Ameren Corporation Issues Junior Subordinated Notes

On September 18, 2026, Ameren Corporation completed the sale of $900 million in principal amount of its Junior Subordinated Notes due 2057. The offering was conducted under a Registration Statement on Form S-3, which became effective on August 4, 2026, and was supplemented by a prospectus dated September 8, 2026. Ameren received net proceeds of $891.0 million from the transaction, after deducting offering expenses. This Form 8-K filing serves to present certain documents related to the notes offering as exhibits. These exhibits include the Underwriting Agreement dated September 8, 2026, the Indenture dated September 1, 2026, establishing the notes, and legal opinions regarding the notes.