SECOND AMENDED AND RESTATED STOCKHOLDERS? AGREEMENT

EXHIBIT 4.5

EXECUTION VERSION

PHARMASSET, INC.

SECOND AMENDED AND RESTATED

STOCKHOLDERS’ AGREEMENT

August 4, 2004

TABLE OF CONTENTS

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PHARMASSET, INC.

SECOND AMENDED AND RESTATED

STOCKHOLDERS’ AGREEMENT

THIS SECOND AMENDED AND RESTATED STOCKHOLDERS’ AGREEMENT (“ Agreement ”) is entered into as of August 4, 2004, by and among Pharmasset, Inc., a Delaware corporation (the “ Company ”), and the Persons (as defined herein) named in Schedule A hereto (collectively, the “ Stockholders ”).

RECITALS

WHEREAS, the Company has at the date hereof authorized share capital consisting of 30,000,000 shares of Common Stock (as defined herein) and 15,956,138 shares of Preferred Stock (as defined herein), with such authorized Preferred Stock including 3,200,000 shares of Series A Stock (as defined herein), 2,300,000 shares of Series B Stock (as defined herein), 1,357,798 shares of Series C Stock (as defined herein), 7,843,380 shares of Series D Stock (as defined herein) and 1,254,960 shares of Series D-1 Preferred Stock (as defined herein); and

WHEREAS, the Company, certain of the Stockholders and certain other Persons entered into a Stockholders’ Agreement as of June 4, 1999, as amended on February 1, 2001 (the “ Stockholders’ Agreement ”); and

WHEREAS, the Company proposes to sell shares of Series D Stock to the Purchasers (as defined herein) and it is a condition to such sale that the Stockholders’ Agreement be amended to include the Purchasers and be further amended and restated in its entirety as set forth herein;

NOW, THEREFORE, in consideration of the mutual promises and covenants hereinafter set forth, the parties hereto agree to amend and restate the Stockholders’ Agreement in its entirety as follows:

SECTION 1

DEFINITIONS; EFFECT

1.1 Definitions . As used herein in this Agreement, the following terms shall have the following respective meanings:

“ Affiliate ” shall mean, as applied to the Company or any other specified Person, any Person directly or indirectly controlling, controlled by or under direct or indirect common control with the Company (or other specified Person) and shall also include (a) any Person who is a director or officer of the Company (or such other specified Person) or beneficial owner of at least 5% of any class of the then outstanding equity securities of the Company (or such other specified Person) and Family Members of any such Person, (b) any Person of which the Company (or such other specified Person) or an Affiliate (as defined in clause (a) above) of the Company (or such other specified Person) shall, directly or indirectly, beneficially own at least ten percent (10%) of any class of such Person’s then outstanding equity securities, and (c) in the case of a specified Person who is an individual, any Family Member of such Person.

“ Board ” shall mean the Board of Directors of the Company or any committee thereof to the extent such committee has the legal authority under Delaware law to act on behalf of the Board of Directors.

“ Certificate of Incorporation ” shall mean the Amended and Restated Certificate of Incorporation of the Company, as filed in Delaware on or prior to the Closing Date, as amended from time to time.

“ Closing Date ” shall have the meaning given to such term in Section 1.2 of this Agreement.

“ Commission ” shall mean the United States Securities and Exchange Commission or any other federal agency at the time administering the Securities Act.

“ Common Stock ” shall mean the Common Stock of the Company, par value $0.001 per share. For purposes of calculating the percentage of Common Stock held by a Stockholder, all Preferred Shares of the Company shall be deemed to have been converted into Common Stock.

“ Dollar ” or “ $ ” shall mean United States Dollars.

“ Equity Incentive Plan ” shall mean the Company’s 1998 Stock Plan, as amended.

“ Family Member ” shall mean, as to any Person, such Person’s spouse, child (including a stepchild or an adopted child), grandchildren and a trust for the exclusive benefit of any one or more of them and a corporation or other entity controlled at all times by such Person and beneficially owned by such Person and any one or more of them.

“ Investors ” shall mean the Series B Holders, the Series C Holders and the Purchasers.

“ Lead Purchaser ” shall mean Burrill Life Sciences Capital Fund, L.P.

