STOCK PURCHASE AGREEMENT

EXHIBIT 99.1

STOCK PURCHASE AGREEMENT

among

ABBOTT LABORATORIES,

and

SELLERS PARTY HERETO

Dated as of November 5, 2006

TABLE OF CONTENTS

     -i-     

     -ii-     

     -iii-     

Defined Terms Cross-Reference Table

     -iv     

STOCK PURCHASE AGREEMENT

     STOCK PURCHASE AGREEMENT, dated as of November 5, 2006 (this “ Agreement ”), among ABBOTT LABORATORIES, an Illinois corporation (“ Acquiror ”), and Michael Jaharis, Kathryn Jaharis, Steven Jaharis, Daniel Bell and Steven K. Aronoff (each a “ Seller ” and collectively, “ Sellers ”). Capitalized terms used but not defined herein shall have the meanings given to such terms in the Merger Agreement.

     WHEREAS, Sellers legally and beneficially own all the issued and outstanding shares of common stock, par value $0.01 per share (the “ Shares ”), of Kos Investments, Inc., a Delaware corporation (“ Kos Investments ”);

     WHEREAS, Kos Investments legally and beneficially owns all of the issued and outstanding capital stock of Kos Holdings, Inc., a Delaware corporation (“ Kos Holdings ”);

     WHEREAS, Kos Investments, directly or indirectly through Kos Holdings legally and beneficially owns 8,570,069 shares of common stock, par value $0.01 per share (the “ Company Common Stock ”), of Kos Pharmaceuticals, Inc., a Florida corporation (the “ Company ”);

     WHEREAS, Acquiror, S&G Nutritionals, Inc., a direct wholly-owned subsidiary of Acquiror (“ Merger Sub ”), and the Company are, concurrently with the execution and delivery of this Agreement, entering into an Agreement and Plan of Merger dated the date hereof (the “ Merger Agreement ”);

     WHEREAS, Acquiror and certain shareholders of the Company (collectively, the “ Jaharis Family ”) are, concurrently with the execution and delivery of the Merger Agreement, entering into a Shareholders Agreement dated the date hereof (the “ Shareholders Agreement ”); and

     WHEREAS, as a condition to their willingness to enter into the Shareholders Agreement, the Jaharis Family has requested that Acquiror enter into this Agreement with Sellers pursuant to which Acquiror shall purchase the Shares subject to the terms and conditions hereof (such purchase and sale of the Shares is referred to in this Agreement as the “ Acquisition ”), which Acquisition is intended to be consummated immediately subsequent to the consummation of the Offer.

     NOW, THEREFORE, in consideration of the foregoing and the mutual covenants, agreements and representations herein contained, and intending to be legally bound hereby, the parties hereto hereby agree as follows:

ARTICLE I

Purchase and Sale of Shares; Closing

          SECTION 1.01. Purchase and Sale of the Shares . On the terms and subject to the conditions of this Agreement, at the Closing, each Seller shall sell, transfer and deliver to Acquiror, and Acquiror shall purchase from such Seller, the Shares owned by such Seller free and clear of all Liens for a purchase price to such Seller (with respect to each such Seller, the “ Purchase Price ”), in cash, without interest, equal to the product of (a) the Closing Payment and (b) the Pro Rata Portion of such Seller.

          SECTION 1.02. Closing . Subject to the provisions of Article V, the closing (the “ Closing ”) of the Acquisition shall take place at the offices of Cravath, Swaine & Moore LLP, 825 Eighth Avenue, New York, New York 10019, on the date of payment by Acquiror for shares of Company Common Stock tendered pursuant to the Offer, or if the conditions set forth in Article V are not satisfied or waived at such time, as soon as practicable thereafter. The date on which the Closing occurs is referred to in this Agreement as the “ Closing Date ”.

          SECTION 1.03. Escrow . Simultaneously with the execution of this Agreement, (x) Acquiror, each Seller and an escrow agent to be mutually agreed (the “ Escrow Agent ”) shall enter into an Escrow Agreement in the form attached hereto as Exhibit A (the “ Escrow Agreement ”) and (y) each Seller shall (and Sellers shall cause Kos Investments and Kos Holdings to) deposit with the Escrow Agent (collectively, the “ Share Certificates ”) (i) certificates representing the Shares owned by Sellers, which certificates shall be duly endorsed in blank or accompanied by stock powers duly endorsed in blank in proper form for transfer, with appropriate transfer tax stamps, if any, affixed, (ii) certificates representing all of the issued and outstanding capital stock of Kos Holdings and (iii) certificates representing the 5,960,069 shares of Company Common Stock directly or indirectly owned by Kos Investments.

