Document:

EX-10.1

 Exhibit 10.1 

FORM OF STOCKHOLDER AGREEMENT 

This STOCKHOLDER AGREEMENT (this “Agreement”) is entered into as of the 7th day of February, 2014, by and among Mast
Therapeutics, Inc., a Delaware corporation (“Parent”), the undersigned holder (“Stockholder”) of capital stock of Aires Pharmaceuticals, Inc., a Delaware corporation (the “Company”), and the
Company. Any capitalized terms not otherwise defined herein shall have the meanings ascribed to them in the Merger Agreement (defined below). 

RECITALS 
 A. Stockholder
has executed and delivered this Agreement in connection with that certain Agreement and Plan of Merger, dated as of February 7, 2014, by and between Parent, the Company, AP Acquisition Sub, Inc. (“Merger Sub”) and
Stockholders’ Representative (the “Merger Agreement”), pursuant to which Merger Sub shall be merged with and into the Company and the separate corporate existence of Merger Sub shall thereupon cease (the
“Merger”) and the Company shall be the surviving corporation (the “Surviving Corporation”) following the Merger. 

B. Whereas simultaneously herewith, the Stockholder has executed and delivered a written consent approving and adopting the Merger and the
Merger Agreement (the “Written Consent”). 
 C. As of the date hereof, Stockholder holds that number of shares of capital
stock of the Company (the “Company Shares”) set forth on the signature page hereto. 
 D. Upon the consummation of the
Merger and in connection therewith, certain holders of capital stock of the Company shall receive a right to receive a portion of the Merger Consideration, which is comprised of shares of common stock, par value $0.001, of Parent (such shares issued
as Merger Consideration, the “Parent Shares” together with the Company Shares, the “Shares”), subject to adjustment as provided in the Merger Agreement and if and when payable in accordance with the terms of the
Merger Agreement, as more specifically set forth in the Merger Agreement and the Distribution Schedule. 
 E. Stockholder understands and
acknowledges that Company and Parent are entitled to rely on (x) the truth and accuracy of Stockholder’s representations contained herein and (y) Stockholder’s performance of the obligations set forth herein. 

NOW, THEREFORE, in consideration of the premises and the covenants and agreements set forth in the Merger Agreement and in this Agreement, and
other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto hereby agree as follows: 

1. Restrictions on Shares. 

(a) Stockholder shall not, at any time prior to the Restriction Expiration Date, (i) offer, sell, assign, transfer, pledge, contract to
sell, or otherwise dispose of, any Parent Shares or securities convertible into or exercisable or exchangeable for capital stock of Parent, (ii) enter into any swap, hedge or other agreement or arrangement that transfers in whole or in part,
the economic risk of ownership of any Parent Shares or securities convertible into or exercisable or exchangeable for capital stock of Parent, or (iii) engage in any short selling of any Parent Shares or securities convertible into or
exercisable or exchangeable for capital stock of Parent, except for transfers (A) to any trust for the direct benefit of Stockholder, (B) if such Stockholder is a natural person, to such Stockholder’s parents, siblings, spouse,
children, nieces, nephews or grandchildren or any person sharing the Stockholder’s household (other than a tenant or employee), or a trust for the direct benefit of any of the foregoing, (C) by will or intestacy to Stockholder’s legal
representative, (D) to an Affiliate (as defined under the Securities Act of 1933, as amended (the “Securities Act”) and the rules and regulations promulgated thereunder) of such Stockholder, or (E) distributions of
securities to partners, members or stockholders of the Stockholder not involving a disposition for value; provided, however, that any such transfer described in clauses (A) – (E) above shall be permitted only if, as a
condition to the effectiveness of such transfer, (x) the transferee agrees in writing to be bound to all of the terms set forth in this Agreement and (y) such transfer would not require the registration of such Parent Shares pursuant to
any applicable federal, state or other securities laws or result in Parent being required to register any class of its equity securities with any Governmental Entity, and, with respect to clauses (D) and (E), unless waived by Parent, Parent
shall receive a written opinion reasonably satisfactory to Parent and Parent’s counsel to such effect that such transfer would not require the registration of such Parent Shares. For clarity, the foregoing restrictions in this Section 1(a)
shall apply only to transactions relating to the Parent Shares and not to transactions relating to securities of Parent acquired in any transactions other than pursuant to the Merger Agreement. As used herein, the term “Restriction
Expiration Date” shall mean the sixth-month anniversary of the Closing Date. 
  

 (b) Stockholder shall not, at any time prior to the Effective Time, (i) offer, sell,
assign, transfer, pledge, contract to sell, or otherwise dispose of, any Company Shares or securities convertible into or exercisable or exchangeable for capital stock of the Company, (ii) enter into any swap, hedge or other agreement or
arrangement that transfers in whole or in part, the economic risk of ownership of any Company Shares or securities convertible into or exercisable or exchangeable for capital stock of the Company, or (iii) engage in any short selling of any
Company Shares or securities convertible into or exercisable or exchangeable for capital stock of the Company, except for transfers (A) to any trust for the direct benefit of Stockholder, (B) by will or intestacy to Stockholder’s
legal representative, or (C) to an Affiliate (as defined under the Securities Act and the rules and regulations promulgated thereunder) of such Stockholder; provided, however, that any such transfer shall be permitted only if, as
a condition to the effectiveness of such transfer, (x) the transferee agrees in writing to be bound to all of the terms set forth in this Agreement and (y) such transfer would not require the registration of such Company Shares pursuant to
any applicable federal, state or other securities laws or result in the Company being required to register any class of its equity securities with any Governmental Entity. 

(c) Except pursuant to the terms of this Agreement or that certain Second Amended and Restated Voting Agreement, dated April 17, 2013, by
and among the Company and the founders, investors and significant holders listed therein (the “Company Voting Agreement”), Stockholder shall not, directly or indirectly, grant any proxies or powers of attorney with respect to any of
the Shares, deposit any of the Shares into a voting trust, or enter into a voting agreement with respect to any of the Shares. 
 (d)
Stockholder shall not, directly or indirectly, take any action that would make any representation or warranty contained herein untrue or incorrect or have the effect of impairing the ability of Stockholder to perform its obligations under this
Agreement or preventing or delaying the consummation of any of the transactions contemplated hereby. 
 (e) At any time prior to the Proxy
Expiration Date (as defined below), to the extent Stockholder holds capital stock of Parent, Stockholder agrees to enter into a lock-up agreement in a form reasonably requested by the underwriters for a public offering of the capital stock of Parent
(an “Underwriter Lock-up Agreement”); provided, however, that (i) under no circumstances shall Stockholder be obligated to enter into, or otherwise restricted by, such an Underwriter Lock-up Agreement to the
extent the lock-up period provided for therein extends past the date which is ninety (90) days from and following the date of the underwriting agreement relating to such offering; (ii) all executive officers and directors of Parent shall
also have agreed not to sell publicly their shares of Parent’s capital stock in the offering on substantially the same terms; and (iii) no such Underwriter Lock-up Agreement related to such a public offering shall be amended, modified,
waived or terminated unless each Underwriter Lock-up Agreement with all holders of capital stock of Parent is also amended, modified or waived in a similar manner or terminated. 

(f) Any shares of capital stock of the Company that Stockholder purchases or with respect to which Stockholder otherwise acquires beneficial
ownership after the date of this Agreement and prior to the Effective Time shall be subject to the terms and conditions of this Agreement to the same extent as if they constituted Company Shares. 

2. Agreement to Vote Company Shares. At any time on or after the date of the Merger Agreement and prior to the Effective Time, at every
meeting of the stockholders of the Company called with respect to any of the following, and at every adjournment thereof, and on every action or approval by written resolution or consent of the stockholders of the Company with respect to any of the
following, Stockholder shall vote the Company Shares in respect of which Stockholder is entitled to vote at any such meeting or in connection with any such written consent (a) in favor of the adoption of the Merger Agreement and the approval of
the Merger and the Merger Agreement and the transactions contemplated thereby, (b) against any Proposal and (c) against any other matter that would reasonably be expected to impede, interfere with, delay, postpone or adversely affect the
Merger or any of the transactions contemplated thereby; provided, however, that nothing in this Agreement shall preclude Stockholder from exercising full power and authority to vote the Company Shares in Stockholder’s sole discretion for or
against any proposal submitted to a vote of the Company Stockholders to approve any payment which would, in the absence of such approval, constitute a parachute payment under Section 280G of the Internal Revenue Code of 1986 (as amended, the
“Code”). 

  
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 3. Irrevocable Proxy. Concurrently with the execution and delivery of this Agreement,
Stockholder shall deliver to Parent a duly executed irrevocable proxy in the form attached hereto as Exhibit A (the “Proxy”) with respect to (i) each and every meeting of stockholders of Parent or action or approval by
written resolution or consent of stockholders of Parent from and after the Effective Time and through the date that is the thirty (30)-month anniversary of the Closing Date (the “Proxy Expiration Date”) covering the total number of
Parent Shares in respect of which Stockholder is entitled to vote at any such meeting or in connection with any such written consent and (ii) each and every meeting of Company Stockholders or action or approval by written resolution or consent
of Company Stockholders from and after the date hereof and prior to the earlier of (A) the Effective Time or (B) termination of the Merger Agreement covering the total number of Company Shares in respect of which Stockholder is entitled to
vote at any such meeting or in connection with any such written consent related to the subject matter of Section 2 hereof. Notwithstanding anything to the contrary in this Agreement, such Proxy shall not apply to any proposal submitted to a
vote of the Company Stockholders to approve any payment which would, in the absence of such approval, constitute a parachute payment under Section 280G of the Code, and Stockholder shall continue to have full power and authority to vote the
Company Shares in Stockholder’s sole discretion for or against any such proposal. Upon the execution of this Agreement by Stockholder, Stockholder hereby revokes any and all prior proxies (other than the Proxy) given by Stockholder and shall
not grant any subsequent proxies until after the Proxy Expiration Date. The parties hereby acknowledge that nothing in this Stockholders’ Agreement or the Proxy shall effect the Company’s existing drag along rights as set forth in
Section 4 of the Company Voting Agreement. 
 4. Representations, Warranties and Covenants of Stockholder. Stockholder hereby
represents, warrants and covenants to Parent as of the date hereof and as of the Effective Time as follows: 
 (a) Stockholder is the
beneficial owner of the Company Shares set forth on the signature page hereto and, except as otherwise set forth on the signature page hereto, (i) has held such Company Shares at all times since the date set forth on such signature page and
(ii) did not acquire any such Company Shares in contemplation of the Merger. The Company Shares set forth on the signature page hereto constitute Stockholder’s entire interest in the outstanding capital stock of the Company. No person not
a signatory to this Agreement has a beneficial interest in or a right to acquire or vote any of the Company Shares (other than, if Stockholder is a partnership, the rights and interest of persons and entities that own partnership interests in
Stockholder under the partnership agreement governing Stockholder and applicable partnership law). The Company Shares are and will be at all times up until the Closing Date free and clear of any and all liens, claims, options, charges or other
encumbrances, other than (x) restrictions on transfer arising under applicable securities laws and the Company’s Bylaws and (y) restrictions on transfer under this Agreement and the Existing Agreements (as defined below) to which the
Stockholder is a party that will terminate as of the Closing. Stockholder’s principal residence or place of business is set forth on the signature page hereto. 