“ Majority Investors ” shall mean those holders of a majority of the Registrable Securities issued or issuable upon conversion of Series B Stock, Series C Stock or Series D Stock to the Investors.

“ New Shares ” shall mean (a) any Common Shares or Preferred Shares or other equity securities of the Company whether now authorized or not, (b) any rights, options, or warrants to purchase said shares, and (c) securities of any type whatsoever that are, or may become, convertible into, exercisable, exchangeable, or carrying rights to subscribe for any equity securities of the Company (collectively with the securities referred to in clause (b) above, “ Options ”); provided, however, that “New Shares” does not include (i) securities offered to the public pursuant to a registration statement filed under the Securities Act in connection with a Qualified IPO; (ii) securities issued pursuant to the acquisition of another Person by the Company by merger, consolidation, amalgamation, exchange of shares, the purchase of substantially all of the assets or otherwise in a transaction that has been approved by the Majority Investors; (iii) up to 3,675,522 shares of Common Stock (appropriately adjusted to take account of any stock split, stock dividend, combination of shares, recapitalization or other similar event) issuable to officers, directors, employees and consultants of the Company or a subsidiary

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pursuant to the exercise of options granted or shares of Common Stock directly issued under the Equity Incentive Plan, subject to vesting, and such options and other rights to acquire Common Stock granted thereunder; (iv) securities issued to the Company’s stockholders in connection with any share split, share dividend, recapitalization, split-up, subdivision or other similar event; (v) shares of Common Stock issued upon conversion of Preferred Stock; (vi) up to 19,960 shares of Common Stock issued to Emory University pursuant to Section 1.3 of that certain Stock Purchase Agreement dated December 10, 1998, between Emory University and the Company; (vii) shares of Common Stock or Preferred Stock issued pursuant to rights of first refusal, pre-emptive, anti-dilution or similar rights outstanding on the date hereof; (viii) securities issued in connection with a strategic business transaction approved by a majority of the Board, including the representative (if any) of the Series D Stock designated by the Lead Purchaser as contemplated by Section 3.1(a)(ii) of this Agreement; and (ix) the Warrants and all securities issued or issuable upon exercise, conversion, exchange or transfer thereof.

“ Person ” shall mean an individual, partnership, limited partnership, corporation, limited liability company, association, trust, joint venture, unincorporated organization and any government, governmental department or agency or political subdivision thereof.

“ Preferred Stock ” shall mean the Series A Stock, the Series B Stock, the Series C Stock, the Series D Stock and the Series D-1 Stock.

“ Purchase Agreement ” shall mean that certain Stock Purchase Agreement dated as of August 4, 2004 among the Company and the Purchasers.

“ Purchased Securities ” shall mean the Series B Stock, the Series C Stock, the Series D Stock and the Series D-1 Stock.

“ Purchasers ” shall mean the Persons named on Schedule A hereto under the heading “Purchasers” and their permitted assigns.

“ Qualified IPO ” shall mean a fully underwritten, firm commitment public offering that is consummated pursuant to an effective registration statement under the Securities Act covering the offer and sale by the Company of Common Stock in which the aggregate offering amount equals or exceeds $30,000,000 and in which the price per share of the Common Stock offered to the public equals or exceeds $12.75 (such price to be equitably adjusted in the event of any stock dividend, stock split, reverse split, combination, recapitalization or other similar event).

“ Registrable Securities ” shall mean (i) the Common Stock issued or issuable to any Investor pursuant to the conversion of the Purchased Securities, (ii) any Common Stock issued or issuable in respect of the shares contemplated by clause (i) above upon any share split, share dividend, recapitalization, split-up, subdivision or other similar event, and (iii) Common Stock issued or issuable in replacement or exchange of any of the securities issued in clauses (i) or (ii) above, provided however that shares of Common Stock that are Registrable Securities shall cease to be Registrable Securities (a) upon any sale pursuant to an effective registration statement or Rule 144 under the Securities Act or (b) upon any transfer or assignment which does not comply with the requirements of Section 2.9 of this Agreement.