          SECTION 1.04. Transactions To Be Effected at the Closing; Payment of Purchase Price .

          (a) At or prior to noon (New York City time) on the Expiration Date, Sellers shall deliver (or caused to be delivered) (i) to Acquiror (x) each Seller’s Closing Certificate, (y) the Resignation Letters and (z) the Payoff Letters and (ii) to Acquiror and the Escrow Agent, the Closing Payment Certificate.

          (b) Pursuant to the Escrow Agreement, upon receipt by the Escrow Agent of a notice that the Offer has been consummated and that payment of the Purchase Price has been received by the Sellers, the Escrow Agent shall release and deliver the Share Certificates to Acquiror.

          (c) The Acquiror and the Sellers shall give effect to the arrangements negotiated between them prior to the closing for the payment to Wachovia Bank N.A. of the aggregate amount of all indebtedness of Kos Investments to Wachovia Bank N.A. (as reflected

on the Payoff Closing Certificate) and the termination and release of any pledge or other security interests in favor of Wachovia Bank N.A. (or its affiliates) encumbering shares of Company Common Stock held directly or indirectly by Kos Investments.

ARTICLE II

Representations and Warranties of Sellers

     Except as set forth in the corresponding sections or subsections of the disclosure letter delivered to Acquiror by Sellers on the date hereof (the “ Disclosure Schedule ”) (it being understood that each item in a particular section of the Disclosure Schedule applies only to such section and to any other section to which its relevance is readily apparent), each Seller hereby jointly and severally represents and warrants to Acquiror that as of the date hereof and as of the Closing Date, except to the extent such representations and warranties relate to an earlier date (in which case such representations and warranties are made as of such earlier date):

          SECTION 2.01. Execution and Delivery; Enforceability . Each Seller has the legal capacity to execute and deliver this Agreement and to consummate the transactions contemplated hereby. Each of the persons executing this Agreement on behalf of each Seller has full power and authority to execute and deliver this Agreement on behalf of such Seller and to thereby bind such Seller. The execution and delivery of this Agreement and the consummation of the transactions contemplated hereby have been duly authorized by all necessary action on the part of each Seller. This Agreement has been duly executed and delivered by each Seller and constitutes its valid and binding obligation, enforceable against it in accordance with its terms (except as enforceability may be limited by applicable bankruptcy, insolvency, reorganization, moratorium or other laws affecting creditors’ rights generally and general equity principles). If a Seller is married and the Shares set forth below such Seller’s signature to this Agreement constitute community property under applicable laws, this Agreement has been duly authorized, executed and delivered by, and constitutes the valid and binding agreement of, such Seller’s spouse.

          SECTION 2.02. No Conflicts; Consents .

          (a) Except as set forth in Section 2.02(a) of the Disclosure Schedule, the execution, delivery and performance of this Agreement by each Seller does not and will not (i) conflict with or violate the articles of incorporation or bylaws of Kos Investments or Kos Holdings, (ii) assuming that all applicable requirements under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended (the “ HSR Act ”), and the Securities Exchange Act of 1934, as amended (the “ Exchange Act ”), have been satisfied, conflict with or violate any federal, state, local or foreign statute, law, ordinance, rule, regulation, order, judgment, decree or legal requirement (“ Law ”) applicable to the Sellers, Kos Investments or Kos Holdings or by which any of their respective properties are bound or (iii) (A) result in any breach or violation of or constitute a default (or an event which with notice or lapse of time or both would become a default), or (B) result in the loss of a benefit under, or give rise to any right of termination, cancellation, amendment or acceleration of, or (C) result in the creation of any Lien on any of the

Shares or any other properties or assets of any Seller, Kos Investments or Kos Holdings under, any Contract to which any Seller, Kos Investments or Kos Holdings is a party or by which and Seller, Kos Investments or Kos Holdings or any of their respective properties are bound.

          (b) Except pursuant to the applicable requirements under the HSR Act and the Exchange Act, no consent, approval, authorization or permit of, action by, filing with or notification to, any federal, state, local or foreign governmental or regulatory (including stock exchange) authority, agency, court, commission, or other governmental body (a “ Governmental Entity ”) or any other person (including with respect to individuals, any spouse, and with respect to trusts, any co-trustee or beneficiary) is required to be obtained or made by Sellers, Kos Investments or Kos Holdings in connection with the execution, delivery and performance of this Agreement or the consummation of the transactions contemplated hereby.

