Document:

2011 Equity Incentive Plan and Form of Stock Option Agreement

 Exhibit 10.3 
 AMBIT BIOSCIENCES CORPORATION 

2011 EQUITY INCENTIVE PLAN 

ADOPTED BY THE BOARD OF DIRECTORS:
NOVEMBER 30, 2010 
 APPROVED BY THE
STOCKHOLDERS: [                    ] 
 1. GENERAL. 
 (a) Successor to and Continuation of
Prior Plan. The Plan is intended as the successor to and continuation of the Ambit Biosciences Corporation 2001 Equity Incentive Plan, as amended (the “Prior Plan”). Following the Effective Date, no additional stock
awards shall be granted under the Prior Plan. Any available shares that are not reserved for issuance pursuant to stock awards issued under the Prior Plan and outstanding as of the Effective Date (the “Prior Plan’s Available
Reserve”) shall become available for issuance pursuant to Stock Awards granted hereunder. From and after the Effective Date, all outstanding stock awards granted under the Prior Plan shall remain subject to the terms of the Prior Plan;
provided, however, any shares subject to outstanding stock awards granted under the Prior Plan that expire or terminate for any reason prior to exercise or settlement or are forfeited because of the failure to meet a contingency or condition
required to vest such shares (the “Returning Shares”) shall become available for issuance pursuant to Awards granted hereunder. All Awards granted on or after the Effective Date of this Plan shall be subject to the terms of
this Plan. 
 (b) Eligible Award Recipients. The persons eligible to receive Awards are Employees, Directors and
Consultants. 
 (c) Available Awards. The Plan provides for the grant of the following Awards: (i) Incentive
Stock Options, (ii) Nonstatutory Stock Options, (iii) Stock Appreciation Rights (iv) Restricted Stock Awards, (v) Restricted Stock Unit Awards, (vi) Performance Stock Awards, (vii) Performance Cash Awards, and
(viii) Other Stock Awards. 
 (d) Purpose. The Company, by means of the Plan, seeks to secure and retain the
services of the group of persons eligible to receive Awards as set forth in Section 1(b), to provide incentives for such persons to exert maximum efforts for the success of the Company and any Affiliate and to provide a means by which such
eligible recipients may be given an opportunity to benefit from increases in value of the Common Stock through the granting of Awards. 
 2.
ADMINISTRATION. 
 (a) Administration by Board. The Board shall administer the Plan unless and
until the Board delegates administration of the Plan to a Committee or Committees, as provided in Section 2(c). 

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

  
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 (i) To determine from time to time (A) which of the persons eligible under the
Plan shall be granted Awards; (B) when and how each Award shall be granted; (C) what type or combination of types of Award shall be granted; (D) the provisions of each Award granted (which need not be identical), including the time or
times when a person shall be permitted to receive cash or Common Stock pursuant to a Stock Award; (E) the number of shares of Common Stock with respect to which a Stock Award shall be granted to each such person; and (F) the Fair Market
Value applicable to a Stock Award. 
 (ii) To construe and interpret the Plan and Awards granted under it, and to
establish, amend and revoke rules and regulations for its administration. The Board, in the exercise of this power, may correct any defect, omission or inconsistency in the Plan or in any Stock Award Agreement or in the written terms of a
Performance Cash Award, in a manner and to the extent it shall deem necessary or expedient to make the Plan or Award fully effective. 
 (iii) To settle all controversies regarding the Plan and Awards granted under it. 
 (iv) To accelerate the time at which an Award may first be exercised or the time during which an Award or any part thereof will vest in accordance with the Plan, notwithstanding the provisions in
the Award stating the time at which it may first be exercised or the time during which it will vest. 
 (v) To suspend or
terminate the Plan at any time. Suspension or termination of the Plan shall not impair rights and obligations under any Award granted while the Plan is in effect except with the written consent of the affected Participant. 

(vi) To amend the Plan in any respect the Board deems necessary or advisable. However, except as provided in Section 9(a)
relating to Capitalization Adjustments, to the extent required by applicable law or listing requirements, stockholder approval shall be required for any amendment of the Plan that either (A) materially increases the number of shares of Common
Stock available for issuance under the Plan, (B) materially expands the class of individuals eligible to receive Awards under the Plan, (C) materially increases the benefits accruing to Participants under the Plan or materially reduces the
price at which shares of Common Stock may be issued or purchased under the Plan, (D) materially extends the term of the Plan, or (E) expands the types of Awards available for issuance under the Plan. Except as provided above, rights under
any Award granted before amendment of the Plan shall not be impaired by any amendment of the Plan unless (1) the Company requests the consent of the affected Participant, and (2) such Participant consents in writing. 

(vii) To submit any amendment to the Plan for stockholder approval, including, but not limited to, amendments to the Plan intended
to satisfy the requirements of (A) Section 162(m) of the Code regarding the exclusion of performance-based compensation from the limit on corporate deductibility of compensation paid to Covered Employees, (B) Section 422 of the
Code regarding “incentive stock options” or (C) Rule 16b-3. 
 (viii) To approve forms of Award Agreements
for use under the Plan and to amend the terms of any one or more Awards, including, but not limited to, amendments to provide terms more favorable to the Participant than previously provided in the Award

  
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Agreement, subject to any specified limits in the Plan that are not subject to Board discretion; provided however, that except with respect to amendments that disqualify or impair the
status of an Incentive Stock Option, a Participant’s rights under any Award shall not be impaired by any such amendment unless (A) the Company requests the consent of the affected Participant, and (B) such Participant consents in
writing. Notwithstanding the foregoing, subject to the limitations of applicable law, if any, the Board may amend the terms of any one or more Awards without the affected Participant’s consent if necessary to maintain the qualified status of
the Award as an Incentive Stock Option or to bring the Award into compliance with Section 409A of the Code. 
 (ix)
Generally, to exercise such powers and to perform such acts as the Board deems necessary or expedient to promote the best interests of the Company and that are not in conflict with the provisions of the Plan or Awards. 

(x) To adopt such procedures and sub-plans as are necessary or appropriate to permit participation in the Plan by Employees,
Directors or Consultants who are foreign nationals or employed outside the United States. 
 (xi) To effect, at any time
and from time to time, with the consent of any adversely affected Participant, (A) the reduction of the exercise price (or strike price) of any outstanding Option or SAR under the Plan; (B) the cancellation of any outstanding Option or SAR
under the Plan and the grant in substitution therefor of (1) a new Option or SAR under the Plan or another equity plan of the Company covering the same or a different number of shares of Common Stock, (2) a Restricted Stock Award,
(3) a Restricted Stock Unit Award, (4) an Other Stock Award, (5) cash and/or (6) other valuable consideration (as determined by the Board, in its sole discretion); or (C) any other action that is treated as a repricing under
generally accepted accounting principles. 
 (c) Delegation to Committee. 

(i) General. The Board may delegate some or all of the administration of the Plan to a Committee or Committees. 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 that have been delegated to the Committee, including the power to
delegate to a subcommittee of the Committee any of the administrative powers the Committee is authorized to exercise (and references in this Plan to the Board shall thereafter be to the Committee or subcommittee), 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 Committee may, at any time, abolish the subcommittee and/or revest in the Committee any powers delegated to the subcommittee. The
Board may retain the authority to concurrently administer the Plan with the Committee and may, at any time, revest in the Board some or all of the powers previously delegated. 
 (ii) Section 162(m) and Rule 16b-3 Compliance. The Committee may consist solely of two or more Outside Directors, in accordance with Section 162(m) of the Code, or solely of two or
more Non-Employee Directors, in accordance with Rule 16b-3. 

  
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 (d) Effect of Board’s Decision. 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. 
 3. SHARES SUBJECT TO THE PLAN. 
 (a) Share Reserve. Subject to Section 9(a) relating to Capitalization Adjustments, the aggregate number of shares of Common Stock that may be issued pursuant to Stock Awards from and
after the Effective Date shall not exceed [            ] shares (the “Share Reserve”), which number is the sum of (i) the number of shares
subject to the Prior Plan’s Available Reserve, (ii) an additional [            ] new shares, plus (iii) an additional number of shares in an amount not to exceed
[            ] shares (which number consists of the Returning Shares, if any, as such shares become available from time to time). In addition, the number of shares of Common Stock available
for issuance under the Plan shall automatically increase on January 1st of each year for a period of [            ] years commencing on January 1,
[            ] and ending on (and including) January 1, [            ], in an amount equal to [__]% of the total number
of shares of Common Stock outstanding on December 31st of the preceding calendar year. Notwithstanding the foregoing, the Board may act prior to the first day of any calendar year, to provide that there shall be no increase in the share reserve
for such calendar year or that the increase in the share reserve for such calendar year shall be a lesser number of shares of Common Stock than would otherwise occur pursuant to the preceding sentence. For clarity, the Share Reserve in this
Section 3(a) is a limitation on the number of shares of the Common Stock that may be issued pursuant to the Plan. Accordingly, this Section 3(a) does not limit the granting of Stock Awards except as provided in Section 7(a). Shares
may be issued in connection with a merger or acquisition as permitted by NASDAQ Listing Rule 5635(c), or, if applicable, NYSE Listed Company Manual Section 303A.08, AMEX Company Guide Section 711 or other applicable rule, and such
issuance shall not reduce the number of shares available for issuance under the Plan. Furthermore, if a Stock Award or any portion thereof (i) expires or otherwise terminates without all of the shares covered by such Stock Award having been
issued or (ii) is settled in cash (i.e., the Participant receives cash rather than stock), such expiration, termination or settlement shall not reduce (or otherwise offset) the number of shares of Common Stock that may be available for
issuance under the Plan. 
 (b) Reversion of Shares to the Share Reserve. If any shares of Common Stock issued
pursuant to a Stock Award are forfeited back to or repurchased by the Company because of the failure to meet a contingency or condition required to vest such shares in the Participant, then the shares that are forfeited or repurchased shall revert
to and again become available for issuance under the Plan. Any shares reacquired by the Company pursuant to Section 8(g) or as consideration for the exercise of an Option shall again become available for issuance under the Plan. For the
avoidance of doubt, if an appreciation distribution in respect of a Stock Appreciation Right is paid in shares of Common Stock, the number of shares subject to the Stock Award that are not delivered to the Participant shall remain available for
subsequent issuance under the Plan. 
 (c) Incentive Stock Option Limit. Notwithstanding anything to the contrary
in this Section 3 and, subject to the provisions of Section 9(a) relating to Capitalization Adjustments, 

  
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the aggregate maximum number of shares of Common Stock that may be issued pursuant to the exercise of Incentive Stock Options shall be
[            ] shares of Common Stock. 
 (d)
Section 162(m) Limitation on Annual Grants. Subject to the provisions of Section 9(a) relating to Capitalization Adjustments, at such time as the Company may be subject to the applicable provisions of Section 162(m) of the
Code, a maximum of [            ] shares of Common Stock subject to Options, Stock Appreciation Rights and Other Stock Awards whose value is determined by reference to an increase
over an exercise or strike price of at least 100% of the Fair Market Value on the date the Stock Award is granted may be granted to any Participant during any calendar year. Notwithstanding the foregoing, if any additional Options, Stock
Appreciation Rights or Other Stock Awards whose value is determined by reference to an increase over an exercise or strike price of at least 100% of the Fair Market Value on the date the Stock Awards are granted to any Participant during any
calendar year, compensation attributable to the exercise of such additional Stock Awards shall not satisfy the requirements to be considered “qualified performance-based compensation” under Section 162(m) of the Code unless such
additional Stock Awards are approved by the Company’s stockholders. 
 (e) Source of Shares. The stock issuable
under the Plan shall be shares of authorized but unissued or reacquired Common Stock, including shares repurchased by the Company on the open market or otherwise. 
 4. ELIGIBILITY. 
 (a) Eligibility for Specific
Stock Awards. Incentive Stock Options may be granted only to employees of the Company or a “parent corporation” or “subsidiary corporation” thereof (as such terms are defined in Sections 424(e) and (f) of the Code).
Stock Awards other than Incentive Stock Options may be granted to Employees, Directors and Consultants; provided, however, Nonstatutory Stock Options and SARs may not be granted to Employees, Directors and Consultants who are providing
Continuous Service only to any “parent” of the Company, as such term is defined in Rule 405, unless the stock underlying such Stock Awards is treated as “service recipient stock” under Section 409A of the Code because
the Stock Awards are granted pursuant to a corporate transaction (such as a spin off transaction) or unless such Stock Awards comply with the distribution requirements of Section 409A of the Code. 

