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Exhibit 10.3  

 
 

SENOMYX, INC.
  2004 EQUITY INCENTIVE PLAN
  STOCK OPTION AGREEMENT
  (INCENTIVE STOCK OPTION OR NONSTATUTORY STOCK OPTION)    
    

        Pursuant to your Stock Option Grant Notice ("Grant Notice") and this Stock Option Agreement, Senomyx, Inc.
(the "Company") has granted you an option under its 2004 Equity Incentive Plan (the "Plan") to purchase
the number of shares of the Company's Common Stock indicated in your Grant Notice at the exercise price indicated in your Grant Notice. Defined terms not explicitly defined in this Stock Option
Agreement but defined in the Plan shall have the same definitions as in the Plan. 

        The
details of your option are as follows: 

        1.    VESTING.    Subject to the limitations contained herein, your option will vest as
provided in your Grant Notice, provided that vesting will cease upon the termination of your Continuous Service. In addition, if the Company is subject to a Change in Control before your Continuous
Service terminates, and within either one (1) month prior to or eighteen (18) months following the effective date of such Change in Control your Continuous Service is involuntarily
terminated by the Company without Cause (which shall not include a termination resulting from death or Disability) or you resign for Good Reason, then all of the remaining unvested shares subject to
this option will become fully vested and exercisable upon the date of such termination of your Continuous Service. 

        For
purposes of this Section 1, "Good Reason" means the occurrence of one or more of the following without your express written
consent: (i) a change in your position, duties or responsibilities (including reporting responsibilities) that results in a material diminution in your duties; provided,
however, that a change in your title or reporting relationship alone shall not provide the basis for a voluntary termination with Good Reason; (ii) a reduction in your
annual base compensation or (iii) the Company's requiring you to permanently relocate to any place outside a fifty (50) mile radius of your then current work site. 

        2.    NUMBER OF SHARES AND EXERCISE PRICE.    The number of shares of Common Stock subject
to
your option and your exercise price per share referenced in your Grant Notice may be adjusted from time to time for Capitalization Adjustments. 

        3.    METHOD OF PAYMENT.    Payment of the exercise price is due in full upon exercise of
all
or any part of your option. You may elect to make payment of the exercise price in cash or by check or in any other manner permitted by your Grant
Notice, which may include one or more of the following: 

        (a)   In the Company's sole discretion at the time your option is exercised and provided that at the time of exercise the
Common Stock is publicly traded and quoted regularly in The Wall Street Journal, pursuant to a program developed under Regulation T as
promulgated by the Federal Reserve Board that, prior to the issuance of Common Stock, results in either the receipt of cash (or check) by the Company or the receipt of irrevocable instructions to pay
the aggregate exercise price to the Company from the sales proceeds. 

        (b)   Provided that at the time of exercise the Common Stock is publicly traded and quoted regularly in  The Wall Street Journal, by delivery of
already-owned shares of Common Stock either that you have held for the period required to avoid a charge to the
Company's reported earnings (generally six (6) months) or that you did not acquire, directly or indirectly from the Company, that are owned free and clear of any liens, claims, encumbrances or
security interests, and that are valued at Fair Market Value on the date of exercise. "Delivery" for these purposes, in the sole discretion of the Company at the time you exercise your option, shall
include delivery to the 

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Company
of your attestation of ownership of such shares of Common Stock in a form approved by the Company. Notwithstanding the foregoing, you may not exercise your option by tender to the Company of
Common Stock to the extent such tender would violate the provisions of any law, regulation or agreement restricting the redemption of the Company's stock. 

        4.    WHOLE SHARES.    You may exercise your option only for whole shares of Common Stock.

        5.    SECURITIES LAW COMPLIANCE.    Notwithstanding anything to the contrary contained
herein,
you may not exercise your option unless the shares of Common Stock issuable upon such exercise are then registered under the Securities Act or, if such shares of Common Stock are not then so
registered, the Company has determined that such exercise and issuance would be exempt from the registration requirements of the Securities Act. The exercise of your option also must comply with other
applicable laws and regulations governing your option, and you may not exercise your option if the Company determines that such exercise would not be in material compliance with such laws and
regulations. 

        6.    TERM.    You may not exercise your option before the commencement of its term or after
its term expires. The term of your option commences on the Date of Grant and expires upon the earliest of the following: 

        (a)   three (3) months after the termination of your Continuous Service for any reason other than Cause, Disability or
death, provided that if during any part of such three (3) month period you may not exercise your option solely because of the condition set forth in the preceding paragraph relating to
"Securities Law Compliance," your option shall not expire until the earlier of the Expiration Date or until it shall have been exercisable for an aggregate period of three (3) months after the
termination of your Continuous Service; 

        (b)   twelve (12) months after the termination of your Continuous Service due to your Disability; 

        (c)   eighteen (18) months after your death if you die either during your Continuous Service or within three
(3) months after your Continuous Service terminates; 

        (d)   immediately upon the termination of your Continuous Service if for Cause; 

        (e)   the Expiration Date indicated in your Grant Notice; or 

        (f)    the day before the tenth (10th) anniversary of the Date of Grant. 

        If
your option is an Incentive Stock Option, note that to obtain the federal income tax advantages associated with an Incentive Stock Option, the Code requires that at all times
beginning on the date of grant of your option and ending on the day three (3) months before the date of your option's exercise, you must be an employee of the Company or an Affiliate, except in
the event of your death or your permanent and total disability, as defined in Section 22(e) of the Code. (The definition of disability in Section 22(e) of the Code is different from the
definition of the Disability under the Plan). The Company has provided for extended exercisability of your option under certain circumstances for your benefit but cannot guarantee that your option
will necessarily be treated as an Incentive Stock Option if you continue to provide services to the Company or an Affiliate as a Consultant or Director after your employment terminates or if you
otherwise exercise your option more than three (3) months after the date your employment with the Company or an Affiliate terminates. 

        7.    EXERCISE.    

        (a)   You may exercise the vested portion of your option during its term by delivering a Notice of Exercise (in a form
designated by the Company) together with the exercise price to the Secretary of the Company, or to such other person as the Company may designate, during regular business hours, together with such
additional documents as the Company may then require. 

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        (b)   By exercising your option you agree that, as a condition to any exercise of your option, the Company may require you to
enter into an arrangement providing for the payment by you to the Company of any tax withholding obligation of the Company arising by reason of (1) the exercise of your option, (2) the
lapse of any substantial risk of forfeiture to which the shares of Common Stock are subject at the time of exercise, or (3) the disposition of shares of Common Stock acquired upon such
exercise. 

        (c)   If your option is an Incentive Stock Option, by exercising your option you agree that you will notify the Company in
writing within fifteen (15) days after the date of any disposition of any of the shares of the Common Stock issued upon exercise of your option that occurs within two (2) years after the
date of your option grant or within one (1) year after such shares of Common Stock are transferred upon exercise of your option. 

        8.    TRANSFERABILITY.    

        (a)   If your option is an Incentive Stock Option, your option is not transferable, except by will or by the laws of descent
and distribution, and is exercisable during your life only by you. Notwithstanding the foregoing, by delivering written notice to the Company, in a form satisfactory to the Company, you may designate
a third party who, in the event of your death, shall thereafter be entitled to exercise your option. 

        (b)   If your option is a Nonstatutory Stock Option, your option is not transferable, except (i) by will or by the laws
of descent and distribution, (ii) with the prior written approval of the Company, by instrument to an inter vivos or testamentary trust, in a form accepted by the Company, in which the option
is to be passed to beneficiaries upon the death of the trustor (settlor) and (iii) with the prior written approval of the Company, by gift, in a form accepted by the Company, to a permitted
transferee under Rule 701 of the Securities Act. 

        9.    OPTION NOT A SERVICE CONTRACT.    Your option is not an employment or service contract,

and nothing in your option shall be deemed to create in any way whatsoever any obligation on your part to continue in the employ of the Company or an Affiliate, or of the Company or an Affiliate to
continue your employment. In addition, nothing in your option shall obligate the Company or an Affiliate, their
respective stockholders, Boards of Directors, Officers or Employees to continue any relationship that you might have as a Director or Consultant for the Company or an Affiliate. 