(b) If Stockholder is an entity, Stockholder is duly organized, validly existing and in good standing under the laws of the jurisdiction of
its organization. Stockholder has all requisite power and authority (if Stockholder is an entity) or legal capacity (if Stockholder is a natural person) to enter into this Agreement, and each other agreement, document or certificate to which it, he
or she may become a party pursuant to this Agreement or the Merger Agreement (each, a “Stockholder Ancillary Agreement”), and to perform its, his or her obligations under this Agreement and each Stockholder Ancillary Agreement. The
execution and delivery of this Agreement and each Stockholder Ancillary Agreement by Stockholder and the consummation by Stockholder of the transactions contemplated hereby and thereby have been duly authorized by all necessary action, if any, on
the part of Stockholder. This Agreement has been, and on the Closing Date each Stockholder Ancillary Agreement will have been, duly executed and delivered by Stockholder and constitutes, or when executed by Stockholder shall constitute, a valid and
binding obligation of Stockholder, enforceable against Stockholder in accordance with its terms, subject to the effect of (a) applicable bankruptcy, insolvency, reorganization, moratorium or other similar laws now or hereafter in effect
relating to rights of creditors generally and (b) rules of law and equity governing specific performance, injunctive relief and other equitable remedies. 

  
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 (c) No consent, approval, order, authorization, release or waiver of, or registration,
declaration or filing with, any Person (not including a Governmental Entity) or to the knowledge of the Stockholder, any Governmental Entity, is necessary or required to be made or obtained by Stockholder to enable Stockholder to lawfully execute
and deliver, enter into, and perform its, his or her obligations under this Agreement or any Stockholder Ancillary Agreement. 
 (d)
Stockholder understands and agrees that, pursuant to the Merger Agreement, (i) Stockholder has certain obligations to indemnify Parent and certain other Parent Indemnitees as and to the extent set forth in the Merger Agreement and (ii) a
portion of the Closing Consideration to which Stockholder may otherwise be entitled shall constitute security for those obligations and part of which will be held back as the Holdback Amount. 

(e) There is no private or governmental action, suit, proceeding, claim, mediation, arbitration or investigation pending before any
Governmental Entity (each of the foregoing, an “Action”) against Stockholder that relates in any way to this Agreement, the Merger Agreement, any Stockholder Ancillary Agreement or any of the transactions contemplated hereby
or thereby. To the knowledge of Stockholder, (a) no such Action has been threatened and (b) there is no reasonable basis for any such Action. 

(f) Stockholder is not, in his/her/its capacity as such, obligated for the payment of any fees or expenses of any investment banker, broker,
finder or similar party in connection with the origin, negotiation or execution of the Merger Agreement or in connection with the Merger or any other transaction contemplated by the Merger Agreement. Neither Parent nor the Surviving Corporation
shall incur any Liabilities, either directly or indirectly, to any such investment banker, broker, finder or similar party as a result of the Merger Agreement or the Merger or any other transaction contemplated by the Merger Agreement. 

(g) The Stockholder shall observe and comply with the Securities Act, and any and all other applicable federal or state securities laws, as
now in effect and as from time to time amended and including those hereafter enacted or promulgated, in connection with any offer, sale, exchange, transfer, pledge or other disposition of the Parent Shares or any part thereof. 

(h) To the extent received by Stockholder, the Parent Shares will be acquired for investment for the Stockholders’ own account, not as a
nominee or agent, and not with a view to the resale or distribution of any part thereof, and the Stockholder has no present intention of selling, granting any participation in, or otherwise distributing the same. By executing this Agreement, the
Stockholder further represents that such Stockholder does not have any contract, undertaking, agreement or arrangement with any person to sell, transfer or grant participations to such person or to any third person, with respect to any of the Parent
Shares. 
 (i) The Stockholder is, and at the Closing will be, an “accredited investor” within the meaning of Rule 501 under the
Securities Act, as presently in effect. Stockholder has substantial experience in evaluating and investing in securities of companies and acknowledges that it has the capacity to protect its own interests in connection therewith, can bear the
economic risk of its investment and has such knowledge and experience in financial or business matters that it is capable of evaluating the merits and risks of the investment in the Parent Shares. If other than an individual, Stockholder also
represents it has not been organized for the purpose of acquiring the Parent Shares. 
 (j) Stockholder has received or has had full access
to the most recent annual report of Parent on Form 10-K under the Securities Exchange Act of 1934, as amended (the “Exchange Act”) and each subsequent report or document filed by Parent with the Securities and Exchange Commission
(the “SEC”) under Sections 13(a), 14 and 15(d) of the Exchange Act, and any other information Stockholder considered necessary or appropriate to make an informed investment decision with respect to the Merger and the Parent Shares,
in each case a reasonable period of time prior to entering into this Agreement. Stockholder has had an opportunity to ask questions and receive answers from Parent regarding the terms and conditions of the Merger Agreement and to obtain additional
information necessary to verify any information furnished to Stockholder or to which Stockholder had access, in each case a reasonable period of time prior to entering into this Agreement. Stockholder further understands and acknowledges that Parent
may raise additional funds in the future through debt or equity financings to support its operations and any future equity financing could result in dilution to Stockholder and any future debt financing could likely involve covenants restricting
Parent’s business activities. 

  
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 (k) Stockholder understands that the Parent Shares are characterized as “restricted
securities” under the federal securities laws inasmuch as they are being acquired from Parent in a transaction not involving a public offering and that under such laws and applicable regulations such securities may be resold without
registration under the Securities Act only in certain limited circumstances. In this connection, Stockholder represents that it is familiar with Rule 144 under the Securities Act, as presently in effect, and understands the resale limitations
imposed thereby and by the Securities Act. 
 (l) Subject to terms of any Underwriter Lock Up Agreement, Stockholder shall not offer, sell,
exchange, transfer, pledge or otherwise dispose of any of the Parent Shares until the trading day after the Restriction Expiration Date and unless at that time either: 

(i) such transaction is permitted pursuant to the provisions of Rule 144 under the Securities Act or is pursuant to an effective registration
statement; 
 (ii) counsel representing Stockholder, reasonably satisfactory to Parent, shall have advised Parent in a written opinion
letter reasonably satisfactory to Parent and Parent’s counsel, and upon which Parent and its counsel may rely, that no registration under the Securities Act is required in connection with the proposed offer, sale, exchange, transfer, pledge or
other disposition; or 
 (iii) an authorized representative of the SEC shall have rendered written advice to Stockholder (sought by
Stockholder or counsel to Stockholder, with a copy thereof and of all other related communications delivered to Parent) to the effect that the SEC will take no action, or that the staff of the SEC will not recommend that the SEC take action, with
respect to the proposed offer, sale, exchange, transfer, pledge or other disposition if consummated. 
 5. Covenants of Stockholder.
Stockholder hereby covenants to Parent, as follows: 
 (a) Stockholder (in its, his or her capacity as such) shall not, directly or
indirectly, take any action prohibited by Section 5.1 of the Merger Agreement. 
 (b) Stockholder hereby irrevocably and
unconditionally waives and agrees not to exercise any rights of appraisal or any dissenters’ rights that Stockholder may have (whether under Section 262 of the Delaware General Corporation Law or, if applicable, Chapter 13 of the
California Corporations Code) or could potentially have or acquire in connection with the execution and delivery of the Merger Agreement or the consummation of the Merger. 

(c) Stockholder hereby agrees not to modify, revoke or rescind the Written Consent or any resolution contained therein and further agrees not
to adopt any resolutions modifying, rescinding or revoking the Written Consent or any resolution contained therein or otherwise precluding approval of the Merger, the Merger Agreement or the adoption of the Merger Agreement, unless and until the
Merger Agreement is terminated pursuant to Article 8 thereof. Stockholder agrees that it will not bring, commence, institute, maintain, prosecute, participate in or voluntarily aid any action, claim, suit or cause of action, in law or in equity, in
any court or before any Governmental Entity, which (a) challenges the validity of or seeks to enjoin the operation of any provision of the Written Consent or this Agreement or the execution and delivery of the Merger Agreement or the
consummation of the Merger and the other transactions contemplated thereby or (b) alleges that the execution and delivery of the Written Consent or this Agreement by Stockholder, either alone or together with the other written consents or
voting or stockholder agreements and proxies to be delivered in connection with the execution of the Merger Agreement, breaches any fiduciary duty, whether of the board of directors of the Company or any member thereof or of any holder of capital
stock of the Company. 
 (d) Stockholder has received and reviewed and understands the terms of the Merger Agreement and agrees to be bound
by the terms and conditions of those provisions of the Merger Agreement purporting to bind the Company Stockholders, including, without limitation, the designation and empowerment of the Stockholders’ Representative, and any and all provisions
relating to the Holdback Amount and any and all indemnification obligations of the Company Stockholders. 

