Guides
The largest commercial insurance brokers, ranked by 2025 revenue
The biggest insurance brokers by 2025 revenue, from company filings and Business Insurance's 2026 list, why the order shifted, and what size means for a buyer.
Marsh is the largest insurance broker in the world and in the United States by 2025 revenue, followed by Aon and Arthur J. Gallagher. In Business Insurance's 2026 ranking of brokers by U.S. revenue, Gallagher passed Aon for second place after buying AssuredPartners in 2025. Below the top 10 sit hundreds of private-equity-backed and employee-owned firms, which is where most small and mid-size businesses actually buy.
How the ranking is built
Brokers do not report revenue the same way, so this guide uses two sources. For public brokers, the figures are what each company reported for calendar 2025 in its earnings release or annual filing. Private firms publish no financials, so the industry yardstick is the annual survey by Business Insurance. Its July/August 2026 issue ranks the 100 largest brokers of U.S. business by 2025 brokerage revenue from U.S.-based clients, and lists the world's 10 largest by global brokerage revenue. Firms that earn more than 49% of gross revenue from personal lines are not eligible.
Two cautions before you use any list like this:
- Revenue is not premium. A broker's revenue is the commissions and fees it earns, not the premium it places. Revenue is a percentage of the premium or a negotiated fee, and the percentage varies by line and carrier; see how commercial insurance brokers get paid.
- Surveys are not audited ledgers. Business Insurance's figures come from its own survey, and some are its estimates. Lockton's fiscal year ends April 30, Howden's September 30, so the periods do not line up exactly. A public company's total can also include consulting or claims-administration revenue that is not brokerage.
The world's 10 largest brokers
Ranked by 2025 global brokerage revenue, per Business Insurance (July/August 2026), with what each public company reported itself:
| Rank | Broker | 2025 brokerage revenue (Business Insurance) | Ownership | Company-reported 2025 revenue |
|---|---|---|---|---|
| 1 | Marsh | $26.66 billion | Public (NYSE: MRSH) | $26.98 billion, including Mercer and Oliver Wyman |
| 2 | Aon | $16.99 billion | Public | $17.18 billion |
| 3 | Arthur J. Gallagher | $13.17 billion | Public | $13.94 billion total revenues |
| 4 | WTW | $9.77 billion | Public | $9.71 billion |
| 5 | Brown & Brown | $5.76 billion | Public | $5.9 billion total; $5.76 billion commissions and fees |
| 6 | Alliant Insurance Services | $5.72 billion | Private | Not published |
| 7 | Hub International | $4.75 billion | Private | Not published |
| 8 | Lockton | $4.37 billion | Private | Not published |
| 9 | Howden Insurance Brokers | $4.01 billion | Private, London-based | Not published |
| 10 | Acrisure | $3.75 billion | Private | Not published |
Marsh is the company formerly branded Marsh McLennan; it took the Marsh name in January 2026 and trades as MRSH. Next in the private-firm ranking after Acrisure comes USI Insurance Services, at $2.89 billion.
The largest brokers of U.S. business
Business Insurance's U.S. list counts only revenue from U.S.-based clients, which reorders the field because Aon, WTW, Marsh and Howden earn a large share abroad.
| 2026 rank | Broker | 2025 U.S. brokerage revenue | 2025 rank |
|---|---|---|---|
| 1 | Marsh | $13.06 billion | 1 |
| 2 | Gallagher | $8.83 billion | 3 |
| 3 | Aon | $8.15 billion | 2 |
| 4 | Alliant | $5.70 billion | 5 |
| 5 | Brown & Brown | $4.94 billion | 6 |
| 6 | WTW | $4.69 billion | 4 |
| 7 | Hub | $3.92 billion | 7 |
| 8 | Lockton | $3.19 billion | 9 |
| 9 | Acrisure | $3.11 billion | 8 |
| 10 | USI | $2.89 billion | 11 |
The biggest movers were Gallagher (up 24.4%), Brown & Brown (up 22.4%) and The Baldwin Group, which grew 33.6% and climbed three places to 12th. WTW's U.S. revenue fell 7.5%, dropping it from fourth to sixth, even though Business Insurance adjusted WTW's 2025 figure to include Newfront, which WTW bought in January 2026.
Mid-size and regional brokers with profiles on this site
Further down the same list, with Business Insurance's rank by 2025 U.S. brokerage revenue: BroadStreet Partners (11), The Baldwin Group (12), Higginbotham (16), IMA Financial Group (17), The Hilb Group (22), World Insurance Associates (23), Patriot Growth Insurance Services (24), Leavitt Group (25) and Heffernan Group (38). Newfront is now part of WTW, Risk Strategies part of Brown & Brown, and NFP part of Aon.
What the public brokers reported for 2025
These come from each company's own results release or filing for the year ended December 31, 2025:
- Marsh: $26,981 million of revenue, split roughly $14.4 billion for Marsh Risk, $2.5 billion for Guy Carpenter, $6.2 billion for Mercer and $3.6 billion for Oliver Wyman (SEC filing of its Q4 2025 release).
- Aon: $17,181 million, with Commercial Risk Solutions at $8,497 million and Reinsurance Solutions at $2,793 million (Aon, Jan. 30, 2026).
