Company Overview
About Marsh McLennan
Marsh McLennan is the world's leading professional services firm in risk, strategy, and human resources, formed through the merger of Marsh & McLennan Companies and operating four market-leading subsidiaries: Marsh (global insurance broker and risk management advisor), Guy Carpenter (global reinsurance broker), Mercer (human resources and employee benefits consulting), and Oliver Wyman (management consulting). Headquartered in New York City and trading on NYSE (MMC), the company generated approximately $23.4 billion in revenues for FY2024 under CEO John Doyle, who succeeded longtime CEO Dan Glaser in 2022 and has maintained the firm's organic growth momentum and selective acquisition strategy. Marsh, the flagship insurance brokerage, is the world's largest insurance broker by revenue, advising corporations globally on risk placement, captive insurance programs, and risk management strategies across property, casualty, marine, and specialty lines.
Business Model & Competitive Advantage
Marsh McLennan's four-subsidiary model creates significant cross-sell opportunities: large corporations that rely on Marsh for insurance placement often engage Mercer for employee benefits consulting, Oliver Wyman for strategic transformation projects, and Guy Carpenter to structure their captive reinsurance programs. This institutional relationship ecosystem, deepened through decades of serving the same Global 1000 companies across risk and people dimensions, creates switching costs that insulate Marsh McLennan from pure price competition. The insurance hard market of 2019-2024, characterized by rising commercial insurance premiums driven by elevated loss trends from social inflation and catastrophe activity, has been a significant tailwind for Marsh's commission-based revenue, as broker commissions are percentage-based on premium volume.
Competitive Landscape 2025–2026
In 2025-2026, Marsh McLennan competes with Aon plc (AON) and Willis Towers Watson (WTW) as the three dominant global insurance broking and consulting conglomerates, known as the "Big Three" of insurance intermediation. Gallagher (AJG) competes aggressively as a fourth player through acquisitions, having been particularly active in the UK and Australian markets. Cyber insurance has become a major growth area: Marsh is the world's largest cyber insurance broker, helping corporations structure coverage for data breach, ransomware, and business interruption exposures that have grown dramatically as digital dependencies and threat actor sophistication have escalated. Oliver Wyman's reputation in financial services consulting—advising regulators, central banks, and systemically important financial institutions—provides differentiated positioning versus traditional management consultants.
The Marsh McLennan Story
Founders
Company Timeline
Major milestones in Marsh McLennan's journey
Leadership Team
Meet the leaders behind Marsh McLennan
John Q. Doyle
John Q. Doyle is President and CEO of Marsh McLennan, appointed to the role effective January 1, 2023, and joining the company's board of directors on the same date. Previously, Mr. Doyle served as Group President and Chief Operating Officer with responsibility for strategy and operational objectives across Marsh McLennan's four global businesses. He joined the firm in 2016 as President of Marsh, then led Marsh as President and CEO from 2017 to 2021. An industry veteran with more than 35 years of management experience, Mr. Doyle began his career at AIG where he held several executive positions. He leads a company generating $24.5 billion in annual revenue with over 90,000 colleagues worldwide.
Mark McGivney
Mark McGivney serves as Chief Financial Officer of Marsh McLennan Companies, overseeing all financial management, corporate development, treasury, and investor relations functions for the global organization. He joined the company in 2007 and has held numerous senior financial management positions including CFO of Marsh, CFO and COO of Mercer, and Senior Vice President of Corporate Finance for Marsh McLennan where he led Corporate Development, Treasury and Investor Relations. In his current role, McGivney has overseen the company's 17 consecutive years of margin expansion and led the financial aspects of major acquisitions including the $7.75 billion McGriff Insurance Services acquisition in 2024.
Martin South
Martin South serves as President and Chief Executive Officer of Marsh, the world's largest insurance broker and risk advisor, which generates over $13 billion in annual revenue (53% of Marsh McLennan's total). South leads Marsh's global operations across commercial and consumer insurance broking, risk management, insurance program management, risk consulting, analytical modeling, and alternative risk financing services. Under his leadership, Marsh achieved 10% revenue growth in 2024 with 7% underlying growth, serving clients across every industry sector and geographic region through Marsh's extensive global network.
Dean Klisura
Dean Klisura serves as President and Chief Executive Officer of Guy Carpenter, the global leader in risk and reinsurance services, and as Vice Chair of Marsh McLennan. He leads Guy Carpenter's $2.4 billion business (representing 10% of Marsh McLennan revenues) which achieved 8% underlying growth in 2024. Klisura oversees the company's reinsurance broking expertise, strategic advisory services, and analytics capabilities that help insurance companies manage their risk portfolios through sophisticated reinsurance strategies. His dual role as Vice Chair of Marsh McLennan reflects Guy Carpenter's strategic importance and his cross-business leadership responsibilities.
Pat Tomlinson
Pat Tomlinson serves as President and Chief Executive Officer of Mercer, the global leader in human resources consulting, health, wealth, and career solutions. Tomlinson leads Mercer's $5.7 billion business which achieved 3% revenue growth in 2024, delivering advice and technology-driven solutions that help organizations redefine the world of work, reshape retirement and investment outcomes, and unlock health and well-being for a changing workforce. Mercer serves clients globally with expertise in talent strategy, retirement plan design and administration, health and benefits consulting, investment consulting, and HR technology platforms.
Nick Studer
Nick Studer serves as President and Chief Executive Officer of Oliver Wyman Group, the premier management consulting firm specializing in strategy, economic analysis, and industry expertise. Studer leads Oliver Wyman's $3.4 billion business which achieved impressive 9% revenue growth in 2024. Oliver Wyman Group serves as a critical strategic, economic, and brand advisor to private sector and governmental clients across financial services, retail, transportation, energy, healthcare, and other industries. The firm combines deep industry knowledge with advanced analytics, economic modeling, and strategic frameworks to help clients navigate complex business challenges and capture growth opportunities.
Katherine J. Brennan
Katherine J. Brennan serves as Senior Vice President and General Counsel of Marsh McLennan, leading the company's global legal, compliance, and public affairs functions that support all four businesses—Marsh, Guy Carpenter, Mercer, and Oliver Wyman. Brennan also leads the company's Environmental, Social, and Governance (ESG) efforts, overseeing sustainability initiatives, diversity and inclusion programs, and corporate responsibility strategies. Her portfolio includes managing legal and regulatory compliance across 130 countries, intellectual property protection, corporate governance, major transaction support including the $7.75 billion McGriff acquisition, and stakeholder engagement with regulators, policymakers, and industry associations globally.
Paul Beswick
Paul Beswick serves as Senior Vice President and Global Chief Information and Operations Officer of Marsh McLennan, leading the company's Business and Client Services function which integrates Operations and Technology teams supporting all four global businesses. Beswick oversees technology infrastructure, cybersecurity, data management and analytics platforms, digital transformation initiatives, operational excellence programs, and client service delivery systems that enable 90,000+ colleagues to serve clients across 130 countries. His organization drives the technology and operational capabilities that support Marsh McLennan's data-driven risk advisory, consulting, and analytics services while ensuring security, reliability, and scalability of critical business systems.
Open Positions
Reddit Discussions
Key Differentiators
Market Leader
Marsh McLennan is recognized as a market leader in the Consumer Finance sector, demonstrating strong industry presence and customer trust.
Enterprise Scale
With $23400M in revenue, Marsh McLennan operates at enterprise scale with proven market validation.
Frequently Asked Questions
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