  
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 6. Releases. Stockholder acknowledges and agrees, on behalf of itself (or, as applicable,
himself or herself) and each of its (or, as applicable, his or her) current or former affiliates, officers, directors, employees, managers, general partners, principals, advisors, agents, servants, or other representatives (including without
limitation attorneys, accountants, consultants, bankers and financial advisors), heirs, beneficiaries, estates, executors, administrators, trustees, successors or assigns (each a “Releasing Party”) that: 

(a) Releasing Party (i) has no Claims (defined below), (ii) has not transferred or assigned, or purported to transfer or assign, any
Claims and (iii) shall not transfer or assign, or purport to transfer or assign, any Claims, in each case, relating to the Company against the Company, Parent or Merger Sub, or their respective current or former affiliates, officers, directors,
employees, managers, partners, principals, advisors, agents, servants, stockholders, members, investors, equity holders or other representatives (including without limitation attorneys, accountants, consultants, bankers and financial advisors),
successors or assigns (collectively, the “Released Parties”). 
 (b) Releasing Party hereby irrevocably and unconditionally
releases and forever discharges the Released Parties from any and all claims, demands, allegations, assertions, complaints, controversies, charges, duties, grievances, rights, causes of action, suits, liabilities, debts, obligations, promises,
commitments, agreements, guarantees, endorsements, duties, damages, costs, losses, debts and expenses (including attorneys’ fees and costs incurred) of any nature whatsoever (whether direct or indirect, known or unknown, disclosed or
undisclosed, matured or unmatured, accrued or unaccrued, asserted or unasserted, absolute or contingent, determined or conditional, express or implied, fixed or variable and whether vicarious, derivative, joint, several or secondary) relating to the
Company (collectively, “Claims”); provided, however, that the foregoing release shall not cover (i) rights of Company Stockholders under the Merger Agreement or any other rights that Stockholder may have under
this Agreement, or any Stockholder Ancillary Agreement, (ii) if Stockholder is a present or former employee of the Company, rights to earned but unpaid cash compensation and unpaid vacation, or unreimbursed business expenses incurred in the
ordinary course and reimbursable pursuant to the Company’s business expense policy, (iii) rights to separation benefits (e.g., severance, equity acceleration) upon termination of service in connection with the Merger, (iv) Claims
under the Benefit Plans, if any, or (v) Claims for exculpation, indemnification or advancement of expenses from the Company, if any (whether pursuant to any agreement, the Company’s certificate of incorporation, the Company’s by-laws
or any Law). 
 (c) Releasing Party acknowledges and agrees that it, he or she is familiar with Section 1542 of the Civil Code of the
State of California (“Section 1542”), which provides as follows: 
 A GENERAL RELEASE DOES NOT EXTEND TO CLAIMS WHICH THE
CREDITOR DOES NOT KNOW OR SUSPECT TO EXIST IN HIS OR HER FAVOR AT THE TIME OF EXECUTING THE RELEASE, WHICH IF KNOWN BY HIM OR HER MUST HAVE MATERIALLY AFFECTED HIS OR HER SETTLEMENT WITH THE DEBTOR. 

Releasing Party hereby waives and relinquishes any rights and benefits that Releasing Party may have under Section 1542 or any similar statute or common
law principle of any jurisdiction. Releasing Party acknowledges that it, he or she may hereafter discover facts in addition to or different from those that Releasing Party now knows or believes to be true with respect to the subject matter of this
release, but it is Releasing Party’s intention to fully and finally and forever settle and release any and all Claims (other than as set forth in the proviso included in subsection (b) above) that do now exist, may exist or heretofore have
existed with respect to the subject matter of this release. In furtherance of this intention, the releases contained herein shall be and remain in effect as full and complete releases notwithstanding the discovery or existence of any such additional
or different facts. 
 (d) Releasing Party acknowledges and agrees that it, he or she (i) has read this release and understands its
terms and has been given an opportunity to ask questions of the Company’s representatives, and (ii) does not rely, and has not relied, on any representation or statement not set forth in this release made by any representative of the
Company or any other Person with regard to the subject matter, basis or effect of this release or otherwise. 
 (e) This release is
effective upon, and subject to, the consummation of the Merger as contemplated in the Merger Agreement, and shall become null and void, and shall have no effect whatsoever, without any action on the part of any Person, upon termination of the Merger
Agreement in accordance with its terms. 

  
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 (f) For the avoidance of doubt and notwithstanding anything to the contrary in this Agreement,
“Releasing Party” shall not include any stockholder, member, limited partner, other equity holder or any portfolio company of a Stockholder that is in the business of making investments in companies. 

7. Appointment of Stockholders’ Representative. The Stockholders’ Representative has been designated, and Stockholder hereby
confirms the designation of the Stockholders’ Representative, as the representative of Stockholder and as the attorney-in-fact and agent for and on behalf of Stockholder with respect to claims for indemnification under Article 9 of the Merger
Agreement and the taking by the Stockholders’ Representative of any and all actions and the making of any decisions required or permitted to be taken by the Stockholders’ Representative under the Merger Agreement, including without
limitation the exercise of all powers, authority and responsibilities set forth in Section 9.10 of the Merger Agreement. 
 8.
Confidentiality. Except with the prior written consent of Parent, from the date hereof and until the later of (i) the date of *** , and (iii) solely with respect to any terms in the Merger Agreement or any ancillary documents
thereto for which Parent obtains confidential treatment from the SEC, the date such confidential treatment expires and is not renewed or pending renewal by Parent, Stockholder agrees to keep confidential and not disclose (other than to its officers,
directors, employees, trustees, beneficiaries, attorneys and other advisors with a bona fide need to know, or any general partner, limited partner, member, subsidiary or parent (and their respective representatives) for the purpose of evaluating its
investment in the Company, provided that such Persons have an obligation or duty of confidentiality, whether pursuant to the ethical or professional rules of such Person’s profession or have agreed to confidentiality restrictions at least as
restrictive as those contained herein) (a) the terms and conditions and existence of this Agreement and Stockholder Ancillary Agreements and the Merger Agreement and the transactions contemplated hereby and thereby, (b) matters regarding
the interpretation, performance, breach or termination hereof or thereof, and (c) all confidential and/or proprietary information of the Company or Parent (including, without limitation, Company Intellectual Property) obtained by Stockholder or
its directors, officers, employees, agents or representatives prior to the Effective Time, except to the extent that (i) such information has otherwise been made public, (ii) any such information is reasonably necessary for enforcing
Stockholder’s rights hereunder or thereunder, (iii) any such information is disclosed to any Governmental Entity or arbitrators in connection with any legal or other proceedings involving a dispute between Stockholder and Parent,
(iv) any such information is independently developed by Stockholder without reference or usage of any information that would otherwise be considered confidential and/or proprietary information of the Company or Parent (including, without
limitation, Company Intellectual Property) hereunder, (v) Stockholder is required by applicable Law to divulge or disclose any such information (in which case Stockholder shall promptly notify Parent in advance of disclosing such information
and use commercially reasonable efforts to cooperate with Parent to limit such disclosure to the extent permitted under applicable Law), or (vi) disclosure or use of such information by any Stockholder who remains an employee or consultant of
the Company, solely in connection with the performance of Stockholder’s responsibilities and in accordance with any other confidentiality obligations or Company policies that such Stockholder may be subject to. *** . 

9. Termination of Existing Agreements. Each Stockholder and the Company hereby agrees that the following agreements (to the extent the
Stockholder is a party thereto) shall terminate effective as of the Effective Time without the need for any further action: the Second Amended and Restated Investor Rights Agreement, dated April 17, 2013, by and between the Company and the
investors listed on Schedule A thereto; the Second Amended and Restated Voting Agreement, dated April 17, 2013, by and among the Company and the founders, investors and significant holders listed on Schedule A thereto; and the Second Amended
and Restated Co-Sale Agreement, dated April 17, 2013, by and among the Company and the founders, investors and other holders listed on Schedule A thereto (collectively, the “Existing Agreements”). Each Stockholder further
agrees that following the Effective Time such agreements shall no longer be in force or effect and that following the Effective Time any and all rights of such Stockholder under such agreements shall be terminated. Following the termination of the
Merger Agreement, this covenant and agreement to terminate shall have no further force or effect and be deemed null and void. 
  

	***	Portions of this page have been omitted pursuant to a request for Confidential Treatment and filed separately with the Commission. 

  
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 10. Miscellaneous. 

10.1 Notices. All notices and other communications hereunder shall be in writing and shall be deemed given if delivered personally or
by commercial delivery service, or mailed by registered or certified mail (return receipt requested) to the parties hereto at the following address (or at such other address for a party as shall be specified by like notice) or sent via facsimile
(with confirmation of receipt) or electronic mail to the parties hereto if a facsimile number or an e-mail address is provided below (or is provided subsequently by a party by notice given pursuant to this provision): 

 

	 	(i)	if to Parent, to: 

 Mast Therapeutics, Inc. 

12390 El Camino Real, Suite 150, 

San Diego, California 

Attention: Brian Culley 

Facsimile No.: (858) 552-0876 
  

	 	with	a copy (which shall not constitute notice) to: 

 DLA Piper LLP (US) 

4365 Executive Drive, Suite 100 

San Diego, CA 92121 

Attention: Michael Kagnoff 

Facsimile No.: (858) 638-5122 
  

	 	(ii)	if to the Company, to: 

 Aires Pharmaceuticals, Inc. 

4365 Executive Drive Suite 1500 

San Diego, CA 92121 

Facsimile No.: (858) 366-9671 
  

	 	with	a copy (which shall not constitute notice) to: 

 Latham & Watkins LLP

 12670 High Bluff Drive 

San Diego, CA 92130 

Attention: Cheston J. Larson 

Facsimile No.: (858) 523-5450 

(iii) if to Stockholder, at the address set forth below Stockholder’s signature at the end hereof, or, at the election of Parent, to the
Stockholders’ Representative at the address set forth below. 
 Fortis Advisors LLC 

Attention: Notice Department 

Facsimile No.: (858) 408-1843 

Email: notices@fortisrep.com 

  
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 10.2 Interpretation. When a reference is made in this Agreement to Sections or Exhibits,
such reference shall be to a Section of or an Exhibit to this Agreement unless otherwise indicated. The words “include,” “includes” and “including” when used herein shall be deemed in each case to be followed by the
words “without limitation.” The phrases “the date of this Agreement”, “the date hereof”, and terms of similar import, unless the context otherwise requires, shall be deemed to refer to the date first above written. 