        10.    WITHHOLDING OBLIGATIONS.    

        (a)   At the time you exercise your option, in whole or in part, or at any time thereafter as requested by the Company, you
hereby authorize withholding from payroll and any other amounts payable to you, and otherwise agree to make adequate provision as instructed by the Company (including by means of a "cashless exercise"
pursuant to a program developed under Regulation T as promulgated by the Federal Reserve Board to the extent instructed by the Company), for any sums required to satisfy the federal, state,
local and foreign tax withholding obligations of the Company or an Affiliate, if any, which arise in connection with the exercise of your option. 

        (b)   The Company may, in its sole discretion, and in compliance with any applicable legal conditions or restrictions, withhold
from fully vested shares of Common Stock otherwise issuable to you upon the exercise of your option a number of whole shares of Common Stock having a Fair Market Value, determined by the Company as of
the date of exercise, not in excess of the minimum amount of tax required to be withheld by law (or such lower amount as may be necessary to avoid variable award accounting). Any adverse consequences
to you arising in connection with such share withholding procedure shall be your sole responsibility. 

        (c)   You may not exercise your option unless the tax withholding obligations of the Company and/or any Affiliate are
satisfied. Accordingly, you may not be able to exercise your option when desired even though your option is vested, and the Company shall have no obligation to issue a 

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certificate
for such shares of Common Stock or release such shares of Common Stock from any escrow provided for herein unless such obligations are satisfied. 

        (d)   If any payment or benefit you would receive pursuant to a Change in Control from the Company or otherwise
("Payment") would (i) constitute a "parachute payment" within the meaning of Section 280G
of the Code, and (ii) but for this sentence, be subject to the excise tax imposed by Section 4999 of the Code (the "Excise
Tax"), then such Payment shall be equal to the Reduced Amount. The "Reduced Amount" shall be either (x) the largest portion of the Payment that
would result in no portion of the Payment being subject to the Excise Tax or (y) the largest portion, up to and including the total, of the Payment, whichever amount, after taking into account
all applicable federal, state and local employment taxes, income taxes, and the Excise Tax (all computed at the highest applicable marginal rate), results in your receipt, on an after-tax
basis, of the greater amount of the Payment notwithstanding that all or some portion of the Payment may be subject to the Excise Tax. If a reduction in payments or benefits constituting "parachute
payments" is necessary so that the Payment equals the Reduced Amount, reduction shall occur in the following order unless you elect in writing a different order (provided,
however, that such election shall be subject to Company approval if made on
or after the effective date of the event that triggers the Payment): reduction of cash payments; cancellation of accelerated vesting of Stock Awards; reduction of employee benefits. In the event that
acceleration of vesting of Stock Award compensation is to be reduced, such acceleration of vesting shall be cancelled in the reverse order of the date of grant of your Stock Awards (i.e., earliest
granted Stock Award cancelled last) unless you elect in writing a different order for cancellation. 

        The
accounting firm engaged by the Company for general audit purposes as of the day prior to the effective date of the Change in Control shall perform the foregoing calculations. If the
accounting firm so engaged by the Company is serving as accountant or auditor for the individual, entity or group effecting the Change in Control, the Company shall appoint a nationally recognized
accounting firm to make the determinations required hereunder. The Company shall bear all expenses with respect to the determinations by such accounting firm required to be made hereunder. 

        The
accounting firm engaged to make the determinations hereunder shall provide its calculations, together with detailed supporting documentation, to you and the Company within fifteen
(15) calendar days after the date on which your right to a Payment is triggered (if requested at that time by you or the Company) or such other time as requested by you or the Company. If the
accounting firm determines that no Excise Tax is payable with respect to a Payment, either before or after the application of the Reduced Amount, it shall furnish you and the Company with an opinion
reasonably acceptable to you that no Excise Tax will be imposed with respect to such Payment. Any good faith determinations of the accounting firm made hereunder shall be final, binding and conclusive
upon you and the Company. 

        11.    NOTICES.    Any notices provided for in your option or the Plan shall be given in
writing and shall be deemed effectively given upon receipt or, in the case of notices delivered by mail by the Company to you, five (5) days after deposit in the United States mail, postage
prepaid, addressed to you at the last address you provided to the Company. 

        12.    GOVERNING PLAN DOCUMENT.    Your option is subject to all the provisions of the Plan,
the provisions of which are hereby made a part of your option, and is further subject to all interpretations, amendments, rules and regulations, which may from time to time be promulgated and adopted
pursuant to the Plan. In the event of any conflict between the provisions of your option and those of the Plan, the provisions of the Plan shall control. 

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SENOMYX, INC.
  2004 EQUITY INCENTIVE PLAN    
    
    NON-EMPLOYEE DIRECTORS' STOCK OPTION PROGRAM    
    
    STOCK OPTION AGREEMENT
  (NONSTATUTORY STOCK OPTION)    
    

        Pursuant
to your Stock Option Grant Notice ("Grant Notice") and this Stock Option Agreement, Senomyx, Inc. (the  "Company") has granted you an
option under its 2004 Equity Incentive Plan (the "Plan") and
Non-Employee Directors' Stock Option Program to purchase the number of shares of the Company's Common Stock indicated in your Grant Notice at the exercise price indicated in your Grant
Notice. Defined terms not explicitly defined in this Stock Option Agreement but defined in the Plan shall have the same definitions as in the Plan. 

        The
details of your option are as follows: 

        1.    VESTING.    Subject to the limitations contained herein, your option will vest as
provided in your Grant Notice, provided that vesting will cease upon the termination of your Continuous Service. In addition, if the Company is subject to a Change in Control before your Continuous
Service terminates, then all of the unvested shares subject to this option shall become fully vested and exercisable immediately prior to the effective date of such Change in Control. 

        2.    NUMBER OF SHARES AND EXERCISE PRICE.    The number of shares of Common Stock subject
to
your option and your exercise price per share referenced in your Grant Notice may be adjusted from time to time for Capitalization Adjustments, as provided in the Plan. 

        3.    EXERCISE PRIOR TO VESTING ("EARLY EXERCISE").    If permitted in your Grant Notice
(i.e., the "Exercise Schedule" indicates that "Early Exercise" of your option is permitted) and subject to the provisions of your option, you may elect at any time that is both (i) during the
period of your Continuous Service and (ii) during the term of your option, to exercise all or part of your option, including the nonvested portion of your option;  provided, however, that:

        (a)   a partial exercise of your option shall be deemed to cover first vested shares of Common Stock and then the earliest
vesting installment of unvested shares of Common Stock; 

        (b)   any shares of Common Stock so purchased from installments that have not vested as of the date of exercise shall be
subject to the purchase option in favor of the Company as described in the Company's form of Early Exercise Stock Purchase Agreement; and 

        (c)   you shall enter into the Company's form of Early Exercise Stock Purchase Agreement with a vesting schedule that will
result in the same vesting as if no early exercise had occurred. 

        4.    METHOD OF PAYMENT.    Payment of the exercise price is due in full upon exercise of
all
or any part of your option. You may elect to make payment of the exercise price in cash or by check or in any other manner permitted by your Grant
Notice, which may include one or more of the following: 

        (d)   In the Company's sole discretion at the time your option is exercised and provided that at the time of exercise the
Common Stock is publicly traded and quoted regularly in The Wall Street Journal, pursuant to a program developed under Regulation T as
promulgated by the Federal Reserve Board that, prior to the issuance of Common Stock, results in either the receipt of cash (or check) by the Company or the receipt of irrevocable instructions to pay
the aggregate exercise price to the Company from the sales proceeds. 

        (e)   Provided that at the time of exercise the Common Stock is publicly traded and quoted regularly in  The Wall Street Journal, by delivery of
already-owned shares of Common Stock either that you have held for the period required to avoid a charge to the
Company's reported earnings 

1

 

(generally
six months) or that you did not acquire, directly or indirectly from the Company, that are owned free and clear of any liens, claims, encumbrances or security interests, and that are valued
at Fair Market Value on the date of exercise. "Delivery" for these purposes, in the sole discretion of the Company at the time you exercise your option, shall include delivery to the Company of your
attestation of ownership of such shares of Common Stock in a form approved by the Company. Notwithstanding the foregoing, you may not exercise your option by tender to the Company of Common Stock to
the extent such tender would violate the provisions of any law, regulation or agreement restricting the redemption of the Company's stock. 