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“ Registration Expenses ” shall mean all expenses incurred by the Company in complying with Sections 2.1, 2.2 and 2.5 hereof, including, without limitation, all registration, qualification and filing fees, printing expenses, escrow fees, fees and disbursements of counsel for the Company, fees and disbursements of one counsel for the Investors, blue sky fees and expenses, and the expense of any special audits incident to or required by any such registration (but excluding the compensation of regular employees of the Company which shall be paid in any event by the Company), but not including Selling Expenses.

“ Restricted Stockholders ” shall mean the Persons listed on Schedule A hereto under the heading “Restricted Stockholders.”

“ Sale of the Company ” shall mean a single transaction or group of related transactions between the Company and/or its stockholders and any Person or group of Persons (other than stockholders of the Company) pursuant to which such Person or Persons will (i) acquire Shares possessing the voting power to elect a majority of the Board; (ii) consummate a merger, amalgamation or consolidation or other similar transaction as a result of which the stockholders of the Company who own voting securities prior to such transaction(s) shall own less than fifty percent (50%) of the voting securities of the surviving corporation or its parent; or (iii) acquire all or substantially all of the Company’s assets (determined on a consolidated basis).

“ Securities Act ” shall mean the United States Securities Act of 1933, as amended, or any similar federal statute and the rules and regulations of the Commission thereunder.

“ Selling Expenses ” shall mean all underwriting fees, discounts, selling commissions and stock transfer taxes applicable to the Registrable Securities registered by the Investors and securities registered by the other Stockholders.

“ Series A Stock ” shall mean the Series A Stock of the Company, par value $0.001 per share.

“ Series B Holders ” shall mean the Persons named on Schedule A hereto under the heading “Series B Holders.”

“ Series B Stock ” shall mean the Series B Preferred Stock of the Company, par value $0.001 per share.

“ Series C Holders ” shall mean the Persons named on Schedule A hereto under the heading “Series C Holders.”

“ Series C Stock ” shall mean the Series C Preferred Stock of the Company, par value $0.001 per share.

“ Series D Stock ” shall mean the Series D Preferred Stock of the Company, par value $0.001 per share.

“ Series D-1 Stock ” shall mean the Series D-1 Preferred Stock of the Company, par value $0.001 per share.

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“ Shares ” shall mean the Common Stock, Preferred Stock or other equity securities of the Company.

“ Stockholders ” shall have the meaning given such term in the first paragraph of this Agreement.

“ Subsidiary ” shall mean any Person which the Company now or hereafter shall own, directly or indirectly through a subsidiary, at least a majority of the outstanding capital stock (or other beneficial interest) entitled to vote generally; and the term “ Subsidiaries ” shall mean all of such Persons collectively.

“ Transfer ” shall mean, with respect to any security of the Company, any transfer, sale, gift, exchange, assignment, pledge or other disposition by a Restricted Stockholder and in the case of a Restricted Stockholder which is not an individual, a Transfer of Common Stock or other security held by such Stockholder shall be deemed to have been made if any equity interest in such Stockholder is directly or indirectly transferred, sold, given, exchanged, assigned, pledged or disposed of to any other Person.

“ Warrants ” shall mean those Warrants to Purchase Shares of Preferred Stock of Pharmasset, Inc. that are issued to the Purchasers on the Closing Date with respect to an aggregate of 1,254,960 shares of Series D-1 Stock, together with all warrants issued in replacement or substitution thereof, including, without limitation, balance warrants issued upon the partial exercise of such warrants.

1.2 Effect . This Agreement shall come into effect forthwith upon the closing of the purchase by the Purchasers of the Series D Stock pursuant to the Purchase Agreement (the date of such closing being the “ Closing Date ”). This Agreement and the Certificate of Incorporation filed in connection with the closing of the transactions contemplated by the Purchase Agreement supersede and replace in their entirety the Stockholders’ Agreement and all other prior agreements between the Company and any one or more of the Stockholders with respect to the subject matter hereof and thereof, which shall be of no further force or effect once this Agreement comes into effect. Without limiting the generality of the foregoing, upon the effectiveness of this Agreement (i) the provisions of Section 3 of this Agreement shall supersede, replace and terminate in their entirety the information and access rights and similar provisions of the Stock Purchase Agreement dated February 1, 2001 by and among the Company, the Series B Holders, the Series C Holders and certain other Persons (the “ 2001 Stock Purchase Agreement ”) and any similar rights set forth in any other agreements previously entered into by and among the Company and the Stockholders party thereto and (ii) the provisions of the 2001 Stock Purchase Agreement and any other agreements previously entered into by and among the Company and the Stockholders party thereto with respect to voting or approval rights of the Stockholders shall be terminated in their entirety and shall be superseded and replaced by the voting and approval rights set forth in Section 3 of this Agreement by the rights set forth in the Certificate of Incorporation filed in connection with the closing of the transactions contemplated by the Purchase Agreement.

