The law firm of Wohl & Fruchter LLP is investigating the proposed acquisition of Optimer Pharmaceuticals, Inc. (Optimer) (Nasdaq: OPTR) by Cubist Pharmaceuticals, Inc. (Cubist). On July 30, 2013, Optimer and Cubist announced they had signed an agreement under which Cubist will acquire all of the outstanding shares of Optimer stock for $10.75 per share in cash – over 20% below the $13.29/share closing price of OPTR on July 30, 2013. In addition to the upfront cash payment, each Optimer stockholder will receive a Contingent Value Right, which is expected to be publicly traded, entitling the holder to receive an additional one-time cash payment of up to $5.00 for each Optimer share they own – but only if certain net sales of Optimer’s drug DIFICID® are achieved. DIFICID is an antibacterial drug used to treat a severe form of diarrhea resulting from intestinal infections in hospitalized adults 18 years of age or older. In April 2011, Cubist and Optimer entered into a two-year agreement under which Cubist has been co-promoting DIFICID with Optimer to physicians, hospitals, and other healthcare institutions. According to Reuters, earlier this year, Cubist offered to buy Optimer for $20 per share, or nearly $1 billion – nearly double the price that Cubist has agreed to pay for Optimer in the current transaction. Wohl & Fruchter’s investigation concerns whether the Optimer Board of Directors breached their fiduciary duties to stockholders by agreeing to sell the Company to Cubist for an inadequate price, and failing to adequately shop the Company before agreeing to enter into the transaction with Cubist. Additional information is available at http://www.wohlfruchter.com/cases/optr. Persons with relevant information, and Optimer shareholders with questions about this investigation, are invited to contact our Firm by calling 866.833.6245, or contacting the attorney below. About Wohl & Fruchter Wohl & Fruchter LLP represents plaintiffs in litigation arising from fraud and other fiduciary breaches by corporate managers, as well as other complex litigation matters. Please visit our website, www.wohlfruchter.com, to learn more about our Firm, or contact one of our partners. This release may be deemed to constitute attorney advertising.