2008 Employee Stock Purchase Plan



 Exhibit 10.28 
 EXPONENT, INC. 
 2008 EMPLOYEE STOCK PURCHASE PLAN 
 1. ESTABLISHMENT OF PLAN 
 Exponent, Inc. (the
“Company”) adopted this plan in 2008 to grant options for the purchase of shares (“Shares”) of the Company’s Common Stock to eligible employees of the Company and Subsidiaries (as hereinafter defined) pursuant to this
Employee Stock Purchase Plan (the “Plan”). For purposes of this Plan, “parent corporation” and “Subsidiary” (collectively, “Subsidiaries”) shall have the same meanings as “parent corporation” and
“subsidiary corporation” in Section 424, of the Internal Revenue Code of 1986, as amended (the “Code”). The Company intends that the Plan shall qualify as an “employee stock purchase plan” under Section 423 of
the Code (including any amendments or replacements of such section), and the Plan shall be so construed. Any term not expressly defined in the Plan but defined for purposes of Section 423 of the Code shall have the same definition in this Plan.
A total of 200,000 Shares of Common Stock may be issued under the Plan. Such number shall be subject to adjustments effected in accordance with Section 14 of the Plan. 
 2. PURPOSES 
 The purpose of the Plan is to provide employees of the Company and any Subsidiary
designated by the Company’s Board of Directors (the “Board”) as one whose employees are eligible to participate in the Plan with a convenient means to acquire an equity interest in the Company through payroll deductions, to enhance
such employees’ sense of participation in the affairs of the Company and Subsidiaries, and to provide an incentive for continued employment. 
 3.
ADMINISTRATION 
 (a) The Plan is administered by the Board or by a committee designated by the Board (in which event all references
herein to the Board shall be to the committee). Subject to the provisions of the Plan and the limitations of Section 423 of the Code or any successor provision in the Code, all questions of interpretation or application of the Plan shall be
determined by the Board and its decisions shall be final and binding upon all participants. Members of the Board shall receive no compensation for their services in connection with the administration of the Plan, other than standard fees as
established from time to time by the Board of Directors of the Company for services rendered by Board members serving on Board committees. All expenses incurred in connection with the administration of the Plan shall be paid by the Company.

 (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 options to purchase Shares shall be granted and the provisions of each Offering Period (which need not be
identical); 
 (ii) To designate from time to time a Subsidiary as one whose employees shall be eligible to participate in the Plan (any such
designated Subsidiary, a “Designated Corporation”); 
 (iii) To construe and interpret the Plan and rights to purchase (options on)
Shares, and to establish, amend and revoke rules and procedures for its administration, including that 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 or terminate the Plan as provided in Section 24 below;








 (v) To adopt rules and procedures (including sub-plans and/or special provisions) relating to the
operation and administration of the Plan to permit participation in the Plan by employees who are foreign nationals or employed outside the United States; and 
 (vi) Generally, to exercise such powers and to perform such acts it deems necessary, desirable, convenient or expedient to promote the best interests of the Company and its Subsidiaries and to carry out that intent
that the Plan be treated as an “employee stock purchase plan” under Section 423 of the Code. 
 4. ELIGIBILITY 
 Any employee of the Company or any of its Subsidiaries whom the Board designates as a participating Subsidiary (a “Designated Subsidiary”) is
eligible to participate in an Offering Period (as hereinafter defined) under the Plan except the following: 
 (a) employees who are not
employed by the Company or a Designated Subsidiary on a date specified by the Board before the beginning of such Offering Period; 
 (b)
employees who are customarily employed for less than 20 hours per week; 
 (c) employees who are customarily employed for less than
5 months in a calendar year; 
 (d) employees who, together with any other person whose stock would be attributed to such employee
pursuant to Section 425(d) of the Code, own stock or hold options to purchase stock or who, as a result of being granted an option under the Plan with respect to such Offering Period, would own stock or hold options to purchase stock possessing
5 percent or more of the total combined voting power or value of all classes of stock of the Company or any of its Subsidiaries; and 
 (e) individuals who provide services to the Company or a Designated Subsidiary as independent contractors who are reclassified as common law employees for any reason except for federal income and employment tax purposes. 
 5. OFFERING PERIODS; OFFERING DATES; AND PURCHASE DATES 
 (a) Each Offering Period under the Plan (each an “Offering Period”) shall be of the duration provided for or permitted herein. The first trading day (a day on which the Common Stock trades on the principal exchange or system on
which the Common Stock is listed) of each Offering Period is referred to as the “Offering Date.” The Board may but need not provide for multiple purchases within a single Offering Period. The Board shall have the power to change the
duration of Offering Periods without stockholder approval. The last trading day of each Offering Period (or in the case of an Offering Period encompassing multiple purchases, each such purchase period) is hereinafter referred to as the
“Purchase Date.” 
 (b) Subject to Section 5(c) below, each Offering Period shall be of three months’ duration commencing
on the first business day of each fiscal quarter and ending on the last business day of the fiscal quarter, and shall have a single Purchase Date. 
 (c) Notwithstanding 5(b) above and the other provisions of the Plan, the Board of Directors may, but need not, vary the terms and structure of the Offering Periods under this Plan, on such basis as it shall determine in its sole discretion
(including without limitation, the length of each Offering Period and Offering Periods during which more than one Purchase Date shall occur; provided however that no Offering Period may have a duration in excess of twenty-seven (27) months (or
such longer period as may be permitted under Code Section 423). 
 6. PARTICIPATION IN THE PLAN 
 An eligible employee may become a participant in an Offering Period under the Plan if (a) as of the Offering Date with respect to the Offering Period
he or she satisfies the eligibility requirements set forth above, and 