          SECTION 2.03. The Shares . Except as set forth in Section 2.03 of the Disclosure Schedule, each Seller owns and has good and valid title to the number of Shares set forth below such Seller’s signature to this Agreement, free and clear of all Liens other than Permitted Liens. Assuming Acquiror has the requisite power and authority to be the lawful owner of the Shares, upon delivery to Acquiror at the Closing of certificates representing the Shares owned by Seller, duly endorsed by Seller for transfer to Acquiror, and upon Seller’s receipt of the applicable portion of the Closing Payment, good and valid title to such Shares will pass to Acquiror, free and clear of any Liens, other than those arising from acts of Acquiror or its Affiliates. Other than this Agreement, the Shares are not subject to any voting trust agreement or other Contract, including any Contract restricting or otherwise relating to the voting, dividend rights or disposition of the Shares, and no proxies with respect to the Shares have been granted by Sellers.

          SECTION 2.04. Organization, Standing and Power . Each of Kos Investments and Kos Holdings is duly organized, validly existing and in good standing under the laws of Delaware and has all requisite corporate power and authority to own the Assets. Sellers have delivered to Acquiror true and complete copies of the certificate of incorporation and by-laws of Kos Investments and Kos Holdings, in each case as amended through the date of this Agreement.

          SECTION 2.05. Assets .

          (a) Kos Investments owns and has good and valid title to (i) 960,069 shares of Company Common Stock and (ii) all of the issued and outstanding capital stock of Kos Holdings, in each case, free and clear of all Liens other than as set forth in Section 2.05(a) of the Disclosure Schedule.

          (b) Kos Holdings owns and has good and valid title to 7,610,000 shares of Company Common Stock, free and clear of all Liens other than as set forth in Section 2.05(b) of the Disclosure Schedule.

          (c) Except for (i) 960,069 shares of Company Common Stock owned by Kos Investments, (ii) the shares of Kos Holdings owned by Kos Investments and (iii) 7,610,000

shares of Company Common Stock owned by Kos Holdings (collectively, the “ Assets”) , neither Kos Investments nor Kos Holdings (A) owns, directly or indirectly, any capital stock, partnership interest, limited liability company interest, joint venture interest or any other equity in any person or any other asset or (B) has since January 1, 1999, directly or indirectly owned any other asset, in each case except as set forth in Section 2.05(c) of the Disclosure Schedule. Other than the Merger Agreement, the Shareholders Agreement and the other agreement set forth in Section 2.05(c) of the Disclosure Schedule, the Assets are not subject to any voting trust agreement or other Contract, including any Contract restricting or otherwise relating to the voting, dividend rights or disposition of the Assets, and no proxies have been granted in respect of the Assets.

          SECTION 2.06. Capitalization of Kos Investments and Kos Holdings .

          (a) The authorized capital stock of Kos Investments consists of 50,000 shares of common stock, par value $0.01 per share, of which only 27,200 shares, constituting the Shares, are issued and outstanding. All of the Shares were validly issued, fully paid and nonassessable and were issued free of preemptive rights and in accordance with all applicable Laws.

          (b) Except as set forth in clause (a) of this Section 2.06 or as set forth in Section 2.06(b) of the Disclosure Schedules, (i) there are not outstanding or authorized any (A) shares of capital stock or other voting securities of Kos Investments, (B) securities of Kos Investments convertible into or exchangeable for shares of capital stock or voting securities of Kos Investments or (C) options or other rights to acquire from Kos Investments, or any obligation of Kos Investments to issue, any capital stock, voting securities or securities convertible into or exchangeable for capital stock or voting securities of Kos Investments; and (ii) there are no other options, calls, warrants or other rights, agreements, arrangements or commitments of any character relating to the issued or unissued capital stock or other voting securities of Kos Investments to which Kos Investments or any Seller is a party.

          (c) The authorized capital stock of Kos Holdings consists of 50,000 shares of common stock, par value $0.01 per share, of which only 10,000 shares are issued and outstanding. All of the shares of Kos Holdings were validly issued, fully paid and nonassessable, were issued free of preemptive rights and are owned beneficially and of record by Kos Investments.

