SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q/A X QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15 (d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE QUARTERLY PERIOD ENDED SEPTEMBER 30, 2001 OR TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 (d) OF THE SECURITIES EXCHANGE ACT OF 1934 COMMISSION FILE NUMBER 1-7933 Aon CORPORATION --------------- (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER) DELAWARE 36-3051915 -------- ---------- (STATE OR OTHER JURISDICTION OF (IRS EMPLOYER IDENTIFICATION NO.) INCORPORATION OR ORGANIZATION) 200 E. RANDOLPH ST. CHICAGO, ILLINOIS 60601 - ------------------------------------- ----- (ZIP CODE) (312) 381-1000 -------------- (REGISTRANT'S TELEPHONE NUMBER) Indicate by check mark whether the Registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities and Exchange Act of 1934 during the preceding 3 months (or for such shorter period that the Registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. YES X NO --- --- Number of shares of common stock outstanding: CLASS NO. OUTSTANDING AS OF 9-30-01 ----- ----------------------------- $1.00 par value Common 269,217,702 The purpose of this Form 10-Q/A is to file an amended Exhibit 15 to correct an error in the Exhibit. The date of the letter was November 8, 2001, and should have been November 13, 2001. PART II OTHER INFORMATION ITEM 6. EXHIBITS AND REPORTS ON FORM 8-K (a) Exhibits - The exhibits filed with this report are listed on the -------- attached Exhibit Index. (b) Reports on Form 8-K - ------------------- (i) No Current Reports on Form 8-K were filed for the quarter ended September 30, 2001. (ii) The Registrant filed one Current Report on Form 8-K dated November 8, 2001. The following exhibit was included in the report: Exhibit 99 - Earnings Press Release issued on November 7, 2001. SIGNATURE Pursuant to the Requirements of the Securities and Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized. Aon CORPORATION --------------- (Registrant) November 28, 2001 /s/ Harvey N. Medvin -------------------- HARVEY N. MEDVIN EXECUTIVE VICE PRESIDENT AND CHIEF FINANCIAL OFFICER (Principal Financial and Accounting Officer) - 2 - Aon CORPORATION - --------------- Exhibit Number In Regulation S-K Item 601 Exhibit Table - ---------------------- * (12) Statements regarding Computation of Ratios. (a) Statement regarding Computation of Ratio of Earnings to Fixed Charges. (b) Statement regarding Computation of Ratio of Earnings to Combined Fixed Charges and Preferred Stock Dividends. (15) Letter re: Unaudited Interim Financial Information __________ *Previously filed. - 3 - Exhibit 15 Board of Directors and Stockholders Aon Corporation We are aware of the incorporation by reference in the Registration Statements of Aon Corporation ("Aon") described in the following table of our report dated November 13, 2001 relating to the unaudited condensed consolidated interim financial statements of Aon Corporation that are included in its Form 10-Q for the quarter ended September 30, 2001: Registration Statement ---------------------- Form Number Purpose ---- ------ ------- S-8 33-27984 Pertaining to Aon's savings plan S-8 33-42575 Pertaining to Aon's stock award plan and stock option plan S-8 33-59037 Pertaining to Aon's stock award plan and stock option plan S-4 333-21237 Offer to exchange Capital Securities of Aon Capital A S-3 333-50607 Pertaining to the registration of 369,000 shares of common stock S-8 333-55773 Pertaining to Aon's stock award plan, stock option plan and employee stock purchase plan S-3 333-78723 Pertaining to the registration of debt securities, preferred stock and common stock S-3 333-49300 Pertaining to the registration of 3,864,824 shares of common stock S-4 333-57706 Pertaining to the registration of up to 3,852,184 shares of common stock S-3 333-65624 Pertaining to the registration of 2,000,000 shares of common stock Pursuant to Rule 436(c) of the Securities Act of 1933, our report is not a part of the registration statements prepared or certified by accountants within the meaning of Section 7 or 11 of the Securities Act of 1933. ERNST & YOUNG LLP Chicago, Illinois November 13, 2001