        5.    WHOLE SHARES.    You may exercise your option only for whole shares of Common Stock.

        6.    SECURITIES LAW COMPLIANCE.    Notwithstanding anything to the contrary contained
herein,
you may not exercise your option unless the shares of Common Stock issuable upon such exercise are then registered under the Securities Act or, if such shares of Common Stock are not then so
registered, the Company has determined that such exercise and issuance would be exempt from the registration requirements of the Securities Act. The exercise of your option must also comply with other
applicable laws and regulations governing your option, and you may not exercise your option if the Company determines that such exercise would not be in material compliance with such laws and
regulations. 

        7.    TERM.    You may not exercise your option before the commencement of its term or after
its term expires. The term of your option commences on the Date of Grant and expires upon the earliest of the following: 

        (a)   three (3) months after the termination of your Continuous Service for any reason other than your Disability or
death, provided that if during any part of such three (3) month period your option is not exercisable solely because of the condition set forth in the preceding paragraph relating to
"Securities Law Compliance," your option shall not expire until the earlier of the Expiration Date or until it shall have been exercisable for an aggregate period of three (3) months after the
termination of your Continuous Service; 

        (b)   twelve (12) months after the termination of your Continuous Service due to your Disability or upon a Change in
Control; 

        (c)   eighteen (18) months after your death if you die either during your Continuous Service or within three
(3) months after your Continuous Service terminates; 

        (d)   immediately upon the termination of your Continuous Service for Cause; 

        (e)   the Expiration Date indicated in your Grant Notice; or 

        (f)    the day before the tenth (10th) anniversary of the Date of Grant. 

        8.    EXERCISE.    

        (a)   You may exercise the vested portion of your option (and the unvested portion of your option if your Grant Notice so
permits) during its term by delivering a Notice of Exercise (in a form designated by the Company) together with the exercise price to the Secretary of the Company, or to such other person as the
Company may designate, during regular business hours, together with such additional documents as the Company may then require. 

        (b)   By exercising your option you agree that, as a condition to any exercise of your option, the Company may require you to
enter into an arrangement providing for the payment by you to the Company of any tax withholding obligation of the Company arising by reason of (1) the exercise of your option, (2) the
lapse of any substantial risk of forfeiture to which the shares of Common Stock are subject at the time of exercise, or (3) the disposition of shares of Common Stock acquired upon such
exercise. 

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        9.    TRANSFERABILITY.    Your option is not transferable, except (i) by will or by the
laws of descent and distribution, (ii) with the prior written approval of the Company, by instrument to an inter vivos or testamentary trust, in a form accepted by the Company, in which the
option is to be passed to beneficiaries upon the death of the trustor (settlor) and (iii) with the prior written approval of the Company, by gift, in a form accepted by the Company, to a
permitted transferee under Rule 701 of the Securities Act. 

        10.    OPTION NOT A SERVICE CONTRACT.    Your option is not an employment or service
contract,
and nothing in your option shall be deemed to create in any way whatsoever any obligation on your part to continue
in the employ of the Company or an Affiliate, or of the Company or an Affiliate to continue your employment. In addition, nothing in your option shall obligate the Company or an Affiliate, their
respective shareholders, Boards of Directors, Officers or Employees to continue any relationship that you might have as a Director or Consultant for the Company or an Affiliate. 

        11.    WITHHOLDING OBLIGATIONS.    

        (a)   At the time you exercise your option, in whole or in part, or at any time thereafter as requested by the Company, you
hereby authorize withholding from payroll and any other amounts payable to you, and otherwise agree to make adequate provision as directed by the Company (including by means of a "cashless exercise"
pursuant to a program developed under Regulation T as promulgated by the Federal Reserve Board to the extent directed by the Company), for any sums required to satisfy the federal, state, local
and foreign tax withholding obligations of the Company or an Affiliate, if any, which arise in connection with your option. 

        (b)   The Company may, in its sole discretion, and in compliance with any applicable conditions or restrictions of law,
withhold from fully vested shares of Common Stock otherwise issuable to you upon the exercise of your option a number of whole shares of Common Stock having a Fair Market Value, determined by the
Company as of the date of exercise, not in excess of the minimum amount of tax required to be withheld by law. Any adverse consequences to you arising in connection with such share withholding
procedure shall be your sole responsibility. 

        (c)   You may not exercise your option unless the tax withholding obligations of the Company and/or any Affiliate are
satisfied. Accordingly, you may not be able to exercise your option when desired even though your option is vested, and the Company shall have no obligation to issue a certificate for such shares of
Common Stock or release such shares of Common Stock from any escrow provided for herein. 

        (d)   If any payment or benefit you would receive pursuant to a Change in Control from the Company or otherwise
("Payment") would (i) constitute a "parachute payment" within the meaning of Section 280G
of the Code, and (ii) but for this sentence, be subject to the excise tax imposed by Section 4999 of the Code (the "Excise
Tax"), then such Payment shall be equal to the Reduced Amount. The "Reduced Amount" shall be either (x) the largest portion of the Payment that
would result in no portion of the Payment being subject to the Excise Tax or (y) the largest portion, up to and including the total, of the Payment, whichever amount, after taking into account
all applicable federal, state and local employment taxes, income taxes, and the Excise Tax (all computed at the highest applicable marginal rate), results in your receipt, on an after-tax
basis, of the greater amount of the Payment notwithstanding that all or some portion of the Payment may be subject to the Excise Tax. If a reduction in payments or benefits constituting "parachute
payments" is necessary so that the Payment equals the Reduced Amount, reduction shall occur in the following order unless you elect in writing a different order (provided,
however, that such election shall be subject to Company approval if made on or after the effective date of the event that triggers the Payment): reduction of cash payments;
cancellation of accelerated vesting of Stock Awards; reduction of employee benefits. In the event that acceleration of vesting of Stock Award compensation is to be reduced, such acceleration of
vesting shall be cancelled in the reverse order 

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of
the date of grant of your Stock Awards (i.e., earliest granted Stock Award cancelled last) unless you elect in writing a different order for cancellation. 

        The
accounting firm engaged by the Company for general audit purposes as of the day prior to the effective date of the Change in Control shall perform the foregoing calculations. If the
accounting firm so engaged by the Company is serving as accountant or auditor for the individual, entity or group effecting the Change in Control, the Company shall appoint a nationally recognized
accounting firm to make the determinations required hereunder. The Company shall bear all expenses with respect to the determinations by such accounting firm required to be made hereunder. 

        The
accounting firm engaged to make the determinations hereunder shall provide its calculations, together with detailed supporting documentation, to you and the Company within fifteen
(15) calendar days after the date on which your right to a Payment is triggered (if requested at that time by you or the Company) or such other time as requested by you or the Company. If the
accounting firm determines that no Excise Tax is payable with respect to a Payment, either before or after the application of the Reduced Amount, it shall furnish you and the Company with an opinion
reasonably acceptable to you that no Excise Tax will be imposed with respect to such Payment. Any good faith determinations of the accounting firm made hereunder shall be final, binding and conclusive
upon you and the Company. 

        12.    NOTICES.    Any notices provided for in your option or the Plan shall be given in
writing and shall be deemed effectively given upon receipt or, in the case of notices delivered by mail by the Company to you, five (5) days after deposit in the United States mail, postage
prepaid, addressed to you at the last address you provided to the Company. 

        13.    GOVERNING PLAN DOCUMENT.    Your option is subject to all the provisions of the Plan,
the provisions of which are hereby made a part of your option, and is further subject to all interpretations, amendments, rules and regulations which may from time to time be promulgated and adopted
pursuant to the Plan. In the event of any conflict between the provisions of your option and those of the Plan, the provisions of the Plan shall control. 

