefore new Awards under the Plan
covering the same or a different number of shares of Common Stock and having an
exercise price per share lower than the then-current exercise price per share of
the cancelled Option.

      (e) No Reload Rights. No Option granted under the Plan shall contain any
provision entitling the optionee to the automatic grant of additional Options in
connection with any exercise of the original Option.

      (f) Duration of Options. Each Option shall be exercisable at such times
and subject to such terms and conditions as the Board may specify in the
applicable option agreement; provided however that no Option will be granted for
a term in excess of 10 years.

      (g) Exercise of Option. Options may be exercised by delivery to the
Company of a written notice of exercise signed by the proper person or by any
other form of notice (including electronic notice) approved by the Board
together with payment in full as specified in Section 5(h) for the number of
shares for which the Option is exercised. Shares of Common Stock subject to the
Option will be delivered by the Company following exercise either as soon as
practicable or, subject to such conditions as the Board shall specify, on a
deferred basis (with the Company's obligation to be evidenced by an instrument
providing for future delivery of the deferred shares at the time or times
specified by the Board).

      (h) Payment Upon Exercise. Common Stock purchased upon the exercise of an
Option granted under the Plan shall be paid for as follows:

            (1) in cash or by check, payable to the order of the Company;

            (2) except as the Board may otherwise provide in an option
agreement, by (i) delivery of an irrevocable and unconditional undertaking by a
creditworthy broker to deliver promptly to the Company sufficient funds to pay
the exercise price and any required tax withholding or (ii) delivery by the
Participant to the Company of a copy of irrevocable and unconditional
instructions to a creditworthy broker to deliver promptly to the Company cash or
a check sufficient to pay the exercise price and any required tax withholding;

            (3) when the Common Stock is registered under the Securities
Exchange Act of 1934 (the "Exchange Act"), by delivery of shares of Common Stock
owned by the Participant valued at their fair market value as determined by (or
in a manner approved by) the Board ("Fair Market Value"),

                                       3

<PAGE>

provided (i) such method of payment is then permitted under applicable law, (ii)
such Common Stock, if acquired directly from the Company, was owned by the
Participant for at least six months (or such other period as the Board may deem
appropriate for purposes of satisfaction of applicable accounting rules), if
any, as may be established by the Board in its discretion, and (iii) such Common
Stock is not subject to any repurchase, forfeiture, unfulfilled vesting or other
similar requirements;

            (4) by payment of such other lawful consideration as the Board may
determine; or

            (5) by any combination of the above permitted forms of payment.

      (i) Substitute Options. In connection with a merger or consolidation of an
entity with the Company or the acquisition by the Company of property or stock
of an entity, the Board may grant Options in substitution for any options or
other stock or stock-based awards granted by such entity or an affiliate
thereof. Substitute Options may be granted on such terms as the Board deems
appropriate in the circumstances, notwithstanding any limitations on Options
contained in the other sections of this Section 5 or in Section 2. Substitute
Options shall not count against the overall share limit set forth in Section
4(a), except as may be required by reason of Section 422 and related provisions
of the Code.

6. Stock Appreciation Rights.

      (a) General. A Stock Appreciation Right, or SAR, is an Award entitling the
holder, upon exercise, to receive an amount in Common Stock determined by
reference to appreciation, from and after the date of grant, in the fair market
value of a share of Common Stock. The date as of which such appreciation or
other measure is determined shall be the exercise date.

      (b) Grants. Stock Appreciation Rights may be granted in tandem with, or
independent of, Options granted under the Plan.

      (c) Exercise. Stock Appreciation Rights may be exercised by delivery to
the Company of a written notice of exercise signed by the proper person or by
any other form of notice (including electronic notice) approved by the Board,
together with any other documents required by the Board.

7. Restricted Stock; Restricted Stock Units.

      (a) General. The Board may grant Awards entitling recipients to acquire
shares of Common Stock ("Restricted Stock"), subject to the right of the Company
to repurchase all or part of such shares at their issue price or other stated or
formula price from the recipient in the event that conditions specified by the
Board in the applicable Award are not satisfied prior to the end of the
applicable restriction period or periods established by the Board for such
Award. Instead of granting Awards for Restricted Stock, the Board may grant
Awards entitling the recipient to receive shares of Common Stock to be delivered
at the time such shares of Common Stock vest ("Restricted Stock Units")
(Restricted Stock and Restricted Stock Units are each referred to herein as a
"Restricted Stock Award").

