Company Update

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): December 10, 2013 Commission File Number Exact Name of Registrant as Specified in Charter; State of Incorporation; Address and Telephone Number IRS Employer Identification Number 1-14756 Ameren Corporation (Missouri Corporation) 1901 Chouteau Avenue St. Louis, Missouri 63103 (314) 621-3222 43-1723446 1-3672 Ameren Illinois Company (Illinois Corporation) 6 Executive Drive Collinsville, Illinois 62234 (618) 343-8150 37-0211380 Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ITEM 8.01 Other Events. On December 10, 2013, Ameren Illinois Company (“Ameren Illinois”), a subsidiary of Ameren Corporation (“Ameren”), issued and sold $280,000,000 principal amount of its 4.80% Senior Secured Notes due 2043 (the “Notes”), pursuant to a Registration Statement on Form S-3 (File No. 333-182258-01), which became effective on June 21, 2012, and a Prospectus Supplement dated December 5, 2013 to a Prospectus dated June 21, 2012. Ameren Illinois received net offering proceeds of approximately $276 million, before expenses, upon the closing of the transaction. Ameren Illinois intends to use the net offering proceeds, together with other available cash, to repay at maturity $150 million aggregate principal amount of its 8.875% senior secured notes due December 15, 2013 and to repay its short-term debt (consisting of borrowing under the Ameren utility money pool). Ameren Illinois is filing this Current Report on Form 8-K to report as exhibits certain documents in connection with the offering of the Notes. ITEM 9.01 Financial Statements and Exhibits. (d) Exhibits Exhibit Number Title 1 Underwriting Agreement, dated December 5, 2013, between Ameren Illinois and the several underwriters named therein, for whom BNP Paribas Securities Corp., Merrill Lynch, Pierce, Fenner & Smith Incorporated, RBC Capital Markets, LLC and Mitsubishi UFJ Securities (USA), Inc. are acting as representatives. *4.1 Indenture, dated as of June 1, 2006, between Ameren Illinois and The Bank of New York Mellon Trust Company, N.A., as trustee, relating to the Notes (Current Report on Form 8-K filed on June 19, 2006, Exhibit 4.4, File No. 1-3004). 4.2 Company Order establishing the Notes. 4.3 Global Note. *4.4 General Mortgage Indenture and Deed of Trust, dated as of November 1, 1992, from Ameren Illinois to The Bank of New York Mellon Trust Company, N.A., as successor trustee to Harris Trust and Savings Bank (Annual Report on Form 10-K for the year ended December 31, 1992, Exhibit 4(cc), File No. 1-3004). 4.5 Supplemental Indenture, dated as of December 1, 2013, by and between Ameren Illinois and The Bank of New York Mellon Trust Company, N.A., as successor trustee to Harris Trust and Savings Bank, relating to the First Mortgage Bonds, Senior Notes Series FF securing the Notes. 5.1 Opinion of Craig W. Stensland, Esq., Senior Corporate Counsel of Ameren Services Company, regarding the legality of the Notes (including consent). 5.2 Opinion of Morgan, Lewis & Bockius LLP regarding the legality of the Notes (including consent). * Incorporated by reference as indicated. This combined Form 8-K is being filed separately by Ameren Corporation and Ameren Illinois Company (each a “registrant”). Information contained herein relating to any individual registrant has been filed by such registrant on its own behalf. No registrant makes any representation as to information relating to any other registrant. - 2 - SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, each registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized. The signature for each undersigned company shall be deemed to relate only to matters having reference to such company or its subsidiaries. AMEREN CORPORATION (Registrant) By: /s/ Ryan J. Martin Name: Ryan J. Martin Title: Assistant Vice President and Treasurer AMEREN ILLINOIS COMPANY (Registrant) By: /s/ Ryan J. Martin Name: Ryan J. Martin Title: Assistant Vice President and Treasurer Date: December 10, 2013 Exhibit Index Exhibit Number Title 1 Underwriting Agreement, dated December 5, 2013 between Ameren Illinois and the several underwriters named therein, for whom BNP Paribas Securities Corp., Merrill Lynch, Pierce, Fenner & Smith Incorporated, RBC Capital Markets, LLC and Mitsubishi UFJ Securities (USA), Inc. are acting as representatives. 4.2 Company Order establishing the Notes. 4.3 Global Note. 4.5 Supplemental Indenture, dated as of December 1, 2013, by and between Ameren Illinois and The Bank of New York Mellon Trust Company, N.A., as successor trustee to Harris Trust and Savings Bank, relating to the First Mortgage Bonds, Senior Notes Series FF securing the Notes. 5.1 Opinion of Craig W. Stensland, Esq., Senior Corporate Counsel of Ameren Services Company, regarding the legality of the Notes (including consent). 5.2 Opinion of Morgan, Lewis & Bockius LLP regarding the legality of the Notes (including consent). - 4 -