UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-Q

ý QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d)
OF THE SECURITIES EXCHANGE ACT OF 1934

FOR THE QUARTERLY PERIOD ENDED SEPTEMBER 30, 2004

o 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 Incorporation or Organization)	(I.R.S. Employer Identification No.)

200 E. RANDOLPH STREET, CHICAGO, ILLINOIS	60601
(Address of Principal Executive Offices)	(Zip Code)

(312) 381-1000
(Registrant’s Telephone Number, Including Area Code)

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 Exchange Act of 1934 during the preceding 12 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 ý NO o

Indicate by check mark whether the registrant is an accelerated filer (as defined in Rule 12b-2 of the Exchange Act). YES ý NO o

Number of shares of common stock outstanding:

		No. Outstanding
Class		as of 9-30-04

$1.00 par value Common		316,455,363

Part 1

Financial Information

Aon Corporation

Condensed Consolidated Statements of Financial Position

	As of
(millions)	Sept. 30, 2004			Dec. 31, 2003
	(Unaudited)
ASSETS
Investments
Fixed maturities at fair value	$	3,338		$	2,751
Equity securities at fair value	37			42
Short-term investments	4,073			3,815
Other investments	746			716
Total investments	8,194			7,324
Cash	396			540
Receivables
Risk and insurance brokerage services and consulting	7,699			8,607
Other receivables	1,482			1,504
Total receivables	9,181			10,111
Deferred Policy Acquisition Costs	1,091			1,021
Goodwill
(net of accumulated amortization: 2004 – $799; 2003 – $805)	4,508			4,509
Other Intangible Assets
(net of accumulated amortization: 2004 – $344; 2003 – $300)	147			176
Property and Equipment	693			827
Other Assets	2,361			2,519
TOTAL ASSETS	$	26,571		$	27,027

LIABILITIES AND STOCKHOLDERS’ EQUITY
Insurance Premiums Payable	$	9,597		$	10,368
Policy Liabilities
Future policy benefits	1,560			1,396
Policy and contract claims	1,816			1,609
Unearned and advance premiums and contract fees	2,878			2,869
Other policyholder funds	59			58
Total Policy Liabilities	6,313			5,932
General Liabilities
General expenses	1,341			1,498
Short-term borrowings	65			53
Notes payable	1,899			2,095
Other liabilities	2,438			2,533
TOTAL LIABILITIES	21,653			22,479
Commitments and Contingent Liabilities
Redeemable Preferred Stock	50			50
Stockholders’ Equity
Common stock – $1 par value	339			336
Paid-in additional capital	2,381			2,283
Accumulated other comprehensive loss	(867		)	(861		)
Retained earnings	3,997			3,679
Less – Treasury stock at cost	(783		)	(784		)
Deferred compensation	(199		)	(155		)
TOTAL STOCKHOLDERS’ EQUITY	4,868			4,498
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$	26,571		$	27,027

See the accompanying notes to the condensed consolidated financial statements.

Aon Corporation

Condensed Consolidated Statements of Income

(Unaudited)

	Third Quarter Ended				Nine Months Ended
(millions except per share data)	Sept. 30, 2004		Sept. 30, 2003		Sept. 30, 2004		Sept. 30, 2003

Revenue
Brokerage commissions and fees	$	1,657	$	1,638	$	5,207	$	4,977
Premiums and other	693		673		2,101		1,940
Investment income	52		57		202		225
Total revenue	2,402		2,368		7,510		7,142

Expenses
General expenses	1,787		1,718		5,442		5,164
Benefits to policyholders	379		367		1,154		1,037
Interest expense	32