4

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SENOMYX, INC. 2004 EQUITY INCENTIVE PLAN STOCK OPTION AGREEMENT (INCENTIVE STOCK OPTION OR NONSTATUTORY STOCK OPTION)

SENOMYX, INC. 2004 EQUITY INCENTIVE PLAN NON-EMPLOYEE DIRECTORS' STOCK OPTION PROGRAM STOCK OPTION AGREEMENT (NONSTATUTORY STOCK OPTION)QuickLinks
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Exhibit 10.4  

 
 

SENOMYX, INC.    
    
    2004 EMPLOYEE STOCK PURCHASE PLAN    
    
    ADOPTED BY THE BOARD OF DIRECTORS APRIL 30, 2004
  APPROVED BY STOCKHOLDERS JUNE 7, 2004    
    

1.     PURPOSE.  

        (a)   The purpose of the Plan is to provide a means by which Employees of the Company and certain designated Related
Corporations may be given an opportunity to purchase shares of the Common Stock of the Company. 

        (b)   The Company, by means of the Plan, seeks to secure and retain the services of current and new Employees and to provide
incentives for such persons to exert maximum efforts for the success of the Company and its Related Corporations. 

        (c)   The Company intends that the Purchase Rights be considered options issued under an Employee Stock Purchase Plan. 

2.     DEFINITIONS.  

        As used in the Plan and any Offering, unless otherwise specified, the following terms have the meanings set forth below: 

        (a)   "Board" means the Board of Directors of the Company. 

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

        (c)   "Committee" means a committee appointed by the Board in accordance with Section 3(c) of
the Plan. 

        (d)   "Common Stock" means the common stock of the Company. 

        (e)   "Company" means Senomyx, Inc., a Delaware corporation. 

        (f)    "Contributions" means the payroll deductions and other additional payments that a Participant
contributes to fund the exercise of a Purchase Right. A Participant may make payments not through payroll deductions only if specifically provided for in the Offering, and then only if the Participant
has not already had the maximum permitted amount withheld through payroll deductions during the Offering. 

        (g)   "Corporate Transaction" means the occurrence, in a single transaction or in a series of related
transactions, of any one or more of the following events: 

        (i)    a sale, lease, license or other disposition of all or substantially all of the consolidated assets of the Company; 

        (ii)   a sale or other disposition of at least ninety percent (90%) of the outstanding securities of the Company; 

        (iii) a merger, consolidation or similar transaction following which the Company is not the surviving corporation; or 

        (iv)  a merger, consolidation or similar transaction following which the Company is the surviving corporation but the shares
of Common Stock outstanding immediately preceding the 

1

 

merger,
consolidation or similar transaction are converted or exchanged by virtue of the merger, consolidation or similar transaction into other property, whether in the form of securities, cash or
otherwise. 

        (h)   "Director" means a member of the Board. 

        (i)    "Eligible Employee" means an Employee who meets the requirements set forth in the Offering for
eligibility to participate in the Offering, provided that such Employee also meets the requirements for eligibility to participate set forth in the Plan. 

        (j)    "Employee" means any person, including Officers and Directors, who is employed for purposes of
Section 423(b)(4) of the Code by the Company or a Related Corporation. Neither service as a Director nor payment of a director's fee shall be sufficient to make an individual an Employee of the
Company or a Related Corporation. 

        (k)   "Employee Stock Purchase Plan" means a plan that grants Purchase Rights intended to be options
issued under an "employee stock purchase plan," as that term is defined in Section 423(b) of the Code. 

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

        (m)  "Fair Market Value" means the value of a security, as determined in good faith by the Board. If
the security is listed on any established stock exchange or traded on the Nasdaq National Market or the Nasdaq SmallCap Market, the Fair Market Value of the security, unless otherwise determined by
the Board, shall be the closing sales price (rounded up where necessary to the nearest whole cent) for such security (or the closing bid, if no sales were reported) as quoted on such exchange or
market (or the
exchange or market with the greatest volume of trading in the relevant security of the Company) on the Trading Day prior to the relevant determination date, as reported in The
Wall Street Journal or such other source as the Board deems reliable. 

        (n)   "IPO Date" means the effective date of the initial public offering of the Common Stock. 

        (o)   "Offering" means the grant of Purchase Rights to purchase shares of Common Stock under the Plan
to Eligible Employees. 

        (p)   "Offering Date" means a date selected by the Board for an Offering to commence. 

        (q)   "Officer" means a person who is an officer of the Company within the
meaning of Section 16 of the Exchange Act and the rules and regulations promulgated thereunder. 

        (r)   "Participant" means an Eligible Employee who holds an outstanding Purchase Right granted pursuant
to the Plan. 

        (s)   "Plan" means this Senomyx, Inc. 2004 Employee Stock Purchase Plan. 

        (t)    "Purchase Date" means one or more dates during an Offering established by the Board on which
Purchase Rights shall be exercised and as of which purchases of shares of Common Stock shall be carried out in accordance with such Offering. 

        (u)   "Purchase Period" means a period of time specified within an Offering beginning on the Offering
Date or on the next day following a Purchase Date within an Offering and ending on a Purchase Date. An Offering may consist of one or more Purchase Periods. 

        (v)   "Purchase Right" means an option to purchase shares of Common Stock granted pursuant to the Plan. 

        (w)  "Related Corporation" means any parent corporation or subsidiary corporation, whether now or
hereafter existing, as those terms are defined in Sections 424(e) and (f), respectively, of the Code. 

2

 

        (x)   "Securities Act" means the Securities Act of 1933, as amended. 

        (y)   "Trading Day" means any day on which the exchange(s) or market(s) on
which shares of Common Stock are listed, whether it be an established stock exchange, the Nasdaq National Market, the Nasdaq SmallCap Market or otherwise, is open for trading. 

3.     ADMINISTRATION.  

        (a)   The Board shall administer the Plan unless and until the Board delegates administration to a Committee, as provided in
Section 3(c). Whether or not the Board has delegated administration, the Board shall have the final power to determine all questions of policy and expediency that may arise in the
administration of the Plan. 

        (b)   The Board (or the Committee) shall have the power, subject to, and within the limitations of, the express provisions of
the Plan: 

        (i)    To determine when and how Purchase Rights to purchase shares of Common Stock shall be granted and the provisions of each
Offering of such Purchase Rights (which need not be identical). 

        (ii)   To designate from time to time which Related Corporations of the Company shall be eligible to participate in the Plan. 

        (iii) To construe and interpret the Plan and Purchase Rights, and to establish, amend and revoke rules and regulations for
the administration of the Plan. The Board, in the exercise of this power, may correct any defect, omission or inconsistency in the Plan, in a manner and to the extent it shall deem necessary or
expedient to make the Plan fully effective. 

        (iv)  To amend the Plan as provided in Section 15. 

        (v)   Generally, to exercise such powers and to perform such acts as it deems necessary or expedient to promote the best
interests of the Company and its Related Corporations and to carry out the intent that the Plan be treated as an Employee Stock Purchase Plan. 

        (vi)  To adopt such procedures and sub-plans as are necessary or appropriate to permit participation in the Plan
by Employees who are foreign nationals or employed outside the United States. 

        (c)   The Board may delegate administration of the Plan to a Committee of the Board composed of one (1) or more members
of the Board. If administration of the Plan is delegated to a Committee, the Committee shall have, in connection with the administration of the Plan, the powers theretofore possessed by the Board,
subject, however, to such resolutions, not inconsistent with the provisions of the Plan, as may be adopted from time to time by the Board. The Board may abolish the Committee at any time and revest in
the Board some or all of the powers previously delegated. If administration is delegated to a Committee, references to the Board in this Plan and in the Offering document shall thereafter be deemed to
be to the Board or the Committee, as the case may be. 

        (d)   All determinations, interpretations and constructions made by the Board in good faith shall not be subject to review by
any person and shall be final, binding and conclusive on all persons. 

4.     SHARES OF COMMON STOCK SUBJECT TO THE PLAN.  

        Subject to the provisions of Section 14(a) relating to adjustments upon changes in Common Stock, the stock that may be sold pursuant to Purchase Rights
granted under the Plan shall not exceed in the aggregate one hundred and forty thousand (140,000) shares of Common Stock, plus an annual increase 

3

 

to
be added on the first day of each Company fiscal year, beginning in 2005 and ending in (and including) 2013, equal to the least of the following amounts: (i) one percent (1%) of the
Company's outstanding shares of Common Stock on the day preceding the first day of the applicable Company fiscal year (rounded to the nearest whole share), (ii) two hundred eighty thousand
(280,000) shares of Common Stock, or (iii) an amount determined by the Board. 

