How a 1927 Chicago agency became a global insurance powerhouse
In short: What began as a single Chicago insurance agency has evolved into a massive global network. Through decades of aggressive acquisitions and innovative policy structures, Arthur J. Gallagher & Co. has expanded from a local firm into a multi-billion dollar leader in risk management and brokerage services.
Founded in 1927 by Arthur Gallagher, the company's roots are tied to early industry innovations. In 1938, Gallagher helped develop The Hartford Group’s Retrospective Rating Program, which incentivized policyholders to maintain low loss records, and authored Chicago’s first large-deductible fire insurance policy for Bowman Dairy Co. Following World War II, the business transitioned into a family-led enterprise when Arthur's three sons—Jim, Bob, and John—joined in 1945, leading to formal incorporation in 1950.
The company's modern scale is the result of a relentless acquisition strategy. A pivotal period occurred between 1990 and 2000, when the firm achieved double-digit growth in nearly every year. In 2000 alone, the company acquired 16 smaller brokerages, eventually establishing a presence in all 50 U.S. states. This expansion moved beyond American borders, with entries into India and Asia in 2002, and subsequent acquisitions in the UK, Brazil, Norway, Australia, Canada, and Germany.
Currently, the business holds a major global position, appearing 367th in the Fortune 500 and 192nd within the Forbes Global 2000. Its revenue is primarily driven by insurance brokerage services, which accounted for 87% of its 2025 revenues, while risk management services—including claims processing for automobile and workers compensation—made up 13%. Its massive reach expanded during August 2025 following a $13.45 billion purchase of AssuredPartners. This transaction represents the biggest deal involving a U.S. insurance broker and a strategic buyer ever recorded in the sector.
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Sources
- Summary by Intellect · source: Arthur J. Gallagher & Co.
- Also: Wikidata — Arthur J. Gallagher & Co. · CC0
- Also: find-and-update.company-information.service.gov.uk — ARTHUR J. GALLAGHER & CO. overview - Find and update company information - GOV.UK
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