Material Event (Form 8-K)

On June 29, 2026, Union Electric Company, doing business as Ameren Missouri ("Ameren Missouri"), a subsidiary of Ameren Corporation, sold $500 million principal amount of its 5.75% First Mortgage Bonds due 2056 (the "Bonds"). The Bonds were offered pursuant to a Registration Statement on Form S-3 (File No. 333-274977-02), which became effective on October 13, 2023, and a Prospectus Supplement dated June 15, 2026, to a Prospectus dated October 13, 2023. Ameren Missouri received net offering proceeds of approximately $492.2 million, before expenses, upon closing of the transaction.

This Current Report on Form 8-K is being filed to report as exhibits certain documents in connection with the offering of the Bonds.