Unrestricted Shares Uses in Additional Terms Applicable to the Rights and Rights Shares Clause

Additional Terms Applicable to the Rights and Rights Shares from Securities Purchase Agreement

This SECURITIES PURCHASE AGREEMENT, dated as of June 17, 2007 (this Agreement), among Invus, L.P., a Bermuda limited partnership (the Investor) and Lexicon Pharmaceuticals, Inc., a Delaware corporation (the Company).

Additional Terms Applicable to the Rights and Rights Shares. (a) The Rights will be issued only to, and exercisable only by, each person who is a holder of record of Company Common Stock on the record date for the distribution of the rights, which shall be the date the Investor delivers the applicable Rights Offering Notice. Beneficial owners of shares of Company Common Stock held in the name of any depository or nominee as of the record date shall be entitled to exercise Rights through their respective depository or nominee. Rights may not be sold, pledged, hypothecated or otherwise transferred, directly or indirectly, and any attempt to do so will cause such Rights to be forfeited and the rights to subscribe for shares of Company Common Stock thereunder irrevocably waived. (b) Notwithstanding anything to the contrary herein, if the Investor elects to exercise less than all its Rights, (i) it shall be entitled to designate whether the shares with respect to which the Rights are exercised shall be Unrestricted Shares (as defined in the Stockholders Agreement) or Restricted Shares (as defined in the Stockholders Agreement), in each case up to the number of Unrestricted Shares or Restricted Shares in respect of which the Investor holds Rights, (ii) the shares of Company Common Stock received upon exercise of the Rights shall accordingly be Unrestricted Shares or Restricted Shares, and (iii) the Investor shall not be required to exercise Rights with respect to any Restricted Shares to be entitled to exercise its Rights Offering Oversubscription rights with respect to its Unrestricted Shares. (c) In connection with each Rights Offering, the Company shall, at its expense, engage a financial advisor reasonably acceptable to the Investor to provide financial advisory services as may customarily be required in connection with such offering. Following the commencement of any Rights Offering, the Company shall furnish or make available to the Investor, promptly after such information becomes available to the Company, all information and progress reports regarding the Rights Offering as shall be received by the Company, including any reports received by the Company from any transfer agents, underwriters, advisors or other third parties retained by the Company in connection with such Rights Offering, and all such

Additional Terms Applicable to the Rights and Rights Shares from Securities Purchase Agreement

This SECURITIES PURCHASE AGREEMENT, dated as of June 17, 2007 (this Agreement), among Invus, L.P., a Bermuda limited partnership (the Investor) and Lexicon Pharmaceuticals, Inc., a Delaware corporation (the Company).

Additional Terms Applicable to the Rights and Rights Shares. (a) The Rights will be issued only to, and exercisable only by, each person who is a holder of record of Company Common Stock on the record date for the distribution of the rights, which shall be the date the Investor delivers the applicable Rights Offering Notice. Beneficial owners of shares of Company Common Stock held in the name of any depository or nominee as of the record date shall be entitled to exercise Rights through their respective depository or nominee. Rights may not be sold, pledged, hypothecated or otherwise transferred, directly or indirectly, and any attempt to do so will cause such Rights to be forfeited and the rights to subscribe for shares of Company Common Stock thereunder irrevocably waived. (b) Notwithstanding anything to the contrary herein, if the Investor elects to exercise less than all its Rights, (i) it shall be entitled to designate whether the shares with respect to which the Rights are exercised shall be Unrestricted Shares (as defined in the Stockholders Agreement) or Restricted Shares (as defined in the Stockholders Agreement), in each case up to the number of Unrestricted Shares or Restricted Shares in respect of which the Investor holds Rights, (ii) the shares of Company Common Stock received upon exercise of the Rights shall accordingly be Unrestricted Shares or Restricted Shares, and (iii) the Investor shall not be required to exercise Rights with respect to any Restricted Shares to be entitled to exercise its Rights Offering Oversubscription rights with respect to its Unrestricted Shares. (c) In connection with each Rights Offering, the Company shall, at its expense, engage a financial advisor reasonably acceptable to the Investor to provide financial advisory services as may customarily be required in connection with such offering. Following the commencement of any Rights Offering, the Company shall furnish or make available to the Investor, promptly after such information becomes available to the Company, all information and progress reports regarding the Rights Offering as shall be received by the Company, including any reports received by the Company from any transfer agents, underwriters, advisors or other third parties retained by the Company in connection with such Rights Offering, and all such