Key Marsh McLennan Stats
Marsh McLennan stands as the world’s largest insurance broker and a global leader in risk management, strategy consulting, and human capital solutions. The company operates through four market-leading businesses: Marsh, Guy Carpenter, Mercer, and Oliver Wyman.
Headquartered in New York City, Marsh McLennan serves 95% of Fortune 1000 companies. The firm advises clients across 130 countries, providing risk advisory services, insurance and reinsurance broking, retirement consulting, and management consulting. In 2024, the company achieved its 17th consecutive year of reported margin expansion.
Marsh McLennan History
Marsh McLennan Co-founders
Marsh McLennan Competitors
The global insurance brokerage market operates as an oligopoly, with Marsh McLennan, Aon, and Willis Towers Watson forming what industry analysts call the “Big Three.” These firms dominate competition for insurance services among the largest corporations worldwide.
Marsh McLennan maintains its position as the largest insurance broker globally. The company competes across multiple segments including commercial property and casualty, employee benefits, reinsurance, and management consulting.
| Company | Headquarters | Primary Services |
|---|---|---|
| Aon plc | London, UK | Risk management, insurance broking, HR solutions |
| Willis Towers Watson (WTW) | London, UK | Insurance broking, risk management, consulting |
| Arthur J. Gallagher & Co. | Rolling Meadows, USA | Insurance brokerage, risk management services |
| Brown & Brown, Inc. | Daytona Beach, USA | Insurance brokerage, third-party administration |
| Lockton Companies | Kansas City, USA | Insurance brokerage, employee benefits |
| Hub International | Chicago, USA | Insurance brokerage, employee benefits |
| Alliant Insurance Services | Newport Beach, USA | Specialty insurance, risk management |
| USI Insurance Services | Valhalla, USA | Insurance brokerage, risk consulting |
| Acrisure | Grand Rapids, USA | Insurance distribution, technology solutions |
| NFP Corp | New York, USA | Insurance distribution, wealth management |
Marsh McLennan Acquisitions
Strategic acquisitions have driven Marsh McLennan’s growth throughout its history. The company consistently pursues buyouts to expand capabilities, enter new geographies, and strengthen its market position across risk management and consulting services.
The 1923 acquisition of Guy Carpenter marked the company’s entry into reinsurance broking. This was followed by the 1975 purchase of Mercer, which established the firm’s presence in human resources consulting. The 1997 acquisition of Johnson & Higgins for $1.8 billion represented one of the largest deals in insurance brokerage history at that time.
In 2003, Marsh McLennan acquired Oliver Wyman & Company, adding management consulting to its service portfolio. The consultancy was merged with existing businesses to form the Oliver Wyman Group, which now serves as a strategic advisor to private sector and governmental clients worldwide.
The 2019 completion of the $5.6 billion Jardine Lloyd Thompson acquisition added more than 10,000 colleagues and significantly expanded the company’s specialty insurance capabilities. JLT brought deep expertise in areas including aviation, marine, and construction insurance.
November 2024 saw Marsh McLennan complete its largest single acquisition with the $7.75 billion purchase of McGriff Insurance Services. This deal added 3,500 employees and strengthened Marsh McLennan Agency’s position in the growing middle market segment. The company completed 14 acquisitions in 2023 alone, spending $716 million on nine acquisitions in the first half of 2024.
Marsh McLennan Market Cap
Marsh McLennan’s market capitalization reached approximately $87 billion in November 2025. This valuation ranks the company among the 250 most valuable publicly traded companies globally and reflects its dominant position in professional services.
Marsh McLennan Revenue
Marsh McLennan generated $24.5 billion in revenue for full-year 2024, representing 8% growth compared to 2023. The company achieved 7% underlying revenue growth and 10% adjusted earnings per share growth during the same period.