Item 8.01. Other Events.

On September 15, 2009, Ameren Corporation ("Ameren"), issued and sold 21,850,000 shares of its common stock, par value $.01 (the "Shares"), pursuant to a Registration Statement on Form S-3 (File No. 333-155416), which became effective on November 17, 2008, and a Prospectus Supplement dated September 9, 2009, to a Prospectus dated November 17, 2008. The Shares included the full exercise of the over-allotment option granted to the underwriters for the offering. Ameren received net offering proceeds of approximately $534.7 million. Ameren intends to use the net offering proceeds to make investments in its rate-regulated utility subsidiaries in the form of equity capital contributions and for general corporate purposes. Pending such use, the net offering proceeds may be temporarily used to reduce borrowings under Ameren's bank credit facilities. Ameren is filing this Current Report on Form 8-K to report as exhibits certain documents in connection with the offering.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits.

1.1 Underwriting Agreement, dated September 9, 2009, between Ameren and the several underwriters named therein, for whom Barclays Capital Inc., J.P. Morgan Securities Inc., Merrill Lynch, Pierce, Fenner & Smith Incorporated, Morgan Stanley & Co. Incorporated and UBS Securities LLC are acting as representatives.

5.1 Opinion of Steven R. Sullivan, Esq., Senior Vice President, General Counsel and Secretary of Ameren, regarding the validity of the Shares (including consent).

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