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SECTION 2

REGISTRATION RIGHTS

2.1 Demand Registration .

(a) Registration Upon Demand . If at any time after the earlier of (i) August 4, 2007, or (ii) six (6) months after the effective date of the Company’s initial public offering, the Company shall receive from the holders of a minimum of fifty-one percent (51%) of the Registrable Securities issued to the Investors a written request that the Company effect the registration under the Securities Act of Registrable Securities held by or issuable to such Investors (a “ Request for Registration ”), the Company will:

(i) promptly, and in any event within fifteen (15) days, give written notice of the proposed registration to all other Investors; and

(ii) use its best efforts to effect such registration of the Registrable Securities (including, without limitation, the execution of an undertaking to file post-effective amendments, appropriate qualification under applicable blue sky or other state securities laws and appropriate compliance with applicable regulations issued under the Securities Act and any other governmental requirements or regulations) as may be so requested and as would permit or facilitate the sale and distribution of all or such portion of such Registrable Securities as are specified in such request, together with all or such portion of the Registrable Securities of any Purchaser joining in such request as are specified in a written request received by the Company within fifteen (15) days after receipt of such written notice from the Company;

Provided, however, that the Company shall not be obligated to take any action to effect any such registration pursuant to this Section 2.1(a):

(A) Within one hundred eighty (180) days immediately following the effective date of any registration statement on the Commission’s Form S-1 (or any successor form to Form S-1) pertaining to an underwritten offering of securities of the Company part or all of which was for its own account unless otherwise consented to by the underwriter of such offering; or

(B) After the Company has effected two (2) such Requests for Registration from the Investors pursuant to this Section 2.1(a), and such registrations have been declared or ordered effective, or

(C) Within one hundred eighty (180) days from the effective date of any registration on the Commission’s Form S-1 (or any successor form to Form S-1) pertaining to an underwritten offering of Registrable Securities held by the Investors initiated pursuant to a Request for Registration;

(D) If the aggregate price to the public of any offering of Registrable Securities pursuant to this Section 2.1 is less than the lesser of (1) $10,000,000 or (2) such number that would register at least twenty percent (20%) of the Registrable Securities held by the Investors as of the date hereof;

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(E) If at the time of any Request for Registration, the Company is engaged or has fixed plans to engage within thirty (30) days of the time of the Request for Registration in a registered public offering as to which the Stockholders may include Registrable Securities pursuant to Section 2.2 of this Agreement, then the Company may at its option direct that such Request for Registration be delayed for a period not in excess of ninety (90) days from the effective date of such offering, such right to delay a Request for Registration to be exercised by the Company not more than once in any one-year period; or

(F) If prohibited under Section 2.12 below.

Subject to the foregoing clauses (A) through (F), the Company shall file a registration statement covering the Registrable Securities so requested to be registered as soon as practicable after receipt of the Request for Registration.

(b) Underwriting . The distribution of the Registrable Securities covered by a Request for Registration may be effected by means of a firm commitment underwriting. The right of any Investor to registration pursuant to Section 2.1 shall be conditioned upon such Investor’s participation in such underwriting and the inclusion of such Investor’s Registrable Securities in the underwriting to the extent provided herein.

The Company, together with all Investors proposing to distribute their securities through such underwriting, shall enter into an underwriting agreement in customary form with the managing underwriter(s) selected for such underwriting by the Company which underwriter(s) shall be reasonably acceptable to Investors initiating the Request for Registration pursuant to Section 2.1(a).