5.     GRANT OF PURCHASE RIGHTS; OFFERING.  

        (a)   The Board may from time to time grant or provide for the grant of Purchase Rights to purchase shares of Common Stock
under the Plan to Eligible Employees in an Offering (consisting of one or more Purchase Periods) on an Offering Date or Offering Dates selected by the Board. Each Offering shall be in such form and
shall contain such terms and conditions as the Board shall deem appropriate, which shall comply with the requirement of Section 423(b)(5) of the Code that all Employees granted Purchase Rights
shall have the same rights and privileges. The terms and conditions of an Offering shall be incorporated by reference into the Plan and treated as part of the Plan. The provisions of separate
Offerings need not be identical, but each Offering shall include (through incorporation of the provisions of this Plan by reference in the document comprising the Offering or otherwise) the period
during which the Offering shall be effective, which period shall not exceed twenty-seven (27) months beginning with the Offering Date, and the substance of the provisions contained in Sections
6 through 9, inclusive. 

        (b)   If a Participant has more than one Purchase Right outstanding under the Plan, unless he or she otherwise indicates in
agreements or notices delivered hereunder: (i) each agreement or notice delivered by that Participant shall be deemed to apply to all of his or her Purchase Rights under the Plan, and
(ii) a Purchase Right with a lower exercise price (or an earlier-granted Purchase Right, if different Purchase Rights have identical exercise prices) shall be exercised to the fullest possible
extent before a Purchase Right with a higher exercise price (or a later-granted Purchase Right if different Purchase Rights have identical exercise prices) shall be exercised. 

6.     ELIGIBILITY.  

        (a)   Purchase Rights may be granted only to Employees of the Company or, as the Board may designate as provided in
Section 3(b), to Employees of a Related Corporation. Except as provided in Section 6(b), an Employee shall not be eligible to be granted Purchase Rights under the Plan unless, on the
Offering Date, such Employee has been in the employ of the Company or the Related Corporation, as the case may be, for such continuous period preceding such Offering Date as the Board may require, but
in no event shall the required period of continuous employment be greater than two (2) years. In addition, the Board may provide that no Employee shall be eligible to be granted Purchase Rights
under the Plan unless, on the Offering Date, such Employee's customary employment with the Company or the Related Corporation is more than twenty (20) hours per week and/or more than five
(5) months per calendar year. 

        (b)   The Board may provide that each person who, during the course of an Offering, first becomes an Eligible Employee shall,
on a date or dates specified in the Offering which coincides with the day on which such person becomes an Eligible Employee or which occurs thereafter, receive a Purchase Right under that Offering,
which Purchase Right shall thereafter be deemed to be a part of that Offering. Such Purchase Right shall have the same characteristics as any Purchase Rights originally granted under that Offering, as
described herein, except that: 

        (i)    the date on which such Purchase Right is granted shall be the "Offering Date" of such Purchase Right for all purposes,
including determination of the exercise price of such Purchase Right; 

4

 

        (ii)   the period of the Offering with respect to such Purchase Right shall begin on its Offering Date and end coincident with
the end of such Offering; and 

        (iii) the Board may provide that if such person first becomes an Eligible Employee within a specified period of time before
the end of the Offering, he or she shall not receive any Purchase Right under that Offering. 

        (c)   No Employee shall be eligible for the grant of any Purchase Rights under the Plan if, immediately after any such Purchase
Rights are granted, such Employee owns stock possessing five percent (5%) or more of the total combined voting power or value of all classes of stock of the Company or of any Related Corporation. For
purposes of this Section 6(c), the rules of Section 424(d) of the Code shall apply in determining the stock ownership of any Employee, and stock which such Employee may purchase under
all outstanding Purchase Rights and options shall be treated as stock owned by such Employee. 

        (d)   As specified by Section 423(b)(8) of the Code, an Eligible Employee may be granted Purchase Rights under the Plan
only if such Purchase Rights, together with any other rights granted under all Employee Stock Purchase Plans of the Company and any Related Corporations, do not permit such Eligible Employee's rights
to purchase stock of the Company or any Related Corporation to accrue at a rate which exceeds twenty five thousand dollars ($25,000) of Fair Market Value of such stock (determined at the time such
rights are granted, and which, with respect to the Plan, shall be determined as of their respective Offering Dates) for each calendar year in which such rights are outstanding at any time. 

        (e)   Officers of the Company and any designated Related Corporation, if they are otherwise Eligible Employees, shall be
eligible to participate in Offerings under the Plan. Notwithstanding the foregoing,
the Board may provide in an Offering that Employees who are highly compensated Employees within the meaning of Section 423(b)(4)(D) of the Code shall not be eligible to participate. 

7.     PURCHASE RIGHTS; PURCHASE PRICE.  

        (a)   On each Offering Date, each Eligible Employee, pursuant to an Offering made under the Plan, shall be granted a Purchase
Right to purchase up to that number of shares of Common Stock purchasable either with a percentage or with a maximum dollar amount, as designated by the Board, but in either case not exceeding fifteen
percent (15%), of such Employee's Earnings (as defined by the Board in each Offering) during the period that begins on the Offering Date (or such later date as the Board determines for a particular
Offering) and ends on the date stated in the Offering, which date shall be no later than the end of the Offering. 

        (b)   The Board shall establish one (1) or more Purchase Dates during an Offering as of which Purchase Rights granted
pursuant to that Offering shall be exercised and purchases of shares of Common Stock shall be carried out in accordance with such Offering. 

        (c)   In connection with each Offering made under the Plan, the Board may specify a maximum number of shares of Common Stock
that may be purchased by any Participant on any Purchase Date during such Offering. In connection with each Offering made under the Plan, the Board may specify a maximum aggregate number of shares of
Common Stock that may be purchased by all Participants pursuant to such Offering. In addition, in connection with each Offering that contains more than one Purchase Date, the Board may specify a
maximum aggregate number of shares of Common Stock that may be purchased by all Participants on any Purchase Date under the Offering. If the aggregate purchase of shares of Common Stock issuable upon
exercise of Purchase Rights granted under the Offering would exceed any such maximum aggregate number, then, in the absence of any Board action otherwise, a pro rata allocation of the shares of 

5

 

Common
Stock available shall be made in as nearly a uniform manner as shall be practicable and equitable. 

        (d)   The purchase price of shares of Common Stock acquired pursuant to Purchase Rights shall be not less than the lesser of: 

        (i)    an amount equal to eighty-five percent (85%) of the Fair Market Value of the shares of Common Stock on the
Offering Date; or 

        (ii)   an amount equal to eighty-five percent (85%) of the Fair Market Value of the shares of Common Stock on the
applicable Purchase Date. 

8.     PARTICIPATION; WITHDRAWAL; TERMINATION.  

        (a)   A Participant may elect to authorize payroll deductions pursuant to an Offering under the Plan by completing and
delivering to the Company, within the time specified in the Offering, an enrollment form (in such form as the Company may provide). Each such enrollment form shall authorize an amount of Contributions
expressed as a percentage of the submitting Participant's Earnings (as defined in each Offering) during the Offering (not to exceed the maximum percentage specified by the Board). Each Participant's
Contributions shall remain the property of the Participant at all times prior to the purchase of Common Stock, but such Contributions may be commingled with the assets of the Company and used for
general corporate purposes except where applicable law requires that Contributions be deposited with an independent third party. To the extent provided in the Offering, a Participant may begin making
Contributions after the beginning of the Offering. To the extent provided in the Offering, a Participant may thereafter reduce (including to zero) or increase his or her Contributions. To the extent
specifically provided in the Offering, in addition to making Contributions by payroll deductions, a Participant may make Contributions through the payment by cash or check prior to each Purchase Date
of the Offering. 