      (b) Terms and Conditions. The Board shall determine the terms and
conditions of a Restricted Stock Award, including the conditions for repurchase
(or forfeiture) and the issue price.

      (c) Stock Certificates. Any stock certificates issued in respect of a
Restricted Stock Award shall be registered in the name of the Participant and,
unless otherwise determined by the Board, deposited by the Participant, together
with a stock power endorsed in blank, with the Company (or its designee). At

                                       4

<PAGE>

the expiration of the applicable restriction periods, the Company (or such
designee) shall deliver the certificates no longer subject to such restrictions
to the Participant or if the Participant has died, to the beneficiary
designated, in a manner determined by the Board, by a Participant to receive
amounts due or exercise rights of the Participant in the event of the
Participant's death (the "Designated Beneficiary"). In the absence of an
effective designation by a Participant, "Designated Beneficiary" shall mean the
Participant's estate.

8. Other Stock-Based Awards.

      Other Awards of shares of Common Stock, and other Awards that are valued
in whole or in part by reference to, or are otherwise based on, shares of Common
Stock or other property, may be granted hereunder to Participants ("Other Stock
Unit Awards"), including without limitation Awards entitling recipients to
receive shares of Common Stock to be delivered in the future. Such Other Stock
Unit Awards shall also be available as a form of payment in the settlement of
other Awards granted under the Plan or as payment in lieu of compensation to
which a Participant is otherwise entitled. Other Stock Unit Awards may be paid
in shares of Common Stock or cash, as the Board shall determine. Subject to the
provisions of the Plan, the Board shall determine the conditions of each Other
Stock Unit Awards, including any purchase price applicable thereto.

9. Adjustments for Changes in Common Stock and Certain Other Events.

      (a) Changes in Capitalization. In the event of any stock split, reverse
stock split, stock dividend, recapitalization, combination of shares,
reclassification of shares, spin-off or other similar change in capitalization
or event, or any distribution to holders of Common Stock other than an ordinary
cash dividend, (i) the number and class of securities available under this Plan,
(ii) the sub-limit set forth in Section 4(b), (iii) the number and class of
securities and exercise price per share of each outstanding Option, (iv) the
share- and per-share provisions of each Stock Appreciation Right, (v) the
repurchase price per share subject to each outstanding Restricted Stock Award
and (vi) the share- and per-share-related provisions of each outstanding Other
Stock Unit Award, shall be appropriately adjusted by the Company (or substituted
Awards may be made, if applicable) to the extent determined by the Board. If
this Section 9(a) applies and Section 9(b) also applies to any event, Section
9(b) shall be applicable to such event, and this Section 9(a) shall not be
applicable.

      (b) Reorganization Events.

            (1) Definition. A "Reorganization Event" shall mean: (a) any merger
or consolidation of the Company with or into another entity as a result of which
all of the Common Stock of the Company is converted into or exchanged for the
right to receive cash, securities or other property or is cancelled, (b) any
exchange of all of the Common Stock of the Company for cash, securities or other
property pursuant to a share exchange transaction or (c) any liquidation or
dissolution of the Company.

            (2) Consequences of a Reorganization Event on Awards Generally. Upon
the occurrence of a Reorganization Event, or the execution by the Company of any
agreement with respect to a Reorganization Event, the Board shall provide that
all outstanding Awards shall be assumed, or substantially equivalent awards
shall be substituted, by the acquiring or succeeding corporation (or an
affiliate thereof). Notwithstanding the foregoing, if the acquiring or
succeeding corporation (or an affiliate thereof) does not agree to assume, or
substitute for, such Awards, then the Board may (i) upon written notice to a
Participant, provide that the Participant's unexercised Options or other
unexercised

