United States Securities and Exchange Commission Washington, D.C. 20549 Form 13F Form 13F Cover Page Report for the Calendar Quarter Ended September 30, 2003 Check here if Amendment{ }: Amendment Number: This Amendment (Check only one): { } is a restatement. { } adds new holdings entries. Institutional Investment Manager Filing this Report: NAME: ALLMERICA FINANCIAL CORPORATION STREET: 440 LINCOLN STREET CITY: WORCESTER, STATE: MA. ZIP: 01653 Form 13F File Number: 028-05087 The institutional investment manager filing this report and the person by whom it is signed hereby represent that the person signing the report is authorized to submit it, that all information contained herein is true, correct and complete, and that it is understood that all required items, statements, schedules, lists and tables, are considered integral parts of this form. Person Signing this Report on Behalf of reporting Manager: Name: John P. Kavanaugh Title: Chief Investment Officer Phone: 508-855-2151 SIGNATURE, Place and Date Signing: Name: John P. Kavanaugh CITY: WORCESTER STATE: MA DATE: 11/12/03 Report Type (Check only one): 13F HOLDING REPORT. (Check here if all holdings ----- of this reporting manager are reported in this report.) X 13F NOTICE. (Check here if no holdings reported are ----- in this report, and all holdings are reported by other reporting manager(s).) 13F COBINATION REPORT. (Check here if a portion of the ----- holdings for this reporting manager are reported in this report and a portion are reported by other reporting manager(s).) Form 13F Summary Page Report Summary: Number of Other Included Managers: 1 Form 13F Information Table Entry Total: none Form 13F Information Table Value Total: none List of Other Included Managers: NAME: OPUS INVESTMENT MANAGEMENT, INC. STREET: 440 LINCOLN STREET CITY: WORCESTER, STATE: MA ZIP: 01653 Form 13F File Number: 028-05067