        (b)   During an Offering, a Participant may cease making Contributions and withdraw from the Offering by delivering to the
Company a notice of withdrawal in such form as the Company may provide. Such withdrawal may be elected at any time prior to the end of the Offering, except as provided otherwise in the Offering. Upon
such withdrawal from the Offering by a Participant, the Company shall distribute to such Participant all of his or her accumulated Contributions (reduced to the extent, if any, such Contributions have
been used to acquire shares of Common Stock for the Participant) under the Offering, and such Participant's Purchase Right in that Offering shall thereupon terminate. A Participant's withdrawal from
an Offering shall have no effect upon such Participant's eligibility to participate in any other Offerings under the Plan, but such Participant shall be required to deliver a new enrollment form in
order to participate in subsequent Offerings. 

        (c)   Purchase Rights granted pursuant to any Offering under the Plan shall terminate immediately upon a Participant ceasing to
be an Employee for any reason or for no reason (subject to any post-employment participation period required by law) or other lack of eligibility. The Company shall distribute to such
terminated or otherwise ineligible Employee all of his or her accumulated Contributions (reduced to the extent, if any, such Contributions have been used to acquire shares of Common Stock for the
terminated or otherwise ineligible Employee) under the Offering. 

        (d)   Purchase Rights shall not be transferable by a Participant otherwise than by will, the laws of descent and distribution,
or a beneficiary designation as provided in Section 13. During a Participant's lifetime, Purchase Rights shall be exercisable only by such Participant. 

        (e)   Unless otherwise specified in an Offering, the Company shall have no obligation to pay interest on Contributions. 

6

 

9.     EXERCISE.  

        (a)   On each Purchase Date during an Offering, each Participant's accumulated Contributions shall be applied to the purchase
of shares of Common Stock up to the maximum number of shares of Common Stock permitted pursuant to the terms of the Plan and the applicable Offering, at the purchase price specified in the Offering.
No fractional shares shall be issued upon the exercise of Purchase Rights unless specifically provided for in the Offering. 

        (b)   If any amount of accumulated Contributions remains in a Participant's account after the purchase of shares of Common
Stock and such remaining amount is less than the amount required to purchase one share of Common Stock on the final Purchase Date of an Offering, then such remaining amount shall be held in such
Participant's account for the purchase of shares of Common Stock under the next Offering under the Plan, unless such Participant withdraws from such next Offering, as provided in Section 8(b),
or is not eligible to participate in such Offering, as provided in Section 6, in which case such amount shall be distributed to such Participant after the final Purchase Date, without interest.
If the amount of Contributions remaining in a Participant's account after the purchase of shares of Common Stock is at least equal to the amount required to purchase one (1) whole share of
Common Stock on the final Purchase Date of the Offering, then such remaining amount shall be distributed in full to such Participant at the end of the Offering. 

        (c)   No Purchase Rights may be exercised to any extent unless the shares of Common Stock to be issued upon such exercise under
the Plan are covered by an effective registration statement pursuant to the Securities Act and the Plan is in material compliance with all laws applicable to the Plan. If on a Purchase Date during any
Offering hereunder the shares of Common Stock are not so registered or the Plan is not in such compliance, no Purchase Rights or any Offering shall be exercised on such Purchase Date, and the Purchase
Date shall be delayed until the shares of Common Stock are subject to such an
effective registration statement and the Plan is in such compliance, except that the Purchase Date shall not be delayed more than twelve (12) months and the Purchase Date shall in no event be
more than twenty-seven (27) months from the Offering Date. If, on the Purchase Date under any Offering hereunder, as delayed to the maximum extent permissible, the shares of Common Stock are
not registered and the Plan is not in such compliance, no Purchase Rights or any Offering shall be exercised and all Contributions accumulated during the Offering (reduced to the extent, if any, such
Contributions have been used to acquire shares of Common Stock) shall be distributed to the Participants. 

10.   COVENANTS OF THE COMPANY.  

        The Company shall seek to obtain from each federal, state, foreign or other regulatory commission or agency having jurisdiction over the Plan such authority as
may be required to issue and sell shares of Common Stock upon exercise of the Purchase Rights. If, after commercially reasonable efforts, the Company is unable to obtain from any such regulatory
commission or agency the authority that counsel for the Company deems necessary for the lawful issuance and sale of shares of Common Stock under the Plan, the Company shall be relieved from any
liability for failure to issue and sell shares of Common Stock upon exercise of such Purchase Rights unless and until such authority is obtained. 

11.   USE OF PROCEEDS FROM SHARES OF COMMON STOCK.  

        Proceeds from the sale of shares of Common Stock pursuant to Purchase Rights shall constitute general funds of the Company. 

12.   RIGHTS AS A STOCKHOLDER.  

        A Participant shall not be deemed to be the holder of, or to have any of the rights of a holder with respect to, shares of Common Stock subject to Purchase Rights
unless and until the Participant's 

7

 

shares
of Common Stock acquired upon exercise of Purchase Rights are recorded in the books of the Company (or its transfer agent). 

13.   DESIGNATION OF BENEFICIARY.  

        (a)   A Participant may file a written designation of a beneficiary who is to receive any shares of Common Stock and/or
cash, if any, from the Participant's account under the Plan in the event of such Participant's death subsequent to the end of an Offering but prior to delivery to the Participant of such shares of
Common Stock or cash. In addition, a Participant may file a written designation of a beneficiary who is to receive any cash from the Participant's account under the Plan in the event of such
Participant's death during an Offering. Any such designation shall be on a form provided by or otherwise acceptable to the Company. 

        (b)   The Participant may change such designation of beneficiary at any time by written notice to the Company. In the event of
the death of a Participant and in the absence of a beneficiary validly designated under the Plan who is living at the time of such Participant's death, the Company shall deliver such shares of Common
Stock and/or cash to the executor or administrator of the estate of the Participant, or if no such executor or administrator has been appointed (to the knowledge of the Company), the Company, in its
sole discretion, may deliver such shares of Common Stock and/or cash to the spouse or to any one or more dependents or relatives of the Participant, or if no spouse, dependent or relative is known to
the Company, then to such other person as the Company may designate. 

14.   ADJUSTMENTS UPON CHANGES IN SECURITIES; CORPORATE TRANSACTIONS.  

        (a)   If any change is made in the shares of Common Stock, subject to the Plan, or subject to any Purchase Right, without the
receipt of consideration by the Company (through merger, consolidation, reorganization, recapitalization, reincorporation, stock dividend, dividend in property other than cash, stock split,
liquidating dividend, combination of shares, exchange of shares, change in corporate structure or other transaction not involving the receipt of consideration by the Company), the Plan shall be
appropriately adjusted in the type(s), class(es) and maximum number of shares of Common Stock subject to the Plan pursuant to Section 4(a), and the outstanding Purchase Rights shall be
appropriately adjusted in the type(s), class(es), number of shares and purchase limits of such outstanding Purchase Rights. The Board shall make such adjustments, and its determination shall be final,
binding and conclusive. (Notwithstanding the foregoing, the conversion of any convertible securities of the Company shall not be treated as a "transaction not involving the receipt of consideration by
the Company.") 

        (b)   In the event of a Corporate Transaction, then: (i) any surviving or acquiring corporation may continue or assume
Purchase Rights outstanding under the Plan or may substitute similar rights (including a right to acquire the same consideration paid to stockholders in the Corporate Transaction) for those
outstanding under the Plan, or (ii) if any surviving or acquiring corporation does not continue or assume such Purchase Rights or does not substitute similar rights for Purchase Rights
outstanding under the Plan, then, the Participants' accumulated Contributions shall be used to purchase shares of Common Stock within ten (10) business days prior to the Corporate Transaction
under the ongoing Offering, and the Participants' Purchase Rights under the ongoing Offering shall terminate immediately after such purchase. 

15.   AMENDMENT OF THE PLAN.  

        (a)   The Board at any time, and from time to time, may amend the Plan. However, except as provided in Section 14
relating to adjustments upon changes in securities and except as to amendments solely to benefit the administration of the Plan, to take account of a change in 

8

 

legislation
or to obtain or maintain favorable tax, exchange control or regulatory treatment for Participants or the Company or any Related Corporation, no amendment shall be effective unless approved
by the stockholders of the Company to the extent stockholder approval is necessary for the Plan to satisfy the requirements of Section 423 of the Code or other applicable laws or regulations. 