                                       5

<PAGE>

Awards shall become exercisable in full and will terminate immediately prior to
the consummation of such Reorganization Event unless exercised by the
Participant within a specified period following the date of such notice, (ii)
provide that outstanding Awards shall become realizable or deliverable, or
restrictions applicable to an Award shall lapse, in whole or in part prior to or
upon such Reorganization Event, (iii) in the event of a Reorganization Event
under the terms of which holders of Common Stock will receive upon consummation
thereof a cash payment for each share surrendered in the Reorganization Event
(the "Acquisition Price"), make or provide for a cash payment to a Participant
equal to (A) the Acquisition Price times the number of shares of Common Stock
subject to the Participant's Options or other Awards (to the extent the exercise
price does not exceed the Acquisition Price) minus (B) the aggregate exercise
price of all such outstanding Options or other Awards, in exchange for the
termination of such Options or other Awards, (iv) provide that, in connection
with a liquidation or dissolution of the Company, Awards shall convert into the
right to receive liquidation proceeds (if applicable, net of the exercise price
thereof) and (v) any combination of the foregoing.

            (3) Consequences of a Reorganization Event on Awards Other than
Restricted Stock Awards. For purposes of Section (2) above, an Option, SAR or
Other Stock Unit Award shall be considered assumed if, following consummation of
the Reorganization Event, the Option, SAR or Other Stock Unit Award confers the
right to receive, for each share of Common Stock subject to the Option, SAR or
Other Stock Unit Award immediately prior to the consummation of the
Reorganization Event, the consideration (whether cash, securities or other
property) received as a result of the Reorganization Event by holders of Common
Stock for each share of Common Stock held immediately prior to the consummation
of the Reorganization Event (and if holders were offered a choice of
consideration, the type of consideration chosen by the holders of a majority of
the outstanding shares of Common Stock); provided, however, that if the
consideration received as a result of the Reorganization Event is not solely
common stock of the acquiring or succeeding corporation (or an affiliate
thereof), the Company may, with the consent of the acquiring or succeeding
corporation, provide for the consideration to be received upon the exercise or
other payment of Options, SARs or Other Stock Unit Awards to consist solely of
common stock of the acquiring or succeeding corporation (or an affiliate
thereof) equivalent in value (as determined by the Board) to the per share
consideration received by holders of outstanding shares of Common Stock as a
result of the Reorganization Event. To the extent all or any portion of an
Option becomes exercisable solely as a result of clause (2)(i) above, the Board
may provide that upon exercise of such Option the Participant shall receive
shares subject to a right of repurchase by the Company or its successor at the
Option exercise price; such repurchase right (x) shall lapse at the same rate as
the Option would have become exercisable under its terms and (y) shall not apply
to any shares subject to the Option that were exercisable under its terms
without regard to clause (2)(i) above.

            (4) Consequences of a Reorganization Event on Restricted Stock
Awards. Upon the occurrence of a Reorganization Event other than a liquidation
or dissolution of the Company, the repurchase and other rights of the Company
under each outstanding Restricted Stock Award shall inure to the benefit of the
Company's successor and shall apply to the cash, securities or other property
which the Common Stock was converted into or exchanged for pursuant to such
Reorganization Event in the same manner and to the same extent as they applied
to the Common Stock subject to such Restricted Stock Award. Upon the occurrence
of a Reorganization Event involving the liquidation or dissolution of the
Company, except to the extent specifically provided to the contrary in the
instrument evidencing any Restricted Stock Award or any other agreement between
a Participant and the Company, all restrictions and conditions on all Restricted
Stock Awards then outstanding shall automatically be deemed terminated or
satisfied.

                                       6

<PAGE>

10. General Provisions Applicable to Awards

      (a) Transferability of Awards. Except as the Board may otherwise determine
or provide in an Award, Awards shall not be sold, assigned, transferred, pledged
or otherwise encumbered by the person to whom they are granted, either
voluntarily or by operation of law, except by will or the laws of descent and
distribution or, other than in the case of an Incentive Stock Option, pursuant
to a qualified domestic relations order, and, during the life of the
Participant, shall be exercisable only by the Participant. References to a
Participant, to the extent relevant in the context, shall include references to
authorized transferees.

      (b) Documentation. Each Award shall be evidenced in such form (written,
electronic or otherwise) as the Board shall determine. Each Award may contain
terms and conditions in addition to those set forth in the Plan.

      (c) Board Discretion. Except as otherwise provided by the Plan, each Award
may be made alone or in addition or in relation to any other Award. The terms of
each Award need not be identical, and the Board need not treat Participants
uniformly.