- Gallagher: $13,942 million total revenues, of which brokerage was $12,192 million and risk management, which includes the Gallagher Bassett claims administrator, was $1,749 million including $164 million of reimbursements (Gallagher, Jan. 29, 2026).
- WTW: $9,708 million, with Risk & Broking at $4,334 million and Health, Wealth & Career at $5,254 million (WTW 8-K exhibit).
- Brown & Brown: commissions and fees of $5,763 million, including $255 million of profit-sharing contingent commissions, and total revenues of $5.9 billion, up 22.8% with 2.8% organic growth (Brown & Brown, January 2026).
- Ryan Specialty: $3,051 million of total revenue, up 21.3% with 10.1% organic growth (Ryan Specialty, Feb. 12, 2026). It is a wholesale and specialty distributor, so it is not comparable with retail rankings.
Organic growth strips out acquisitions and currency. It is the better measure of whether a broker is winning business. Gallagher's 21% total growth in 2025 came with 6% organic, and Brown & Brown's 22.8% with 2.8%, so most of the jump was purchased.
Why the order keeps changing
Acquisition is the main driver. Gallagher closed its purchase of AssuredPartners on August 18, 2025 at about $13.45 billion of gross consideration per trade press, and added about 10,900 employees; it also closed 33 mergers in the year with more than $3.5 billion of estimated annualized revenue. Brown & Brown credited its 2025 growth largely to buying Accession, the parent of Risk Strategies. WTW announced the completion of its purchase of Newfront on January 27, 2026 (up to $1.3 billion in total). Aon closed NFP on April 25, 2024, and Marsh closed McGriff on November 15, 2024 for $7.75 billion in cash. Each deal moves revenue from a private firm's column to a public one. The private-equity roll-up model behind many of the firms in the 11-to-50 range is covered in private equity and the consolidation of insurance brokers.
Pending deals that could change the ranking
On August 31, 2026 Aon agreed to buy USI from KKR and other shareholders for $17.0 billion, with closing expected in the fourth quarter of 2026, subject to regulatory approvals. As of October 2026 it had not closed. If it does, USI leaves the private-firm list, and on Business Insurance's 2025 U.S. figures, simple addition of Aon's $8.15 billion and USI's $2.89 billion gives about $11.0 billion, which would put Aon ahead of Gallagher at $8.83 billion for second place among U.S. brokers, behind Marsh at $13.06 billion. Lockton and Acrisure would each move up a place on the U.S. list. The world order of the top three would not change. The Baldwin Group agreed on September 14, 2026 to a $7.7 billion take-private by Sequence Holdings and DFO Management, expected to close in the first quarter of 2027; that changes its ownership, not its rank. The table figures above are 2025 results and do not include either deal.
Retail, benefits and wholesale are different leaderboards
A single revenue list blurs three businesses. Business Insurance also ranks leading U.S. commercial retail brokers (excluding employee benefits): Marsh at $8.52 billion, Aon at $4.08 billion (a Business Insurance estimate), Gallagher at $3.81 billion, Alliant at $2.72 billion and Hub at $1.98 billion. Its global employee benefits ranking runs Marsh at $6.19 billion, WTW at $5.13 billion, then Aon, Gallagher and Hub.
Wholesale firms such as Amwins, CRC Group and Ryan Specialty sell to other brokers, not to you. A retail broker hands them the risks standard carriers decline, and they place these with surplus lines insurers and MGAs. See wholesale brokers and surplus lines placement: how hard risks get insured and Managing general agents (MGAs): what they are and what they mean for buyers.
What size means when you buy
Size tells you about resources, not about fit. J.D. Power's 2026 U.S. Small Commercial Insurance Study found satisfaction of 750 when both the insurer and the agent understood the customer's business, against 547 when neither did (Insurance Journal, Aug. 21, 2026). Understanding the business, not the revenue rank, drove the score.
| Type of broker | Usually suits | Ask about |
|---|---|---|
| Global and national | Large or complex accounts, multinational programs, big benefits plans | Who is on your team, and whether a smaller account gets senior attention |
| Regional or private-equity-backed | Middle-market accounts that want specialists and local service | Ownership changes, and whether the producer and service staff are staying |
| Local independent | Small and owner-run businesses | Carrier access, claims advocacy, and a succession plan |
Questions that tell you more than a ranking:
- Who will service my account day to day, and how many accounts does that person handle?
- How many clients in my industry and size do you place, and can I speak to two?
- What do you earn on my account, including contingent or supplemental commissions? Start with how to choose a commercial insurance broker.
- Which carriers can you reach directly, and which go through a wholesaler?
- If you are acquired, what changes in service, staff and compensation?
Key takeaways
- By 2025 revenue the top three are Marsh, Aon and Gallagher worldwide; in Business Insurance's U.S. ranking Gallagher is second and Aon third.
- Public brokers report their own totals, which include non-brokerage work; private firms are ranked from Business Insurance's survey, so treat all lists as approximate.
- Much of the 2025 growth at the leaders was bought, not organic. Acquisitions explain most of the reshuffling.
- Retail, benefits and wholesale are separate businesses with separate leaders.
- A broker's rank says little about fit. Choose on industry experience, service model and disclosed compensation.