          (d) Except as set forth in clause (c) of this Section 2.06, (i) there are not outstanding or authorized any (A) shares of capital stock or other voting securities of Kos Holdings, (B) securities of Kos Holdings convertible into or exchangeable for shares of capital stock or voting securities of Kos Holdings or (C) options or other rights to acquire from Kos Holdings, or any obligation of Kos Holdings to issue, any capital stock, voting securities or securities convertible into or exchangeable for capital stock or voting securities of Kos Holdings; and (ii) there are no other options, calls, warrants or other rights, agreements, arrangements or commitments of any character relating to the issued or unissued capital stock or other voting securities of Kos Holdings to which Kos Holdings, Kos Investments or any Seller is a party.

          SECTION 2.07. Taxes . Except as set forth in Section 2.07 of the Disclosure Schedules, since July 1, 1997 (i) all Tax Returns required to be filed by or with respect to Kos Investments and Kos Holdings have been timely filed and such Tax Returns are true, correct and complete in all material respects, (ii) all Taxes of Kos Investments and Kos Holdings that are due and payable have been paid, (iii) since July 1, 1997, neither Kos Investments nor Kos Holdings has received written notice of any Proceeding against or audit of, or with respect to, any Taxes of Kos Investments or Kos Holdings that has not been finally resolved, (iv) there are no liens for Taxes (other than statutory liens for Taxes not yet due and payable) upon any of the assets of Kos Investments or Kos Holdings, (v) since July 1, 1997, neither Kos Investments nor Kos Holdings has been a “distributing corporation” or a “controlled corporation” in a distribution intended to qualify under Section 355(a) of the Code or otherwise as part of a “plan (or series of related transactions)” (within the meaning of Section 355(e) of the Code) of which the Merger is also a part, (vi) neither Kos Investments nor Kos Holdings is a party to or is bound by any Tax sharing, allocation or indemnification agreement or arrangement (other than solely between Kos Investments and Kos Holdings), (vii) for any period beginning on or after July 1, 1997, neither Kos Investments nor Kos Holdings (A) has been a member of a group filing a consolidated, combined or unitary Tax Return (other than a group consisting solely of Kos Investments and Kos Holdings or (B) has any liability for the Taxes of any person under Treasury regulation section 1.1502-6 (or any similar provision of state, local or foreign Law), (viii) Kos Investments is an S corporation as defined in Section 1361 of the Code and has been since July 1, 1997, Kos Holdings is a qualified subchapter S subsidiary as defined in Section 1361(b)(3)(B) of the Code and has been since July 1, 1997, (ix) neither Kos Investments nor Kos Holdings has been a party to a transaction that, as of the date of this Agreement, constitutes a “reportable transaction” for purposes of Section 6011 of the Code and applicable Treasury regulations thereunder (or a similar provision of state Law), (x) Kos Investments and Kos Holdings have properly and timely withheld all Taxes required to be withheld, and properly remitted to the applicable Taxing Authorities all Taxes required to be remitted for, with respect to amounts paid or owed to any employee, independent contractor, stockholder or other party , and (xi) neither Kos Investments nor Kos Holdings will be required to include in a taxable period ending after the Closing Date taxable income attributable to income that accrued in a prior taxable period (or portion of a taxable period) but was not recognized for tax purposes in any prior taxable period as a result of (A) a disposition by Kos Investments, nor Kos Holdings made by on or before the Closing Date that was accounted for as an “open transaction”, (B) a prepaid amount received on or prior to the Closing Date, (C) the installment method of accounting, (D) the completed contract method of accounting, (E) the long-term contract method of accounting, (F) the cash method of accounting or Section 481 of the Code or (G) any comparable provisions of state, local, or foreign tax law.

          SECTION 2.08. Accounts; Safe Deposit Boxes; Powers of Attorney; Officers and Directors . Section 2.08 of the Disclosure Schedule sets forth (i) a true and correct list of all bank and savings accounts, certificates of deposit and safe deposit boxes of Kos Investments and Kos Holdings and those persons authorized to sign thereon, (ii) a true and correct list of all powers of attorney granted by Kos Investments or Kos Holdings and those persons authorized to act thereunder and (iii) a true and correct list of all officers and directors of Kos Investments and Kos Holdings.

          SECTION 2.09. Brokers; Schedule of Fees and Expenses . Except as set forth in Section 2.09 of the Disclosure Schedule, no broker, finder or investment banker is entitled to any brokerage, finder’s or other fee or commission in connection with the Acquisition and the other transactions contemplated by the Merger Agreement based upon arrangements made by or on behalf of or with respect to Kos Investments or Kos Holdings.