      (d) Termination of Status. The Board shall determine the effect on an
Award of the disability, death, retirement, authorized leave of absence or other
change in the employment or other status of a Participant and the extent to
which, and the period during which, the Participant, or the Participant's legal
representative, conservator, guardian or Designated Beneficiary, may exercise
rights under the Award.

      (e) Withholding. Each Participant shall pay to the Company, or make
provision satisfactory to the Company for payment of, any taxes required by law
to be withheld in connection with an Award to such Participant. If provided for
in an Award or otherwise approved by the Company, for so long as the Common
Stock is registered under the Exchange Act, Participants may satisfy such tax
obligations in whole or in part by delivery of shares of Common Stock, including
shares retained from the Award creating the tax obligation, valued at their Fair
Market Value; provided, however, except as otherwise provided by the Board, that
the total tax withholding where stock is being used to satisfy such tax
obligations cannot exceed the Company's minimum statutory withholding
obligations (based on minimum statutory withholding rates for federal and state
tax purposes, including payroll taxes, that are applicable to such supplemental
taxable income). Shares surrendered to satisfy tax withholding requirements
cannot be subject to any repurchase, forfeiture, unfulfilled vesting or other
similar requirements. The Company may, to the extent permitted by law, deduct
any such tax obligations from any payment of any kind otherwise due to a
Participant.

      (f) Amendment of Award. Except as otherwise provided in Section 5(d), the
Board may amend, modify or terminate any outstanding Award, including but not
limited to, substituting therefor another Award of the same or a different type,
changing the date of exercise or realization, and converting an Incentive Stock
Option to a Nonstatutory Stock Option, provided that the Participant's consent
to such action shall be required unless the Board determines that the action,
taking into account any related action, would not materially and adversely
affect the Participant.

      (g) Conditions on Delivery of Stock. The Company will not be obligated to
deliver any shares of Common Stock pursuant to the Plan or to remove
restrictions from shares previously delivered under the Plan until (i) all
conditions of the Award have been met or removed to the satisfaction of the
Company, (ii) in the opinion of the Company's counsel, all other legal matters
in connection with the issuance and

                                       7

<PAGE>

delivery of such shares have been satisfied, including any applicable securities
laws and any applicable stock exchange or stock market rules and regulations,
and (iii) the Participant has executed and delivered to the Company such
representations or agreements as the Company may consider appropriate to satisfy
the requirements of any applicable laws, rules or regulations.

      (h) Acceleration. The Board may at any time provide that any Award shall
become immediately exercisable in full or in part, free of some or all
restrictions or conditions, or otherwise realizable in full or in part, as the
case may be.

      (i) Performance Conditions.

            (1) This Section 10(i) shall be administered by a Committee approved
by the Board, all of the members of which are "outside directors" as defined by
Section 162(m) or in the absence of a committee so constituted, the Board as a
whole (the "Section 162(m) Committee").

            (2) Notwithstanding any other provision of the Plan, if the Section
162(m) Committee determines, at the time a Restricted Stock Award or Other Stock
Unit Award is granted to a Participant, that such Participant is, or may be as
of the end of the tax year in which the Company would claim a tax deduction in
connection with such Award, a Covered Employee (as defined in Section 162(m)),
then the Section 162(m) Committee may provide that this Section 10(i) is
applicable to such Award.

            (3) If a Restricted Stock Award or Other Stock Unit Award is subject
to this Section 10(i), then the lapsing of restrictions thereon and the
distribution of cash or Shares pursuant thereto, as applicable, shall be subject
to the achievement of one or more objective performance goals established by the
Section 162(m) Committee, which shall be based on the relative or absolute
attainment of specified levels of one or any combination of the following: (a)
stock price, (b) market share, (c) regulatory compliance, (d) total shareholder
return, (e) cash flow, (f) filing of regulatory applications with respect to new
product candidates and drug products, (g) commercial launch of new drug
products, (h) successful completion of clinical trials, and (i) successful
discovery of new drug candidates and may be absolute in their terms or measured
against or in relationship to other companies comparably, similarly or otherwise
situated. Such performance goals: (i) may vary by Participant and may be
different for different Awards; (ii) may be particular to a Participant or the
department, branch, line of business, subsidiary or other unit in which the
Participant works and may cover such period as may be specified by the Section
162(m) Committee; and (iii) shall be set by the Section 162(m) Committee within
the time period prescribed by, and shall otherwise comply with the requirements
of, Section 162(m).