        (b)   It is expressly contemplated that the Board may amend the Plan in any respect the Board deems necessary or advisable to
provide Employees with the maximum benefits provided or to be provided under the provisions of the Code and the regulations promulgated thereunder relating to Employee Stock Purchase Plans or to bring
the Plan and/or Purchase Rights into compliance therewith. 

        (c)   The rights and obligations under any Purchase Rights granted before amendment of the Plan shall not be impaired by any
amendment of the Plan except: (i) with the consent of the person to whom such Purchase Rights were granted, or (ii) as necessary to comply with any laws or governmental regulations
(including, without limitation, the provisions of the Code and the regulations promulgated thereunder relating to Employee Stock Purchase Plans). 

16.   TERMINATION OR SUSPENSION OF THE PLAN.  

        (a)   The Board in its discretion may suspend or terminate the Plan at any time. Unless sooner terminated, the Plan shall
terminate at the time that all of the shares of Common Stock reserved for issuance under the Plan, as increased and/or adjusted from time to time, have been issued under the terms of the Plan. No
Purchase Rights may be granted under the Plan while the Plan is suspended or after it is terminated. 

        (b)   Any benefits, privileges, entitlements and obligations under any Purchase Rights while the Plan is in effect shall not be
impaired by suspension or termination of the Plan except (i) as expressly provided in the Plan or with the consent of the person to whom such Purchase Rights were granted, (ii) as
necessary to comply with any laws, regulations, or listing requirements, or (iii) as necessary to ensure that the Plan and/or Purchase Rights comply with the requirements of Section 423
of the Code. 

17.   EFFECTIVE DATE OF PLAN.  

        The Plan shall become effective on the IPO Date, but no Purchase Rights shall be exercised unless and until the Plan has been approved by the stockholders of the
Company within twelve (12) months before or after the date the Plan is adopted by the Board. 

18.   MISCELLANEOUS PROVISIONS.  

        (a)   The Plan and Offering do not constitute an employment contract. Nothing in the Plan or in the Offering shall in any way
alter the at will nature of a Participant's employment or be deemed to create in any way whatsoever any obligation on the part of any Participant to continue in the employ of the Company or a Related
Corporation, or on the part of the Company or a Related Corporation to continue the employment of a Participant. 

        (b)   The provisions of the Plan shall be governed by the law of the State of California without resort to that state's
conflicts of laws rules. 

9

 
 

SENOMYX, INC.    
    
    2004 EMPLOYEE STOCK PURCHASE PLAN    
    
    OFFERING DOCUMENT    
    

Adopted by the Board of Directors: April 30, 2004  

        In this document, capitalized terms not otherwise defined shall have the same definitions as set forth in Senomyx, Inc., 2004 Employee Stock Purchase Plan. 

1.     Grant; Offering Date.  

        (a)   The Board hereby authorizes a series of Offerings pursuant to the terms of this Offering document. 

        (b)   The first Offering hereunder (the "Initial Offering") shall begin on June     , 2004 (the "IPO Date")
and shall end on August 30, 2006, unless terminated earlier as provided below. After the Initial Offering, an additional new Offering shall begin on the day after the first Purchase Date of the
immediately preceding Offering; provided, however, the first additional new Offering shall begin on September 1, 2004 rather than March 1, 2005. The first day of an Offering is that
Offering's "Offering Date." Except as provided below, each Offering shall be approximately twenty-four (24) months in duration, with four (4) Purchase Periods which, except
for the first Purchase Period of the Initial Offering (which may be longer or shorter) and except as otherwise provided herein, shall be six (6) months in length. Except as provided below, a
Purchase Date is the last day of a Purchase Period or of an Offering, as the case may be. The Initial Offering shall consist of four (4) Purchase Periods with the first Purchase Period of the
Initial Offering ending on February 28, 2005. 

        (c)   Notwithstanding the foregoing: (i) if any Offering Date falls on a day that is not a Trading Day, then such
Offering Date shall instead fall on the next subsequent Trading Day, and (ii) if any Purchase Date falls on a day that is not a Trading Day, then such Purchase Date shall instead fall on the
immediately preceding Trading Day. 

        (d)   Prior to the commencement of any Offering, the Board may change any or all terms of such Offering and any subsequent
Offerings. The granting of Purchase Rights pursuant to each Offering hereunder shall occur on each respective Offering Date unless prior to such date (i) the Board determines that such Offering
shall not occur, or (ii) no shares of Common Stock remain available for issuance under the Plan in connection with the Offering. 

        (e)   Notwithstanding anything in this Section 1 to the contrary, if on the first day of a Purchase Period during an
Offering the Fair Market Value of the shares of Common Stock is less than it was on the Offering Date for that Offering, the Offering that would otherwise have continued in effect shall immediately
terminate and the Employees who were enrolled in the terminated Offering shall automatically be enrolled in the new Offering that starts such day. Notwithstanding the foregoing, if on the Offering
Date of the Offering that begins on September 1, 2004, the Fair Market Value of the shares of Common Stock is less than it was on the Offering Date for the Initial Offering, the Initial
Offering shall immediately terminate and the Employees who were enrolled in such terminated Offering shall automatically be enrolled in the new Offering that starts on September 1, 2004. 

        (f)    If the Company's accountants advise the Company that the accounting treatment of purchases under the Plan will change or
has changed in a manner that the Company determines is detrimental to its best interests, then the Company may, in its discretion, take any or all of the following actions: (i) terminate each
ongoing Offering as of the next Purchase Date (after the purchase of stock on such Purchase Date) under such Offering; (ii) set a new Purchase Date for each ongoing Offering and terminate each
such Offering after the purchase of stock on such Purchase Date; (iii) amend the Plan and each ongoing Offering to reduce or eliminate an accounting treatment that is detrimental to the
Company's best interests and (iv) terminate each ongoing Offering and refund any money contributed to the Participants. 

 

2.     Eligible Employees.  

        (a)   Each Eligible Employee who, on the Offering Date of an Offering hereunder, is (i) an employee of the Company;
(ii) an employee of a Subsidiary incorporated in the United States; or (iii) an employee of a Subsidiary that is not incorporated in the United States, provided that the Board or
Committee has designated the employees of such Subsidiary as eligible to participate in the Offering, shall be granted a Purchase Right on the Offering Date of such Offering. 

        (b)   Notwithstanding the foregoing, the following Employees shall not be Eligible Employees or be granted Purchase Rights
under an Offering: 

        (i)    part-time or seasonal Employees whose customary employment is twenty (20) hours per week or less or
five (5) months per calendar year or less; 

        (ii)   five percent (5%) stockholders (including ownership through unexercised and/or unvested stock options) as described in
Section 6(c) of the Plan; or 

        (iii) Employees in jurisdictions outside of the United States if, as of the Offering Date of the Offering, the grant of such
Purchase Rights would not be in compliance with the applicable laws of any jurisdiction in which the Employee resides or is employed. 

        (c)   Notwithstanding the foregoing, each person who first becomes an Eligible Employee during an ongoing Offering shall not be
able to participate in such Offering. 

3.     Purchase Rights.  

        (a)   Subject to the limitations set forth herein and in the Plan, a Participant's Purchase Right shall permit the purchase of
the number of shares of Common Stock purchasable with up to fifteen percent (15%) of such Participant's Earnings paid during the period of such Offering beginning immediately after such Participant
first commences participation; provided, however, that no Participant may have more than fifteen percent (15%) of such Participant's Earnings applied to
purchase shares of Common Stock under all ongoing Offerings under the Plan and all other plans of the Company and Related Corporations that are intended to qualify as Employee Stock Purchase Plans. 