(b) Ten Percent Stockholders. A Ten Percent Stockholder shall not be granted an Incentive Stock Option unless the exercise
price of such Option is at least 110% of the Fair Market Value on the date of grant and the Option is not exercisable after the expiration of five years from the date of grant. 
 5. PROVISIONS RELATING TO OPTIONS AND STOCK APPRECIATION RIGHTS. 

Each Option or SAR shall be in such form and shall contain such terms and conditions as the Board shall deem appropriate. All Options
shall be separately designated Incentive Stock Options or Nonstatutory Stock Options at the time of grant, and, if certificates are issued, a separate certificate or certificates shall be issued for shares of Common Stock purchased on exercise of
each type of Option. If an Option is not specifically designated as an Incentive Stock Option, then the Option shall be a Nonstatutory Stock Option. The provisions of separate 

  
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Options or SARs need not be identical; provided, however, that each Option Agreement or Stock Appreciation Right Agreement shall conform to (through incorporation of provisions hereof by
reference in the applicable Stock Award Agreement or otherwise) the substance of each of the following provisions: 
 (a)
Term. Subject to the provisions of Section 4(b) regarding Ten Percent Stockholders, no Option or SAR shall be exercisable after the expiration of ten (10) years from the date of its grant or such shorter period specified in the
Stock Award Agreement. 
 (b) Exercise Price. Subject to the provisions of Section 4(b) regarding Ten Percent
Stockholders, the exercise price (or strike price) of each Option or SAR shall be not less than 100% of the Fair Market Value of the Common Stock subject to the Option or SAR on the date the Option or SAR is granted. Notwithstanding the foregoing,
an Option or SAR may be granted with an exercise price (or strike price) lower than 100% of the Fair Market Value of the Common Stock subject to the Option or SAR if such Option or SAR is granted pursuant to an assumption of or substitution for
another option or stock appreciation right pursuant to a Corporate Transaction and in a manner consistent with the provisions of Sections 409A and, if applicable, 424(a) of the Code. Each SAR will be denominated in shares of Common Stock
equivalents. 
 (c) Purchase Price for Options. The purchase price of Common Stock acquired pursuant to the
exercise of an Option shall be paid, to the extent permitted by applicable law and as determined by the Board in its sole discretion, by any combination of the methods of payment set forth below. The Board shall have the authority to grant Options
that do not permit all of the following methods of payment (or otherwise restrict the ability to use certain methods) and to grant Options that require the consent of the Company to utilize a particular method of payment. The permitted methods of
payment are as follows: 
 (i) by cash, check, bank draft or money order payable to the Company; 

(ii) pursuant to a program developed under Regulation T as promulgated by the Federal Reserve Board that, prior to the issuance of
the stock subject to the Option, 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; 

(iii) by delivery to the Company (either by actual delivery or attestation) of shares of Common Stock; 

(iv) if the option is a Nonstatutory Stock Option, by a “net exercise” arrangement pursuant to which the Company will
reduce the number of shares of Common Stock issuable upon exercise by the largest whole number of shares with a Fair Market Value that does not exceed the aggregate exercise price; provided, however, that the Company shall accept a cash or
other payment from the Participant to the extent of any remaining balance of the aggregate exercise price not satisfied by such reduction in the number of whole shares to be issued; provided, further, that shares of Common Stock will no
longer be subject to an Option and will not be exercisable thereafter to the extent that (A) shares issuable upon exercise are reduced to 

  
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pay the exercise price pursuant to the “net exercise,” (B) shares are delivered to the Participant as a result of such exercise, and (C) shares are withheld to satisfy tax
withholding obligations; or 
 (v) in any other form of legal consideration that may be acceptable to the Board and
specified in the applicable Stock Award Agreement. 
 (d) Exercise and Payment of a SAR. To exercise any
outstanding Stock Appreciation Right, the Participant must provide written notice of exercise to the Company in compliance with the provisions of the Stock Appreciation Right Agreement evidencing such Stock Appreciation Right. The appreciation
distribution payable on the exercise of a Stock Appreciation Right will be not greater than an amount equal to the excess of (A) the aggregate Fair Market Value (on the date of the exercise of the Stock Appreciation Right) of a number of shares
of Common Stock equal to the number of Common Stock equivalents in which the Participant is vested under such Stock Appreciation Right, and with respect to which the Participant is exercising the Stock Appreciation Right on such date, over
(B) the strike price that will be determined by the Board at the time of grant of the Stock Appreciation Right. The appreciation distribution in respect to a Stock Appreciation Right may be paid in Common Stock, in cash, in any combination of
the two or in any other form of consideration, as determined by the Board and contained in the Stock Appreciation Right Agreement evidencing such Stock Appreciation Right. 
 (e) Transferability of Options and SARs. The Board may, in its sole discretion, impose such limitations on the transferability of Options and SARs as the Board shall determine. In the
absence of such a determination by the Board to the contrary, the following restrictions on the transferability of Options and SARs shall apply: 
 (i) Restrictions on Transfer. An Option or SAR shall not be transferable except by will or by the laws of descent and distribution and shall be exercisable during the lifetime of the
Participant only by the Participant; provided, however, that the Board may, in its sole discretion, permit transfer of the Option or SAR in a manner that is not prohibited by applicable tax and securities laws upon the Participant’s
request. Except as explicitly provided herein, neither an Option nor a SAR may be transferred for consideration. 
 (ii)
Domestic Relations Orders. Notwithstanding the foregoing, an Option or SAR may be transferred pursuant to a domestic relations order; provided, however, that if an Option is an Incentive Stock Option, such Option may be deemed to be a
Nonstatutory Stock Option as a result of such transfer. 
 (iii) Beneficiary Designation. Notwithstanding the
foregoing, the Participant may, by delivering written notice to the Company, in a form provided by or otherwise satisfactory to the Company and any broker designated by the Company to effect Option exercises, designate a third party who, in the
event of the death of the Participant, shall thereafter be entitled to exercise the Option or SAR and receive the Common Stock or other consideration resulting from such exercise. In the absence of such a designation, the executor or administrator
of the Participant’s estate shall be entitled to exercise the Option or SAR and receive the Common Stock or other consideration resulting from such exercise. 

  
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 (f) Vesting Generally. The total number of shares of Common Stock subject to an
Option or SAR may vest and therefore become exercisable in periodic installments that may or may not be equal. The Option or SAR may be subject to such other terms and conditions on the time or times when it may or may not be exercised (which may be
based on the satisfaction of Performance Goals or other criteria) as the Board may deem appropriate. The vesting provisions of individual Options or SARs may vary. The provisions of this Section 5(f) are subject to any Option or SAR provisions
governing the minimum number of shares of Common Stock as to which an Option or SAR may be exercised. 
 (g) Termination of
Continuous Service. Except as otherwise provided in the applicable Stock Award Agreement or other agreement between the Participant and the Company, if a Participant’s Continuous Service terminates (other than for Cause or upon the
Participant’s death or Disability), the Participant may exercise his or her Option or SAR (to the extent that the Participant was entitled to exercise such Award as of the date of termination of Continuous Service) but only within such period
of time ending on the earlier of (i) the date three months following the termination of the Participant’s Continuous Service (or such longer or shorter period specified in the applicable Stock Award Agreement), or (ii) the expiration
of the term of the Option or SAR as set forth in the Stock Award Agreement. If, after termination of Continuous Service, the Participant does not exercise his or her Option or SAR within the time specified herein or in the Stock Award Agreement (as
applicable), the Option or SAR shall terminate. 
 (h) Extension of Termination Date. If the exercise of an Option or SAR
following the termination of the Participant’s Continuous Service (other than for Cause or upon the Participant’s death or Disability) would be prohibited at any time solely because the issuance of shares of Common Stock would violate the
registration requirements under the Securities Act, then the Option or SAR shall terminate on the earlier of (i) the expiration of a total period of three months (that need not be consecutive) after the termination of the Participant’s
Continuous Service during which the exercise of the Option or SAR would not be in violation of such registration requirements, or (ii) the expiration of the term of the Option or SAR as set forth in the applicable Stock Award Agreement. In
addition, unless otherwise provided in a Participant’s Stock Award Agreement, if the immediate sale of any Common Stock received upon exercise of an Option or SAR following the termination of the Participant’s Continuous Service (other
than for Cause) would violate the Company’s insider trading policy, then the Option or SAR shall terminate on the earlier of (i) the expiration of a period equal to the applicable post-termination exercise period after the termination of
the Participant’s Continuous Service during which the sale of Common Stock received upon exercise of the Option or SAR would not be in violation of the Company’s insider trading policy, or (ii) the expiration of the term of the Option
or SAR as set forth in the applicable Stock Award Agreement. 
 (i) Disability of Participant. Except as otherwise
provided in the applicable Stock Award Agreement or other agreement between the Participant and the Company, if a Participant’s Continuous Service terminates as a result of the Participant’s Disability, the Participant may exercise his or
her Option or SAR (to the extent that the Participant was entitled to exercise such Option or SAR as of the date of termination of Continuous Service), but only within such period of time ending on the earlier of (i) the date 12 months
following such termination of Continuous Service (or such longer or shorter period specified in the Stock Award 

  
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Agreement), or (ii) the expiration of the term of the Option or SAR as set forth in the Stock Award Agreement. If, after termination of Continuous Service, the Participant does not exercise
his or her Option or SAR within the time specified herein or in the Stock Award Agreement (as applicable), the Option or SAR (as applicable) shall terminate. 
 (j) Death of Participant. Except as otherwise provided in the applicable Stock Award Agreement or other agreement between the Participant and the Company, if (i) a Participant’s
Continuous Service terminates as a result of the Participant’s death, or (ii) the Participant dies within the period (if any) specified in the Stock Award Agreement after the termination of the Participant’s Continuous Service (for a
reason other than death), then the Option or SAR may be exercised (to the extent the Participant was entitled to exercise such Option or SAR as of the date of death) by the Participant’s estate, by a person who acquired the right to exercise
the Option or SAR by bequest or inheritance or by a person designated to exercise the Option or SAR upon the Participant’s death, but only within the period ending on the earlier of (i) the date 18 months following the date of death (or
such longer or shorter period specified in the Stock Award Agreement), or (ii) the expiration of the term of such Option or SAR as set forth in the Stock Award Agreement. If, after the Participant’s death, the Option or SAR is not
exercised within the time specified herein or in the Stock Award Agreement (as applicable), the Option or SAR shall terminate. 

