Marsh & McLennan Companies

Marsh McLennan, historically known as Marsh & McLennan Companies, is a United States-based professional services group headquartered in New York City. Its principal activities span insurance brokerage, risk management, reinsurance intermediation, employee benefits, retirement and investment consulting, organizational and human-capital advisory, and management consulting. The group operates through four principal businesses: Marsh, Marsh Re, Mercer, and Oliver Wyman. It is widely described as the world's largest insurance broker. The company's origins date to Chicago in 1905, when Henry W. Marsh and Donald R. McLennan combined their respective businesses. Henry Marsh had established an insurance-related business after the Great Chicago Fire, when the failure of many insurers highlighted the need for professional risk advice and brokerage. The combined enterprise adopted the Marsh & McLennan name in 1906. Over the following decades, the group expanded beyond traditional insurance placement by acquiring or building businesses in reinsurance, employee benefits, investment consulting, and management consulting. Guy Carpenter, founded in 1923 and acquired by Marsh & McLennan in the same decade, became the foundation of the group's reinsurance-intermediary activities. Mercer was acquired in 1959 and developed into a major provider of employer consulting, including health benefits, retirement plans, pensions, investment advice, and workforce strategy. The company became publicly traded through an initial public offering in 1962 and adopted a holding-company structure in 1969, allowing separately managed businesses to serve clients under distinct specialist brands. The group strengthened its insurance-brokerage position through the 1997 acquisition of Johnson & Higgins, a major competitor at the time. Its consulting platform also evolved through the combination of Temple, Barker & Sloane, Strategic Planning Associates, Mercer Management Consulting, and related businesses. The 2003 acquisition of Oliver Wyman created a stronger management-consulting presence, particularly in financial services and other complex industries. In 2007, several Mercer consulting units were consolidated into Oliver Wyman, while Putnam Investments was sold as the company concentrated on risk, insurance, and human-capital services. Kroll was subsequently divested in 2010. Marsh McLennan suffered a major human loss during the September 11, 2001 attacks. Its Marsh offices occupied floors 93 through 100 of the World Trade Center's North Tower, and the company lost 295 employees and 63 contractors. A memorial is located near the group's New York headquarters. The company faced a severe reputational and legal crisis during the 2004 insurance-industry bid-rigging investigation. New York Attorney General Eliot Spitzer alleged that Marsh's compensation arrangements and placement practices compromised its neutrality as an insurance broker. Marsh agreed in early 2005 to pay $850 million to settle the case and compensate affected commercial-insurance clients. The episode prompted organizational changes and reinforced the group's focus on risk and consulting services. In more recent years, the company has pursued scale in insurance distribution and specialist advice. It acquired Jardine Lloyd Thompson in 2019 for £4.3 billion, rebranded as Marsh McLennan in 2021, and acquired McGriff Insurance Services in 2024 for $7.75 billion. In 2025, its subsidiaries were rebranded under the Marsh name, including the former Guy Carpenter business as Marsh Re. Based on the cited reference material, 2025 revenue was distributed approximately 54% to Marsh, 10% to Marsh Re, 23% to Mercer, and 13% to Oliver Wyman. The group therefore combines a dominant insurance and risk platform with substantial consulting and human-capital operations.

