Segment Information (Tables)

9 Months Ended

Sep. 30, 2025

Segment Reporting [Abstract]

Schedule of Reportable Operating Segments, Consolidated Revenue and Segment Operating Income

The following tables include information about Aon’s reportable segments, including total segment revenue, consolidated revenue, segment operating income, and income before income taxes:

	Three Months Ended September 30,
	Risk Capital		Human Capital		Corporate/Eliminations		Total Consolidated
	2025	2024	2025	2024	2025	2024	2025	2024
Revenue
Total revenue (1)	$2,525	$2,355	$1,475	$1,369	$(3)	$(3)	$3,997	$3,721
Expenses
Compensation and benefits	1,455	1,368	776	740	28	42	2,259	2,150
Information technology	94	93	44	47	2	1	140	141
Premises	56	57	28	31	1	—	85	88
Other expenses (2)	335	276	295	349	67	94	697	719
Total operating expenses	1,940	1,794	1,143	1,167	98	137	3,181	3,098
Operating income	$585	$561	$332	$202	$(101)	$(140)	$816	$623
Operating margin	23.2%	23.8%	22.5%	14.8%			20.4%	16.7%
Non-operating expenses
Interest income							—	4
Interest expense							(206)	(213)
Other income (expense)							(13)	35
Income before income taxes							$597	$449

	Nine Months Ended September 30,
	Risk Capital		Human Capital		Corporate/Eliminations		Total Consolidated
	2025	2024	2025	2024	2025	2024	2025	2024
Revenue
Total revenue (1)	$8,582	$7,980	$4,311	$3,597	$(12)	$(26)	$12,881	$11,551
Expenses
Compensation and benefits	4,457	4,112	2,346	1,977	65	74	6,868	6,163
Information technology	272	275	134	121	6	1	412	397
Premises	162	161	87	80	3	—	252	241
Other expenses (2)	1,045	902	892	740	276	364	2,213	2,006
Total operating expenses	5,936	5,450	3,459	2,918	350	439	9,745	8,807
Operating income	$2,646	$2,530	$852	$679	$(362)	$(465)	$3,136	$2,744
Operating margin	30.8%	31.7%	19.8%	18.9%			24.3%	23.8%
Non-operating expenses
Interest income							5	63
Interest expense							(624)	(582)
Other income (expense)							33	346
Income before income taxes							$2,550	$2,571

(1)Includes fiduciary investment income of $72 million and $201 million, respectively, in Risk Capital and $3 million and $7 million, respectively, in Human Capital for the three and nine months ended September 30, 2025. Includes fiduciary investment income of $83 million and $234 million, respectively, in Risk Capital and $2 million and $5 million, respectively, in Human Capital for the three and nine months ended September 30, 2024.

(2)Includes expenses related to Depreciation of fixed assets, Amortization and impairment of intangible assets, Accelerating Aon United Program expenses, and Other general expenses.