Notwithstanding any other provisions of this Section 2.1, if the managing underwriter(s) advises the Company and the Investors in writing that because the number of shares requested by the Investors to be included in the registration exceeds the number which can be sold in an orderly manner in such offering within a price range acceptable to the Investors requesting registration, marketing factors require a limitation of the number of shares to be underwritten on behalf of the Investors (the “ Demand Registration Cutback ”), then the Company will include in such registration, to the extent of the number and type which the Company is so advised can be sold in (or during the time of) such offering without such interference or affect on the price, first , all Registrable Securities requested to be included by the Investors and second , the securities proposed to be sold by the Company for its own account. In the event a Demand Registration Cutback results in less than all of the Registrable Securities of the Investors that are requested to be included in such registration to actually be included in such registration, then the number of Registrable Securities that will be included in such registration shall be shared pro rata among all of the Investors of Registrable Securities of such category that were requested to be included in such registration based on the number of shares of Common Stock held by each such Investor.

If any Investor disapproves of the terms of the underwriting, such Person may elect to withdraw therefrom by written notice to the Company, the managing underwriter(s) and the other Investors. The Registrable Securities and/or other securities so withdrawn shall also be withdrawn from registration; provided , however , that, if by the withdrawal of such Registrable Securities a greater number of Registrable Securities held by the other Investors may be included

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in such registration (up to the maximum of any limitation imposed by the underwriters), then the Company shall offer to the Investors who have included Registrable Securities in the registration the right to include additional Registrable Securities in the same proportion used in determining the underwriter limitation in this Section 2.1(b).

2.2 Piggyback Registration .

(a) Notice of Registration to Investors . If at any time or from time to time, the Company shall determine to register any of its securities, either for its own account or the account of a security holder or holders, other than (i) a registration relating solely to employee benefit plans, or (ii) a registration relating solely to a Commission Rule 145 transaction, the Company will:

(i) promptly give to each Investor and each other Stockholder written notice thereof; and

(ii) include in such registration (and any related qualification under blue sky laws or other compliance), all the Registrable Securities held by such Investors and all Common Stock held by such other Stockholders or issuable upon exercise or conversion of other securities of the Company held by such other Stockholders specified in a written request or requests, made within twenty (20) days after receipt of such written notice from the Company, by such Investors and other Stockholders, subject to the provisions of Section 2.2(b).

(b) Underwriting . If the registration of which the Company gives notice is for a registered public offering involving an underwriting, the Company shall so advise the Investors and other Stockholders as a part of the written notice given pursuant to Section 2.2(a)(i). In such event the right of any Investor or other Stockholder to registration pursuant to this Section 2.2 shall be conditioned upon such Investor’s or other Stockholder’s participation in such underwriting and the inclusion of such Investor’s Registrable Securities or other Stockholder’s securities in the underwriting to the extent provided herein. All Investors proposing to distribute their securities through such underwriting shall (together with the Company and the other Stockholders distributing their securities through such underwriting) enter into an underwriting agreement in the form agreed to by the Company and the managing underwriter selected for such underwriting by the Company. Notwithstanding any other provision of this Section 2.2, if the managing underwriter determines the number of shares requested to be included in the registration exceeds the number which can be sold in an orderly manner in such offering within a price range acceptable to the Company or marketing factors require a limitation of the number of shares to be underwritten on behalf of the Company (the “ Company Registration Cutback ”), then the number of shares of Common Stock requested to be registered by the other Stockholders shall first be reduced, on a pro rata basis among all such other Stockholders based on the number of shares of Common Stock (with all convertible securities and options held by such other Stockholders being included on an as-if-converted or as-if-exercised basis), and the Company will include in such registration (other than the Company’s initial public offering) Registrable Securities in an amount equal to a minimum of twenty-five percent (25%) of the total offering amount. In the event a Company Registration Cutback results in less than all of the Registrable Securities that are requested to be included in such registration to actually be included in such registration, then no securities held by the other Stockholders and requested to be included in the

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registration will be so included and the number of Registrable Securities that will be included in such registration shall be shared pro rata among all of the holders of Registrable Securities that were requested to be included in such registration based on the number of shares of Registrable Securities held by each holder of Registrable Securities in relation to the aggregate number of Registrable Securities.