Marsh McLennan began in Chicago in 1905 through the merger of businesses established by Henry W. Marsh and Donald R. McLennan. Marsh's earlier business emerged in the aftermath of the Great Chicago Fire, when widespread insurer failures increased demand for professional insurance advice. The combined company became known as Marsh & McLennan in 1906. The group expanded its insurance capabilities through the acquisition of Guy Carpenter in 1923. Founded by Guy Carpenter one year earlier, the firm became a major reinsurance intermediary and adviser. In 1959, Marsh acquired Mercer, adding a human-resources and employee-consulting business that later grew into a global platform covering health benefits, retirement, pensions, investments, and workforce strategy. Marsh & McLennan became a public company through an initial public offering in 1962. In 1969, it reorganized as a holding company whose businesses operated through separately managed specialist companies. The group entered investment management through the 1970 acquisition of Putnam Investments. It later broadened its consulting operations through the acquisition of Temple, Barker & Sloane in 1987 and the merger with Strategic Planning Associates in 1989. Those consulting activities were combined in 1990 to form Mercer Management Consulting. The 1997 acquisition of Johnson & Higgins for $1.8 billion substantially increased Marsh's insurance-brokerage scale and restored the group to a leading position over Aon in global brokerage. Mercer acquired Delta Consulting Group in 2000, adding organizational-development and change-management capabilities. The September 11 attacks caused an exceptional loss for the company: Marsh's North Tower offices occupied floors 93 through 100, and 295 employees and 63 contractors died. Marsh & McLennan acquired Oliver Wyman in 2003. In 2004, Marsh's brokerage business became involved in an industry-wide bid-rigging controversy. New York Attorney General Eliot Spitzer alleged that the broker's compensation and placement practices could lead to conflicts of interest and higher client costs. Marsh settled the lawsuit in early 2005 for $850 million, including client compensation. The episode led to organizational changes and a sharper emphasis on insurance services and consulting. The group expanded internationally in 2007 when Marsh received a Chinese license for a wholly owned foreign insurance brokerage. That year, Mercer consulting units were consolidated into Oliver Wyman, while Putnam Investments was sold to Power Financial for $3.9 billion. Brian Duperreault became chief executive in 2008. The company sold Kroll to Altegrity in 2010 after divesting several related activities, continuing its focus on core risk and consulting businesses. In 2019, Marsh McLennan acquired Jardine Lloyd Thompson for £4.3 billion. The company adopted the Marsh McLennan corporate name in 2021. John Doyle, who led Marsh from 2017 to 2022, became president and chief executive of the parent company on January 1, 2023. The group announced the acquisition of McGriff Insurance Services for $7.75 billion in 2024. Reference material for 2025 describes further brand consolidation under Marsh, including the renaming of Guy Carpenter as Marsh Re. The modern group combines insurance brokerage and risk services, reinsurance, human-capital consulting, and management consulting through its four principal operating businesses.

1. 2025Subsidiary brands consolidated under Marsh

   Reference material describes the rebranding of subsidiaries under the Marsh identity, including the former Guy Carpenter business as Marsh Re.

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2. 2024McGriff Insurance Services acquisition

   The company acquired McGriff Insurance Services for $7.75 billion.

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3. 2021Corporate rebrand to Marsh McLennan

   The group changed its corporate brand from Marsh & McLennan Companies to Marsh McLennan.

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4. 2019Jardine Lloyd Thompson acquisition

   Marsh McLennan acquired Jardine Lloyd Thompson for £4.3 billion.

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5. 2007China brokerage license and consulting consolidation

   Marsh obtained a wholly owned foreign brokerage license in China, while three Mercer consulting units were combined into Oliver Wyman.

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6. 2005Insurance-practices settlement

   Marsh agreed to an $850 million settlement connected with bid-rigging allegations and client compensation.

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7. 2003Oliver Wyman is acquired

   The acquisition strengthened management consulting, especially in financial services.

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8. 1997Johnson & Higgins is acquired

   The $1.8 billion acquisition substantially expanded Marsh's insurance-brokerage operations.

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9. 1990Mercer Management Consulting is formed

   Temple, Barker & Sloane and Strategic Planning Associates were combined into Mercer Management Consulting.

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10. 1989Strategic Planning Associates joins the group

    The Washington, D.C.-based strategy consultancy merged with Marsh & McLennan.

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11. 1987Temple, Barker & Sloane is acquired

    The acquisition strengthened Marsh & McLennan's management-consulting activities.

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12. 1970Putnam Investments is acquired

    The acquisition added investment and mutual-fund management to the group's portfolio.

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13. 1969Holding-company reorganization

    The company reorganized under a holding-company structure with separately managed operating businesses.

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14. 1962Initial public offering

    Marsh & McLennan became a publicly traded company.

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15. 1959Mercer is acquired

    The acquisition of Mercer expanded the group into human-resources and employer consulting.