  

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(b) prior to such Offering Date (at such time and in such manner as may be specified with respect to such Offering Period) he or she delivers to the Company
or its authorized representative a subscription agreement indicating his or her desire to enroll in the Offering Period and authorizing payroll deductions in a manner consistent with Section 9 below. An eligible employee who does not timely
deliver a subscription agreement by the date specified in advance of the applicable Offering Date shall not participate in that Offering Period and shall not participate in any subsequent Offering Period unless such employee enrolls in the Plan by
timely delivering a subscription agreement to the Company or its representative prior the Offering Date of the applicable, subsequent Offering Period. Once an employee becomes a participant in an Offering Period, such employee will automatically
participate in the Offering Period commencing immediately following the last day of that Offering Period unless the employee withdraws from the Plan or terminates further participation in the Offering Period as set forth in Section 11 below.
Such participant is not required to file any additional subscription agreements in order to continue participation in the Plan with respect to subsequent Offering Periods. Any participant who has not withdrawn from the Plan pursuant to
Section 11 below will automatically be re-enrolled in the Plan and granted a new option on the Offering Date of the next Offering Period. 
 7. GRANT
OF OPTION 
 (a) Each employee enrolled in an Offering Period will be granted on the Offering Date an option to purchase on each Purchase
Date up to that number of Shares determined by dividing the amount accumulated in such employee’s payroll deduction account during such Offering Period by the Purchase Price (as defined in Section 8 below) applicable to that Offering
Period. 
 (b) In no event, however, shall the number of Shares of the Company’s Common Stock subject to any option granted pursuant to
this Plan exceed the limitations set forth in Section 10 below. The Purchase Price and fair market value of a Share shall be determined as provided in Section 8 hereof. 
 8. PURCHASE PRICE 
 The “Purchase Price” per Share at which a Share will be sold in any
Offering Period shall be ninety-five percent (95%) of the fair market value on the applicable Purchase Date. For purposes of the Plan, the term “fair market value” on a given date shall mean: (a) the closing price on the Purchase
Date of a Share as reported on the Nasdaq Stock Market (or any other exchange or market quotation system that is then the primary exchange or market on which the Common Stock trades), (b) if the relevant date does not fall on a trading day, the
closing price of a Share as of the last preceding day on which the Common Stock traded, or (c) such other value as the Board determines in its good faith judgment to be a reasonable valuation for a Share as of such date. 
  

