| Important Additional Information 16 Important Additional Information about the Proposed Optimer Transaction and Where to Find it. This presentation and the statements during this call shall not constitute an offer of any securities for sale. The acquisition will be submitted to Optimer’s stockholders for their consideration. In connection with the acquisition, Cubist and Optimer intend to file relevant materials with the Securities and Exchange Commission (SEC), including a registration statement on Form S-4, which will include a proxy statement/prospectus and other relevant documents concerning the merger. Investors and stockholders of Cubist and Optimer are urged to read the registration statement, the proxy statement/prospectus and other relevant documents filed with the SEC when they become available, as well as any amendments or supplements to the documents because they will contain important information about Cubist, Optimer and the merger. Stockholders of Cubist and Optimer can obtain more information about the proposed transaction by reviewing the Form 8-K to be filed by Cubist and Optimer in connection with the announcement of the entry into the merger agreement, and any other relevant documents filed with the SEC when they become available. The registration statement, the proxy statement/prospectus and any other relevant materials (when they become available), and any other documents filed by Cubist and Optimer with the SEC, may be obtained free of charge at the SEC's web site at www.sec.gov. In addition, investors and stockholders may obtain free copies of the documents filed with the SEC by directing a written request to: Cubist, 65 Hayden Avenue, Lexington, MA 02421, Attention: Investor Relations, or Optimer, 4755 Nexus Center Drive, San Diego, CA 92121, Attention: Investor Relations. Investors and stockholders are urged to read the registration statement, the proxy statement/prospectus and the other relevant materials when they become available before making any voting or investment decision with respect to the merger. Participants in Solicitations Optimer and its directors, executive officers and other members of their management and employees may be deemed to be participants in the solicitation of proxies from stockholders of Optimer in connection with the merger. Information regarding Optimer's directors and executive officers and their ownership of Optimer common stock is available in Optimer’s annual report on Form 10-K for the year ended December 31, 2012, filed with the SEC on March 18, 2013 and the proxy statement on Schedule 14A for Optimer’s 2013 annual meeting of stockholders, filed with the SEC on April 12, 2013 and as amended on April 19, 2013. Certain directors and executive officers of Optimer and other persons may have direct or indirect interests in the proposed merger due to securities holdings, pre-existing or future indemnification arrangements and rights to severance payments if their employment is terminated prior to or following the merger. If and to the extent that any of the Optimer participants will receive any additional benefits in connection with the merger, the details of those benefits will be described in the proxy statement/prospectus relating to the merger. Investors and security holders may obtain additional information regarding the direct and indirect interests of Optimer and its executive officers and directors in the merger by reading the proxy statement/prospectus regarding the Merger when it becomes available. |