          SECTION 2.10. Private Offering . None of the Sellers, Kos Investments, Kos Holdings, their affiliates and their representatives has issued, sold or offered any security of Kos Investments or Kos Holdings to any person under circumstances that would cause the sale of the Shares, as contemplated by this Agreement, to be subject to the registration requirements of the Securities Act. None of the Sellers, Kos Investments, Kos Holdings, their affiliates and their representatives will offer the Shares or any part thereof or any similar securities for issuance or sale to, or solicit any offer to acquire any of the same from, anyone so as to make the issuance and sale of the Shares subject to the registration requirements of Section 5 of the Securities Act. Assuming the representations of Acquiror contained in Section 3.04 are true and correct, the sale and delivery of the Shares hereunder are exempt from the registration and prospectus delivery requirements of the Securities Act.

          SECTION 2.11. Information . None of the information relating to Kos Investments, Kos Holdings or the Sellers provided by or on behalf of the Sellers for inclusion in the Offer Documents, the Schedule 14D-9 or any Proxy Statement will, at the respective times such documents are filed with the SEC or are first published, sent or given to shareholders of the Company, contain any untrue statement of material fact or omit to state any material fact required to be stated therein or necessary in order to make the statements therein, in light of the circumstances under which they were made, not misleading.

          SECTION 2.12. Reliance . Sellers understand and acknowledge that Acquiror is entering into the Merger Agreement and the Shareholders Agreement in reliance upon the Sellers’ execution and delivery of this Agreement.

ARTICLE III

Representations and Warranties Relating to Acquiror

     Acquiror represents and warrants to Sellers that:

          SECTION 3.01. Organization, Standing and Power . Acquiror is a corporation duly organized, validly existing and in good standing or active status under the laws of the jurisdiction in which it is incorporated and has all requisite corporate power and authority to own, operate and lease its properties and to carry on its business as it is now being conducted. Acquiror is duly qualified or licensed to do business, and is in good standing, in each jurisdiction where the character of the properties owned, leased or operated by it or the nature of its activities makes such qualification or licensing necessary.

          SECTION 3.02. Authority; Execution and Delivery; Enforceability . Acquiror has all requisite power and authority to execute and deliver this Agreement and to consummate the transactions contemplated hereby. The execution and delivery by Acquiror of this Agreement and the consummation by it of the transactions contemplated hereby have been duly authorized by all necessary action of Acquiror, and no other corporate proceedings on the part of Acquiror are necessary to authorize this Agreement, to perform its obligations hereunder, or to consummate the transactions contemplated hereby. Neither the approval or adoption of this Agreement nor the consummation of the transactions contemplated hereby requires any approval of the shareholders of Acquiror. This Agreement has been duly executed and delivered by Acquiror and constitutes its valid and binding obligation, enforceable against it in accordance with its terms (except as enforceability may be limited by applicable bankruptcy, insolvency, reorganization, moratorium or other laws affecting creditors’ rights generally and general equity principles).

          SECTION 3.03. No Conflicts; Consents .

          (a) The execution, delivery and performance of this Agreement by Acquiror does not and will not (i) conflict with or violate the articles of incorporation or bylaws of Acquiror, (ii) assuming that all applicable requirements under the HSR Act and the Exchange Act have been satisfied, conflict with or violate any Law applicable to Acquiror or by which any of its properties are bound or (iii) (A) result in any breach or violation of or constitute a default (or an event which with notice or lapse of time or both would become a default), or (B) result in the loss of a benefit under, or give rise to any right of termination, cancellation, amendment or acceleration of, or (C) result in the creation of any Lien on any of the properties or assets of Acquiror under, any Contract to which Acquiror or its subsidiaries is a party or by which Acquiror or its subsidiaries or any of their respective properties are bound.

          (b) Except pursuant to applicable requirements under the HSR Act and the Exchange Act, no consent, approval, authorization or permit of, action by, filing with or notification to, any Governmental Entity is required to be obtained or made by Acquiror in connection with the execution, delivery and performance of this Agreement or the consummation of the transactions contemplated hereby.

          SECTION 3.04. Securities Act . Acquiror is an Accredited Investor, as defined in Regulation 501 under the Securities Act. The Shares purchased by Acquiror pursuant to this Agreement are being acquired for investment only and not with a view to any public distribution thereof, and Acquiror shall not offer to sell or otherwise dispose of the Shares so acquired by it in violation of any of the registration requirements of the Securities Act.

