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Largest insurance broker β Marsh + Guy Carpenter + Mercer + Oliver Wyman; ~$24B 2024 revenue; fee-based, not balance-sheet risk.
Largest insurance broker β Marsh + Guy Carpenter + Mercer + Oliver Wyman; ~$24B 2024 revenue; fee-based, not balance-sheet risk.
Key Milestones
Henry Marsh enters insurance brokerage 1871 in Chicago founding Marsh & McLennan precursor. Post-Chicago Fire (Oct 8-10 1871, 17,500 buildings destroyed, $222M damages) brokerage demand surges as commercial fire insurance becomes mandatory for lenders. Cornerstone of modern insurance brokerage.
Donald McLennan founds D.R. McLennan & Co 1905 in Duluth MN; specializes in railroad/lumber industry insurance. McLennan's midwest practice + Henry Marsh's east coast practice merge 1923 forming Marsh & McLennan in Chicago β origin of MMC.
Marsh & McLennan formally merged Mar 1923 in Chicago combining Henry Marsh's east coast practice + Donald McLennan's midwest practice. Becomes largest US insurance broker by 1930; pioneers concept of dedicated risk advisory rather than just product placement.
Marsh & McLennan acquires Sedgwick 1998 for $1.9B + Putnam Investments asset management 1970s + various retirement/benefits firms β builds 'risk + people + capital' platform. Jeff Greenberg (Hank Greenberg's son) leads MMC 1999-2004. Greenberg ousted Oct 2004 over Spitzer bid-rigging probe.
Marsh & McLennan Eliot Spitzer settlement Jan 2005 β pays $850M without admitting wrongdoing after Spitzer's Oct 2004 lawsuit alleging bid-rigging + steering commissions on commercial insurance placements. CEO Jeff Greenberg (son of Hank) resigns Oct 2004. Triggers industry-wide ban on contingent commissions in many states.
Brian Duperreault becomes Marsh CEO Jan 2008 β recruited from ACE; later moves to AIG CEO 2017. Brought stability after Spitzer-era controversies. Predecessor to Dan Glaser (CEO 2013-2022). MMC stock recovers from $20 (2008) to $80 (2014); Duperreault's discipline drives recovery.
Marsh McLennan acquires Jardine Lloyd Thompson (JLT) Apr 2019 for $5.6B all-cash β UK-based specialty insurance broker; largest MMC acquisition. Adds top-5 global insurance + reinsurance brokerage capabilities. CEO Dan Glaser executes acquisition; combined Marsh + JLT becomes #1 global broker by revenue.
John Doyle becomes MMC CEO Jan 2023 succeeding Dan Glaser (CEO 2013-2022). Doyle continues acquisition strategy + tech investment. MMC stock 4x's 2020-2025 from $90 to $230+ as broker fee model proves resilient through hard market + soft market.
John Doyle becomes Marsh McLennan CEO Jan 2023 β succeeds Dan Glaser (CEO 2013-2022). Doyle previously head of Marsh USA. Continues acquisition strategy + tech investment ($1.5B+ over 5 years). MMC reports $24B revenue 2024.
Marsh McLennan announces $7.75B all-cash acquisition of McGriff Insurance Brokers Sep 2024 β closes Nov 2024. McGriff (top-25 US retail commercial broker, $1.5B revenue) bought from Truist Financial as bank divests non-core. Largest broker acquisition since Aon-WTW failed. Combines with Marsh USA.
Marsh McLennan acquires McGriff Insurance Brokers Nov 2024 for $7.75B all-cash β McGriff (top-25 US retail commercial broker, $1.5B revenue) bought from Truist Financial as bank divested non-core. Largest broker acquisition since Aon-WTW failed 2021. Combines with Marsh USA to form $12B+ revenue retail commercial broker.
Marsh McLennan Q4 2025 β John Doyle CEO reports $25B+ revenue 2025; McGriff (acquired Nov 2024 $7.75B) integrating well. MMC stock $245+ all-time high. World's largest insurance broker continues compounding through hard market + soft market via diversified Marsh + Mercer + Oliver Wyman + Guy Carpenter.