10.3 Specific Performance; Injunctive Relief. The parties hereto acknowledge that Parent will be irreparably harmed and that there will
be no adequate remedy at law for a violation of any of the covenants or agreements of Stockholder set forth herein or in the Proxy. Therefore, it is agreed that, in addition to any other remedies that may be available to Parent upon any such
violation of this Agreement or the Proxy, Parent shall have the right to enforce such covenants and agreements and the Proxy by specific performance, injunctive relief or by any other means available to Parent at law or in equity and Stockholder
hereby waives the defense that there is an adequate remedy at law or that the award of specific performance, injunctive relief or other means available in equity is not an appropriate remedy for any reason of law or equity and waives any requirement
for the security or posting of any bond in connection with such enforcement. 
 10.4 Counterparts. This Agreement may be executed in
one or more counterparts, all of which shall be considered one and the same instrument and shall become effective when one or more counterparts have been signed by each of the parties and delivered to the other parties hereto; it being understood
that all parties need not sign the same counterpart. 
 10.5 Entire Agreement; Nonassignability; Parties in Interest. This Agreement
and the documents and instruments and other agreements specifically referred to herein or delivered pursuant hereto (including the proxies granted by Stockholder pursuant to Section 3) (i) constitute the entire agreement among the parties
with respect to the subject matter hereof and supersede all prior agreements and understandings, both written and oral, among the parties with respect to the subject matter hereof, and (ii) are not intended to confer, and shall not be construed
as conferring, upon any person other than the parties hereto any rights or remedies hereunder. Except as provided in Section 1(a) and Section 1(b), neither this Agreement nor any of the rights, interests, or obligations under this
Agreement may be assigned or delegated, in whole or in part, by operation of law or otherwise, by either party without the prior written consent of the other party, and any such assignment or delegation that is not consented to shall be null and
void, except this Agreement, together with any rights, interests or obligations of Parent hereunder, may be assigned or delegated in whole or in part by Parent without the prior written consent of the Stockholder. Subject to the preceding sentence,
this Agreement shall be binding upon, inure to the benefit of, and be enforceable by and against, the parties hereto and their respective permitted successors and assigns (including, without limitation, any Person to whom any Shares are sold,
transferred or assigned pursuant to Section 1). All authority conferred herein shall survive the death or incapacity of the Stockholder and in the event of Stockholder’s death or incapacity, any obligation of the Stockholder hereunder
shall be binding upon the heirs, personal representatives, successors and assigns of the Stockholder. 
 10.6 Severability. In the
event that any provision of this Agreement, or the application thereof, becomes or is declared by a court of competent jurisdiction to be illegal, void or unenforceable, the remainder of this Agreement shall continue in full force and effect and the
application of such provision to other persons or circumstances shall be interpreted so as reasonably to effect the intent of the parties hereto. The parties hereto further agree to use their reasonable best efforts to replace such void or
unenforceable provision of this Agreement with a valid and enforceable provision that shall achieve, to the extent possible, the economic, business and other purposes of such void or unenforceable provision. 

10.7 Remedies Cumulative. Except as otherwise provided herein, any and all remedies herein expressly conferred upon a party shall be
deemed cumulative with and not exclusive of any other remedy conferred hereby, or by law or equity upon such party, and the exercise by a party of any one remedy shall not preclude the exercise of any other remedy. 

  
 9 

 10.8 Governing Law. This Agreement shall be governed by and construed in accordance with
the laws of the State of Delaware without reference to such state’s principles of conflicts of law. Each of the parties hereto irrevocably consents to the exclusive jurisdiction of any court located within the State of Delaware, in connection
with any matter based upon or arising out of this Agreement or the matters contemplated herein, agrees that process may be served upon them in any manner authorized by the laws of the State of Delaware for such persons and waives and covenants not
to assert or plead any objection which they might otherwise have to such jurisdiction and such process. 
 10.9 Additional Documents,
Etc. Stockholder shall execute and deliver any additional documents necessary or desirable, in the reasonable opinion of Parent, to carry out the purpose and intent of this Agreement. Without limiting the generality or effect of the foregoing or
any other obligation of Stockholder hereunder, Stockholder hereby authorizes Parent to deliver a copy of this Agreement to Company and hereby agrees that each of Company and Parent may rely upon such delivery as conclusively evidencing the
representations, warranties, covenants, releases and waivers of Stockholder, in each case for purposes of all agreements and instruments to which such representations, warranties, covenants, releases and/or waivers are applicable or relevant. 

10.10 Term; Termination; Waiver. 

(a) This Agreement shall not be effective unless and until the Merger Agreement is executed by all parties thereto and shall thereafter remain
in effect in accordance with its terms unless and until terminated in accordance with this Section 10.10. 
 (b) This Agreement and the
parties’ obligations provided herein shall automatically terminate, without any notice or other action by any Person, upon the termination of the Merger Agreement pursuant to Section 8.1(a) thereof. Upon such automatic termination of this
Agreement, no party shall have any further obligations or liabilities under this Agreement, provided, however, that the provisions of Sections 6, 8 and 10 shall survive the termination of this Agreement. 

(c) Sections 1(b) and 2 and the Irrevocable Proxy with respect to the Company Shares under Section 3 shall expire and terminate at the
earlier of (i) the termination of the Merger Agreement pursuant to Section 8.1(a) thereof, and (ii) the Effective Time. 

(d) Section 1(c) and the Irrevocable Proxy with respect to the Parent Shares shall expire and terminate on the earlier of the
(i) the termination of the Merger Agreement pursuant to Section 8.1(a) thereof and (ii) the Proxy Expiration Date. Stockholder acknowledges and understands that the specific date on which the Proxy Expiration Date will occur is not
presently known. 
 (e) Stockholder hereby waives all notice and other applicable provisions under the Existing Agreements to which the
Stockholder is a party and the Company Certificate of Incorporation with respect to the transactions contemplated by the Merger Agreement. 

10.11 Acknowledgements. Each party to this Agreement acknowledges that (a) Latham & Watkins LLP, counsel for the Company,
represented the Company in connection with the Merger and related transactions, (b) DLA Piper LLP (US), counsel for Parent, represented Parent and Merger Sub in connection with this Agreement, the Merger and related transactions,
(c) neither such firm has represented Stockholder in connection with this Agreement, the Merger or otherwise and (d) Stockholder acknowledges that it, he or she has had the opportunity to consult with its, his or her own counsel. 

[Remainder of Page Left Intentionally Blank] 

  
 10 

 IN WITNESS WHEREOF, the parties hereto have caused this Stockholder Agreement to be executed as
of the date first above written. 
  

			
	 MAST THERAPEUTICS, INC.

		
	 By:
	 	  

	 Name:
	 	  

	 Title:
	 	  

 [SIGNATURE PAGE TO STOCHOLDER
AGREEMENT] 

 IN WITNESS WHEREOF, the parties hereto have caused this Stockholder Agreement to be executed as
of the date first above written. 
  

			
	 AIRES PHARMACEUTICALS, INC.

		
	 By:
	 	 
	 Name:
	 	 Wendy Johnson

	 Title:
	 	 President and Chief Executive Officer

 [SIGNATURE PAGE TO STOCHOLDER
AGREEMENT] 

 IN WITNESS WHEREOF, the parties hereto have caused this Stockholder Agreement to be executed as
of the date first above written. 
  

			
		 	 Name of
Stockholder:                                       
                 

		
		 	 
		
		 	 Address:

		
		 	 
		 	(Print Telephone Number)
		
		 	 
		 	(Social Security or Tax I.D. Number)
		
		 	
		 	 Company Shares beneficially owned on the date hereof:
  

__________ shares of Common Stock
  

_________ shares of Series A Preferred Stock
  

_________ shares of Series B-1 Preferred Stock
  

_________ shares of Series B-2 Preferred Stock
  

_________ shares of Series C-1 Preferred Stock
  

_________ shares of Series C-2 Preferred Stock
  

State of Residence:
                        

  

[SIGNATURE PAGE TO STOCHOLDER AGREEMENT] 

 STOCKHOLDER AGREEMENT & WRITTEN CONSENT OF THE STOCKHOLDERS 

SPOUSAL CONSENT 

I                         
   , spouse of                         , have read and approve the foregoing Stockholder Agreement,
including the attached Proxy, (the “Agreement”), and the written consent of the stockholders of Aires Pharmaceuticals, Inc. (the “Consent”). In consideration of the terms and conditions as set forth in the Agreement
and the matters set forth in the Consent, I hereby appoint my spouse as my attorney-in-fact with respect to the exercise of any rights and obligations under the Agreement and the Consent, and agree to be bound by the provisions of the Agreement and
the Consent insofar as I may have any rights or obligations in the Agreement or in the Consent under the community property laws or similar laws relating to marital or community property in effect in the state of our residence as of the date of the
Agreement or the Consent. 
 Date_____________________________________________________ 

Signature of Spouse_________________________________________ 

Printed Name of Spouse______________________________________ 

 EXHIBIT A 

IRREVOCABLE PROXY 
 TO
VOTE STOCK OF 
 MAST THERAPEUTICS, INC. and AIRES PHARMACEUTICALS, INC. 

The undersigned stockholder (each a “Stockholder”) of Aires Pharmaceuticals, Inc., a Delaware corporation
(“Company”), hereby irrevocably (to the fullest extent permitted by the Delaware General Corporation Law) appoints (i) the officers of Mast Therapeutics, Inc., a Delaware corporation (“Parent”), and each of
them, or any other designee of Parent, as the sole and exclusive attorneys and proxies of the undersigned, with full power of substitution and resubstitution, to vote and exercise all voting and related rights (to the fullest extent that the
undersigned is entitled to do so) with respect to each and every meeting of stockholders of Parent or action or approval by written resolution or consent of stockholders of Parent from and after the Effective Time and through the date that is the
thirty (30)-month anniversary of the Closing Date (the “Proxy Expiration Date”) covering the total number of shares of capital stock of Parent issued to such Stockholder as Merger Consideration pursuant to the Merger Agreement
(defined below) (such shares issued as Merger Consideration, the “Parent Shares”) in respect of which the undersigned is entitled to vote at any such meeting or in connection with any such written consent and (ii) the officers
of the Company, and each of them, or any other designee of the Company, as the sole and exclusive attorneys and proxies of the undersigned, with full power of substitution and resubstitution, to vote and exercise all voting and related rights (to
the fullest extent that the undersigned is entitled to do so) with respect to each and every meeting of stockholders of the Company or action or approval by written resolution or consent of stockholders of the Company from and after the date hereof
and prior to the earlier of (A) the Effective Time or (B) termination of the Merger Agreement covering the total number of number of shares of capital stock of the Company (the “Company Shares” and together with the Parent
Shares, the “Shares”) in respect of which such Stockholder is entitled to vote at any such meeting or in connection with any such written consent related to the subject matter of Section 2 of the Stockholder Agreement (defined
below). Notwithstanding anything to the contrary in this Agreement, this Irrevocable Proxy shall not apply to any proposal submitted to a vote of the Company Stockholders to approve any payment which would, in the absence of such approval,
constitute a parachute payment under Section 280G of the Code, and such Stockholder shall continue to have full power and authority to vote the Company Shares in such Stockholder’s sole discretion for or against any such proposal. Upon the
undersigned’s execution of this Irrevocable Proxy, any and all prior proxies given by the undersigned with respect to any Shares are hereby revoked and the undersigned agrees not to grant any subsequent proxies with respect to the Shares until
after the Proxy Expiration Date (as defined below). Any capitalized terms not otherwise defined herein shall have the meanings ascribed to them in the Merger Agreement. 