(k) Termination for Cause. Except as explicitly provided otherwise in a Participant’s Stock Award Agreement or other
individual agreement between the Company or any Affiliate and the Participant, if a Participant’s Continuous Service is terminated for Cause, the Option or SAR shall immediately terminate upon such Participant’s termination of Continuous
Service, and the Participant shall be prohibited from exercising his or her Option or SAR from and after the time of such termination of Continuous Service. 
 (l) Non-Exempt Employees. No Option or SAR, whether or not vested, granted to an Employee who is a non-exempt employee for purposes of the Fair Labor Standards Act of 1938, as amended, shall be
first exercisable for any shares of Common Stock until at least six months following the date of grant of the Option or SAR. Notwithstanding the foregoing, consistent with the provisions of the Worker Economic Opportunity Act, (i) in the event
of the Participant’s death or Disability, (ii) upon a Corporate Transaction in which such Option or SAR is not assumed, continued, or substituted, (iii) upon a Change in Control, or (iv) upon the Participant’s retirement (as
such term may be defined in the Participant’s Stock Award Agreement or in another applicable agreement or in accordance with the Company’s then current employment policies and guidelines), any such vested Options and SARs may be exercised
earlier than six months following the date of grant. The foregoing provision is intended to operate so that any income derived by a non-exempt employee in connection with the exercise or vesting of an Option or SAR will be exempt from his or her
regular rate of pay. 
 6. PROVISIONS OF STOCK AWARDS OTHER
THAN OPTIONS AND SARS. 
 (a) Restricted Stock Awards.
Each Restricted Stock Award Agreement shall be in such form and shall contain such terms and conditions as the Board shall deem appropriate. To the extent consistent with the Company’s Bylaws, at the Board’s election, shares of Common
Stock may be (i) held in book entry form subject to the Company’s instructions until any 

  
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restrictions relating to the Restricted Stock Award lapse; or (ii) evidenced by a certificate, which certificate shall be held in such form and manner as determined by the Board. The terms
and conditions of Restricted Stock Award Agreements may change from time to time, and the terms and conditions of separate Restricted Stock Award Agreements need not be identical; provided, however, that each Restricted Stock Award Agreement
shall conform to (through incorporation of the provisions hereof by reference in the agreement or otherwise) the substance of each of the following provisions: 
 (i) Consideration. A Restricted Stock Award may be awarded in consideration for (A) cash, check, bank draft or money order payable to the Company, (B) past services to the Company or an
Affiliate, or (C) any other form of legal consideration (including future services) that may be acceptable to the Board, in its sole discretion, and permissible under applicable law. 

(ii) Vesting. Shares of Common Stock awarded under the Restricted Stock Award Agreement may be subject to forfeiture to the
Company in accordance with a vesting schedule to be determined by the Board. 
 (iii) Termination of Participant’s
Continuous Service. If a Participant’s Continuous Service terminates, the Company may receive through a forfeiture condition or a repurchase right any or all of the shares of Common Stock held by the Participant that have not vested as of
the date of termination of Continuous Service under the terms of the Restricted Stock Award Agreement. 
 (iv)
Transferability. Rights to acquire shares of Common Stock under the Restricted Stock Award Agreement shall be transferable by the Participant only upon such terms and conditions as are set forth in the Restricted Stock Award Agreement, as the
Board shall determine in its sole discretion, so long as Common Stock awarded under the Restricted Stock Award Agreement remains subject to the terms of the Restricted Stock Award Agreement. 

(v) Dividends. A Restricted Stock Award Agreement may provide that any dividends paid on Restricted Stock will be subject to the
same vesting and forfeiture restrictions as apply to the shares subject to the Restricted Stock Award to which they relate. 

(b) Restricted Stock Unit Awards. Each Restricted Stock Unit Award Agreement shall be in such form and shall contain such terms
and conditions as the Board shall deem appropriate. The terms and conditions of Restricted Stock Unit Award Agreements may change from time to time, and the terms and conditions of separate Restricted Stock Unit Award Agreements need not be
identical; provided, however, that each Restricted Stock Unit Award Agreement shall conform to (through incorporation of the provisions hereof by reference in the Agreement or otherwise) the substance of each of the following provisions:

 (i) Consideration. At the time of grant of a Restricted Stock Unit Award, the Board will determine the consideration,
if any, to be paid by the Participant upon delivery of each share of Common Stock subject to the Restricted Stock Unit Award. The consideration to be paid (if any) by the Participant for each share of Common Stock subject to a Restricted Stock

  
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Unit Award may be paid in any form of legal consideration that may be acceptable to the Board, in its sole discretion, and permissible under applicable law. 

(ii) Vesting. At the time of the grant of a Restricted Stock Unit Award, the Board may impose such restrictions on or conditions
to the vesting of the Restricted Stock Unit Award as it, in its sole discretion, deems appropriate. 
 (iii) Payment. A
Restricted Stock Unit Award may be settled by the delivery of shares of Common Stock, their cash equivalent, any combination thereof or in any other form of consideration, as determined by the Board and contained in the Restricted Stock Unit Award
Agreement. 
 (iv) Additional Restrictions. At the time of the grant of a Restricted Stock Unit Award, the Board, as it
deems appropriate, may impose such restrictions or conditions that delay the delivery of the shares of Common Stock (or their cash equivalent) subject to a Restricted Stock Unit Award to a time after the vesting of such Restricted Stock Unit Award.

 (v) Dividend Equivalents. Dividend equivalents may be credited in respect of shares of Common Stock covered by a
Restricted Stock Unit Award, as determined by the Board and contained in the Restricted Stock Unit Award Agreement. At the sole discretion of the Board, such dividend equivalents may be converted into additional shares of Common Stock covered by the
Restricted Stock Unit Award in such manner as determined by the Board. Any additional shares covered by the Restricted Stock Unit Award credited by reason of such dividend equivalents will be subject to all of the same terms and conditions of the
underlying Restricted Stock Unit Award Agreement to which they relate. 
 (vi) Termination of Participant’s Continuous
Service. Except as otherwise provided in the applicable Restricted Stock Unit Award Agreement, such portion of the Restricted Stock Unit Award that has not vested will be forfeited upon the Participant’s termination of Continuous Service.

 (c) Performance Awards. 
 (i) Performance Stock Awards. A Performance Stock Award is a Stock Award that may vest or may be exercised contingent upon the attainment during a Performance Period of certain Performance Goals. A
Performance Stock Award may, but need not, require the completion of a specified period of Continuous Service. The length of any Performance Period, the Performance Goals to be achieved during the Performance Period, and the measure of whether and
to what degree such Performance Goals have been attained shall be conclusively determined by the Committee, in its sole discretion. The maximum number of shares covered by an Award that may be granted to any Participant in a calendar year
attributable to Stock Awards described in this Section 6(c)(i) (whether the grant, vesting or exercise is contingent upon the attainment during a Performance Period of the Performance Goals) shall not exceed
[            ] shares of Common Stock. The Board may provide for or, subject to such terms and conditions as the Board may specify, may permit a Participant to elect for, the payment of any
Performance Stock Award to be deferred to a specified date or event. In 

  
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addition, to the extent permitted by applicable law and the applicable Award Agreement, the Board may determine that cash may be used in payment of Performance Stock Awards. 

(ii) Performance Cash Awards. A Performance Cash Award is a cash award that may be paid contingent upon the attainment during a
Performance Period of certain Performance Goals. A Performance Cash Award may also require the completion of a specified period of Continuous Service. At the time of grant of a Performance Cash Award, the length of any Performance Period, the
Performance Goals to be achieved during the Performance Period, and the measure of whether and to what degree such Performance Goals have been attained shall be conclusively determined by the Committee, in its sole discretion. In any calendar year,
the Committee may not grant a Performance Cash Award that has a maximum value that may be paid to any Participant in excess of $[            ]. The Board may provide for or, subject to such
terms and conditions as the Board may specify, may permit a Participant to elect for, the payment of any Performance Cash Award to be deferred to a specified date or event. The Committee may specify the form of payment of Performance Cash Awards,
which may be cash or other property, or may provide for a Participant to have the option for his or her Performance Cash Award, or such portion thereof as the Board may specify, to be paid in whole or in part in cash or other property. 

(iii) Board Discretion. The Board retains the discretion to reduce or eliminate the compensation or economic benefit due upon
attainment of Performance Goals and to define the manner of calculating the Performance Criteria it selects to use for such Performance Period. 
 (iv) Section 162(m) Compliance. Unless otherwise permitted in compliance with the requirements of Section 162(m) of the Code with respect to an Award intended to qualify as
“performance-based compensation” thereunder, the Committee shall establish the Performance Goals applicable to, and the formula for calculating the amount payable under, the Award no later than the earlier of (a) the date 90 days
after the commencement of the applicable Performance Period, or (b) the date on which 25% of the Performance Period has elapsed, and in either event at a time when the achievement of the applicable Performance Goals remains substantially
uncertain. Prior to the payment of any compensation under an Award intended to qualify as “performance-based compensation” under Section 162(m) of the Code, the Committee shall certify the extent to which any Performance Goals and any
other material terms under such Award have been satisfied (other than in cases where such relate solely to the increase in the value of the Common Stock). Notwithstanding satisfaction of any completion of any Performance Goals, to the extent
specified at the time of grant of an Award to “covered employees” within the meaning of Section 162(m) of the Code, the number of shares of Common Stock , Options, cash or other benefits granted, issued, retainable and/or vested under
an Award on account of satisfaction of such Performance Goals may be reduced by the Committee on the basis of such further considerations as the Committee, in its sole discretion, shall determine. 

(d) Other Stock Awards. Other forms of Stock Awards valued in whole or in part by reference to, or otherwise based on, Common
Stock, including the appreciation in value thereof (e.g., options or stock rights with an exercise price or strike price less than 100% of the Fair Market Value of the Common Stock at the time of grant) may be granted either alone or in addition to
Stock Awards provided for under Section 5 and the preceding provisions of this 

  
 12 

 
Section 6. Subject to the provisions of the Plan, the Board shall have sole and complete authority to determine the persons to whom and the time or times at which such Other Stock Awards
will be granted, the number of shares of Common Stock (or the cash equivalent thereof) to be granted pursuant to such Other Stock Awards and all other terms and conditions of such Other Stock Awards. 

7. COVENANTS OF THE COMPANY. 

(a) Availability of Shares. During the terms of the Stock Awards, the Company shall keep available at all times the number of
shares of Common Stock reasonably required to satisfy such Stock Awards. 
 (b) Securities Law Compliance. The Company
shall seek to obtain from each regulatory commission or agency having jurisdiction over the Plan such authority as may be required to grant Stock Awards and to issue and sell shares of Common Stock upon exercise of the Stock Awards; provided,
however, that this undertaking shall not require the Company to register under the Securities Act the Plan, any Stock Award or any Common Stock issued or issuable pursuant to any such Stock Award. If, after 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 Common Stock under the Plan, the Company shall be relieved from any liability for failure
to issue and sell Common Stock upon exercise of such Stock Awards unless and until such authority is obtained. A Participant shall not be eligible for the grant of a Stock Award or the subsequent issuance of Common Stock pursuant to the Stock Award
if such grant or issuance would be in violation of any applicable securities law. 
 (c) No Obligation to Notify or Minimize
Taxes. The Company shall have no duty or obligation to any Participant to advise such holder as to the time or manner of exercising such Stock Award. Furthermore, the Company shall have no duty or obligation to warn or otherwise advise such
holder of a pending termination or expiration of a Stock Award or a possible period in which the Stock Award may not be exercised. The Company has no duty or obligation to minimize the tax consequences of a Stock Award to the holder of such Stock
Award. 
 8. MISCELLANEOUS. 
 (a) Use of Proceeds from Sales of Common Stock. Proceeds from the sale of shares of Common Stock pursuant to Stock Awards shall constitute general funds of the Company. 

(b) Corporate Action Constituting Grant of Stock Awards. Corporate action constituting a grant by the Company of a Stock Award to
any Participant shall be deemed completed as of the date of such corporate action, unless otherwise determined by the Board, regardless of when the instrument, certificate, or letter evidencing the Stock Award is communicated to, or actually
received or accepted by, the Participant. 
 (c) Stockholder Rights. No Participant shall be deemed to be the holder of,
or to have any of the rights of a holder with respect to, any shares of Common Stock subject to such Stock Award unless and until (i) such Participant has satisfied all requirements for exercise of

  
 13 

 
the Stock Award pursuant to its terms, if applicable, and (ii) the issuance of the Common Stock subject to such Stock Award has been entered into the books and records of the Company.