          SECTION 3.05. Available Funds . Acquiror has sufficient funds to (i) consummate the Acquisition, (ii) pay the applicable Purchase Price to each Seller and (iii) pay any and all fees and expenses incurred by Acquiror in connection with the Acquisition or the financing thereof.

          SECTION 3.06. No Other Representations . Acquiror is not relying on any statement or representation made by or on behalf of Sellers with respect to its acquisition of the Shares other than the representations made in this Agreement.

ARTICLE IV

Covenants and Agreements

          SECTION 4.01. Covenants Relating to Conduct of Business . Sellers covenant and agree that, during the period from the date hereof until the Closing or earlier termination of this Agreement, neither Kos Investments nor Kos Holdings shall (and Sellers shall cause neither of Kos Investments nor Kos Holdings to) (i) acquire any additional assets or (ii) carry on any business or conduct any operations other than (A) those actions incidental to holding the Assets that are consistent with past practice and (B) performing its obligations under, and consummating the transactions contemplated by, this Agreement (including engaging counsel and other advisors the fees of which will be paid by Sellers) and repaying or causing to be repaid the following indebtedness: (a) a $75,000,000 line of credit between Kos Investments and Wachovia Bank N.A. (on which approximately $60,000,000 is outstanding as of the date hereof) and (b) a $25,000,000 Promissory Note dated August 2, 2006 between Kos Investments and Mary Jaharis. Without limiting the generality of the foregoing, between the date of this Agreement and the Closing, Sellers covenant and agree that none of Sellers shall, and Sellers shall cause Kos Investments or Kos Holdings to not, without the prior written consent of Acquiror:

          (a) amend or otherwise change the articles of incorporation or bylaws or any similar governing instruments of Kos Investments or Kos Holdings;

          (b) issue, deliver, sell, pledge, dispose of or encumber (whether by merger or otherwise by operation of law) any shares of capital stock, voting securities, or other equity interests, or any options, warrants, convertible securities or other rights of any kind to acquire or receive any shares of capital stock, voting securities, or other equity interests, of Kos Investments or Kos Holdings;

          (c) adjust, recapitalize, reclassify, combine, split, subdivide, redeem, purchase or otherwise acquire any shares of capital stock of Kos Investments or Kos Holdings;

          (d) in the case of Kos Investments and Kos Holdings only (i) enter into any business or (ii) make any capital contribution or investment in any other person;

          (e) (i) grant any proxies or enter into a voting trust or other agreement or arrangement with respect to the voting of any of the Assets or (ii) Transfer, grant a Lien on, or enter into any Contract, option or other arrangement or understanding with respect to any Transfer (whether by actual disposition or effective economic disposition) of any of the Assets or any rights thereto or therein;

          (f) in the case of Kos Investments or Kos Holdings only, acquire any asset, or enter into, modify or amend any Contract (other than in accordance with Section 4.02);

          (g) in the case of Kos Investments or Kos Holdings only, incur any indebtedness or other liability that will not be discharged at Closing;

          (h) in the case of or with respect to Kos Investments or Kos Holdings only, (i) make, change or revoke any material Tax election or, except as required by applicable Law, change any method of Tax accounting, (ii) enter into any settlement or compromise of any material Tax liability, (iii) file any amended Tax Return with respect to any material Tax, (iv) change any annual Tax accounting period, (v) enter into any closing agreement relating to any material Tax, (vi) claim or surrender any right to claim a material Tax refund or (vii) become a party to a transaction that constitutes a “reportable transaction” for purposes of Section 6011 of the Code and applicable Treasury regulations thereunder (or a similar provision of state Law); or

          (i) commit or agree to take any of the actions described in Sections 4.01(a) through 4.01(g).

          SECTION 4.02. Contracts; Affiliate Transactions; Powers of Attorney . On or prior to the Closing Date, Sellers shall cause to be terminated, effective no later than the Closing, (a) all Contracts between Kos Investments or Kos Holdings, on the one hand, and any other person (including any Seller or any of their respective Affiliates), on the other hand, (other than this Agreement), (b) any interest any Seller or any of its Affiliates has in any asset (real or personal, tangible or intangible) (including the Assets) or Contract of Kos Investments or Kos Holdings and (c) all powers of attorney to any person granted by Kos Investments or Kos Holdings. Sellers shall cause the Stockholder’s Agreement dated as of July 1, 1988 among Kos Investments and the Sellers to be terminated effective as of the Closing Date.