This Irrevocable Proxy is irrevocable (to the fullest extent provided in the Delaware General Corporation Law), is coupled with an interest,
including, but not limited to, that certain Stockholder Agreement dated as of even date herewith by and between Parent and the undersigned (the “Stockholder Agreement”), and is granted in consideration of Parent entering into that
certain Agreement and Plan of Merger, dated as of February 7, 2014, by and between Parent, Company, AP Acquisition Sub, Inc. (“Merger Sub”) and Stockholders’ Representative (the “Merger Agreement”), which
agreement provides for the merger of Company with and into Merger Sub (the “Merger”). 
 This Irrevocable Proxy with
respect to the Company Shares shall expire and terminate at the earlier of (i) the termination of the Merger Agreement pursuant to Section 8.1(a) thereof, and (ii) the Effective Time (as defined in the Merger Agreement). This
Irrevocable Proxy with respect to the Parent Shares shall expire and terminate on the earlier of the (i) the termination of the Merger Agreement pursuant to Section 8.1(a) thereof and (ii) the Proxy Expiration Date. The undersigned
Stockholder acknowledges and understands that the specific date on which the Proxy Expiration Date will occur is not presently known. As used herein, the term “Proxy Expiration Date” shall mean the thirty (30) month anniversary
of the Closing Date (as defined in the Merger Agreement). 

 The attorneys and proxies named above, and each of them, are hereby authorized and empowered by
the undersigned, at any time prior to the Proxy Expiration Date, to act as the undersigned’s attorney and proxy to vote the Shares, and to exercise all voting and other rights of the undersigned with respect to the Shares (including, without
limitation, the power to execute and deliver written consents pursuant to the Delaware General Corporation Law), at every annual, special or adjourned meeting of the stockholders of Company or Parent, as applicable, and in every written consent in
lieu of such meeting, to the extent related to the subject matter of Section 2 or Section 3 of the Stockholder Agreement, as applicable. However, this Irrevocable Proxy with respect to the Company Shares shall not apply to any proposal
submitted to the Company Stockholders to approve any payment which would, in the absence of such approval, constitute parachute payments under Section 280G of the Internal Revenue Code of 1986, as amended, and the undersigned Stockholder shall
continue to have full power and authority to vote the Shares in the undersigned’s sole discretion for or against any such proposal and/or any other matter not specifically described as a Proposal in the Stockholder Agreement. 

All authority herein conferred shall survive the death or incapacity of the undersigned and any obligation of the undersigned hereunder shall
be binding upon the heirs, personal representatives, successors and assigns of the undersigned. 
 This Irrevocable Proxy may not be amended
or otherwise modified without the prior written consent of Parent. This Irrevocable Proxy shall terminate, and be of no further force and effect, automatically at 5:30 p.m. (Pacific time) the Proxy Expiration Date. 

[Remainder of Page Left Intentionally Blank] 

 Dated: _____________, ____ 

Name of Stockholder: ___________________ 
  

 

Address: 

Company Shares beneficially owned on the date hereof: 

_________ shares of Common Stock 

_________ shares of Series A Preferred Stock 

_________ shares of Series B-1 Preferred Stock 

_________ shares of Series B-2 Preferred Stock 

_________ shares of Series C-1 Preferred Stock 

_________ shares of Series C-2 Preferred Stock 

[SIGNATURE PAGE TO IRREVOCABLE PROXY]EX-10.1

 Exhibit 10.1 

FORRESTER RESEARCH, INC. 

EXECUTIVE SEVERANCE PLAN 

The Company has adopted this Forrester Research, Inc. Executive Severance Plan for the benefit of certain employees of the Company and its
Subsidiaries, on the terms and conditions hereinafter stated. All capitalized terms used herein are defined in Section 1 hereof. The Plan, as set forth herein, is intended to help retain qualified employees, maintain a stable work environment
and provide economic security to Eligible Executives in the event of certain terminations of employment. 
  

	SECTION 1.	DEFINITIONS. As hereinafter used: 

 1.1 “Accountants”
shall have the meaning ascribed to that term in Section 4.1. 
 1.2 “Affiliate” means, with respect to
any individual or entity, any other individual or entity who, directly or indirectly through one or more intermediaries, controls, is controlled by or is under common control with, such individual or entity. 

1.3 “Board” means the Board of Directors of the Company. 

1.4 “Cause” shall mean that the Eligible Executive has: (a) willfully and continually failed to
substantially perform, or been willfully grossly negligent in the discharge of, his or her reasonably assigned duties to the Company or any of its Subsidiaries (in any case, other than by reason of a Disability, physical or mental illness or
analogous condition and excluding any such failure occurring after the Eligible Executive has given written notice of termination for Good Reason), which failure or negligence continues for a period of 10 business days after a written demand for
performance is delivered to the Eligible Executive by the Board, which specifically identifies the manner in which the Board believes that the Eligible Executive has not substantially performed, or been grossly negligent in the discharge of, his or
her duties; (b) committed or engaged in an act of theft, embezzlement or fraud, or committed a willful and material breach of confidentiality with respect to the Company or any of its subsidiaries or a willful unauthorized disclosure or use of
inside information, customer lists, trade secrets or other confidential information of the Company or any of its Subsidiaries which in any case is materially and demonstrably injurious to the Company or any of its Subsidiaries; (c) willfully
breached a fiduciary duty; (d) willfully and materially violated any duty, law, rule, regulation or policy of the Company or any of its Subsidiaries; or (e) been indicted, convicted or pled no contest to a felony (other than involving a
traffic-related infraction), or any crime involving fraud or dishonesty. No act or failure to act on the part of the Eligible Executive shall be deemed “willful” unless done, or omitted to be done, by the Eligible Executive not in good
faith or without reasonable belief that the Eligible Executive’s act or failure to act was in the best interests of the Company. The Company must notify the Eligible Executive of an act or failure to act constituting Cause within 90 days
following the date that the Board of Directors 

 of the Company (or any duly authorized Committee thereof) first obtained actual knowledge of the
existence of Cause, or such Eligible Executive’s act or failure to act shall not constitute cause under this Plan. For the avoidance of doubt, this definition of Cause shall control for all purposes of determining the rights to benefits for
Eligible Executives under the Plan, regardless of any inconsistency between this definition and a definition of “Cause” that is set forth in any employment, severance or other agreement between the Eligible Executive on the one hand, and
the Company or any Subsidiary or any Affiliate, on the other hand. 
 1.5 A “Change in Control” shall be
deemed to mean the first of the following events to occur after the Effective Date: 
  

	 	(a)	The acquisition by any individual, entity or group (within the meaning of Section 13(d)(3) or 14(d)(2) of the Exchange Act (a “Person”)) of beneficial ownership (within the meaning of Rule 13d-3
promulgated under the Exchange Act) of 50% or more of either (1) the then-outstanding shares of common stock of the Company (the “Outstanding Company Common Stock”) or (2) the combined voting power of the then-outstanding
voting securities of the Company entitled to vote generally in the election of directors (the “Outstanding Company Voting Securities”); provided, however, that, for purposes of this Section 1.4(a), the following acquisitions
shall not constitute a Change in Control; (A) any acquisition directly from the Company, (B) any acquisition by the Company, (C) any acquisition by any employee benefit plan (or related trust) sponsored or maintained by the Company or
any Affiliate of the Company or a successor, or (D) any acquisition by any entity pursuant to a transaction that complies with Section (c)(1) or (c)(2) below, or (E) any acquisition by George F. Colony or any member of the family of George
F. Colony or any trust or entity substantially all of the beneficial interests of which are owned by the Colony family (an “Exempt Person”); 

  

	 	(b)	Individuals who, as of the Effective Date, constitute the Board (the “Incumbent Board”) cease for any reason to constitute at least a majority of the Board; provided, however, that any individual becoming a
director subsequent to the Effective Date whose election, or nomination for election by the Company’s shareholders, was approved by a vote of at least two-thirds of the directors then comprising the Incumbent Board shall be considered as though
such individual was a member of the Incumbent Board, but excluding, for this purpose, any such individual whose initial assumption of office occurs as a result of an actual or threatened election contest with respect to the election or removal of
directors or other actual or threatened solicitation of proxies or consents by or on behalf of a Person other than the Board; 

  

	 	(c)	 The consummation of a merger or consolidation of the Company or any Subsidiary with any other entity, other than (1) a merger or consolidation
which results in the directors of the Company immediately prior to such 

  
 2 

	 	
merger or consolidation continuing to constitute at least a majority of the board of directors of the Company, the surviving entity or any parent thereof or (2) a merger or consolidation
effected to implement a recapitalization of the Company (or similar transaction) in which no Person other than an Exempt Person acquires beneficial ownership, directly or indirectly, of securities of the Company (not including in the securities
beneficially owned by such Person any securities acquired directly from the Company) representing 50% or more of the Outstanding Company Common Stock or the Outstanding Company Voting Securities; or 

 

	 	(d)	Shareholders of the Company approve a plan of complete liquidation or dissolution of the Company or there is consummated an agreement for the sale or disposition by the Company of all or substantially all of the
Company’s assets, other than a sale or disposition by the Company of all or substantially all of the Company’s assets to an entity, at least 50% of the combined voting power of the voting securities of which are owned by shareholders of
the Company in substantially the same proportions as their ownership of the Company immediately prior to such sale. 

1.6 “Change in Control Protection Period” shall mean the period commencing on the first date a Change in
Control occurs and ending eighteen (18) months following such date. 
 1.7 “Change in Control Severance
Event” means (i) the earlier of (x) the involuntary termination of an Eligible Executive’s employment by the Company or (y) the provision of written notice of the termination of an Eligible Executive’s employment by
the Company if the Company is required by law or contract to provide advance notice of such termination, in either case other than for Cause, death or Disability, in all such cases following the Effective Date and during the Change in Control
Protection Period, (ii) the earlier of (x) the termination of an Eligible Executive’s employment by the Eligible Executive for Good Reason or (y) the provision of written notice of the termination of an Eligible Executive’s
employment with the Company by the Eligible Executive for Good Reason, if such Eligible Executive is required by law or contract to provide advance notice of such termination, in all such cases following the Effective Date and during the Change in
Control Protection Period, or (iii) the Eligible Executive’s employment with the Company is involuntarily terminated following the Effective Date but prior to the date on which Change in Control occurs, and it is demonstrated by the
Eligible Executive to the reasonable satisfaction of the Company that such termination of employment prior to the Change in Control (x) was at the request of a third party who has taken steps reasonably calculated to effect a Change in Control,
or (y) otherwise arose in connection with or in anticipation of a Change in Control. 
 1.8 “Chief Executive
Officer” means the chief executive officer of the Company. 

  
 3 

 1.9 “Code” means the Internal Revenue Code of 1986, as amended.

 1.10 “Committee” means the Compensation and Nominating Committee of the Board. 