 (d) No Employment or Other Service Rights. Nothing in the Plan, any Stock Award Agreement or any other instrument
executed thereunder or in connection with any Award granted pursuant thereto shall confer upon any Participant any right to continue to serve the Company or an Affiliate in the capacity in effect at the time the Award was granted or shall affect the
right of the Company or an Affiliate to terminate (i) the employment of an Employee with or without notice and with or without cause, (ii) the service of a Consultant pursuant to the terms of such Consultant’s agreement with the
Company or an Affiliate, or (iii) the service of a Director pursuant to the Bylaws of the Company or an Affiliate, and any applicable provisions of the corporate law of the state in which the Company or the Affiliate is incorporated, as the
case may be. 
 (e) Incentive Stock Option $100,000 Limitation. To the extent that the aggregate Fair Market Value
(determined at the time of grant) of Common Stock with respect to which Incentive Stock Options are exercisable for the first time by any Optionholder during any calendar year (under all plans of the Company and any Affiliates) exceeds $100,000, the
Options or portions thereof that exceed such limit (according to the order in which they were granted) shall be treated as Nonstatutory Stock Options, notwithstanding any contrary provision of the applicable Option Agreement(s). 

(f) Investment Assurances. The Company may require a Participant, as a condition of exercising or acquiring Common Stock under any
Stock Award, (i) to give written assurances satisfactory to the Company as to the Participant’s knowledge and experience in financial and business matters and/or to employ a purchaser representative reasonably satisfactory to the Company
who is knowledgeable and experienced in financial and business matters and that he or she is capable of evaluating, alone or together with the purchaser representative, the merits and risks of exercising the Stock Award; and (ii) to give
written assurances satisfactory to the Company stating that the Participant is acquiring Common Stock subject to the Stock Award for the Participant’s own account and not with any present intention of selling or otherwise distributing the
Common Stock. The foregoing requirements, and any assurances given pursuant to such requirements, shall be inoperative if (A) the issuance of the shares upon the exercise or acquisition of Common Stock under the Stock Award has been registered
under a then currently effective registration statement under the Securities Act, or (B) as to any particular requirement, a determination is made by counsel for the Company that such requirement need not be met in the circumstances under the
then applicable securities laws. The Company may, upon advice of counsel to the Company, place legends on stock certificates issued under the Plan as such counsel deems necessary or appropriate in order to comply with applicable securities laws,
including, but not limited to, legends restricting the transfer of the Common Stock. 
 (g) Withholding Obligations.
Unless prohibited by the terms of an Award Agreement, the Company may, in its sole discretion, satisfy any federal, state or local tax withholding obligation relating to an Award by any of the following means or by a combination of such means:
(i) causing the Participant to tender a cash payment; (ii) withholding shares of Common Stock from the shares of Common Stock issued or otherwise issuable to the Participant in connection with the Award; provided, however, that no
shares of Common Stock are withheld 

  
 14 

 
with a value exceeding the minimum amount of tax required to be withheld by law (or such lesser amount as may be necessary to avoid classification of the Stock Award as a liability for financial
accounting purposes); (iii) withholding cash from an Award settled in cash; (iv) withholding payment from any amounts otherwise payable to the Participant; or (v) by such other method as may be set forth in the Award Agreement.

 (h) Electronic Delivery. Any reference herein to a “written” agreement or document shall include any
agreement or document delivered electronically, filed publicly with the Securities and Exchange Commission at www.sec.gov (or any successor website thereto) or posted on the Company’s intranet (or other shared electronic medium
controlled by the Company to which the Participant has access). 
 (i) Deferrals. To the extent permitted by applicable
law, the Board, in its sole discretion, may determine that the delivery of Common Stock or the payment of cash, upon the exercise, vesting or settlement of all or a portion of any Award may be deferred and may establish programs and procedures for
deferral elections to be made by Participants. Deferrals by Participants will be made in accordance with Section 409A of the Code. Consistent with Section 409A of the Code, the Board may provide for distributions while a Participant is
still an employee or otherwise providing services to the Company. The Board is authorized to make deferrals of Awards and determine when, and in what annual percentages, Participants may receive payments, including lump sum payments, following the
Participant’s termination of Continuous Service, and implement such other terms and conditions consistent with the provisions of the Plan and in accordance with applicable law. 

(j) Compliance with Section 409A. To the extent that the Board determines that any Award granted hereunder is subject to
Section 409A of the Code, the Award Agreement evidencing such Award shall incorporate the terms and conditions necessary to avoid the consequences specified in Section 409A(a)(1) of the Code. To the extent applicable, the Plan and Award
Agreements shall be interpreted in accordance with Section 409A of the Code. Notwithstanding anything to the contrary in this Plan (and unless the Award Agreement specifically provides otherwise), if the shares of Common Stock are publicly
traded and a Participant holding an Award that constitutes “deferred compensation” under Section 409A of the Code is a “specified employee” for purposes of Section 409A of the Code, no distribution or payment of any
amount shall be made upon a “separation from service” before a date that is six months following the date of such Participant’s “separation from service” (as defined in Section 409A of the Code without regard to
alternative definitions thereunder) or, if earlier, the date of the Participant’s death, unless such distribution or payment can be made in a manner that complies with Section 409A of the Code. 

9. ADJUSTMENTS UPON CHANGES IN COMMON STOCK;
OTHER CORPORATE EVENTS. 
 (a) Capitalization Adjustments. In the event
of a Capitalization Adjustment, the Board shall appropriately and proportionately adjust: (i) the class(es) and maximum number of securities subject to the Plan pursuant to Section 3(a), (ii) the class(es) and maximum number of
securities that may be issued pursuant to the exercise of Incentive Stock Options pursuant to Section 3(c), (iii) the class(es) and maximum number of securities that may be awarded to any person pursuant to Sections 3(d) and 6(c)(i), and
(iv) the class(es) and number of securities and 

  
 15 

 
price per share of stock subject to outstanding Stock Awards. The Board shall make such adjustments, and its determination shall be final, binding and conclusive. 

(b) Dissolution or Liquidation. Except as otherwise provided in the Stock Award Agreement, in the event of a dissolution or
liquidation of the Company, all outstanding Stock Awards (other than Stock Awards consisting of vested and outstanding shares of Common Stock not subject to a forfeiture condition or the Company’s right of repurchase) shall terminate
immediately prior to the completion of such dissolution or liquidation, and the shares of Common Stock subject to the Company’s repurchase rights or subject to a forfeiture condition may be repurchased or reacquired by the Company
notwithstanding the fact that the holder of such Stock Award is providing Continuous Service, provided, however, that the Board may, in its sole discretion, cause some or all Stock Awards to become fully vested, exercisable and/or no longer
subject to repurchase or forfeiture (to the extent such Stock Awards have not previously expired or terminated) before the dissolution or liquidation is completed but contingent on its completion. 

(c) Corporate Transaction. The following provisions shall apply to Stock Awards in the event of a Corporate Transaction unless
otherwise provided in the instrument evidencing the Stock Award or any other written agreement between the Company or any Affiliate and the Participant or unless otherwise expressly provided by the Board at the time of grant of a Stock Award. In the
event of a Corporate Transaction, then, notwithstanding any other provision of the Plan, the Board shall take one or more of the following actions with respect to Stock Awards, contingent upon the closing or completion of the Corporate Transaction:

 (i) arrange for the surviving corporation or acquiring corporation (or the surviving or acquiring corporation’s
parent company) to assume or continue the Stock Award or to substitute a similar stock award for the Stock Award (including, but not limited to, an award to acquire the same consideration paid to the stockholders of the Company pursuant to the
Corporate Transaction); 
 (ii) arrange for the assignment of any reacquisition or repurchase rights held by the Company
in respect of Common Stock issued pursuant to the Stock Award to the surviving corporation or acquiring corporation (or the surviving or acquiring corporation’s parent company); 

(iii) accelerate the vesting of the Stock Award (and, if applicable, the time at which the Stock Award may be exercised) to a date
prior to the effective time of such Corporate Transaction as the Board shall determine (or, if the Board shall not determine such a date, to the date that is five days prior to the effective date of the Corporate Transaction), with such Stock Award
terminating if not exercised (if applicable) at or prior to the effective time of the Corporate Transaction; 
 (iv)
arrange for the lapse of any reacquisition or repurchase rights held by the Company with respect to the Stock Award; 

  
 16 

 (v) cancel or arrange for the cancellation of the Stock Award, to the extent not
vested or not exercised prior to the effective time of the Corporate Transaction, in exchange for such cash consideration, if any, as the Board, in its sole discretion, may consider appropriate; and 

(vi) make a payment, in such form as may be determined by the Board equal to the excess, if any, of (A) the value of the
property the Participant would have received upon the exercise of the Stock Award immediately prior to the effective time of the Corporate Transaction, over (B) any exercise price payable by such holder in connection with such exercise.

 The Board need not take the same action or actions with respect to all Stock Awards or portions thereof or with respect to all Participants.

 (d) Change in Control. A Stock Award may be subject to additional acceleration of vesting and exercisability
upon or after a Change in Control as may be provided in the Stock Award Agreement for such Stock Award or as may be provided in any other written agreement between the Company or any Affiliate and the Participant, but in the absence of such
provision, no such acceleration shall occur. 
 10. TERMINATION OR SUSPENSION OF
THE PLAN. 
 (a) Plan Term. The Board may suspend or terminate the Plan at any
time; provided, however that Incentive Stock Options may no longer be granted under the Plan after the day before the tenth anniversary of the earlier of (i) the date the Plan is adopted by the Board, or (ii) the date the Plan is approved
by the stockholders of the Company. No Awards may be granted under the Plan while the Plan is suspended or after it is terminated. 
 (b) No Impairment of Rights. Suspension or termination of the Plan shall not impair rights and obligations under any Award granted while the Plan is in effect except with the written consent
of the affected Participant. 
 11. EFFECTIVE DATE OF PLAN. 

The Plan shall become effective on the Effective Date. 
 12. CHOICE OF LAW. 
 The law of the State of
California shall govern all questions concerning the construction, validity and interpretation of this Plan, without regard to that state’s conflict of laws rules. 
 13. DEFINITIONS. As used in the Plan, the following definitions shall apply to the capitalized terms indicated below: 

(a) “Affiliate” means, at the time of determination, any “parent” or “subsidiary” of
the Company as such terms are defined in Rule 405. The Board shall have the authority to determine the time or times at which “parent” or “subsidiary” status is determined within the foregoing definition. 

  
 17 

 (b) “Award” means a Stock Award or a Performance Cash Award.

 (c) “Award Agreement” means a written agreement between the Company and a Participant
evidencing the terms and conditions of an Award. 
 (d) “Board” means the Board of Directors of
the Company. 
 (e) “Capitalization Adjustment” means any change that is made in, or other events
that occur with respect to, the Common Stock subject to the Plan or subject to any Stock Award after the Effective Date without the receipt of consideration by the Company through merger, consolidation, reorganization, recapitalization,
reincorporation, stock dividend, dividend in property other than cash, large nonrecurring cash dividend, stock split, liquidating dividend, combination of shares, exchange of shares, change in corporate structure or any similar equity restructuring
transaction, as that term is used in Statement of Financial Accounting Standards No. 123 (revised). Notwithstanding the foregoing, the conversion of any convertible securities of the Company shall not be treated as a Capitalization Adjustment.