(c) Inclusion of Securities held by other Stockholders . In addition to the rights granted pursuant to Sections 2.2(a) and (b), the other Stockholders will be entitled to receive notice of, and to participate in, registrations pursuant to Sections 2.1 and 2.5 in accordance with the procedures set forth in Section 2.2(a) and (b), subject to the limitation that such Stockholder(s) will not be entitled to include securities in such registration unless and until the full amount requested to be registered by the Investors in such registration has been included. If securities held by other Stockholders are included in a registration pursuant to this Section 2.2, references in Sections 2.3, 2.4, 2.6, 2.7 and 2.12 to “Investors” and “Registrable Securities” shall be deemed to include such Stockholders and the securities held by such Stockholders.

2.3 Expenses of Registration . All Registration Expenses incurred in connection with any registration pursuant to Sections 2.1, 2.2 and 2.5, other than the fees of counsel for any selling Stockholders (except for the fees and expenses of one counsel to the Investors, which shall be paid by the Company), shall, to the extent permitted by applicable law, be borne by the Company. All Selling Expenses relating to Registrable Securities registered by the Investors shall be borne by such Investors pro rata on the basis of the number of shares so registered.

2.4 Registration Procedures . In the case of each registration effected by the Company pursuant to this Agreement, the Company will keep each Investor advised in writing as to the initiation of each registration, qualification and compliance and as to the completion thereof. The Company will:

(a) keep such registration, qualification or compliance effective and current for a period of one hundred twenty (120) days (or such longer period as may be necessary to accommodate the filing of amendments or supplements necessary to comply with the Securities Act) or until the Investor or Investors have completed the distribution described in the registration statement relating thereto, whichever first occurs;

(b) furnish such number of prospectuses and other documents incident thereto as an Investor from time to time may reasonably request;

(c) use commercially reasonable efforts to register or qualify the securities covered by such registration statement under such other securities or blue sky laws of such jurisdictions as any seller holding of at least ten percent (10%) of the Registrable Securities then being registered reasonably requests and do any and all other acts and things which may be reasonably necessary or advisable to enable such seller to consummate the disposition in such jurisdictions of the Registrable Securities owned by such seller;

(d) in the event of any underwritten public offering, enter into and perform its obligations under an underwriting agreement, in usual and customary form, with the managing

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underwriter of such offering, and each Investor participating in such underwriting shall also enter into and perform its obligations under such an agreement;

(e) notify each Investor with Registrable Securities covered by such registration statement, at any time when a prospectus relating thereto covered by such registration statement is required to be delivered under the Securities Act, of the happening of any event as a result of which the prospectus included in such registration statement, as then in effect, includes an untrue statement of a material fact or omits to state a material fact required to be stated therein or necessary to make the statements therein not misleading in the light of the circumstances then existing and of any Commission stop orders or other material modifications in connection therewith;

(f) cause all such Registrable Securities covered by such registration statement to be listed on each securities exchange or quoted on each quotation system on which the same class of securities issued by the Company are then listed or quoted, if the listing or quotation of such Registrable Securities is then permitted under the rules and regulations of such exchange or system;

(g) provide a transfer agent and registrar for all such Registrable Securities not later than the effective date of such registration statement;

(h) enter into such customary agreements (including underwriting agreements in customary form) and take all such other actions as the Investors or the underwriters, if any, reasonably request in order to expedite or facilitate the disposition of such Registrable Securities (including effecting a stock split or a combination of shares);

(i) make available for inspection by any seller who holds ten percent (10%) or more of the Registrable Securities then being registered, any underwriter participating in any disposition pursuant to such registration statement and any attorney, accountant or other agent retained by any such seller or underwriter, all financial and other records, pertinent corporate documents and properties of the Company, and cause the Company’s officers, directors, employees and independent accountants to supply all information reasonably requested by any such seller, underwriter, attorney, accountant or agent in connection with such registration statement;

