X0306 4 2013-10-24 1 0001142576 OPTIMER PHARMACEUTICALS INC OPTR 0001570990 Schaum Meredith 101 HUDSON STREET SUITE 3501 JERSEY CITY NJ 07302 0 1 0 0 Gen Counsel and Chief Comp Off Common stock 2013-10-24 4 D 0 2937 10.75 D 0 D Stock option (right to buy) 10.72 2013-10-24 4 D 0 30000 2.06 D 2023-02-26 Common stock 30000 0 D Includes 1,148 shares acquired under the Optimer Pharmaceuticals, Inc. ("Optimer") employee stock purchase plan on October 22, 2013. Pursuant to the Agreement and Plan of Merger, dated as of July 30, 2013 (the "Merger Agreement"), among Optimer, Cubist Pharmaceuticals, Inc. ("Cubist"), and PDRS Corporation, shares were converted into the right to receive per share consideration of: (i) $10.75 cash and (ii) one contingent value right issued by Cubist in accordance with the Contingent Value Rights Agreement, dated as of October 24, 2013, between Cubist and American Stock Transfer & Trust Company, LLC (together, the "Per Share Merger Consideration"). Pursuant to the terms of the Merger Agreement, each option was fully vested and converted into the right to receive a cash payment equal to the excess, if any, of $12.78 (the last reported sale price of a share of Optimer common stock on The NASDAQ Global Select Market on October 23, 2013) over such option's per share exercise price. Meredith Schaum 2013-10-28