News Releases

Ameren Corporation (NYSE:AEE) announced today its plan to offer 9.5 million shares of common stock, subject to market conditions, and to grant the underwriters an option with respect to the offering to purchase an additional 1,425,000 shares of common stock. Ameren expects to use the net proceeds from the issuance of the common stock, along with proceeds from its February 2004 issuance of common stock, to pay the cash portion of the purchase price for its pending acquisition of Illinois Power Company from Dynegy Inc. (NYSE: DYN) and Dynegy's 20 percent interest in Electric Energy, Inc., and to reduce Illinois Power debt, assumed as a part of this transaction, and pay related premiums. Pending such use of proceeds, and/or if the acquisition is not completed, Ameren plans to use the net proceeds to reduce current or future indebtedness and/or repurchase securities of Ameren or its subsidiaries.

Ameren has appointed Goldman, Sachs & Co. as the book-running lead manager and Lehman Brothers Inc. as the co-lead manager for the offering.

A shelf registration statement related to this offering has been declared effective by the Securities and Exchange Commission. This press release does not constitute an offer to sell or a solicitation of an offer to buy the securities described herein, nor shall there be any sale of these securities in any jurisdiction in which such an offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. The offering may be made only by means of a prospectus and a related prospectus supplement, copies of which may be obtained when available from Goldman, Sachs & Co., at 85 Broad Street, New York, New York, or Lehman Brothers Inc., at 745 Seventh Avenue, New York, New York.

With assets of $14.6 billion, Ameren, through its subsidiaries, serves 1.7 million electric customers and 500,000 natural gas customers in a 49,000 square- mile area of Missouri and Illinois.

# # #