            (4) Notwithstanding any provision of the Plan, with respect to any
Restricted Stock Award or Other Stock Unit Award that is subject to this Section
10(i), the Section 162(m) Committee may adjust downwards, but not upwards, the
cash or number of Shares payable pursuant to such Award, and the Section 162(m)
Committee may not waive the achievement of the applicable performance goals
except in the case of the death or disability of the Participant.

            (5) The Section 162(m) Committee shall have the power to impose such
other restrictions on Awards subject to this Section 10(i) as it may deem
necessary or appropriate to ensure that such Awards satisfy all requirements for
"performance-based compensation" within the meaning of Section 162(m)(4)(C) of
the Code, or any successor provision thereto.

                                       8

<PAGE>

11. Miscellaneous

      (a) No Right To Employment or Other Status. No person shall have any claim
or right to be granted an Award, and the grant of an Award shall not be
construed as giving a Participant the right to continued employment or any other
relationship with the Company. The Company expressly reserves the right at any
time to dismiss or otherwise terminate its relationship with a Participant free
from any liability or claim under the Plan, except as expressly provided in the
applicable Award.

      (b) No Rights As Stockholder. Subject to the provisions of the applicable
Award, no Participant or Designated Beneficiary shall have any rights as a
stockholder with respect to any shares of Common Stock to be distributed with
respect to an Award until becoming the record holder of such shares.
Notwithstanding the foregoing, in the event the Company effects a split of the
Common Stock by means of a stock dividend and the exercise price of and the
number of shares subject to such Option are adjusted as of the date of the
distribution of the dividend (rather than as of the record date for such
dividend), then an optionee who exercises an Option between the record date and
the distribution date for such stock dividend shall be entitled to receive, on
the distribution date, the stock dividend with respect to the shares of Common
Stock acquired upon such Option exercise, notwithstanding the fact that such
shares were not outstanding as of the close of business on the record date for
such stock dividend.

      (c) Effective Date and Term of Plan. The Plan shall become effective on
the date on which it is adopted by the Board, but no Award may be granted unless
and until the Plan has been approved by the Company's stockholders. No Awards
shall be granted under the Plan after the completion of 10 years from the
earlier of (i) the date on which the Plan was adopted by the Board or (ii) the
date the Plan was approved by the Company's stockholders, but Awards previously
granted may extend beyond that date.

      (d) Amendment of Plan. The Board may amend, suspend or terminate the Plan
or any portion thereof at any time; provided that, to the extent determined by
the Board, no amendment requiring stockholder approval under any applicable
legal, regulatory or listing requirement shall become effective until such
stockholder approval is obtained. No Award shall be made that is conditioned
upon stockholder approval of any amendment to the Plan.

      (e) Provisions for Foreign Participants. The Board may modify Awards or
Options granted to Participants who are foreign nationals or employed outside
the United States or establish subplans or procedures under the Plan to
recognize differences in laws, rules, regulations or customs of such foreign
jurisdictions with respect to tax, securities, currency, employee benefit or
other matters.

      (f) Compliance With Code Section 409A. No Award shall provide for deferral
of compensation that does not comply with Section 409A of the Code, unless the
Board, at the time of grant, specifically provides that the Award is not
intended to comply with Section 409A of the Code.

      (g) Governing Law. The provisions of the Plan and all Awards made
hereunder shall be governed by and interpreted in accordance with the laws of
the State of Delaware, excluding choice-of-law principles of the law of such
state that would require the application of the laws of a jurisdiction other
than such state.

      (h) Authorization of Sub-Plans. The Board may from time to time establish
one or more sub-plans under the Plan for purposes of satisfying applicable blue
sky, securities or tax laws of various jurisdictions. The Board shall establish
such sub-plans by adopting supplements to this Plan containing (i)

                                       9

<PAGE>

such limitations on the Board's discretion under the Plan as the Board deems
necessary or desirable or (ii) such additional terms and conditions not
otherwise inconsistent with the Plan as the Board shall deem necessary or
desirable. All supplements adopted by the Board shall be deemed to be part of
the Plan, but each supplement shall apply only to Participants within the
affected jurisdiction and the Company shall not be required to provide copies of
any supplement to Participants in any jurisdiction which is not the subject of
such supplement.

                                       10