Global insurance brokerage and risk advisory firm Marsh remains the world’s largest insurance brokerage, with revenue approaching $27 billion in 2025, according to ratings agency AM Best.
AM Best’s annual rankings, based on total revenue through 2025, highlight the continued growth of the world’s largest insurance brokerages. You can view our table of the top insurance brokers in the world here.
“Consistency is the theme of this year’s list, with Marsh topping the list for the 16th consecutive year,” the agency said.
Marsh will increase revenue by more than $2 billion in 2025, positioning the company to maintain its long-standing leadership position in the global brokerage market. Aon remains in second place, followed by Arthur J. Gallagher & Co. in third and WTW in fourth, with all four brokers maintaining the same positions as last year.
The biggest change among the top five is Brown & Brown. AM Best noted: “A big change in the fifth spot is that this year it’s taken by Brown & Brown, which increased its revenue by more than $1 billion to $5.9 billion, moving up two places in the rankings.”
The brokerage group has grown with the acquisition of Accession Risk Management Group holdings, which Brown & Brown said was the largest acquisition in its history. Accession ranked 17th in the last ranking, with revenue of $1.74 billion.
Alliant Insurance Services ranked sixth despite revenue growing to $5.8 billion, while Hub International ranked seventh after revenue grew to $5.28 billion. Howden moved up two spots to eighth with $4.84 billion in revenue, and Acrisure ranked ninth with $4.82 billion. Lockton rounds out the top 10 with revenue of $4.48 billion.
The remaining members of the top 20 include Amwins, Ryan Specialty, USI Insurance Services, The Ardonagh Group, CRC Group, BroadStreet Partners, Alera Group, The Baldwin Group, Diot-Siaci and OneDigital.
Diot-Siaci enters the top 20 for the first time, ranking 19th with revenue of $1.48 billion. The company’s inclusion marks its first appearance among the world’s leading insurance brokers in AM Best’s annual rankings.
The latest edition of AM Best shows that the largest brokers continue to expand in 2025, with acquisitions and revenue growth driving changes in the rankings. While Marsh maintains its leadership position, several companies have strengthened their positions in the global insurance brokerage market.