1.11 “Company” means Forrester Research, Inc. and any successors thereto and, where the context requires, its
Subsidiaries. 
 1.12 “Disability” means a physical or mental condition entitling the Eligible Executive to
benefits under the applicable long-term disability plan of the Company or any its Subsidiaries, or if no such plan exists, a “permanent and total disability” (within the meaning of Section 22(e)(3) of the Code). 

1.13 “Effective Date” shall mean May 15, 2014. 

1.14 “Effective Period” means the period beginning on the Effective Date, excluding the Change in Control
Protection Period. 
 1.15 “Eligible Executive” means those individuals and/or positions listed on Exhibit
A hereto, including the Chief Executive Officer of the Company. 
 1.16 “ERISA” means the Employee
Retirement Income Security Act of 1974, as amended. 
 1.17 “Exchange Act” means the Securities Exchange
Act of 1934, as amended. 
 1.18 “Excise Tax” shall have the meaning ascribed to that term in
Section 4.1. 
 1.19 “Good Reason” means (i) a material adverse alteration or material diminution
in the nature or status of an Eligible Executive’s duties or responsibilities with the Company or any Subsidiary thereof (other than as a result of the Eligible Executive’s physical or mental incapacity that impairs his or her ability to
materially perform his or her duties or responsibilities and such alteration or diminution lasts only for so long as the Eligible Executive’s doctor determines such incapacity impairs the Eligible Executive’s ability to materially perform
his or her duties or responsibilities) as an Eligible Executive without the Eligible Executive’s consent; (ii) a reduction in base salary or aggregate cash target bonus and other incentive opportunity of an Eligible Executive; (iii) a
material reduction in the aggregate level of employee benefits made available to the Eligible Executive when compared to the benefits made available to the Eligible Executive immediately prior to the Change in Control; or (iii) a relocation of
an Eligible Executive’s principal place of business of more than 35 miles (other than to the extent agreed to or requested by the Eligible Executive), which, in each case, is not cured within 30 days following the Company’s or one of its
Subsidiaries, as applicable, receipt of written notice from such Eligible Executive describing the event constituting Good Reason. Such notice must be provided within 90 days of the initial existence of the event constituting Good Reason. 

  
 4 

 1.20 “Notice Period” shall have the meaning ascribed to that
term in Section 6.2. 
 1.21 “Payments” shall have the meaning ascribed to that term in
Section 4.1. 
 1.22 “Person” shall have the meaning given in Section 3(a)(9) of the Exchange
Act, as modified and used in Sections 13(d) and 14(d) thereof. 
 1.23 “Plan” means the Forrester Research,
Inc. Executive Severance Plan, as set forth herein, as it may be amended from time to time. 
 1.24 “Plan
Administrator” means the Committee or such other person or persons appointed from time to time by the Committee to administer the Plan. 

1.25 “Safe Harbor Amount” shall mean the greatest pre-tax amount of Payments that could be paid to an
Eligible Executive without causing an Eligible Executive to become liable for any Excise Tax in connection therewith. 

1.26 “Severance Event” means the involuntary termination of an Eligible Executive’s employment by the
Company or any Subsidiary thereof, other than for Cause, death or Disability during the Effective Period. 
 1.27
“Severance Date” means the date on which an Eligible Executive incurs a Severance Event. 
 1.28
“Subsidiary” means, with respect to the Company, as of any date of determination, any other Person as to which the Company owns or otherwise controls, directly or indirectly, more than 50% of the voting shares or other similar
interests or a sole general partner interest or managing member or similar interest of such other Person. 
  

	SECTION 2.	SEVERANCE BENEFITS. 

 2.1 Generally. Subject to Sections 2.8,
2.9, 2.10, 2.11 and Section 4, each Eligible Executive shall be entitled to severance payments and/or benefits pursuant to applicable provisions of Section 2 of this Plan if the Eligible Executive incurs a Severance Event or a Change in
Control Severance Event. 
 2.2 Payment of Accrued Obligations. If an Eligible Executive incurs (i) a Severance
Event during the Effective Period, or (ii) a Change in Control Severance Event during the Change in Control Protection Period, the Company shall pay to such Eligible Executive on the Severance Date or as soon as practicable thereafter in
accordance with applicable law, a lump sum payment in cash equal to 

  
 5 

 
the sum of (a) the Eligible Executive’s accrued but previously unpaid annual base salary and any accrued vacation pay through the Severance Date, (b) the Eligible Executive’s
annual bonus earned for the fiscal year immediately preceding the fiscal year in which the Severance Date occurs (if such bonus is determinable and has not been paid as of the Severance Date) and (c) if applicable, the amount of the annual
bonus earned, if any, and/or the amount of sales commissions determinable and earned by the Eligible Executive and unpaid as of the Severance Date for the then current fiscal year and any prior periods. 

2.3 Payment after a Severance Event or Change in Control Severance Event. 

2.3.1 Subject to Sections 2.8, 2.9, 2.10, 2.11 and Section 4 hereof, the Company shall pay to: 

(a) each Eligible Executive other than the Chief Executive Officer who incurs a Severance Event during the Effective Period, in equal
installments over twelve months in accordance with the Company’s regular payroll practices commencing with the first administratively practical regular payroll date next following the effectiveness of the release as described in
Section 2.8, (i) one times the Eligible Executive’s annual base salary as in effect on the Severance Date, and (ii) in a lump sum as soon as reasonably practicable following the effectiveness of the release described in
Section 2.8, but in no event later than March 15th of the calendar year following the calendar year that includes the Severance Date, an amount equal to the lesser of (x) one times
the Eligible Executive’s annual target bonus and if applicable, sales commission amounts as in effect on the Severance Date, or (y) the average of the actual bonus and if applicable, sales commissions earned by the Eligible Executive under
applicable executive incentive plans and sales commission plans for each of the two fiscal years preceding the year of the Severance Event, provided the Eligible Executive was employed by the Company during both fiscal years, or, if the Eligible
Executive was employed by the Company for only one fiscal year, the actual bonus and if applicable, sales commissions, earned by such Eligible Executive for that fiscal year, or, if the Eligible Executive was employed by the Company for less than
one fiscal year, the actual bonus and if applicable, sales commissions, earned by the Eligible Executive while employed by the Company; and 

(b) the Chief Executive Officer if he or she incurs a Severance Event during the Effective Period, in equal installments over eighteen
(18) months in accordance with the Company’s regular payroll practices commencing with the first administratively practical regular payroll date next following the effectiveness of the release as described in Section 2.8, (i) one
and one-half times the Chief Executive Officer’s annual base salary as in effect on the Severance Date, and (ii) in a lump sum as soon as reasonably practicable following the effectiveness of the release described in Section 2.8, but
in no event later than March 15th of the calendar year following the calendar year that includes the Severance Date, an amount equal to the lesser of (x) one and one-half times the Chief
Executive Officer’s annual target bonus and if applicable, sales commission amounts as in effect on the Severance Date, or (y) one and one-half times the average of the actual bonus and if applicable, sales commissions earned by the

  
 6 

 
Chief Executive Officer under applicable executive incentive plans and sales commission plans for each of the two fiscal years preceding the year of the Severance Event, provided the Chief
Executive Officer was employed by the Company during both fiscal years, or, if the Chief Executive Officer was employed by the Company for only one fiscal year, one and one-half times the actual bonus and if applicable, sales commissions, earned by
such Chief Executive Officer for that fiscal year, or, if the Chief Executive Officer was employed by the Company for less than one fiscal year, one and one-half times the actual bonus and if applicable, sales commissions, earned by the Chief
Executive Officer while employed by the Company. 
 2.3.2 Subject to Sections 2.8, 2.9, 2.10, 2.11 and Section 4 hereof, the Company
shall pay to: 
 (a) each Eligible Executive other than the Chief Executive Officer who incurs a Change in Control Severance Event a lump
sum cash payment on the first administratively practical regular payroll date following the effectiveness of the release described in Section 2.8 hereof equal to the sum of (i) one times the Eligible Executive’s annual base salary (as
in effect immediately prior to the Change in Control or immediately prior to the Severance Date, whichever is higher); (ii) the delta between (x) the amount, if any, payable under Section 2.2 for actual bonus and/or sales commissions
earned up to and through the Severance Date, if any and (y) the Eligible Executive’s annual target bonus amount and/or annual target sales commissions amount, as applicable, pro-rated as of the Severance Date (without giving effect to any
reduction in such Eligible Executive’s target annual incentive opportunity following the Change in Control); and (iii) the higher of (x) one times the Eligible Executive’s target annual incentive opportunity, including target
bonus opportunity, and if applicable, target sales commissions (without giving effect to any reduction in such Eligible Executive’s target annual incentive opportunity following the Change in Control) or (y) the average of the actual bonus
and if applicable, sales commissions earned by the Eligible Executive under applicable executive incentive plans and sales commission plans for each of the two fiscal years preceding the year of the Change in Control Severance Event, provided the
Eligible Executive was employed by the Company during both fiscal years, or, if the Eligible Executive was employed by the Company for only one fiscal year, the actual bonus and if applicable, sales commissions, earned by such Eligible Executive for
that fiscal year, or, if the Eligible Executive was employed by the Company for less than one fiscal year, the actual bonus and if applicable, sales commissions, earned by the Eligible Executive while employed by the Company. 

(b) the Chief Executive Officer if he or she incurs a Change in Control Severance Event a lump sum cash payment on the first administratively
practical regular payroll date following the effectiveness of the release described in Section 2.8 hereof equal to the sum of (i) two times the Chief Executive Officer’s annual base salary (as in effect immediately prior to the Change
in Control or immediately prior to the Severance Date, whichever is higher); (ii) the delta between (x) the amount, if any, payable under Section 2.2 for actual bonus and/or sales commissions earned up to and through the Severance
Date, if any, and (y) the Chief Executive Officer’s annual target bonus amount and/or annual target sales commissions amount, as applicable, pro-rated as of the 

  
 7 

 
Severance Date (without giving effect to any reduction in such Chief Executive Officer’s target annual incentive opportunity following the Change in Control); and (iii) the higher of
(x) two times the Chief Executive Officer’s target annual incentive opportunity, including target bonus opportunity, and if applicable, target sales commissions (without giving effect to any reduction in such target annual incentive
opportunity following the Change in Control), or (y) two times the average of the actual bonus and if applicable, sales commissions earned by the Chief Executive Officer under applicable executive incentive plans and sales commission plans for
each of the two fiscal years preceding the year of the Change in Control Severance Event, provided the Eligible Executive was employed by the Company during both fiscal years, or, if the Chief Executive Officer was employed by the Company for only
one fiscal year, two times the actual bonus and if applicable, sales commissions, earned by such Chief Executive Officer for that fiscal year, or, if the Chief Executive Officer was employed by the Company for less than one fiscal year, two times
the actual bonus and if applicable, sales commissions, earned by the Chief Executive Officer while employed by the Company. 