(j) otherwise use commercially reasonable efforts to comply with all applicable rules and regulations of the Commission, and make available to its security holders, as soon as reasonably practicable, an earnings statement covering the period of at least twelve (12) months beginning with the first day of the Company’s first full calendar quarter after the effective date of the registration statement, which earnings statement shall satisfy the provisions of Section 11(a) of the Securities Act and Rule 158 thereunder;

(k) permit any Investor which, in its reasonable judgment, might be deemed to be an underwriter or a controlling Person of the Company, to participate in the preparation of such registration or comparable statement and to require the insertion therein of material furnished to the Company in writing, which in the reasonable judgment of such Investors and their counsel should be included;

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(l) in the event of the issuance of any stop order suspending the effectiveness of a registration statement, or of any order suspending or preventing the use of any related prospectus or suspending the qualification of any Registrable Securities included in such registration statement for sale in any jurisdiction, the Company shall use commercially reasonable efforts promptly to obtain the withdrawal of such order;

(m) use commercially reasonable efforts to cause such Registrable Securities covered by such registration statement to be registered with or approved by such other governmental agencies or authorities as may be necessary to enable the sellers thereof to consummate the disposition of such Registrable Securities; and

(n) obtain a comfort letter from the Company’s independent accountants in customary form and covering such matters of the type customarily covered by comfort letters as the Company may reasonably request.

2.5 Registration on Form S-3 . In addition to the rights set forth in Sections 2.1 and 2.2, if one or more Investors request that the Company file a registration statement on Form S-3 (or any successor form to Form S-3) for a public offering of shares of Registrable Securities, and the Company is a registrant entitled to use Form S-3 to register the Registrable Securities for such an offering, the Company shall use its best efforts to cause such shares to be registered for the offering as soon as practicable on Form S-3 (or any successor form to Form S-3). The procedures and other limitations for effecting the registration of the Registrable Securities on Form S-3 (or any successor form to Form S-3), including the procedure used for any underwriting limitation, shall be as set forth in Section 2.2 above; provided , however , that (i) not more than two (2) registrations may be requested by Investors on Form S-3 (or any successor form to Form S-3) in any calendar year and (ii) the Company shall not be obligated to effect a registration under this Section 2.5 if the minimum estimated dollar value of any offering of Registrable Securities pursuant to this Section 2.5 is less than $3,000,000.

2.6 Indemnification .

(a) The Company will indemnify each Investor, each of its officers and directors and partners and such Investor’s legal counsel and independent accountants, and each Person controlling any such Persons within the meaning of Section 15 of the Securities Act, with respect to any registration, qualification or compliance that has been effected pursuant to this Agreement, and each underwriter, if any, and each Person who controls any underwriter within the meaning of Section 15 of the Securities Act, against all expenses, claims, losses, damages and liabilities (or actions in respect thereof), including any of the foregoing incurred in the investigation or settlement of any litigation, commenced or threatened, arising out of or based on any untrue statement (or alleged untrue statement) of a material fact contained in any registration statement, prospectus, offering circular or other document, or any amendment or supplement thereto, incident to any such registration, qualification or compliance, or based on any omission (or alleged omission) to state therein a material fact required to be stated therein or necessary to make the statements therein, not misleading, or any violation by the Company of any rule or regulation promulgated under the Securities Act or any state securities laws applicable to the Company and relating to action or inaction required of the Company in connection with any such registration, qualification or compliance, and will reimburse each such Investor, each of its

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officers and directors and such Investor’s legal counsel and independent accountants, and each Person controlling any such Persons, each such underwriter and each Person who controls any such underwriter, for any legal and any other expenses reasonably incurred in connection with investigating, preparing or defending any such claim, loss, damage, liability or action, provided that the Company will not be liable in any such case to the extent that any such claim, loss, damage, liability or expense arises out of or is based on any untrue statement or omission or alleged untrue statement or omission, made in reliance upon and in conformity with written information furnished to the Company by an instrument duly executed by such Investor or underwriter and stated to be specifically for use therein.