 (f) “Cause” shall have the meaning ascribed to such term in any written agreement between the
Participant and the Company defining such term and, in the absence of such agreement, such term shall mean with respect to a Participant, the occurrence of any of the following events: (i) such Participant’s conviction of any felony or any
crime involving fraud or dishonesty that has a material adverse effect on the Company; (ii) such Participant’s participation (whether by affirmative act or omission) in a fraud, act of dishonesty or other act of misconduct against the
Company and/or any of its Affiliates; (iii) such Participant’s conduct which, based upon a good faith and reasonable factual investigation by the Company (or, if such Participant is an Officer, by the Board), demonstrates such
Participant’s gross unfitness to serve; (iv) such Participant’s violation of any statutory or fiduciary duty, or duty of loyalty, owed to the Company and/or its Affiliates; (v) such Participant’s breach of any material term
of any material contract or agreement between the Participant and the Company and/or its Affiliates; or (vi) such Participant’s repeated violation of any material Company policy. The determination that a termination of the
Participant’s Continuous Service is either for Cause or without Cause shall be based upon a good faith determination by the Company (or, if such Participant is an Officer, by the Board) in its sole and exclusive judgment and discretion.
Notwithstanding the foregoing, such Participant’s Disability shall not constitute Cause as set forth herein. Any determination by the Company that the Continuous Service of a Participant was terminated with or without Cause for the purposes of
outstanding Awards held by such Participant shall have no effect upon any determination of the rights or obligations of the Company or such Participant for any other purpose. 
 (g) “Change in Control” means the consummation, in a single transaction or in a series of related transactions, of any one or more of the following events: 

(i) any Exchange Act Person becomes the Owner, directly or indirectly, of securities of the Company representing more than 50% of
the combined voting power of the Company’s then outstanding securities other than by virtue of a merger, consolidation or similar transaction. Notwithstanding the foregoing, a Change in Control shall not be deemed to occur (A) on account
of the acquisition of securities of the Company directly from the Company, 

  
 18 

 
(B) on account of the acquisition of securities of the Company by an investor, any affiliate thereof or any other Exchange Act Person that acquires the Company’s securities in a
transaction or series of related transactions the primary purpose of which is to obtain financing for the Company through the issuance of equity securities, or (C) solely because the level of Ownership held by any Exchange Act Person (the
“Subject Person”) exceeds the designated percentage threshold of the outstanding voting securities as a result of a repurchase or other acquisition of voting securities by the Company reducing the number of
shares outstanding, provided that if a Change in Control would occur (but for the operation of this sentence) as a result of the acquisition of voting securities by the Company, and after such share acquisition, the Subject Person becomes the Owner
of any additional voting securities that, assuming the repurchase or other acquisition had not occurred, increases the percentage of the then outstanding voting securities Owned by the Subject Person over the designated percentage threshold, then a
Change in Control shall be deemed to occur; 
 (ii) there is consummated a merger, consolidation or similar transaction
involving (directly or indirectly) the Company and, immediately after the consummation of such merger, consolidation or similar transaction, the stockholders of the Company immediately prior thereto do not Own, directly or indirectly, either
(A) outstanding voting securities representing more than 50% of the combined outstanding voting power of the surviving Entity in such merger, consolidation or similar transaction or (B) more than 50% of the combined outstanding voting
power of the parent of the surviving Entity in such merger, consolidation or similar transaction, in each case in substantially the same proportions as their Ownership of the outstanding voting securities of the Company immediately prior to such
transaction; 
 (iii) there is consummated a sale, lease, exclusive license or other disposition of all or substantially
all of the consolidated assets of the Company and its Subsidiaries, other than a sale, lease, license or other disposition of all or substantially all of the consolidated assets of the Company and its Subsidiaries to an Entity, more than 50% of the
combined voting power of the voting securities of which are Owned by stockholders of the Company in substantially the same proportions as their Ownership of the outstanding voting securities of the Company immediately prior to such sale, lease,
license or other disposition; or 
 (iv) individuals who, on the date the Plan is adopted by the Board, are members of
the Board (the “Incumbent Board”) cease for any reason to constitute at least a majority of the members of the Board; provided, however, that if the appointment or election (or nomination for election) of any new Board
member was approved or recommended by a majority vote of the members of the Incumbent Board then still in office, such new member shall, for purposes of this Plan, be considered as a member of the Incumbent Board. 

Notwithstanding the foregoing or any other provision of this Plan, (A) the term Change in Control shall not include a sale of
assets, merger or other transaction effected exclusively for the purpose of changing the domicile of the Company, and (B) the definition of Change in Control (or any analogous term) in an individual written agreement between the Company or any
Affiliate and the Participant shall supersede the foregoing definition with respect to Awards subject to such agreement; provided, however, that if no definition of Change in Control or any analogous term is set forth in such an individual
written agreement, the foregoing definition shall apply. 

  
 19 

 (h) “Code” means the Internal Revenue Code of 1986, as
amended, including any applicable regulations and guidance thereunder. 
 (i) “Committee” means a
committee of one or more Directors to whom authority has been delegated by the Board in accordance with Section 2(c). 

(j) “Common Stock” means the common stock of the Company. 

(k) “Company” means Ambit Biosciences Corporation, a Delaware corporation. 

(l) “Consultant” means any person, including an advisor, who is (i) engaged by the Company or an
Affiliate to render consulting or advisory services and is compensated for such services, or (ii) serving as a member of the board of directors of an Affiliate and is compensated for such services. However, service solely as a Director, or
payment of a fee for such service, shall not cause a Director to be considered a “Consultant” for purposes of the Plan. Notwithstanding the foregoing, a person is treated as a Consultant under this Plan only if a Form S-8 Registration
Statement under the Securities Act is available to register either the offer or the sale of the Company’s securities to such person. 
 (m) “Continuous Service” means that the Participant’s service with the Company or an Affiliate, whether as an Employee, Director or Consultant, is not interrupted or
terminated. A change in the capacity in which the Participant renders service to the Company or an Affiliate as an Employee, Consultant or Director or a change in the entity for which the Participant renders such service, provided that there is no
interruption or termination of the Participant’s service with the Company or an Affiliate, shall not terminate a Participant’s Continuous Service; provided, however, if the Entity for which a Participant is rendering services ceases
to qualify as an Affiliate, as determined by the Board, in its sole discretion, such Participant’s Continuous Service shall be considered to have terminated on the date such Entity ceases to qualify as an Affiliate. To the extent permitted by
law, the Board or the chief executive officer of the Company, in that party’s sole discretion, may determine whether Continuous Service shall be considered interrupted in the case of (i) any leave of absence approved by the Board or chief
executive officer, including sick leave, military leave or any other personal leave, or (ii) transfers between the Company, an Affiliate, or their successors. Notwithstanding the foregoing, a leave of absence shall be treated as Continuous
Service for purposes of vesting in a Stock Award only to such extent as may be provided in the Company’s leave of absence policy, in the written terms of any leave of absence agreement or policy applicable to the Participant, or as otherwise
required by law. 
 (n) “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) the consummation of a sale or
other disposition of all or substantially all, as determined by the Board, in its sole discretion, of the consolidated assets of the Company and its Subsidiaries; 
 (ii) the consummation of a sale or other disposition of at least 90% of the outstanding securities of the Company; 

  
 20 

 (iii) the consummation of a merger, consolidation or similar transaction following
which the Company is not the surviving corporation; or 
 (iv) the consummation of a merger, consolidation or similar
transaction following which the Company is the surviving corporation but the shares of Common Stock outstanding immediately preceding the 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. 
 (o)
“Covered Employee” shall have the meaning provided in Section 162(m)(3) of the Code. 
 (p)
“Director” means a member of the Board. 
 (q) “Disability” means, with
respect to a Participant, the inability of such Participant to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment which can be expected to result in death or which has lasted or can be
expected to last for a continuous period of not less than 12 months, as provided in Sections 22(e)(3) and 409A(a)(2)(c)(i) of the Code, and shall be determined by the Board on the basis of such medical evidence as the Board deems warranted under the
circumstances. 
 (r) “Effective Date” means the effective date of this Plan document, which is
the date of the underwriting agreement between the Company and the underwriter(s) managing the initial public offering of the Common Stock, pursuant to which the Common Stock is priced for the initial public offering. 

(s) “Employee” means any person employed by the Company or an Affiliate. However, service solely as a
Director, or payment of a fee for such services, shall not cause a Director to be considered an “Employee” for purposes of the Plan. 
 (t) “Entity” means a corporation, partnership, limited liability company or other entity. 
 (u) “Exchange Act” means the Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder. 

(v) “Exchange Act Person” means any natural person, Entity or “group” (within the meaning of
Section 13(d) or 14(d) of the Exchange Act), except that “Exchange Act Person” shall not include (i) the Company or any Subsidiary of the Company, (ii) any employee benefit plan of the Company or any Subsidiary of the
Company or any trustee or other fiduciary holding securities under an employee benefit plan of the Company or any Subsidiary of the Company, (iii) an underwriter temporarily holding securities pursuant to a registered public offering of such
securities, (iv) an Entity Owned, directly or indirectly, by the stockholders of the Company in substantially the same proportions as their Ownership of stock of the Company; or (v) any natural person, Entity or “group” (within
the meaning of Section 13(d) or 14(d) of the Exchange Act) that, as of the Effective Date, is the Owner, directly or indirectly, of securities of the Company representing more than 50% of the combined voting power of the Company’s then
outstanding securities. 

  
 21 

 (w) “Fair Market Value” means, as of any date, the value of
the Common Stock determined as follows: 
 (i) If the Common Stock is listed on any established stock exchange or traded
on any established market, the Fair Market Value of a share of Common Stock shall be the closing sales price for such stock as quoted on such exchange or market (or the exchange or market with the greatest volume of trading in the Common Stock) on
the date of determination, as reported in a source the Board deems reliable. 
 (ii) Unless otherwise provided by the
Board, if there is no closing sales price for the Common Stock on the date of determination, then the Fair Market Value shall be the closing selling price on the last preceding date for which such quotation exists. 

(iii) In the absence of such markets for the Common Stock, the Fair Market Value shall be determined by the Board in good faith
and in a manner that complies with Sections 409A and 422 of the Code. 
 (x) “Incentive Stock
Option” means a stock option granted pursuant to Section 5 of the Plan that is intended to be, and qualifies as, an “incentive stock option” within the meaning of Section 422 of the Code. 

(y) “Non-Employee Director” means a Director who either (i) is not a current employee or officer of
the Company or an Affiliate, does not receive compensation, either directly or indirectly, from the Company or an Affiliate for services rendered as a consultant or in any capacity other than as a Director (except for an amount as to which
disclosure would not be required under Item 404(a) of Regulation S-K promulgated pursuant to the Securities Act (“Regulation S-K”)), does not possess an interest in any other transaction for which disclosure would
be required under Item 404(a) of Regulation S-K, and is not engaged in a business relationship for which disclosure would be required pursuant to Item 404(b) of Regulation S-K; or (ii) is otherwise considered a “non-employee
director” for purposes of Rule 16b-3. 
 (z) “Nonstatutory Stock Option” means any
stock option granted pursuant to Section 5 of the Plan that does not qualify as an Incentive Stock Option. 
 (aa)
“Officer” means a person who is an officer of the Company within the meaning of Section 16 of the Exchange Act. 
 (bb) “Option” means an Incentive Stock Option or a Nonstatutory Stock Option to purchase shares of Common Stock granted pursuant to the Plan. 

(cc) “Option Agreement” means a written agreement between the Company and an Optionholder evidencing the
terms and conditions of an Option grant. Each Option Agreement shall be subject to the terms and conditions of the Plan. 

(dd) “Optionholder” means a person to whom an Option is granted pursuant to the Plan or, if applicable,
such other person who holds an outstanding Option. 

  
 22 

 (ee) “Other Stock Award” means an award based in whole or in
part by reference to the Common Stock which is granted pursuant to the terms and conditions of Section 6(d). 
 (ff)
“Other Stock Award Agreement” means a written agreement between the Company and a holder of an Other Stock Award evidencing the terms and conditions of an Other Stock Award grant. Each Other Stock Award Agreement shall be
subject to the terms and conditions of the Plan. 
 (gg) “Outside Director” means a Director who
either (i) is not a current employee of the Company or an “affiliated corporation” (within the meaning of Treasury Regulations promulgated under Section 162(m) of the Code), is not a former employee of the Company or an
“affiliated corporation” who receives compensation for prior services (other than benefits under a tax-qualified retirement plan) during the taxable year, has not been an officer of the Company or an “affiliated corporation,” and
does not receive remuneration from the Company or an “affiliated corporation,” either directly or indirectly, in any capacity other than as a Director, or (ii) is otherwise considered an “outside director” for purposes of
Section 162(m) of the Code. 
 (hh) “Own,” “Owned,”
“Owner,” “Ownership” A person or Entity shall be deemed to “Own,” to have “Owned,” to be the “Owner” of, or to have acquired “Ownership” of securities if
such person or Entity, directly or indirectly, through any contract, arrangement, understanding, relationship or otherwise, has or shares voting power, which includes the power to vote or to direct the voting, with respect to such securities.

