SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 -------------------------------------------- IN THE MATTER OF CERTIFICATE AMEREN CORPORATION PURSUANT TO RULE 24 File No. 70-10133 (Public Utility Holding Company Act of 1935) -------------------------------------------- This Certificate of Notification pursuant to Rule 24 under the Public Utility Holding Company Act of 1935, as amended (the "Act"), is filed by Ameren Corporation ("Ameren"), a registered holding company, in connection with Ameren's indirect acquisition of a membership interest in PowerTree Carbon Company, LLC ("PowerTree"), a Delaware limited liability company, as authorized by Order of the Securities and Exchange Commission (the "Commission") dated November 10, 2003, in this proceeding (Holding Co. Act Release No. 27758). Ameren hereby certifies to the Commission pursuant to Rule 24 that Ameren, indirectly through its wholly-owned non-utility subsidiary, CIPSCO Investment Company, has acquired a membership interest in PowerTree and made its initial capital contribution to PowerTree. A "past tense" opinion of counsel is filed as Exhibit F hereto. SIGNATURE Pursuant to the requirements of the Act, the undersigned company has duly caused this document to be signed on its behalf by the undersigned thereunto duly authorized. Ameren Corporation By: /s/ Steven R. Sullivan ------------------ Name: Steven R. Sullivan Title: Senior Vice President Governmental/Regulatory Policy, General Counsel, and Secretary Dated: November 26, 2003