(b) Each Investor will, if Registrable Securities held by such Investor are included in the securities as to which such registration is being effected, indemnify the Company, each of its directors and officers and its legal counsel and independent accountants, each underwriter, if any, of the Company’s securities covered by such a registration statement, each Person who controls the Company or such underwriter within the meaning of Section 15 of the Securities Act, and each other such Investor, each of its officers and directors, and each Person controlling such Investor within the meaning of Section 15 of the Securities Act, with respect to any registration, qualification or compliance that has been effected pursuant to this Agreement, against all claims, losses, damages and liabilities (or actions in respect thereof), including any of the foregoing incurred in the investigation or settlement of any litigation, commenced or threatened, arising out of or based on any untrue statement (or alleged untrue statement) of a material fact contained in any such registration statement, prospectus, offering circular or other document, or any amendment or supplement thereto, or any omission (or alleged omission) to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, and will reimburse the Company, such other Investors, and such directors, officers, legal counsel, independent accountants, underwriters or control Persons of the Company or any other Investor for any legal or any other expenses reasonably incurred in connection with investigating or defending any such claim, loss, damage, liability or action, in each case to the extent, but only to the extent, that such untrue statement (or alleged untrue statement) or omission (or alleged omission) is made in, or omitted from, as the case may be, such registration statement, prospectus, offering circular or other document in reliance upon and in conformity with information furnished to the Company by such Investor and stated to be specifically for use therein; provided, however, that the obligation of such Investor hereunder shall be limited to an amount equal to the proceeds received by such Investor upon the sale of the Registrable Securities sold in the offering covered by such registration.

(c) Each party entitled to indemnification under this Section 2.6 (the “ Indemnified Party ”) shall give notice to the party required to provide indemnification (the “ Indemnifying Party ”) promptly after such Indemnified Party has actual knowledge of any claim as to which indemnity may be sought, and shall permit the Indemnifying Party to assume the defense of any such claim or any litigation resulting therefrom, provided that counsel for the Indemnifying Party, who shall conduct the defense of such claim or litigation, shall be approved by the Indemnified Party (whose approval shall not unreasonably be withheld). The Indemnified Party may participate in such defense at such party’s expense; provided, however, that the Indemnifying Party shall bear the expense of such defense of the Indemnified Party if representation of both parties by the same counsel would be inappropriate due to actual conflicts of interest (as determined in good faith by the Indemnified Party). The failure of any

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Indemnified Party to give notice as provided herein shall not relieve the Indemnifying Party of its obligations under this Agreement unless the failure to do so materially prejudices the Indemnifying Party. No Indemnifying Party, in the defense of any such claim or litigation, shall, except with the consent of each Indemnified Party, consent to entry of any judgment or enter into any settlement which does not include as an unconditional term thereof the giving by the claimant or plaintiff to such Indemnified Party of a release from all liability in respect to such claim or litigation.

(d) The obligations of the Company and Investors under this Section 2.6 shall survive the completion of any offering of Registrable Securities under this Agreement.

(e) An Indemnifying Party shall make payment in satisfaction of its obligations under this Section 2.6 within thirty (30) days upon receiving written confirmation from the Indemnified Party of the nature and amount of the expenses to be indemnified.

(f) If the indemnification provided for in this Section 2.6 is unavailable or insufficient to hold harmless an Indemnified Party, then each Indemnifying Party shall contribute to the amount paid or payable to such Indemnified Party as a result of the losses, claims, damages or liabilities referred to in this Section 2.6 an amount or additional amount, as the case may be, in such proportion as is appropriate to reflect the relative fault of the Indemnifying Party or parties on the one hand and the Indemnified Party on the other in connection with the statements or omissions which resulted in such losses, claims, demands or liabilities as well as any other relevant equitable considerations. The relative fault shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by the Indemnifying Party or parties on the one hand or the Indemnified Party on the other and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such untrue statement or omission. The amount paid to an Indemnified Party as a result of the losses, claims, damages or liabilities referred to in the first sentence of this Section 2.6(f) shall be deemed to include any legal or other expenses reasonably incurred by such Indemnified Party in connection with investigating or defending any action or claim which is the subject of this Section 2.6. No Person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act) shall be entitled to contribution from any Person who was not guilty of such fraudulent misrepresentation.

(g) The indemnification provided for under this Agreement shall remain in full force and effect regardless of any investigation made by or on behalf of the Indemnified Party or any officer, director or controlling Person of such Indemnified Party and shall survive the transfer of s