 (ii) “Participant” means a person to whom an Award is granted pursuant to the Plan or, if
applicable, such other person who holds an outstanding Stock Award. 
 (jj) “Performance Cash
Award” means an award of cash granted pursuant to the terms and conditions of Section 6(c)(ii). 
 (kk)
“Performance Criteria” means the one or more criteria that the Board shall select for purposes of establishing the Performance Goals for a Performance Period. The Performance Criteria that shall be used to establish such
Performance Goals may be based on any one of, or combination of, the following as determined by the Board: (i) earnings (including earnings per share and net earnings); (ii) earnings before interest, taxes and depreciation;
(iii) earnings before interest, taxes, depreciation and amortization; (iv) total stockholder return; (v) return on equity or average stockholder’s equity; (vi) return on assets, investment, or capital employed;
(vii) stock price; (viii) margin (including gross margin); (ix) income (before or after taxes); (x) operating income; (xi) operating income after taxes; (xii) pre-tax profit; (xiii) operating cash flow;
(xiv) sales or revenue targets; (xv) increases in revenue or product revenue; (xvi) expenses and cost reduction goals; (xvii) improvement in or attainment of working capital levels; (xiii) economic value added (or an
equivalent metric); (xix) market share; (xx) cash flow; (xxi) cash flow per share; (xxii) share price performance; (xxiii) debt reduction; (xxiv) implementation or completion of projects or processes;
(xxv) customer satisfaction; (xxvi) stockholders’ equity; (xxvii) capital expenditures; (xxiii) debt levels; (xxix) operating profit or net operating profit; (xxx) workforce diversity; (xxxi) growth of net
income or operating income; (xxxii) billings; and (xxxiii) to the extent that an Award is not intended to comply with Section 162(m) of the Code, other measures of performance selected by the Board. 

  
 23 

 (ll) “Performance Goals” means, for a Performance Period, the
one or more goals established by the Board for the Performance Period based upon the Performance Criteria. Performance Goals may be based on a Company-wide basis, with respect to one or more business units, divisions, Affiliates, or business
segments, and in either absolute terms or relative to the performance of one or more comparable companies or the performance of one or more relevant indices. Unless specified otherwise by the Board (i) in the Award Agreement at the time the
Award is granted or (ii) in such other document setting forth the Performance Goals at the time the Performance Goals are established, the Board shall appropriately make adjustments in the method of calculating the attainment of Performance
Goals for a Performance Period as follows: (1) to exclude restructuring and/or other nonrecurring charges; (2) to exclude exchange rate effects, as applicable, for non-U.S. dollar denominated Performance Goals; (3) to exclude the
effects of changes to generally accepted accounting principles; (4) to exclude the effects of any statutory adjustments to corporate tax rates; and (5) to exclude the effects of any “extraordinary items” as determined under
generally accepted accounting principles. 
 (mm) “Performance Period” means the period of time
selected by the Board over which the attainment of one or more Performance Goals will be measured for the purpose of determining a Participant’s right to and the payment of a Stock Award or a Performance Cash Award. Performance Periods may be
of varying and overlapping duration, at the sole discretion of the Board. 
 (nn) “Performance Stock
Award” means a Stock Award granted under the terms and conditions of Section 6(c)(i). 
 (oo)
“Plan” means this Ambit Biosciences Corporation 2011 Equity Incentive Plan. 
 (pp)
“Restricted Stock Award” means an award of shares of Common Stock which is granted pursuant to the terms and conditions of Section 6(a). 
 (qq) “Restricted Stock Award Agreement” means a written agreement between the Company and a holder of a Restricted Stock Award evidencing the terms and conditions of a
Restricted Stock Award grant. Each Restricted Stock Award Agreement shall be subject to the terms and conditions of the Plan. 

(rr) “Restricted Stock Unit Award” means a right to receive shares of Common Stock which is granted
pursuant to the terms and conditions of Section 6(b). 
 (ss) “Restricted Stock Unit Award
Agreement” means a written agreement between the Company and a holder of a Restricted Stock Unit Award evidencing the terms and conditions of a Restricted Stock Unit Award grant. Each Restricted Stock Unit Award Agreement shall be
subject to the terms and conditions of the Plan. 
 (tt) “Rule 16b-3” means Rule 16b-3
promulgated under the Exchange Act or any successor to Rule 16b-3, as in effect from time to time. 
 (uu)
“Rule 405” means Rule 405 promulgated under the Securities Act. 
 (vv) “Securities
Act” means the Securities Act of 1933, as amended. 

  
 24 

 (ww) “Stock Appreciation Right” or
“SAR” means a right to receive the appreciation on Common Stock that is granted pursuant to the terms and conditions of Section 5. 
 (xx) “Stock Appreciation Right Agreement” means a written agreement between the Company and a holder of a Stock Appreciation Right evidencing the terms and conditions of a
Stock Appreciation Right grant. Each Stock Appreciation Right Agreement shall be subject to the terms and conditions of the Plan. 
 (yy) “Stock Award” means any right to receive Common Stock granted under the Plan, including an Incentive Stock Option, a Nonstatutory Stock Option, a Restricted Stock
Award, a Restricted Stock Unit Award, a Stock Appreciation Right, a Performance Stock Award or any Other Stock Award. 

(zz) “Stock Award Agreement” means a written agreement between the Company and a Participant evidencing
the terms and conditions of a Stock Award grant. Each Stock Award Agreement shall be subject to the terms and conditions of the Plan. 
 (aaa) “Subsidiary” means, with respect to the Company, (i) any corporation of which more than 50% of the outstanding capital stock having ordinary voting power to elect
a majority of the board of directors of such corporation (irrespective of whether, at the time, stock of any other class or classes of such corporation shall have or might have voting power by reason of the happening of any contingency) is at the
time, directly or indirectly, Owned by the Company, and (ii) any partnership, limited liability company or other entity in which the Company has a direct or indirect interest (whether in the form of voting or participation in profits or capital
contribution) of more than 50%. 
 (bbb) “Ten Percent Stockholder” means a person who Owns (or is
deemed to Own pursuant to Section 424(d) of the Code) stock possessing more than 10% of the total combined voting power of all classes of stock of the Company or any Affiliate. 

  
 25 

 AMBIT BIOSCIENCES CORPORATION 

2011 EQUITY INCENTIVE PLAN 

OPTION AGREEMENT 
 (INCENTIVE STOCK OPTION OR NONSTATUTORY STOCK OPTION) 

Pursuant to your Stock Option Grant Notice (“Grant Notice”) and this Option Agreement, Ambit Biosciences
Corporation (the “Company”) has granted you an option under its 2011 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. Capitalized terms not explicitly defined in this 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. 
 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. EXERCISE RESTRICTION FOR NON-EXEMPT
EMPLOYEES. In the event that you are an Employee eligible for overtime compensation under the Fair Labor Standards Act of 1938, as amended (i.e., a “Non-Exempt Employee”), and except as otherwise
provided in the Plan, you may not exercise your option until you have completed at least six months of Continuous Service measured from the Date of Grant specified in your Grant Notice, notwithstanding any other provision of your option. 

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, bank draft or money order or in any one or more of the following manners unless otherwise provided in your Grant
Notice: 
 (a) Provided that at the time of exercise the Common Stock is publicly traded, 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, by delivery to the Company (either by actual delivery or attestation) of already-owned shares of Common Stock 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 

  
 1 

 
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. 

(c) If the Option is a Nonstatutory Stock Option, subject to the consent of the Company at the time of exercise, by
a “net exercise” arrangement pursuant to which the Company will reduce the number of shares of Common Stock issued upon exercise of your option by the largest whole number of shares with a Fair Market Value that does not exceed the
aggregate exercise price; provided, however, that the Company shall accept a cash or other payment from you to the extent of any remaining balance of the aggregate exercise price not satisfied by such reduction in the number of whole shares to be
issued; provided further, however, that shares of Common Stock will no longer be outstanding under your option and will not be exercisable thereafter to the extent that (i) shares are used to pay the exercise price pursuant to the “net
exercise,” (ii) shares are delivered to you as a result of such exercise, and (iii) shares are withheld to satisfy tax withholding obligations. 
 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 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. 
 7. TERM. You may not exercise your option
before the commencement or after the expiration of its term. The term of your option commences on the Date of Grant and expires, subject to the provisions of Section 5(h) of the Plan, upon the earliest of the following: 

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

(b) three months after the termination of your Continuous Service for any reason other than Cause, your Disability or death,
provided that if during any part of such three month period your option is not exercisable solely because of the condition set forth in the section above 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 months after the termination of your Continuous Service; and if (i) you are a Non-Exempt Employee, (ii) your Continuous Service
terminates within six months after the Date of Grant specified in your Grant Notice, and (iii) you have vested in a portion of your option at the time of your termination of Continuous Service, your option shall not expire until the earlier of
(x) the later of (A) the date that is seven months after the Date of Grant specified in your Grant Notice 

  
 2 

 
or (B) the date that is three months after the termination of your Continuous Service, or (y) the Expiration Date; 

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

(d) 18 months after your death if you die during your Continuous Service; 

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

(f) the day before the tenth anniversary of the Date of Grant. 
 Notwithstanding the foregoing, if you die during the period provided in Section 7(b) or 7(c) above, the term of your option shall not expire until the earlier of 18 months after your death, the
Expiration Date indicated in your Grant Notice, or the day before the tenth 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 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 Disability. 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 months after the date your employment with the Company or an Affiliate terminates. 
 8. 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. 
 (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 (i) the
exercise of your option, (ii) the lapse of any substantial risk of forfeiture to which the shares of Common Stock are subject at the time of exercise, or (iii) 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 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 years after the date of your option grant or within one year after such shares of Common
Stock are transferred upon exercise of your option. 

  
 3 

 9. TRANSFERABILITY. Except as otherwise provided in
this Section 9, 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. 
 (a) Certain Trusts. Upon receiving written permission from the Board or its duly authorized designee, you may transfer your option to a trust if you are considered to be the sole beneficial
owner (determined under Section 671 of the Code and applicable state law) while the option is held in the trust, provided that you and the trustee enter into transfer and other agreements required by the Company. 

(b) Domestic Relations Orders. Upon receiving written permission from the Board or its duly authorized designee, and
provided that you and the designated transferee enter into transfer and other agreements required by the Company, you may transfer your option pursuant to a domestic relations order that contains the information required by the Company to effectuate
the transfer. You are encouraged to discuss the proposed terms of any division of this option with the Company prior to finalizing the domestic relations order to help ensure the required information is contained within the domestic relations order.
If this option is an Incentive Stock Option, this option may be deemed to be a Nonstatutory Stock Option as a result of such transfer. 
 (c) Beneficiary Designation. Upon receiving written permission from the Board or its duly authorized designee, you may, by delivering written notice to the Company, in a form provided by or
otherwise satisfactory to the Company and any broker designated by the Company to effect option exercises, designate a third party who, in the event of your death, shall thereafter be entitled to exercise this option and receive the Common Stock or
other consideration resulting from such exercise. In the absence of such a designation, your executor or administrator of your estate shall be entitled to exercise this option and receive, on behalf of your estate, the Common Stock or other
consideration resulting from such exercise. 
 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 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. 
 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 for (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 permitted by the Company), 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. 

  
 4 

 (b) Upon your request and subject to approval by the Company, in its sole discretion,
and in compliance with any applicable legal conditions or restrictions, the Company may 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 classification of your option as a liability for
financial accounting purposes). If the date of determination of any tax withholding obligation is deferred to a date later than the date of exercise of your option, share withholding pursuant to the preceding sentence shall not be permitted unless
you make a proper and timely election under Section 83(b) of the Code, covering the aggregate number of shares of Common Stock acquired upon such exercise with respect to which such determination is otherwise deferred, to accelerate the
determination of such tax withholding obligation to the date of exercise of your option. Notwithstanding the filing of such election, shares of Common Stock shall be withheld solely from fully vested shares of Common Stock determined as of the date
of exercise of your option that are otherwise issuable to you upon such exercise. 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 unless such obligations are satisfied.