          SECTION 4.03. Access to Information; Confidentiality . (a) From the date hereof to the Closing or the earlier termination of this Agreement, upon reasonable prior written notice, Sellers shall cause Kos Investments and Kos Holdings to afford the officers, employees, auditors and representatives of Acquiror reasonable access, consistent with applicable Law, at all reasonable times to all books and records, all officers, directors, representatives, properties, and to all books and records of Kos Investments and Kos Holdings, and shall furnish Acquiror with all financial and other data and information as Acquiror, through its officers, employees or authorized representatives, may from time to time reasonably request in writing. Neither Kos Investments nor Kos Holdings shall be required to provide access to or to disclose information where such access or disclosure would jeopardize the attorney-client privilege of Kos Investments or Kos Holdings or contravene any Law. No investigation pursuant to this Section 4.03 or otherwise shall affect any representation or warranty in this Agreement or any condition to the obligations of the parties hereto.

          (b) Acquiror will hold and treat and will cause its officers, employees, auditors and other authorized representatives to hold and treat in confidence all documents and information concerning Kos Investments or Kos Holdings or its shareholders furnished to

Acquiror in connection with the transactions contemplated by this Agreement in accordance with the Confidentiality Agreement, dated September 26, 2006, between the Kos Investments, Kos Holdings, Oikos Ventures LLC and Acquiror (the “ Confidentiality Agreement ”).

          SECTION 4.04. Further Action; Efforts . Subject to the terms and conditions of this Agreement, each party will use reasonable best efforts to take, or cause to be taken, all actions and to do, or cause to be done, all things necessary, proper or advisable under applicable laws and regulations to consummate the Acquisition and the other transactions contemplated by this Agreement as promptly as practicable and no party hereto shall take or cause to be taken any action which would reasonably be expected to prevent, impede or delay the consummation of the Acquisition; provided that this covenant shall not expand, limit or otherwise affect the rights and obligations of any party or any of its Affiliates under the Merger Agreement, the Shareholders Agreement or pursuant to the Offer.

          SECTION 4.05. Fees and Expenses . Except as expressly set forth herein, all fees and expenses incurred in connection with the Acquisition and the other transactions contemplated hereby shall be paid by the party incurring such fees or expenses, whether or not the Acquisition is consummated; provided that all such fees and expenses of either Kos Investments or Kos Holdings which have not been paid at or prior to the Closing shall be for the account of Sellers who jointly and severally agree to pay such fees and expenses when due.

          SECTION 4.06. Public Announcements . Each of Acquiror, on the one hand, and Sellers (on their own behalf and on behalf of Kos Investments and Kos Holdings), on the other hand, agrees that no public release or announcement concerning the Acquisition or the other transactions contemplated hereby shall be issued by any party without the prior written consent of Kos Investments and Acquiror (which consent shall not be unreasonably withheld or delayed), except as such release or announcement may be required by Law or the rules or regulations of any applicable Governmental Entity to which the relevant party is subject, wherever situated, in which case the party required to make the release or announcement shall use its reasonable best efforts to allow each other party reasonable time to comment on such release or announcement in advance of such issuance, it being understood that the final form and content of any such release or announcement, to the extent so required, shall be at the final discretion of the disclosing party.

          SECTION 4.07. Preparation and Filing of Tax Returns .

          (a) Sellers shall prepare and timely file or shall cause to be prepared and timely filed all Federal, state, local and foreign Tax Returns in respect of Kos Investments and Kos Holdings, their assets or activities that are required to be filed taking into account any applicable extensions on or before the Closing Date. Sellers shall prepare or cause to be prepared and Acquiror shall file or cause to be filed all federal, state, local and foreign Tax Returns in respect of Kos Investments and Kos Holdings, their assets or activities that are required to be filed after the Closing Date and are with respect to any Tax period ending on or before the Closing Date. Sellers shall permit Acquiror to review and comment on all such Tax Returns prepared by Sellers. Acquiror shall prepare or cause to be prepared and shall file or

cause to be filed all other Tax Returns required of Kos Investments and Kos Holdings for any Tax period that includes and ends after the Closing Date.

          (b) To the extent permitted by applicable Law, all federal, state and local income Tax Returns of Kos Investments and Kos Holdings shall be filed on the basis that (i) their taxable year ends at the end of the day before the Closing Date and (ii) there was a closing of books at such time under Section 1362(e)(3) of the Code.

          (c) No election under Section 338(h)(10) of the Code shall be made with respect to the stock of Kos Investments.

          SECTION 4.08. Amended Tax Returns for Preclosing Periods . Acquiror shall, at Sellers’ reasonable request, file amended Tax Returns for any period before the Closing Date and shall not amend any such Tax Returns without Sellers’ consent.