2.4 Equity Treatment. Without limitation of an Eligible Executive’s rights under any other plan, program or
agreement, all unvested equity and equity-based awards for each Eligible Executive who incurs a Change in Control Severance Event (including stock options and RSU’s and, for the avoidance of doubt, any equity or equity-based awards of either
the Company or a successor into which unvested equity of the Company held by an Eligible Executive at the time of a Change in Control is converted in connection with the Change in Control) shall become fully vested immediately prior to such Change
in Control Severance Event; provided that any such equity or equity-based awards which vest contingent upon the attainment of performance goals shall become vested at the target level of performance. In addition, in the event that a Change in
Control occurs in which either (a) the Company’s common stock is exchanged for or converted into consideration consisting solely of cash or (b) the successor or acquirer does not assume or equitably substitute outstanding equity or
equity-based awards, each such equity or equity-based award shall be cancelled at the time of such transaction in exchange for a payment equal to the product of (i) the consideration per share of Company common stock in the transaction (less
any applicable per share exercise price) and (ii) the number of shares of Company common stock subject to such award; provided that in the case of any such equity or equity-based awards which vest contingent upon the attainment of performance
goals the number of shares subject to such award shall be measured at the target level of performance. 
 2.5 Benefits
Supplement. Subject to Sections 2.8, 2.9, 2.10. 2.11 and Section 4 hereof, in the case of each Eligible Executive who incurs a Severance Event or Change in Control Severance Event, the Company shall, at its sole expense, pay to each such
Eligible Executive in equal installments in accordance with the Company’s regular payroll schedule pursuant to Section 2.3.1 in the case of a Severance Event, or with the lump sum payment pursuant to Section 2.3.2 in the case of a
Change in Control Severance Event an amount equal to the Company’s portion of the cost of such Eligible Executive’s (including eligible dependents as of the Severance Date) medical and dental benefits under applicable Company plans on

  
 8 

 
the Severance Date for a twelve-month period for Eligible Executives other than the Chief Executive Officer, and for an eighteen-month period for the Chief Executive Officer in the case of a
Severance Event or twenty-four month period for the Chief Executive Officer in the case of a Change in Control Severance Event. For the avoidance of doubt, the supplemental payment referenced in this Section 2.5 is taxable to the Eligible
Executive and may be used by the Eligible Executive for any purpose, including, but not limited to, health care continuation coverage under COBRA. 

2.6 Outplacement Services. Subject to Sections 2.8, 2.9, 2.10 and Section 4 hereof, each Eligible Executive who
incurs a Severance Event or a Change in Control Severance Event shall be provided with appropriate outplacement services as selected by the Company (i) in the case of a Severance Event, for a period of six months, which period may be extended
for an additional six (6) months upon request of the Eligible Executive and at the discretion of the Company; and (ii) in the case of a Change in Control Severance Event, for a period of twelve months. 

2.7 Legal Fees. The Company shall reimburse each Eligible Executive whose termination of employment results from a
Change in Control Severance Event for all reasonable legal fees and expenses incurred by such Eligible Executive in seeking to obtain or enforce any right or benefit provided under this Plan, provided such Eligible Executive prevails in substantial
part on the material issues presented in such legal or other proceeding.  
 2.8 Release. No Eligible
Executive who incurs a Severance Event or a Change in Control Severance Event shall be eligible to receive any payments or other benefits under the Plan (other than payments under Section 2.2 hereof) unless he or she first executes a waiver,
release of claims, and covenant not to sue in favor of the Company and its Subsidiaries in a form as determined by the Company and does not revoke such release within the time permitted therein for such revocation, if any. The Company shall provide
the release to the Eligible Executive no later than five (5) business days after the Eligible Executive’s termination of employment. If such release is not effective on or before the sixtieth
(60th) day following the Eligible Executive’s termination of employment, payments or benefits shall not be paid or otherwise provided to the Eligible Executive under this Plan and
instead shall be forfeited. 
 2.9 Section 409A. It is intended that payments and benefits under this Plan not
subject Eligible Executives to taxation under Section 409A of the Code and, accordingly, this Plan shall be interpreted and administered to be in compliance therewith. Any payments described in this Plan that are due within the “short term
deferral period” as defined in Section 409A of the Code, or that qualify as “involuntary separation pay” within the meaning of Treas. Reg. § 1.409A-1(b)(9) shall not be treated as deferred compensation unless applicable law
requires otherwise. If any amount payable under the Plan upon a termination of employment is determined by the Company to constitute nonqualified deferred compensation for purposes of Section 409A of the Code, such amount shall not be paid
unless and 

  
 9 

 
until the Eligible Executive’s termination of employment also constitutes a “separation from service” under Section 409A of the Code. If current or future regulations or
guidance from the Internal Revenue Service dictates, or the Company’s counsel determines that any payments or benefits due to the Eligible Executive hereunder upon the schedule otherwise provided herein would cause the application of an
accelerated or additional tax under Section 409A, then, to the extent required to avoid an accelerated or additional tax under Section 409A amounts that would otherwise be payable and benefits that would otherwise be provided pursuant to
this Plan during the six-month period immediately following the Eligible Executive’s Severance Date shall instead be paid on the first business day after the date that is six months following the Eligible Executive’s Severance Date (or
upon such Eligible Executive’s death, if earlier) and amounts payable after such six-month period shall be paid in accordance with their original payment schedule. To the extent required to avoid an accelerated or additional tax under
Section 409A, amounts reimbursable to the Eligible Executive under this Plan (including any reasonable legal fee reimbursements described in Section 2.7) shall be paid to the Eligible Executive on or before the last day of the calendar
year following the calendar year in which the expense or tax was incurred and the amount of expenses eligible for reimbursement (and in-kind benefits provided to the Eligible Executive) during any one calendar year may not effect amounts
reimbursable or provided in any subsequent calendar year. Notwithstanding anything herein to the contrary, in no event shall the timing of an Eligible Executive’s execution of the release described in Section 2.8, directly or indirectly,
result in the Eligible Executive designating the calendar year of payment, and if a payment that is subject to execution of the general release could be made in more than one taxable year, payment shall be made in the later taxable year. Each
payment in a series of payments shall be treated as a “separate payment” for purposes of Section 409A of the Code. No interpretation or amendment of this Plan shall require the Company to incur any additional costs or to reimburse any
Eligible Executive for any taxes or penalties that might be imposed upon the Eligible Executive as a result of Section 409A of the Code. 

2.10 Nonduplication; Coordination with Other Arrangements. This Plan shall not be deemed to impair any rights of an
Eligible Executive pursuant to any other agreement, plan or arrangement with the Company, a Subsidiary, or an Affiliate (an “Alternative Arrangement”); provided however that the compensation and benefits provided under this Plan shall be
coordinated with similar compensation and benefits provided under other Company-sponsored plans and individual agreements with Eligible Executives so as to avoid the duplication of any such compensation and benefits. For the avoidance of doubt, in
the event that an Eligible Executive is party to an Alternative Arrangement which provides severance payments or benefits upon a termination of employment, or any retention or “stay” bonuses, the payments and benefits provided under this
Plan shall be reduced.  

  
 10 

 2.11 CESSATION OF SEVERANCE PAY AND BENEFITS.  

Except as otherwise expressly provided in a written agreement signed by the Chief Executive Officer, chief legal officer, or chief people
officer of the Company, severance pay and severance benefits which are being paid or are being provided to an Eligible Executive as a result of a Severance Event or Change in Control Severance Event shall immediately cease (provided the Eligible
Executive has received at least one thousand dollars ($1,000) of severance payments and benefits) and not be resumed in the event that the Eligible Executive is determined by the Company, in its sole discretion, to be in breach of any confidential
information, non-solicitation or non-competition covenant, or any other restrictive covenant agreement with the Company or any Subsidiary. 
  

	SECTION 3.	PLAN ADMINISTRATION. 

 3.1 The Plan Administrator shall have full
discretionary authority and control to administer the Plan and may interpret the Plan, prescribe, amend and rescind rules and regulations under the Plan and make all other determinations necessary or advisable for the administration of the Plan,
subject to all of the provisions of the Plan, including remedying any ambiguities or inconsistencies and supplying any omissions. 

3.2 The Plan Administrator may delegate any of its duties hereunder to such person or persons from time to time as it may
designate. 
 3.3 The Plan Administrator is empowered, on behalf of the Plan, to engage accountants, legal counsel and such
other personnel as it deems necessary or advisable to assist it in the performance of its duties under the Plan. The functions of any such persons engaged by the Plan Administrator shall be limited to the specified services and duties for which they
are engaged, and such persons shall have no other duties, obligations or responsibilities under the Plan. Such persons shall exercise no discretionary authority or discretionary control respecting the management of the Plan. All reasonable expenses
thereof shall be borne by the Company. 
  

	SECTION 4.	EXCISE TAX. 

 4.1 Excise Tax Treatment. Unless a more favorable
treatment is otherwise provided in an individual written employment, change of control, severance or other agreement with an Eligible Executive, in the event it shall be determined that any payment or distribution whether paid or payable or
distributed or distributable pursuant to the terms of this Plan or otherwise pursuant to or by reason of any other agreement, policy, plan, program or arrangement (collectively, a “Payment”), to or for the benefit of an Eligible Executive,
would be subject to the excise tax imposed by Section 4999 of the Code, or any successor provision thereto, or any similar tax imposed by state or local law, or any interest or penalties with respect to such excise tax (such tax or taxes,
together with any such interest and penalties, are hereafter collectively referred to as the “Excise Tax”), then the aggregate amount of Payments payable to the Eligible Executive shall be reduced to

  
 11 

 
the Safe Harbor Amount, with such reduction being applied first to the cash payments under Section 2 hereof (other than the Accrued Obligations described in Section 2.2) and then to
other benefits provided hereunder; provided however that such reduction shall not be effected in the event that the net amount of Payments received by the Eligible Executive, after giving effect to the imposition of the Excise Tax (and all other
applicable taxes) exceeds the net amount of such Payments received by the Eligible Executive after giving effect to the reduction. Unless the Company and an Eligible Executive otherwise agree in writing, any determination required under this
Section 4.1 shall be made in writing by an independent nationally recognized accounting firm (the “Accountants”) to be selected by the Company, whose good faith determination shall be conclusive and binding upon the Eligible Executive
and the Company for all purposes. The Company and the Eligible Executive shall furnish to the Accountants such information and documents as the Accountants may reasonably request in order to make a determination under this Section 4.1. The
Company shall bear all costs the Accountants may incur in connection with any calculations contemplated by this Section 4.1 and any other costs that the Eligible Executive may reasonably incur in connection with such Eligible Executive
responding to or defending any claim by a taxing authority seeking payment of any Excise Tax in connection with amounts paid or payable to an Eligible Executive under this Plan. 

