On April 23, 2009, Calpine Corporation (the "Company") and Harbinger Capital Partners Master Fund I, Ltd. (the "Selling Stockholder") entered into an underwriting agreement (the "Underwriting Agreement") with Morgan Stanley & Co. Incorporated, as underwriter (the "Underwriter"). Pursuant to the Underwriting Agreement, the Selling Stockholder agreed to sell, and the Underwriter agreed to purchase, 20,000,000 shares of the Company's common stock, par value $0.001 per share. In addition, the Selling Stockholder has granted the underwriter a 30-day option to purchase up to 3,000,000 additional shares of common stock solely to cover over-allotments. The public offering and sale (the "Offering") contemplated by the Underwriting Agreement will be completed on or about April 29, 2009. The Company will not sell any shares and will not receive any proceeds from the sale of shares in the Offering.

The Offering of the shares by the Selling Stockholder of the Company's common stock pursuant to the Underwriting Agreement has been registered under the Securities Act of 1933, as amended, by a registration statement on Form S-3 (Registration No. 333-152982). A copy of the Underwriting Agreement is filed as Exhibit 1.1 hereto and is incorporated by reference herein.

(d)     Exhibits

Exhibit No.   Description

    1.1       Underwriting Agreement, dated April 23, 2009, among
              Calpine Corporation, the selling stockholder named
              therein and Morgan Stanley & Co. Incorporated, the
              underwriter named therein.*


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* Filed herewith.