          SECTION 4.09. Tax Cooperation . Each of Acquiror and Sellers shall provide the other party with such information and records and make such of its officers, directors, employees and agents available as may reasonably be requested by such other party in connection with the preparation of any Tax Return or any audit or other proceeding that relates to Kos Investments or Kos Holdings. Acquiror shall deliver to Sellers by the earlier to occur of 60 days after the end of Sellers’ taxable year-end for the year in which the Closing Date occurs, and 120 days after the Closing Date, a tax work paper preparation package or packages necessary to enable Sellers to prepare Tax Returns Sellers are obligated to prepare or cause to be prepared.

          SECTION 4.10. Post-closing Cooperation . After the Closing, upon reasonable written notice, Sellers and Acquiror shall furnish or cause to be furnished to each other and their Affiliates and their respective employees, counsel, auditors and representatives access, during normal business hours, to such information and assistance relating to Kos Investments and Kos Holdings (to the extent within the control of such party) as is reasonably necessary for financial reporting, tax and accounting matters.

          SECTION 4.11. Transfers of Shares . Each Seller agrees not to, directly or indirectly, (i) grant any proxies or enter into a voting trust or other agreement or arrangement with respect to the voting of any Shares or (ii) sell, transfer, pledge, encumber, assign, distribute, gift or otherwise dispose of (collectively, a “ Transfer ”), grant a Lien on, or enter into any Contract, option or other arrangement or understanding with respect to any Transfer (whether by actual disposition or effective economic disposition) of any of its Shares or any rights thereto or therein. The Sellers shall not seek or solicit any such Transfer or any such contract, option or other arrangement or understanding with respect to any Transfer, and shall promptly notify (and provide information requested by) Acquiror, if any Seller shall be approached or solicited, directly or indirectly, by any person with respect to any of the foregoing.

          SECTION 4.12. Alternative Transaction Payment .

          (a) If the Board of Directors of the Company has effected an Adverse Recommendation Change and the Merger Agreement is subsequently terminated pursuant to Section 8.1(h) thereof and, further, if within twelve months after the termination of the Merger Agreement, the Company, any Seller or any of their respective Affiliates enters into a definitive agreement for or consummates an Acquisition Proposal or Superior Proposal with a person other than Acquiror or any of Acquiror’s Affiliates (an “ Alternative Disposition ”), then, upon the closing of such Alternative Disposition, each Seller shall tender and pay to, or shall cause to be tendered and paid to, Acquiror, or its designee, in immediately available funds, 50% of the Excess Profit realized by such Seller from such Alternative Disposition.

          (b) If the Merger Agreement is terminated pursuant to Section 8.1(e) as a result of a breach following an Adverse Recommendation Change or receipt or public disclosure of a bona fide Acquisition Proposal after the date of the Merger Agreement, and, further, if within twelve months after the termination of the Merger Agreement, the Company, any Seller or any of their respective Affiliates effects an Alternative Disposition, then, upon the closing of such Alternative Disposition, each Seller shall tender and pay to, or shall cause to be tendered and paid to, Acquiror, or its designee, in immediately available funds, 50% of the Excess Profit realized by such Seller from such Alternative Disposition.

          (c) If the Merger Agreement is terminated pursuant to Section 8.1(g) thereof and, further, if within twelve months after the termination date, the Company, any Seller or any of their respective Affiliates effects an Alternative Disposition, then, upon the closing of such Alternative Disposition, each Seller shall tender and pay to, or shall cause to be tendered and paid to, Acquiror, or its designee, in immediately available funds, 50% of the Excess Profit realized by such Seller from such Alternative Disposition.

          (d) If, after the date of this Agreement, Acquiror agrees with the Company to increase the amount of the Merger Consideration to be paid by Acquiror and the Offer is consummated (an “ Increased Offer ”), upon the Closing each Seller shall tender and pay to, or shall cause to be tendered and paid to, Acquiror or its designee, in immediately available funds, 50% of the Excess Profit realized by such Seller, if any.

          (e) For purposes of this Section 4.12, “ Acquisition Proposal ” shall having the meaning set forth in the Merger Agreement, except that in each instance where 15% occurs, 50% shall be substituted therefor).

          (f) For purposes of this Section 4.12, “ Excess Profit ” of a Seller shall equal, if positive, (i) the aggregate consideration received by Seller, directly or indirectly, in respect of the Transfer of such Seller&#8217