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 9. PAYMENT OF PURCHASE PRICE; CHANGES IN PAYROLL DEDUCTIONS; ISSUANCE OF SHARES 
 (a) The aggregate purchase price of the Shares is accumulated by regular payroll deductions made during each Offering Period. The deductions are made as a
percentage of the employee’s compensation in one percent (1%) increments not less than one percent (1%) nor greater than fifteen percent (15%). Compensation shall mean all base straight-time gross earnings including commissions,
overtime and paid-time off but exclusive of shift premiums, incentive compensation, bonuses, any amounts relating to Company equity awards, and other compensation not listed above; provided, however, that for purposes of determining a
participant’s compensation, any election by such participant to reduce his or her regular cash remuneration under Sections 125 or 401(k) of the Code shall be treated as if the participant did not make such election. Payroll deductions
shall commence on the first payroll date following the Offering Date and shall continue until the last payroll date immediately preceding the Purchase Date unless sooner altered or terminated as provided in the Plan. 
 (b) Except pursuant to a withdrawal from the Plan under Section 11 below (in which case all payroll deductions shall cease), a participant may not
change his or her rate of payroll deductions during an Offering Period. A participant may increase or decrease the rate of payroll deductions for any subsequent Offering Period by filing with the Administrator a new authorization for payroll
deductions on a date specified by the Board prior to the beginning of such Offering Period. 
 (c) All payroll deductions made for a
participant are credited to his or her account under the Plan and are deposited with the general funds of the Company. No interest accrues on the payroll deductions. All payroll deductions received or held by the Company may be used by the Company
for any corporate purpose, and the Company shall not be obligated to segregate such payroll deductions. 
 (d) On each Purchase Date, so long
as the Plan remains in effect and provided that the participant has not withdrawn from that Offering Period under the Plan in accordance with the provisions of Section 11 below before that date, the Company shall apply the funds then in the
participant’s account to the purchase of whole Shares reserved under the option granted to such participant with respect to the Offering Period to the extent that such option is exercisable on the Purchase Date. The Purchase Price per Share
shall be as specified in Section 8 of the Plan. Any cash remaining in a participant’s account after such purchase of Shares shall be refunded (without interest) to such participant in cash; provided, however, that any amount remaining in
such participant’s account on a Purchase Date which is less than the amount necessary to purchase a full Share of Common Stock of the Company shall be carried forward, without interest, into the next Offering Period (or in the event of an
Offering Period during which multiple purchase will occur, into the next applicable purchase period within the Offering Period). In the event that the Plan has been oversubscribed as provided in Section 10(c), all funds not used to purchase
Shares on the Purchase Date shall be returned to the participant (without interest). No Shares shall be purchased on a Purchase Date on behalf of any employee whose participation in the Plan has terminated prior to such Purchase Date. 
 (e) As promptly as practicable after the Purchase Date, the Company shall arrange the delivery to each participant, as appropriate, of a certificate
representing the Shares purchased upon exercise of his option; provided that the Company may deliver certificates to a broker or brokers that hold such certificate in street name for the benefit of each such participant. 
 (f) During a participant’s lifetime, such participant’s option to purchase Shares hereunder is exercisable only by him or her. The participant
will have no interest or voting right in Shares covered by his or her option until such option has been exercised. Shares to be delivered to a participant under the Plan will be registered in the name of the participant or in the name of the
participant and his or her spouse provided that shares may be registered to a broker or brokers that hold such shares in street name for the benefit of each participant. 
 10. LIMITATIONS ON SHARES TO BE PURCHASED 
 (a) No employee shall be entitled to purchase Shares under
the Plan at a rate which, when aggregated with his or her rights to purchase Shares of Common Stock under all other employee stock purchase plans of the Company or any Subsidiary, exceeds $25,000 in fair market value, determined as of the date such
right is granted (or such other limit as may be imposed by the Code) for each calendar year in which the employee participates in the Plan. 
  

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 (b) Subject to Sections 9(a), 10(a) and 14(a) of the Plan, the maximum number of Shares that a
participant may purchase on any single Purchase Date shall not exceed 2,500 Shares (the “Maximum Share Amount”); provided that prior to the commencement of any Offering Period, the Board may, in its sole discretion and without stockholder
approval, change the Maximum Share Amount with respect to that Offering Period. If a new Maximum Share Amount is set, then all participants must be notified of such Maximum Share Amount prior to the commencement of the next Offering Period. Once a
Maximum Share Amount is set, it shall continue to apply in respect of all succeeding Purchase Dates and Offering Periods unless revised by the Board as set forth above. 
 (c) If the number of Shares to be purchased on a Purchase Date by all employees participating in the Plan exceeds the number of Shares then available for issuance under the Plan, the Company will make a pro rata
allocation of the remaining Shares in as uniform a manner as shall be practicable and as the Board shall determine to be equitable. In such event, the Company shall give written notice of such reduction of the number of Shares to be purchased under
a participant’s option to each employee affected thereby. 
 (d) Any payroll deductions accumulated in a participant’s account
which are not used to purchase stock due to the limitations in this Section 10 shall be returned to the participant (without interest) as soon as practicable after the end of the Offering Period in the manner set forth in Section 9(d).

