Marsh & McLennan Companies Inc.
Marsh McLennan (MMC)
Note: this company's official NYSE ticker is MMC, not MRSH; this file uses the filename requested but the content below refers to the company by its correct market symbol, MMC.
Overview
Marsh McLennan is the world's largest insurance broker and a leading global professional services firm advising clients on risk, strategy, and people. Headquartered in New York City, the company operates in the financial services/insurance sector and trades on the NYSE. Marsh McLennan generated roughly $27-28 billion in annual revenue on a trailing basis heading into 2026, with net income in the multi-billion-dollar range, and employs around 95,000-plus colleagues across more than 130 countries. The firm was built through more than a century of organic growth and large-scale acquisitions, and today functions as a holding company for several distinct, historically independent professional-services brands.
What They Do & How They Make Money
Marsh McLennan does not itself underwrite insurance risk; instead it earns fees and commissions for advising clients on how to identify, transfer, and manage risk, and separately for consulting on human capital, retirement, and corporate strategy. Its largest income stream comes from insurance brokerage: acting as an intermediary between corporations, institutions, and individuals (the insureds) and insurance carriers, negotiating coverage and placing policies in exchange for broker commissions and fees, and helping large or complex risks get reinsured. A second major stream comes from consulting: designing and administering employee benefits and retirement programs for corporate clients, and advising executives on strategy, operations, pricing, and organizational design. Because brokerage and consulting revenue is largely fee- and commission-based rather than balance-sheet risk-based, Marsh McLennan's earnings are less exposed to underwriting losses than a traditional insurer, though brokerage commissions do correlate with insurance pricing cycles ("hard" vs. "soft" markets) and with the overall volume of insured economic activity.
Business Segments
Marsh McLennan organizes itself into two broad reporting groupings — Risk and Insurance Services, and Consulting — built from four operating businesses:
- Marsh — the company's flagship insurance brokerage, placing commercial and personal insurance for corporations, public entities, and individuals worldwide; the largest single contributor to revenue and operating profit.
- Guy Carpenter (rebranded internally in parts of the business toward "Marsh Re") — a reinsurance broker and risk/reinsurance advisor, helping insurance companies transfer catastrophic and large-scale risk to the global reinsurance and capital markets.
- Mercer — a human-capital and retirement consultant, advising employers on health benefits, retirement plans, workforce strategy, and investment consulting for pension assets.
- Oliver Wyman — a management consultancy (which also houses Lippincott, a brand consultancy, and NERA Economic Consulting) advising corporate and public-sector clients on strategy, operations, risk, and economics.
Together, the Risk and Insurance Services businesses (Marsh and Guy Carpenter) contribute roughly three-fifths of revenue and an even larger share of operating profit, while the Consulting businesses (Mercer and Oliver Wyman) contribute the remainder — a split that has shifted somewhat over time as Marsh McLennan has directed more acquisition capital toward brokerage (including its 2024 purchase of McGriff Insurance Services) than consulting.
Competitors
In insurance brokerage and risk management, Marsh McLennan's chief global rivals are Aon plc and Willis Towers Watson (WTW), both of which compete directly with Marsh in commercial brokerage and with Guy Carpenter in reinsurance broking; Arthur J. Gallagher & Co. is a fast-growing mid-market and specialty competitor. In reinsurance broking specifically, Guy Carpenter competes with Aon Reinsurance Solutions and Howden Re (formerly TigerRisk). In human-capital consulting, Mercer competes with Aon's talent/wealth business, WTW's human capital practice, and benefits specialists such as Alight and Willis-adjacent players. In management consulting, Oliver Wyman competes with McKinsey, Boston Consulting Group, Bain, and the consulting arms of the "Big Four" accounting firms (Deloitte, PwC, EY, KPMG) as well as Accenture.
Competitive Position
Marsh McLennan's moat rests on scale, breadth, and client entrenchment: it is the largest broker in a global insurance-distribution market that has consolidated around a handful of major players, giving it negotiating leverage with carriers, a wide specialty-practice footprint (from cyber to aviation to political risk), and a data/analytics advantage from placing an enormous volume of risk each year. Its four-business structure lets it cross-sell risk, reinsurance, benefits, and strategy advice to the same large corporate accounts, deepening client relationships and switching costs. Long-tenured broker relationships and multi-year benefits/retirement mandates provide recurring, relatively sticky revenue. Key risks include cyclicality tied to insurance pricing cycles (a prolonged "soft market" pressures commission growth), regulatory and conflict-of-interest scrutiny of broker compensation practices (an issue that produced a large settlement in the mid-2000s and remains a live regulatory topic globally), integration risk from its acquisition-heavy growth strategy (it has done numerous large deals, including McGriff and Jardine Lloyd Thompson), competitive fee pressure from larger self-insured or captive-insurance clients, and macro sensitivity in the consulting segments to corporate budget cuts during downturns.