 12. TAX CONSEQUENCES. You hereby agree that the Company does not
have a duty to design or administer the Plan or its other compensation programs in a manner that minimizes your tax liabilities. You shall not make any claim against the Company, or any of its Officers, Directors, Employees or Affiliates related to
tax liabilities arising from your option or your other compensation. In particular, you acknowledge that this option is exempt from Section 409A of the Code only if the exercise price per share specified in the Grant Notice is at least equal to
the “fair market value” per share of the Common Stock on the Date of Grant and there is no other impermissible deferral of compensation associated with the option. 
 13. 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 days after deposit in the United States mail, postage prepaid, addressed to you at the last address you provided to the Company. 
 14. 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. 

  
 52011 Employee Stock Purchase Plan and Form of Offering Document

 Exhibit 10.4 
 AMBIT BIOSCIENCES CORPORATION 

2011 EMPLOYEE STOCK PURCHASE PLAN 

ADOPTED BY THE BOARD OF DIRECTORS:
NOVEMBER 30, 2010 
 APPROVED BY THE
STOCKHOLDERS: [                    ] 
 1. GENERAL. 
 (a) The purpose of the Plan is to
provide a means by which Eligible Employees of the Company and certain designated Related Corporations may be given an opportunity to purchase shares of Common Stock. The Plan is intended to permit the Company to grant a series of Purchase Rights to
Eligible Employees under an Employee Stock Purchase Plan. 
 (b) The Company, by means of the Plan, seeks to retain the
services of such Employees, to secure and retain the services of new Employees and to provide incentives for such persons to exert maximum efforts for the success of the Company and its Related Corporations. 

2. ADMINISTRATION. 
 (a) The Board shall administer the Plan unless and until the Board delegates administration of the Plan to a Committee or Committees, as provided in Section 2(c). 

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

(i) To determine how and when 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 its administration. 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 settle all controversies regarding the Plan and
Purchase Rights granted under it. 
 (v) To suspend or terminate the Plan at any time as provided in Section 12.

 (vi) To amend the Plan at any time as provided in Section 12. 

(vii) 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 

  
 1 

 
and to carry out the intent that the Plan be treated as an Employee Stock Purchase Plan. 
 (viii) 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 some or all of the administration of the Plan to a Committee or Committees. If
administration is delegated to a Committee, the Committee shall have, in connection with the administration of the Plan, the powers theretofore possessed by the Board that have been delegated to the Committee, including the power to delegate to a
subcommittee any of the administrative powers the Committee is authorized to exercise (and references in this Plan to the Board shall thereafter be to the Committee or subcommittee), 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 retain the authority to concurrently administer the Plan with the Committee and may, at any time, revest in the Board some or all of the powers previously
delegated. Whether or not the Board has delegated administration of the Plan to a Committee, the Board shall have the final power to determine all questions of policy and expediency that may arise in the administration of the Plan. 

(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. 
 3. SHARES OF COMMON
STOCK SUBJECT TO THE PLAN. 
 (a) Subject
to the provisions of Section 11(a) relating to Capitalization Adjustments, the shares of Common Stock that may be sold pursuant to Purchase Rights shall not exceed in the aggregate
[            ] shares of Common Stock. In addition, the number of shares of Common Stock available for issuance under the Plan shall automatically increase on January 1st of
each year, commencing in [            ] and ending on (and including) January 1, [            ], in an amount equal to the
lesser of (i) [__]% of the total number of shares of Common Stock outstanding on December 31st of the preceding calendar year, and (ii) [            ] shares of Common
Stock. Notwithstanding the foregoing, the Board may act prior to the first day of any calendar year, to provide that there shall be no increase in the share reserve for such calendar year or that the increase in the share reserve for such calendar
year shall be a lesser number of shares of Common Stock than would otherwise occur pursuant to the preceding sentence. 

(b) If any Purchase Right granted under the Plan shall for any reason terminate without having been exercised, the shares of
Common Stock not purchased under such Purchase Right shall again become available for issuance under the Plan. 
 (c) The
stock purchasable under the Plan shall be shares of authorized but unissued or reacquired Common Stock, including shares repurchased by the Company on the open market. 
 4. 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

  
 2 

 
(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 27 months beginning with the Offering Date, and the substance of the provisions contained in Sections 5 through 8,
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. 
 (c) The Board shall
have the discretion to structure an Offering so that if the Fair Market Value of the shares of Common Stock on the first day of a new Purchase Period within that Offering is less than or equal to the Fair Market Value of the shares of Common Stock
on the Offering Date, then (i) that Offering shall terminate immediately, and (ii) the Participants in such terminated Offering shall be automatically enrolled in a new Offering beginning on the first day of such new Purchase Period.

 5. ELIGIBILITY. 
 (a) Purchase Rights may be granted only to Employees of the Company or, as the Board may designate as provided in Section 2(b), to Employees of a Related Corporation. Except as provided in
Section 5(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 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 20 hours per week and more than five months per calendar year or such other criteria as the Board
may determine consistent with Section 423 of the Code. 
 (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:

  
 3 

 (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; 

(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 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 5(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 $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. 
 6. 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 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
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. 

  
 4 

 (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 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 85% of the Fair Market Value of the shares of Common Stock on the Offering Date; or 

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

7. PARTICIPATION; WITHDRAWAL; TERMINATION. 

(a) An Eligible Employee 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 be credited to a bookkeeping account for such Participant under
the Plan and shall be deposited with the general funds of the Company except where applicable law requires that Contributions be deposited with a third party. To the extent provided in the Offering, a Participant may begin such 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 

  
 5 

 
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 except by will, the laws of descent and distribution,
or by a beneficiary designation as provided in Section 10. 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. 
 8. EXERCISE OF PURCHASE RIGHTS. 
 (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 7(b), or is not eligible to participate in such Offering, as provided in
Section 5, 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 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 without interest.

 (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 applicable federal, state, foreign and other securities and other 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 

  
 6 

 
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 12 months and the Purchase
Date shall in no event be more than 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 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
without interest. 
 9. 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 Common Stock under the Plan, and at a commercially reasonable cost, the Company shall be relieved from any liability for failure to issue and sell Common
Stock upon exercise of such Purchase Rights unless and until such authority is obtained. 
 10. 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. 
 11. ADJUSTMENTS UPON CHANGES IN COMMON
STOCK; CORPORATE TRANSACTIONS. 
 (a) In the event of a Capitalization
Adjustment, the Board shall appropriately and proportionately adjust: (i) the class(es) and maximum number of securities subject to the Plan pursuant to Section 3(a), (ii) the class(es) and maximum number of securities by which the
share reserve is to increase automatically each year pursuant to Section 3(a), (iii) the class(es) and number of securities subject to, and the purchase price applicable to outstanding Offerings and

  
 7 

 
Purchase Rights, and (iv) the class(es) and number of securities that are the subject of the purchase limits under each ongoing Offering. The Board shall make such adjustments, and its
determination shall be final, binding and conclusive. 
 (b) In the event of a Corporate Transaction, then: (i) any
surviving corporation or acquiring corporation (or the surviving or acquiring corporation’s parent company) may assume or continue Purchase Rights outstanding under the Plan or may substitute similar rights (including a right to acquire the
same consideration paid to the stockholders in the Corporate Transaction) for those outstanding under the Plan, or (ii) if any surviving or acquiring corporation (or its parent company) does not assume or continue 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 business days prior to the Corporate Transaction under
any ongoing Offerings, and the Participants’ Purchase Rights under the ongoing Offerings shall terminate immediately after such purchase. 

12. AMENDMENT, TERMINATION OR SUSPENSION OF THE
PLAN. 
 (a) The Board may amend the Plan at any time in any respect the Board deems necessary or
advisable. However, except as provided in Section 11(a) relating to Capitalization Adjustments, stockholder approval shall be required for any amendment of the Plan for which stockholder approval is required by applicable law or listing
requirements, including any amendment that either (i) materially increases the number of shares of Common Stock available for issuance under the Plan, (ii) materially expands the class of individuals eligible to become Participants and
receive Purchase Rights under the Plan, (iii) materially increases the benefits accruing to Participants under the Plan or materially reduces the price at which shares of Common Stock may be purchased under the Plan, (iv) materially
extends the term of the Plan, or (v) expands the types of awards available for issuance under the Plan, but in each of (i) through (v) above only to the extent stockholder approval is required by applicable law or listing
requirements. 
 (b) The Board may suspend or terminate the Plan at any time. No Purchase Rights may be granted under the
Plan while the Plan is suspended or after it is terminated. 
 (c) Any benefits, privileges, entitlements and obligations
under any outstanding Purchase Rights granted before an amendment, suspension or termination of the Plan shall not be impaired by any such amendment, suspension or termination except (i) with the consent of the person to whom such Purchase
Rights were granted, (ii) as necessary to comply with any laws, listing requirements, or governmental regulations (including, without limitation, the provisions of Section 423 of the Code and the regulations and other interpretive guidance
issued thereunder relating to Employee Stock Purchase Plans) including without limitation any such regulations or other guidance that may be issued or amended after the Effective Date, or (iii) as necessary to obtain or maintain favorable tax,
listing, or regulatory treatment. 

  
 8 

 13. 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, which approval shall be within 12 months before or after the date the Plan is adopted by the Board. 
 14.
MISCELLANEOUS PROVISIONS. 
 (a) Proceeds from the sale of shares of Common Stock
pursuant to Purchase Rights shall constitute general funds of the Company. 
 (b) 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 shares of Common Stock acquired upon exercise of Purchase Rights are recorded in the
books of the Company (or its transfer agent). 
 (c) 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. 

(d) The provisions of the Plan shall be governed by the laws of the state of California without resort to that state’s
conflicts of laws rules. 
 15. DEFINITIONS. 
 As used in the Plan, the following definitions shall apply to the capitalized terms indicated below: 
 (a) “Board” means the Board of Directors of the Company. 
 (b) “Capitalization Adjustment” means any change that is made in, or other events that occur with respect to, the Common Stock subject to the Plan or subject to any Purchase
Right after the Effective Date 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 similar transaction). Notwithstanding the foregoing, the conversion of any convertible securities of the Company shall not be treated as a Capitalization
Adjustment. 
 (c) “Code” means the Internal Revenue Code of 1986, as amended, including any
applicable regulations and guidance thereunder. 
 (d) “Committee” means a committee of one or
more members of the Board to whom authority has been delegated by the Board in accordance with Section 2(c). 

  
 9 

 (e) “Common Stock” means the common stock of the Company.

 (f) “Company” means Ambit Biosciences Corporation, a Delaware corporation. 

(g) “Contributions” means the payroll deductions and other additional payments specifically provided for
in the Offering, that a Participant contributes to fund the exercise of a Purchase Right. A Participant may make additional payments into his or her account, if specifically provided for in the Offering, and then only if the Participant has not
already had the maximum permitted amount withheld during the Offering through payroll deductions. 
 (h)
“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) the consummation of a sale or other disposition of all or substantially all, as determined by the Board in its sole discretion,
of the consolidated assets of the Company and its Subsidiaries; 
 (ii) the consummation of a sale or other disposition
of at least 90% of the outstanding securities of the Company; 
 (iii) the consummation of a merger, consolidation or
similar transaction following which the Company is not the surviving corporation; or 
 (iv) the consummation of a
merger, consolidation or similar transaction following which the Company is the surviving corporation but the shares of Common Stock outstanding immediately preceding the 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. 
 (i) “Director” means a member of the Board. 

(j) “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. 
 (k) “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. However, service solely as a Director, or payment of a fee for such services, shall not cause a Director to be considered an “Employee” for purposes of the Plan. 