 11. WITHDRAWAL 
 (a) Each participant
may withdraw from an Offering Period under the Plan by signing and delivering to the Administrator notice on a form provided for such purpose. Such withdrawal may be elected at any time prior to the end of an Offering Period at such time and in such
manner as the Board specifies. 
 (b) Upon withdrawal from the Plan, the accumulated payroll deductions shall be returned (without interest)
to the withdrawn employee and his or her interest in the Plan shall terminate. In the event an employee voluntarily elects to withdraw from the Plan, he or she may not resume his or her participation in the Plan during the same Offering Period, but
he or she may participate in any Offering Period under the Plan which commences on a date subsequent to such withdrawal by filing a new authorization for payroll deductions in the same manner as set forth in Section 6 above for initial
participation in the Plan. 
 12. TERMINATION OF EMPLOYMENT 
 Termination of a participant’s employment for any reason, including retirement or death, or the failure of a participant to remain an eligible employee as set forth in Section 4 terminates his or her
participation in the Plan immediately. In such event, the payroll deductions credited to the participant’s account will be returned to him or her or, in the case of his or her death, to his or her legal representative. For this purpose, an
employee will not be deemed to have terminated employment or failed to remain in the continuous employ of the Company in the case of sick leave, military leave, or any other leave of absence approved by the Board of Directors of the Company;
provided that such leave is for a period of not more than ninety (90) days or, if such leave is longer than ninety (90) days, reemployment upon the expiration of such leave is guaranteed by contract or statute. 
 13. RETURN OF PAYROLL DEDUCTIONS 
 In the event an
employee’s interest in the Plan is terminated by withdrawal, termination of employment or otherwise, or in the event the Plan is terminated by the Board, the Company shall promptly deliver to the employee all payroll deductions credited to his
or her account. No interest shall accrue on the payroll deductions of a participant in the Plan. 
  

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 14. CAPITAL CHANGES 
 Subject to any required action by the stockholders of the Company, the number of Shares covered by each option under the Plan which has not yet been exercised, the Maximum Share Amount set forth in Section 10(b)
above, and the number of Shares which have been authorized for issuance under the Plan but have not yet been placed under option (collectively, the “Reserves”), as well as the price per Share covered by each option under the Plan which has
not yet been exercised, shall be proportionately adjusted for any increase or decrease in the number of issued Shares resulting from a stock split or the payment of a stock dividend (but only on the Common Stock) or any other increase or decrease in
the number of Shares effected without receipt of consideration by the Company; provided, however, that conversion of any convertible securities of the Company shall not be deemed to have been “effected without receipt of consideration.”
Such adjustment shall be made by the Board, whose determination in that respect shall be final, binding and conclusive. Except as expressly provided herein, no issue by the Company of shares of stock of any class, or securities convertible into
shares of stock of any class, shall affect, and no adjustment by reason thereof shall be made with respect to, the number or price of Shares subject to an option. 
 In the event of the proposed dissolution or liquidation of the Company, each Offering Period will terminate immediately prior to the consummation of such proposed action, unless otherwise provided by the Board. In
such event, the Board may, in the exercise of its sole discretion in such instances, declare that the options under the Plan shall terminate as of a date fixed by the Board and give each participant the right to exercise his or her option as to all
of the optioned stock. In the event of a proposed sale of all or substantially all of the assets of the Company, or the merger of the Company with or into another corporation, each option under the Plan shall be assumed or an equivalent option shall
be substituted by such successor corporation or a parent or subsidiary of such successor corporation, unless the Board determines, in the exercise of its sole discretion and in lieu of such assumption or substitution, that the participant shall have
the right to exercise the option as to all of the optioned Shares. If the Board makes an option exercisable in lieu of assumption or substitution in the event of a merger or sale of assets, the Board shall notify the participant that the option
shall be fully exercisable on a date specified in such notice, and the option will terminate upon the expiration of such period. 
 The Board
may, if it so determines in the exercise of its sole discretion, also make provision for adjusting the Reserves, as well as the price per Share covered by each outstanding option, in the event that the Company effects one or more reorganizations,
recapitalizations, rights offerings or other increases or reductions of Shares of its outstanding Common Stock, and in the event of the Company being consolidated with or merged into any other corporation. 
 15. NONASSIGNABILITY 
 Neither payroll deductions
credited to a participant’s account nor any rights with regard to the exercise of an option or to receive Shares under the Plan may be assigned, transferred, pledged or otherwise disposed of in any way (other than by will, the laws of descent
and distribution or as provided in Section 22 hereof) by the participant. Any such attempt at assignment, transfer, pledge or other disposition shall be without effect. 
 16. REPORTS 
 Individual accounts will be maintained for each participant in the Plan. Each
participant shall receive any reports required to be delivered by applicable law as well as, after the end of each Offering Period, a report of his account setting forth the total payroll deductions accumulated, the number of Shares purchased, the
per Share price thereof and the remaining cash balance, if any, carried forward to the next Offering Period or Offering Period, as the case may be. 
 17.
NOTICE OF DISPOSITION 
 Each participant shall notify the Company if the participant disposes of any of the Shares purchased in any
Offering Period pursuant to this Plan if such disposition occurs within two years from the Offering Date or within one (1) year from the Purchase Date on which such Shares were purchased (the “Notice Period”). Unless such participant
is disposing of any of such Shares during the Notice Period, such participant shall keep the certificates 