 

	SECTION 5.	PLAN MODIFICATION OR TERMINATION. 

 The Plan may be terminated or amended by the Board
at any time; provided, however, that during the Change in Control Protection Period, (a) the Plan may not be terminated and (b) the Plan may not be amended if such amendment would in any manner be adverse to the interests of any Eligible
Executive. 
  

	SECTION 6.	GENERAL PROVISIONS. 

 6.1 Except as otherwise provided herein or by law,
no right or interest of any Eligible Executive under the Plan shall be assignable or transferable, in whole or in part, either directly or by operation of law or otherwise, including without limitation by execution, levy, garnishment, attachment,
pledge or in any manner; no attempted assignment or transfer thereof shall be effective; and no right or interest of any Eligible Executive under the Plan shall be liable for, or subject to, any obligation or liability of such Eligible Executive.
When a payment is due under this Plan to a severed employee who is unable to care for his or her affairs, payment may be made directly to his or her legal guardian or personal representative. 

6.2 If the Company or any Subsidiary is obligated by law or by contract to pay severance pay, a termination indemnity, or the
like, or if the Company or any Subsidiary is obligated by law or contract to provide advance notice of separation (“Notice Period”), then any severance pay hereunder shall be reduced by the amount of any such severance pay, termination
indemnity, or the like, as applicable, and by the amount of any compensation received during any Notice Period, provided the Eligible Executive was relieved of duties during such Notice Period. 

  
 12 

 6.3 Neither the establishment of the Plan, nor any modification thereof, nor the
creation of any fund, trust or account, nor the payment of any benefits shall be construed as giving any Eligible Executive, or any person whomsoever, the right to be retained in the service of the Company or any Subsidiary, and all Eligible
Executives shall remain subject to discharge to the same extent as if the Plan had never been adopted. 
 6.4 If any
provision of this Plan shall be held invalid or unenforceable, such invalidity or unenforceability shall not affect any other provisions hereof, and this Plan shall be construed and enforced as if such provisions had not been included. 

6.5 This Plan shall inure to the benefit of and be binding upon the heirs, executors, administrators, successors and assigns
of the parties, including each Eligible Executive, present and future, and any successor to the Company. If a severed employee shall die while any amount would still be payable to such severed employee hereunder if the severed employee had continued
to live, all such amounts, unless otherwise provided herein, shall be paid in a lump sum in accordance with the terms of this Plan to the executor, personal representative or administrators of the severed employee’s estate. 

6.6 The headings and captions herein are provided for reference and convenience only, shall not be considered part of the
Plan, and shall not be employed in the construction of the Plan. 
 6.7 The Plan shall not be required to be funded unless
such funding is authorized by the Board. Regardless of whether the Plan is funded, no Eligible Executive shall have any right to, or interest in, any assets of the Company which may be applied by the Company to the payment of benefits or other
rights under this Plan. 
 6.8 Any notice or other communication required or permitted pursuant to the terms hereof shall
have been duly given when delivered or mailed by United States Mail, first class, postage prepaid, addressed to the intended recipient at his, her or its last known address. 

6.9 This Plan shall be construed and enforced according to the laws of the State of Delaware to the extent not preempted by
federal law, which shall otherwise control. All disputes arising out of or in connection with this Plan shall be subject to the jurisdiction of the courts of Massachusetts. 

6.10 All payments and benefits paid or otherwise provided under or pursuant to the Plan shall be reduced by applicable tax
withholding and shall be subject to applicable tax reporting, as determined by the Plan Administrator. 

  
 13 

 6.11 The Plan, as a “severance pay arrangement” within the meaning of
Section 3(2)(B)(i) of ERISA, is intended to be excepted from the definitions of “employee pension benefit plan” and “pension plan” set forth under section 3(2) of ERISA, and is intended to meet the descriptive requirements
of a plan constituting a “severance pay plan” within the meaning of regulations published by the Secretary of Labor at Title 29, Code of Federal Regulations §2510.3-2(b). The Plan is also intended to constitute an “unfunded
welfare plan” maintained by the Company “for the purpose of providing benefits for a select group of management or highly compensated employees” such that it will be, among other things, exempt from the reporting and disclosure
requirements of Part 1 of Title I of ERISA. 
 6.12 All severance benefit payments are subject to set-off, recoupment, or
other recovery or “clawback” as required by applicable law or by any Company policy on the clawback of compensation, as amended from time to time. 

6.13 An Eligible Executive who is receiving or has received payments or other benefits under this Plan following a Severance
Event or Change in Control Severance Event will not be required to seek other employment, nor will there be any offset against amounts due to such Eligible Executive under this Plan for any remuneration payable by any subsequent employer. An
Eligible Executive who is receiving or has received payments or other benefits under this Plan following a Severance Event or Change in Control Severance Event will cooperate fully with the Company in the defense or prosecution of any government
investigations and any government or third-party claims or actions then in existence or which may be brought or threatened in the future against or on behalf of the Company, including any claim or action against its directors, officers and employees
in which the Eligible Executive has personal knowledge of any relevant facts. The Eligible Executive’s cooperation in connection with such claims or actions shall include the Eligible Executive being available, within reason given the
constraints of personal commitments, future employment or job search activities, to meet with the Company to prepare for any proceeding, to provide truthful affidavits, to assist with any audit, inspection, proceeding or other inquiry, and to act as
a witness in connection with any litigation or other legal proceeding affecting the Company. The Company will reimburse the Eligible Executive for any reasonable, out-of-pocket expenses that the Eligible Executive may incur in providing such
assistance. 
  

	SECTION 7.	CLAIMS, INQUIRIES, APPEALS. 

 7.1 Applications for Benefits and
Inquiries. Any application for benefits, inquiries about the Plan or inquiries about present or future rights under the Plan must be submitted to the Plan Administrator in writing, as follows: 

  
 14 

 Plan Administrator 

c/o Forrester Research, Inc. 

60 Acorn Park Drive 
 Cambridge,
MA 02140 
 Attn: Chief People Officer 

With a copy to: Chief Legal Officer 

7.2 Denial of Claims. In the event that any application for benefits is denied in whole or in part, the Plan
Administrator must notify the applicant, in writing, of the denial of the application, and of the applicant’s right to review the denial. The written notice of denial will be set forth in a manner designed to be understood by the employee, and
will include specific reasons for the denial, specific references to the Plan provision upon which the denial is based, a description of any information or material that the Plan Administrator needs to complete the review and an explanation of the
Plan’s review procedure. 
 This written notice will be given to the applicant within ninety (90) days after the Plan Administrator receives the
application, unless special circumstances require an extension of time, in which case, the Plan Administrator has up to an additional ninety (90) days for processing the application. If an extension of time for processing is required, written
notice of the extension will be furnished to the applicant before the end of the initial ninety (90)-day period. 
 This notice of extension will describe
the special circumstances necessitating the additional time and the date by which the Plan Administrator is to render its decision on the application. If written notice of denial of the application for benefits is not furnished within the specified
time, the application shall be deemed to be denied. The applicant will then be permitted to appeal the denial in accordance with the Review Procedure described below. 

7.3 Request for a Review. Any person (or that person’s authorized representative) for whom an application for
benefits is denied (or deemed denied), in whole or in part, may appeal the denial by submitting a request for a review to the Plan Administrator within 60 days after the application is denied (or deemed denied). The Plan Administrator will give the
applicant (or his or her representative) an opportunity to review pertinent documents in preparing a request for a review and submit written comments, documents, records and other information relating to the claim. A request for a review shall be in
writing and shall be addressed to: 
 Plan Administrator 

c/o Forrester Research, Inc. 

60 Acorn Park Drive 
 Cambridge,
MA 02140 
 Attn: Chief People Officer 

With a copy to: Chief Legal Officer 

  
 15 

 A request for review must set forth all of the grounds on which it is based, all facts in support of the request
and any other matters that the applicant feels are pertinent. The Plan Administrator may require the applicant to submit additional facts, documents or other material as he or she may find necessary or appropriate in making his or her review. 

7.4 Decision on Review. The Plan Administrator will act on each request for review within sixty (60) days after
receipt of the request, unless special circumstances require an extension of time (not to exceed an additional sixty (60) days), for processing the request for a review. If an extension for review is required, written notice of the extension
will be furnished to the applicant within the initial sixty (60)-day period. The Plan Administrator will give prompt, written notice of its decision to the applicant. In the event that the Plan Administrator confirms the denial of the application
for benefits in whole or in part, the notice will outline, in a manner calculated to be understood by the applicant, the specific Plan provisions upon which the decision is based. 

7.5 Rules and Procedures. The Plan Administrator may establish rules and procedures, consistent with the Plan and with
ERISA, as necessary and appropriate in carrying out his or her responsibilities in reviewing benefit claims. The Plan Administrator may require an applicant who wishes to submit additional information in connection with an appeal from the denial (or
deemed denial) of benefits to do so at the applicant’s own expense.  
 7.6 Exhaustion of Remedies. No
legal action for benefits under the Plan may be brought until the claimant (a) has submitted a written application for benefits in accordance with the procedures described by Section 7.1 above, (b) has been notified by the Plan
Administrator that the application is denied (or the application is deemed denied due to the Plan Administrator’s failure to act on it within the established time period), (c) has filed a written request for a review of the application in
accordance with the appeal procedure described in Section 7.3 above and (d) has been notified in writing that the Plan Administrator has denied the appeal (or the appeal is deemed to be denied due to the Plan Administrator’s failure
to take any action on the claim within the time prescribed by Section 7.4 above). 
 7.7 Limitation on Civil
Actions. In no event shall a claimant or any other person be entitled to challenge a decision of the Plan Administrator in court or in any other administrative proceeding unless and until the claim and appeal procedures described above have been
complied with and exhausted, nor may a claimant or other person bring any action in a court or other tribunal more than two (2) years after the Eligible Executive has terminated employment, regardless of whether the periods for the claim and
appeal procedures have expired. 
  

  
 16 

 EXHIBIT A 

ELIGIBLE EXECUTIVES 
 Chief Executive Officer

 Other Members of the Company’s Executive Team who are also executive officers of the Company designated in writing by the Board as eligible for the
Plan

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