(l) “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. 
 (m)
“Exchange Act” means the Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder. 
 (n) “Fair Market Value” means, as of any date, the value of the Common Stock 

  
 10 

 
determined as follows: 
 (i) If the Common Stock is listed on any
established stock exchange or traded on any established market, the Fair Market Value of a share of Common Stock shall be the closing sales price for such stock as quoted on such exchange or market (or the exchange or market with the greatest volume
of trading in the Common Stock) on the last trading day prior to the date of determination, as reported in such source as the Board deems reliable. Unless otherwise provided by the Board, if there is no closing sales price for the Common Stock on
the last trading day prior to the date of determination, then the Fair Market Value shall be the closing sales price on the last preceding date for which such quotation exists. 

(ii) In the absence of such markets for the Common Stock, the Fair Market Value shall be determined by the Board in good faith and
in a manner that complies with Sections 409A of the Code. 
 (iii) Notwithstanding the foregoing, for any Offering that
commences on the IPO Date, 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. 
 (o) “IPO Date” means the
date of the underwriting agreement between the Company and the underwriter(s) managing the initial public offering of the Common Stock, pursuant to which the Common Stock is priced for the initial public offering. 

(p) “Offering” means the grant of Purchase Rights to purchase shares of Common Stock under the Plan to
Eligible Employees. 
 (q) “Offering Date” means a date selected by the Board for an Offering to
commence. 
 (r) “Officer” means a person who is an officer of the Company within the meaning of
Section 16 of the Exchange Act. 
 (s) “Participant” means an Eligible Employee who holds an
outstanding Purchase Right granted pursuant to the Plan. 
 (t) “Plan” means this Ambit
Biosciences Corporation 2011 Employee Stock Purchase Plan. 
 (u) “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. 

(v) “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. 

  
 11 

 (w) “Purchase Right” means an option to purchase shares of
Common Stock granted pursuant to the Plan. 
 (x) “Related Corporation” means any “parent
corporation” or “subsidiary corporation” of the Company whether now or subsequently established, as those terms are defined in Sections 424(e) and (f), respectively, of the Code. 

(y) “Securities Act” means the Securities Act of 1933, as amended. 

(z) “Trading Day” means any day on which the exchange(s) or market(s) on which shares of Common Stock are
listed, including the Nasdaq Global Select Market, the Nasdaq Global Market, or the Nasdaq Capital Market, is open for trading. 

  
 12 

 AMBIT BIOSCIENCES CORPORATION 

2011 EMPLOYEE STOCK PURCHASE PLAN 

OFFERING DOCUMENT 
 ADOPTED BY THE BOARD OF DIRECTORS: NOVEMBER 30, 2010 

In this document, capitalized terms not otherwise defined shall have the same definitions of such terms as in the Ambit Biosciences
Corporation 2011 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 the IPO Date and shall end
approximately 24 months following the commencement of the Initial Offering, unless terminated earlier as provided below. The Initial Offering shall consist of four Purchase Periods, approximately six months in length ending on or about
[            ] and [            ] each year with the first Purchase Period ending on
[            ], the second Purchase Period ending on [            ], the third Purchase Period ending on
[            ], and the fourth Purchase Period ending on [            ]. 

(c) After the Initial Offering ends, a new Offering shall automatically begin over the term of the Plan on the day after the last
Purchase Date of the immediately preceding Offering, and each new Offering shall be approximately 24 months in duration. Each Offering shall consist of four Purchase Periods approximately six months in length ending on or about
[            ] and [            ] each year. Except as provided below, a Purchase Date is the last day of a Purchase Period or of
an Offering, as the case may be. 
 (d) 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. 
 (e) 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. 
 (f)
Notwithstanding anything in this Section 1 to the contrary, if the Fair Market Value of a share of Common Stock on any Purchase Date during an Offering is less than or equal to the Fair Market Value of a share of Common Stock on the Offering
Date for that Offering, then that Offering shall terminate immediately following the purchase of shares of Common Stock on such Purchase Date. Participants in the terminated Offering automatically shall be

  
 1 

 
enrolled in the Offering that commences immediately after such Purchase Date. Thereafter, notwithstanding the provisions of Section 1(c) above, instead of a new Offering commencing pursuant
to Section 1(c), a new Offering shall begin on the 24-month anniversary of the new Offering that commences pursuant to this Section 1(f) and every 24 months thereafter, and each such Offering shall end on the day prior to the 24-month
anniversary of its Offering Date. It is intended that Sections 1(c) and 1(f) shall operate so that only one Offering shall be outstanding at any time under the Plan, and that at all times one Offering shall be outstanding under the Plan. 

2. ELIGIBLE EMPLOYEES. 
 (a) Each Eligible Employee, who has been an Employee for a continuous period of at least 10 days ending on the Offering Date of an Offering hereunder is either (i) an employee of the Company
or (ii) an employee of a Related Corporation incorporated in the United States or (iii) an employee of a Related Corporation that is not incorporated in the United States (provided that the Board or Committee has designated the employees
of such Related Corporation as eligible to participate in the Offering) shall be granted a Purchase Right on the Offering Date of such Offering. 
 (b) Each person who, during the course of an Offering, first becomes an Eligible Employee prior to the commencement of the last Purchase Period under the Offering shall, on the first Trading Day of
the first Purchase Period that commences after such person becomes an Eligible Employee, receive a Purchase Right under that Offering, which Purchase Right shall thereafter be deemed to be a part of that Offering; provided, however, that such
Eligible Employee submits the necessary enrollment paperwork required by the Company on or before such date. 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 except for the application of the provision of Section 1(f) above (the application of which shall be determined only by using the Offering
Date of the ongoing Offering that is the first day of the Offering), including determination of the exercise price of such Purchase Right; and 
 (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. 

(c) Notwithstanding the foregoing, the following Employees shall not be Eligible Employees or be granted Purchase Rights
under an Offering: 
 (i) Employees whose customary employment is 20 hours per week or less or five months per calendar
year or less; 
 (ii) 5% stockholders (including ownership through unexercised and/or unvested stock options) as described
in Section 5(c) of the Plan; or 

  
 2 

 (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. 
 3. PURCHASE RIGHTS. 
 (a) Subject to
the limitations 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 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 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 under Section 423 of the Code. 

(b) For Offerings hereunder, “Earnings” means the base compensation paid to a Participant, including all
salary, wages (including amounts elected to be deferred by such 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), but
excluding all of the following: all overtime pay, commissions, bonuses, and 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 and other equity
awards, contributions made by the Company or a Related Corporation under any employee benefit plan, and other 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 other Offering under the Plan, and 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 and 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 under an Offering shall
be the number of shares of Common Stock remaining available under the Plan on the Offering Date, rounded down to the nearest whole share. If the aggregate number of shares of Common Stock to be purchased upon the exercise of

  
 3 

 
all outstanding Purchase Rights on a single Purchase Date would exceed the number of shares of Common Stock remaining available under the Plan, the Board shall make a pro rata (based on each
Participant’s accumulated earnings contributions) allocation, on the applicable Purchase Date, of the shares available in a uniform or equitable manner. Any Contributions not applied to the purchase of available shares of Common Stock shall be
refunded to the Participants without interest. 
 (e) Notwithstanding the foregoing, the maximum number of shares of
Common Stock that may be purchased on any single Purchase Date by any one Eligible Employee during any Offering shall not exceed [            ] shares. 

(f) Notwithstanding the foregoing, the maximum number of shares of Common Stock that may be purchased on any single Purchase Date
by all Eligible Employees during any Offering shall not exceed [            ] shares. 
 (g) If the number of shares of Common Stock to be purchased upon the exercise of all outstanding Purchase Rights on a single Purchase Date would exceed any of the foregoing limits, the Board shall
make a pro rata (based on each Participant’s accumulated earnings contributions) allocation, on the applicable Purchase Date, of the shares available in a uniform or equitable manner. Any Contributions not applied to the purchase of available
shares of Common Stock shall be refunded to the Participants without interest. 
 4. PURCHASE PRICE.

 The purchase price of shares of Common Stock under an Offering shall be the lesser of: (i) 85% of the Fair Market
Value of such shares of Common Stock on the Offering Date, or (ii) 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 to be effective 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 at least ten days 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 1% and a maximum
percentage of 15%. Except as provided in Section 5(g), a Participant may participate only by way of payroll deductions. 

(b) A Participant may increase or decrease his or her participation level at any time with such change to be effective commencing
as of the next Offering. Any such increase or decrease in participation level shall be made by delivering a notice to the Company or a designated Related Corporation in such form as the Company provides prior to the ten day

  
 4 

 
period (or such shorter period of time as determined by the Company and communicated to Participants) immediately preceding the next Offering Date for which it is to be effective. A Participant
may also increase or decrease his or her participation level to be effective in a subsequent Purchase Period of an ongoing Offering in accordance with procedures established by the Company. 

(c) A Participant may increase his or her participation level twice during an Offering. In addition, a Participant may decrease
(including a decrease to 0%) his or her participation level no more than once during an Offering. Any such change in participation level shall be made by delivering a notice to the Company or a designated Related Corporation in such form as the
Company provides prior to the ten day period (or such shorter period of time as determined by the Company and communicated to Participants) immediately preceding the payroll date for which it is to be effective and such change will become effective
as soon as administratively practicable following the Company’s receipt of the notice. Any Participant who has not increased his or her payroll deduction level from 0% to at least 1% by the time proscribed before the start of a new Offering
shall be deemed to have withdrawn from the Plan effective as of, respectively, the first day of that new Offering. 
 (d)
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 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 Related Corporation 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. 
 (e) 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 participation in the Plan shall be given effect until such time as a registration
statement covering the shares reserved under the Plan that are subject to the Offering has been filed by the Company and has become effective. If the provisions of this Section are applicable, the Company shall establish such procedures as will
enable the purposes of the Plan to be satisfied while complying with applicable securities laws. Such procedures may include, for example, allowing Participants to participate other than by means of payroll deduction and/or allowing Participants to
increase their level of participation during a Purchase Period. 
 (f) Notwithstanding the foregoing or any other
provision of this Offering document or of the Plan to the contrary, the Company may determine in its sole discretion at any time, including at any time following the commencement of an Offering or Purchase Period, that it will no longer accept
Participant requests to increase participation levels during such Offering or Purchase Period, as applicable. 
 (g)
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 

  
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who is employed on the Offering Date for the Initial Offering 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 15% of the Eligible Employee’s Earnings, subject to the limitations set forth in Section 3(c)–3(f) 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 15% of the Eligible Employee’s Earnings, and will have a limited opportunity to make all or part of the contributions in a single lump sum cash payment for the purchase of such shares to the Company or a designated Related
Corporation prior to the ten 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. To the extent that the Eligible
Employee’s payroll deductions for such initial Purchase Period are less than 15% of the Eligible Employee’s Earnings paid to the Eligible Employee during the initial Purchase Period of the Offering, the Eligible Employee may make an
additional cash payment at any time or prior to the ten day period (or such shorter period of time as determined by the Company and communicated to Participants) immediately preceding the Purchase Date under the Initial Offering. If an Eligible
Employee neither elects to authorize payroll deductions 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. In order to
participate in any Offerings that follow the Initial Offering, an Eligible Employee must affirmatively enroll and authorize payroll deductions prior to the commencement of the Offering, in accordance with paragraph (a) above. 

(h) Once an Eligible Employee affirmatively 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 Section 5(d) above, is deemed to have withdrawn pursuant to
Section 5(c) above, or terminates his or her participation in the Plan (including through termination of employment). 
 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 of Common Stock, 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 (including documents delivered in electronic form, if authorized by the
Committee), 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 days after deposit in the United States mail,
postage prepaid. 

  
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 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.
CAPITALIZATION ADJUSTMENTS. 
 The limitations set forth in Section 3(e) and 3(f) shall be
adjusted, as appropriate, to reflect Capitalization Adjustments. 
 10. 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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