        (b)   For Offerings hereunder, "Earnings" means the base compensation paid to a Participant, including all salary and wages
(including amounts elected to be deferred by the Participant, that would otherwise have been paid, under any cash or deferred arrangement or other deferred compensation program established by the
Company or a Related Corporation), overtime pay, commissions and bonuses; but excluding all other remuneration paid directly to such Participant, profit sharing, the cost of employee benefits paid for
by the Company or a Related Corporation, education or tuition reimbursements, imputed income arising under any Company or Related Corporation group insurance or benefit program, traveling expenses,
business and moving expense reimbursements, income received in connection with stock options, contributions made by the Company or a Related Corporation under any employee benefit plan, and similar
items of compensation. 

        (c)   Notwithstanding the foregoing, the maximum number of shares of Common Stock that a Participant may purchase on any
Purchase Date in an Offering shall be such number of shares as has a Fair Market Value (determined as of the Offering Date for such Offering) equal to (x) $25,000 multiplied by the number of
calendar years in which the Purchase Right under such Offering has been outstanding at any time, minus (y) the Fair Market Value of any other shares of Common Stock (determined as of the
relevant Offering Date with respect to such shares) that, for purposes of the limitation of Section 423(b)(8) of the Code, are attributed to any of such calendar years in which the Purchase
Right is outstanding. The amount in clause (y) of the previous sentence shall be determined in accordance with regulations applicable under Section 423(b)(8) of the Code based on
(i) the number of shares previously purchased with respect to such calendar years pursuant to such Offering or any 

2

 

other
Offering under the Plan, or pursuant to any other Company or Related Corporation plans intended to qualify as Employee Stock Purchase Plans, and (ii) the number of shares subject to other
Purchase Rights outstanding on the Offering Date for such Offering pursuant to the Plan or any other such Company or Related Corporation Employee Stock Purchase Plan. 

        (d)   The maximum aggregate number of shares of Common Stock available to be purchased by all Participants on a Purchase Date
shall be the number of shares of Common Stock then remaining available under the Plan. If the aggregate purchase of shares of Common Stock upon exercise of Purchase Rights granted under the Offering
would exceed the maximum aggregate number of shares available, the Board shall make a pro rata allocation of the shares available in a uniform and equitable manner. 

4.     Purchase Price.  

        The purchase price of shares of Common Stock under an Offering shall be the lesser of: (i) eighty-five percent (85%) of the Fair Market Value
of such shares of Common Stock on the applicable Offering Date, or (ii) eighty-five percent (85%) of the Fair Market Value of such shares of Common Stock on the applicable Purchase
Date, in each case rounded up to
the nearest whole cent per share. For the Initial Offering, the Fair Market Value of the shares of Common Stock at the time when the Offering commences shall be the price per share at which shares are
first sold to the public in the Company's initial public offering as specified in the final prospectus for that initial public offering. 

5.     Participation.  

        (a)   An Eligible Employee may elect to participate in an Offering on the Offering Date. An Eligible Employee shall elect his
or her payroll deduction percentage on such enrollment form as the Company provides. The completed enrollment form must be delivered to the Company prior to the date participation is to be effective,
unless a later time for filing the enrollment form is set by the Company for all Eligible Employees with respect to a given Offering. Payroll deduction percentages must be expressed in whole
percentages of Earnings, with a minimum percentage of one percent (1%) and a maximum percentage of fifteen percent (15%). Except as provided in paragraph (e) below with respect to the Initial
Offering, Contributions may be made only by way of payroll deductions. 

        (b)   A Participant may increase or decrease his or her participation level once during a Purchase Period. In addition, a
Participant may decrease to zero percent (0%) his or her participation level only once during a Purchase Period. Any such increase or decrease in participation level shall be made by delivering a
notice to the Company or a designated Subsidiary in such form as the Company provides prior to the ten (10) day period (or such shorter period of time as determined by the Company and
communicated to Participants) immediately preceding the next Purchase Date of the Purchase Period for which it is to be effective. 

        (c)   A Participant may withdraw from an Offering and receive a refund of his or her Contributions (reduced to the extent, if
any, such Contributions have been used to acquire shares of Common Stock for the Participant on any prior Purchase Date) without interest, at any time prior to the end of the Offering, excluding only
each ten (10) day period immediately preceding a Purchase Date (or such shorter period of time determined by the Company and communicated to Participants), by delivering a withdrawal notice to
the Company or a designated Subsidiary in such form as the Company provides. A Participant who has withdrawn from an Offering shall not again participate in such Offering, but may participate in
subsequent Offerings under the Plan in accordance with the terms of the Plan and the terms of such subsequent Offerings. 

        (d)   Notwithstanding the foregoing or any other provision of this Offering document or of the Plan to the contrary, neither
the enrollment of any Eligible Employee in the Plan nor any forms relating to 

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participation
in the Plan shall be given effect until such time as a registration statement covering the registration of the shares under the Plan that are subject to the Offering has been filed by
the Company and has become effective. 

        (e)   Notwithstanding the foregoing or any other provision of this Offering document or of the Plan to the contrary, with
respect to the Initial Offering only, each Eligible Employee who is employed on the IPO Date automatically shall be enrolled in the Initial Offering, with a Purchase Right to purchase up to the number
of shares of Common Stock that are purchasable with fifteen percent (15%) of the Eligible Employee's Earnings, subject to the limitations set forth in Section 3 above. Following the filing of
an effective registration statement pursuant to a Form S-8, such Eligible Employee shall be provided a certain period of time, as determined by the Company in its sole discretion,
within which to elect to authorize payroll deductions for the purchase of shares during the Initial Offering (which may be for a percentage that is less than fifteen percent (15%) of the Eligible
Employee's Earnings). If such Eligible Employee elects not to authorize such payroll deductions, the Eligible Employee instead may purchase shares of Common Stock under the Plan by delivering a single
cash payment for the purchase of such shares to the Company or a designated Subsidiary prior to the ten (10) day period (or such shorter period of time as determined by the Company and
communicated to Participants) immediately preceding the first Purchase Date under the Initial Offering. If an Eligible Employee neither elects to authorize payroll deductions (or fails to do so in a
timely manner) nor chooses to make a cash payment in accordance with the foregoing sentence, then the Eligible Employee shall not purchase any shares of Common Stock during the Initial Offering. After
the end of the Initial Offering, in order to participate in any subsequent Offerings, an Eligible Employee must enroll and authorize payroll deductions prior to the commencement of the Offering, in
accordance with paragraph (a) above; provided, however, that once an Eligible Employee enrolls in an Offering and authorizes payroll deductions
(including in connection with the Initial Offering), the Eligible Employee automatically shall be enrolled for all subsequent Offerings until he or she elects to withdraw from an Offering pursuant to
paragraph (c) above or terminates his or her participation in the Plan. 

6.     Purchases.  

        Subject to the limitations contained herein, on each Purchase Date, each Participant's Contributions (without any increase for interest) shall be applied to the
purchase of whole shares, up to the maximum number of shares permitted under the Plan and the Offering. 

7.     Notices and Agreements.  

        Any notices or agreements provided for in an Offering or the Plan shall be given in writing, in a form provided by the Company, and unless specifically provided
for in the Plan or this Offering, shall be deemed effectively given upon receipt or, in the case of notices and agreements delivered by the Company, five (5) days after deposit in the United
States mail, postage prepaid. 

8.     Exercise Contingent on Stockholder Approval.  

        The Purchase Rights granted under an Offering are subject to the approval of the Plan by the stockholders of the Company as required for the Plan to obtain
treatment as an Employee Stock Purchase Plan. 

9.     Offering Subject to Plan.  

        Each Offering is subject to all the provisions of the Plan, and the provisions of the Plan are hereby made a part of the Offering. The Offering is further subject
to all interpretations, amendments, rules and regulations which may from time to time be promulgated and adopted pursuant to the Plan. In the event of any conflict between the provisions of an
Offering and those of the Plan (including interpretations, amendments, rules and regulations which may from time to time be promulgated and adopted pursuant to the Plan), the provisions of the Plan
shall control. 

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QuickLinks

SENOMYX, INC. 2004 EMPLOYEE STOCK PURCHASE PLAN ADOPTED BY THE BOARD OF DIRECTORS APRIL 30, 2004 APPROVED BY STOCKHOLDERS JUNE 7, 2004

SENOMYX, INC. 2004 EMPLOYEE STOCK PURCHASE PLAN OFFERING DOCUMENT

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