Arthur J. Gallagher & Co.
Arthur J. Gallagher & Co. (AJG)
Overview
Arthur J. Gallagher & Co. is one of the world's largest insurance brokerage, risk management, and consulting firms. Founded in Chicago in 1927 by Arthur J. Gallagher and headquartered today in Rolling Meadows, Illinois (a Chicago suburb), the company has grown from a local agency into a global operation serving clients in more than 130 countries. Gallagher is a large-cap company by any measure: it generated roughly $13 billion in revenue in fiscal 2025 (trailing-twelve-month revenue has since climbed toward $15 billion amid a major acquisition), employs more than 72,000 people worldwide, and sits in the S&P 500 Financials sector (Insurance Brokers industry).
What They Do & How They Make Money
Gallagher doesn't underwrite insurance risk itself — it's not an insurance company that pays claims out of its own capital. Instead, it acts as an intermediary: brokering insurance and reinsurance placements between clients (businesses, municipalities, nonprofits, individuals) and the insurance carriers that actually assume the risk, and it earns commissions and fees for doing so. On the brokerage side, Gallagher advises clients on their risk exposures (property, casualty, cyber, executive liability, employee benefits, and specialty lines), shops that risk to insurance and reinsurance markets, negotiates terms and pricing, and places the policy — collecting a commission (typically a percentage of premium) or a flat fee, plus ongoing renewal commissions each year the policy stays in force. It also runs a growing reinsurance brokerage arm that places risk between primary insurers and reinsurers. On the risk management side, Gallagher operates a separate fee-based consulting and third-party claims administration business, helping self-insured employers manage workers' compensation and auto liability claims, safety programs, and risk consulting — a model that earns fees rather than commissions and is less tied to insurance pricing cycles. A defining feature of Gallagher's growth strategy is aggressive, continuous "tuck-in" mergers and acquisitions of smaller regional and specialty brokerages, which it has used for decades to expand geographic reach, add specialty expertise, and grow scale faster than organic growth alone would allow — most recently highlighted by its roughly $13.8 billion acquisition of AssuredPartners, one of the largest deals in brokerage industry history.
Business Segments
Gallagher reports primarily through two major segments, with a growing HR/benefits consulting capability increasingly woven through both:
- Brokerage — By far the largest segment (roughly 86% of revenue). Covers retail insurance brokerage (property/casualty, employee benefits, executive/professional liability for businesses of all sizes), wholesale brokerage (placing hard-to-place, specialty, or excess/surplus lines risk on behalf of other retail brokers), and reinsurance brokerage (advising insurance carriers on ceding risk to reinsurers). This segment earns commissions and fees tied to policy placement and renewal.
- Risk Management — The smaller segment (roughly 14% of revenue), operating mainly under the Gallagher Bassett brand. Provides third-party claims administration, workers' compensation and auto liability claims processing, and risk consulting services for self-insured and large-deductible clients — a fee-for-service business less exposed to insurance-market pricing cycles than brokerage commissions.
Gallagher also has a substantial HR & benefits consulting capability (retirement plan consulting, compensation consulting, HR technology) that spans both segments and has grown significantly through acquisitions.
Competitors
- Global "Big Three" insurance brokers (closest direct competitors): Marsh & McLennan Companies (parent of Marsh and Mercer), Aon plc, and Willis Towers Watson — together with Gallagher these four dominate large commercial and global insurance brokerage.
- Mid-market and specialty brokerage: Brown & Brown, Hub International, Alliant Insurance Services, USI Insurance Services, Lockton (private).
- Reinsurance brokerage: Guy Carpenter (Marsh McLennan), Aon Reinsurance Solutions, Howden Re.
- Risk management/claims administration: Sedgwick, Crawford & Company, ESIS (Chubb).
- Regional/independent agencies: Thousands of smaller local and regional brokerages, many of which are themselves the ongoing acquisition targets that fuel Gallagher's (and its peers') growth.
Competitive Position
Gallagher's competitive advantage rests on scale, breadth, and a distinctive, well-honed M&A engine: the company has built one of the industry's most systematic and disciplined acquisition programs, continuously buying smaller brokerages and specialty firms at reasonable multiples, integrating them onto Gallagher's platform, and cross-selling additional products (benefits, risk management, specialty lines) into the acquired client base — a flywheel that has compounded revenue and earnings for decades and that few competitors execute as consistently. Its Gallagher Bassett risk management arm provides a diversifying, fee-based revenue stream that is less sensitive to the cyclical "hard" and "soft" pricing swings of the insurance market than pure brokerage commissions. Global reach across 130+ countries and deep specialty expertise (construction, healthcare, public entity, cyber, executive liability, and more) give it access to a broad range of client segments, from small businesses to large multinationals.
Key risks include integration risk from its rapid acquisition pace — most notably the roughly $13.8 billion AssuredPartners acquisition, one of the largest deals ever in the brokerage sector, which carries meaningful execution and culture-integration risk even for an experienced acquirer like Gallagher. The brokerage business is also exposed to the insurance underwriting cycle: when property-casualty insurance pricing softens (as it has been doing across several commercial lines), commission revenue growth slows even if the volume of business Gallagher places stays flat, and recent results have shown organic growth moderating even as acquisition-driven growth stays strong. Intensifying competition from both the other "Big Four" global brokers and well-capitalized private-equity-backed regional consolidators (Hub, Alliant, USI) continues to bid up valuations for the same acquisition targets Gallagher relies on for growth, which could compress future deal economics. Finally, like all brokers, Gallagher carries some exposure to errors-and-omissions liability, regulatory scrutiny of broker compensation practices (contingent commissions), and macro sensitivity to insured economic activity.