  

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representing such Shares in his or her name (and not in the name of a nominee) during the Notice Period. The Company may, at any time during the Notice
Period, place a legend or legends on any certificate representing Shares acquired pursuant to the Plan requesting the Company’s transfer agent to notify the Company of any transfer of the Shares. The obligation of the participant to provide
such notice shall continue notwithstanding the placement of any such legend on certificates. 
 18. NO RIGHTS TO CONTINUED EMPLOYMENT 
 Neither this Plan nor the grant of any option hereunder shall confer any right on any employee to remain in the employ of the Company or any Subsidiary or
restrict the right of the Company or any Subsidiary to terminate such employee’s employment. 
 19. EQUAL RIGHTS AND PRIVILEGES 
 All participants in an Offering Period shall have the same rights and privileges with respect to their participation in the Plan for that Offering Period,
in accordance with Section 423 of the Code and the related regulations (and any successor provisions). Any provision of the Plan, a specific Offering Period or an option granted under the Plan which is inconsistent with this Section 19
shall without further act or amendment by the Company or the Board be reformed, if possible, to the extent necessary to render such provision in compliance with the requirements of Section 423 of the Code, or shall otherwise be deleted, and the
remainder of the terms of the Plan, an Offering Period and/or an option shall not be affected. 
 20. NOTICES 
 All notices or other communications by a participant to the Company under or in connection with the Plan shall be deemed to have been duly given when
received in the form specified by the Company at the location, or by the person, designated by the Company for the receipt thereof. 
 21. DESIGNATION OF
BENEFICIARY 
 (a) A participant may file a written designation of a beneficiary who is to receive any Shares and 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 Period but prior to delivery to him of such Shares and 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 prior to a Purchase Date. 
 (b) Such designation of beneficiary may be changed by the participant at any time by written notice. 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 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 discretion, may deliver such Shares 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. 
 22. CONDITIONS UPON ISSUANCE OF SHARES 
 Shares shall not be issued with respect to an option unless the exercise of such option and the issuance and delivery of such Shares pursuant thereto shall comply with all applicable provisions of law, domestic or
foreign, including, without limitation, the Securities Act of 1933, as amended, the Exchange Act, the rules and regulations promulgated thereunder, and the requirements of any stock exchange upon which the Shares may then be listed, and shall be
further subject to the approval of counsel for the Company with respect to such compliance. The Company shall have no liability for failure to issue any Shares under this Plan in the event that such issuance cannot be accomplished in compliance with
all applicable laws. 
  

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 23. APPLICABLE LAW 
 The Plan shall be governed by the substantive laws (excluding the conflict of laws rules) of the State of Delaware. 
 24.
AMENDMENT OR TERMINATION OF THE PLAN 
 The Plan shall continue until the earlier to occur of termination by the Board, issuance of all of
the Shares of Common Stock reserved for issuance under the Plan, or May 29, 2018. The Board of Directors of the Company may at any time amend or terminate the Plan, except that any such termination cannot affect options previously granted under
the Plan, nor may any amendment make any change in an option previously granted which would adversely affect the right of any participant; provided that if the Board determines that a change in applicable accounting rules or a change in applicable
laws, renders an amendment or termination desirable, then the Board may approve such an amendment or termination. The Board may not amend the Plan without approval of the stockholders of the Company obtained in accordance with Section 21 hereof
within 12 months of the adoption of such amendment (or earlier if required by Section 21) if such amendment would: 
 (a) Increase
the number of Shares that may be issued under the Plan; or 
 (b) Expand the designation of the employees (or class of employees) eligible
for participation in the Plan. 
  

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