Understand any stock in simple English
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Marsh & McLennan Companies, Inc.
Marsh McLennan is a professional services firm that helps businesses buy insurance, manage risk, and run their employee benefits and consulting needs.
Marsh McLennan is the world's biggest insurance broker. When a company needs insurance — for its factories, its ships, its office buildings, or the people who work for it — it rarely buys that coverage directly from an insurer. It hires a broker to shop around, negotiate terms, and check that the insurer is good for the money. Marsh McLennan does that, and it gets paid mostly by commission on the policies it places, plus fees for advice. It sits in the middle of the insurance world, not as the risk-taker but as the matchmaker and the expert guide.
The company runs four main businesses. Marsh is the insurance brokerage and risk advisory arm, serving big companies around the world. Guy Carpenter does the same job for reinsurance — insurance for insurance companies, so that a single hurricane doesn't wipe out an insurer. Mercer is the people business: it advises companies on employee benefits, pensions, and talent, and it runs investment consulting for retirement plans. Oliver Wyman is the management consulting arm, helping banks, insurers, and governments with strategy and regulation. Each piece serves a different buyer, but they share the same customer base of large organizations and the same basic skill: deep expertise sold by the hour and the deal. The appeal to customers is simple. Insurance is complicated, and getting it wrong is expensive. A company that buys the wrong coverage, or buys from an insurer that later collapses, can be ruined by one fire or lawsuit. A broker that knows the market, reads the fine print, and has clout with insurers is worth paying for. Scale matters too: Marsh McLennan's size gives it data and relationships that a small local broker can't match. The business is also remarkably steady, because insurance buying doesn't stop in a recession — if anything, hard markets with rising premiums can help, since commissions rise with the price of coverage.
Its main rivals are other big brokers: Aon and Arthur J. Gallagher in insurance, and the consulting arms face a crowded field that includes the big accounting firms. Marsh McLennan is headquartered in New York and has been around since 1871, when it started as a Chicago insurance agency. It has grown largely by buying smaller firms — hundreds of them over the decades — and by keeping the local relationships those firms brought with them. The company generates a lot of cash, and it returns much of it to shareholders through dividends and buybacks while still funding acquisitions. The persistent risk to watch is conflict of interest: a broker that earns commissions from insurers can be tempted to steer clients toward the policies that pay it best, which is why regulators keep a close eye on the industry.
Saved answer · last researched 12 Nov 2026