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16. 1923Guy Carpenter joins the group

    Marsh acquired Guy Carpenter, founded in 1922, establishing a major reinsurance-intermediary capability.

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17. 1906The company adopts the Marsh & McLennan name

    The merged enterprise was renamed Marsh & McLennan.

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18. 1905Marsh and McLennan businesses merge

    Henry W. Marsh and Donald R. McLennan combined their Chicago businesses to form the company that became Marsh & McLennan.

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19. 1871Henry W. Marsh establishes an insurance business

    Henry W. Marsh founded the predecessor business that later became part of Marsh & McLennan, in a period shaped by the insurance failures following the Great Chicago Fire.

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A global specialist-services group positioned at the intersection of insurance, enterprise risk, human capital, investment advisory, and management consulting. Its differentiation rests on the scale of Marsh's brokerage network, the technical reinsurance expertise of Marsh Re, Mercer's employer and workforce advisory capabilities, and Oliver Wyman's strategy and industry consulting platform.

• MarshInsurance brokerage and risk management

  Marsh is the group's principal insurance-brokerage and risk-advisory business. It helps commercial and institutional clients identify, quantify, finance, and transfer risk. Its activities include insurance broking, risk consulting, insurance-program management, analytical modeling, and alternative risk-financing arrangements. The business accounted for approximately 54% of group revenue in the 2025 figures cited in the reference material.

• Marsh ReReinsurance brokerage and advisory1922

  Marsh Re is the group's reinsurance-intermediation and advisory platform, formerly known as Guy Carpenter. It advises insurers and other risk-bearing organizations on reinsurance structures, catastrophe exposure, capital management, analytics, and related risk-transfer solutions. The business represented approximately 10% of 2025 group revenue according to the cited reference material.

• MercerHuman capital and investment consulting

  Mercer advises employers and institutions on employee health benefits, retirement and pension plans, investment strategy, workforce effectiveness, compensation, and broader human-capital questions. It grew from the human-resources consulting business acquired by Marsh in 1959 and remains one of the group's principal operating companies. Mercer represented approximately 23% of 2025 group revenue in the cited reference material.

• Oliver WymanManagement consulting

  Oliver Wyman provides strategy, operations, organization, risk, and transformation consulting. It has a notable financial-services orientation but serves clients across multiple industries. The platform includes Lippincott and NERA Economic Consulting and incorporates consulting activities consolidated from several Mercer units in 2007. Oliver Wyman represented approximately 13% of 2025 group revenue in the cited reference material.

• LippincottBrand and design consulting

  Lippincott is part of the Oliver Wyman consulting platform and provides brand, design, customer-experience, and identity-related advisory services. The available reference material identifies it as part of Oliver Wyman but does not provide a separate founding or launch date for its position within the group.

• NERA Economic ConsultingEconomic consulting

  NERA Economic Consulting operates within the Oliver Wyman platform and provides economic analysis and expert advice for competition, regulation, litigation, policy, and other complex commercial matters. The cited material identifies NERA as part of Oliver Wyman without supplying separate product-launch information.

• 2025Consolidate subsidiary branding under MarshStrategy

  The group pursued greater brand consistency across its insurance and reinsurance operations.

  What changed. Reference material describes the rebranding of subsidiaries under the Marsh name, including Guy Carpenter as Marsh Re.

  Aftermath. The change created a more unified Marsh identity across the group's insurance businesses.

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• 2024Acquire McGriff Insurance ServicesM&A

  Marsh McLennan continued expanding its insurance-distribution platform through acquisitions.

  What changed. The company acquired McGriff Insurance Services.

  Aftermath. The transaction strengthened the group's insurance-brokerage presence.

  Acquisition consideration. $7.75 billion (2024)

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• 2021Adopt the Marsh McLennan corporate brandStrategy

  The company sought a corporate identity that connected the parent group with its best-known Marsh operating business while retaining specialist businesses.

  What changed. Marsh & McLennan Companies rebranded as Marsh McLennan.

  Aftermath. The new identity became the group's principal corporate brand.

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• 2019Acquire Jardine Lloyd ThompsonM&A

  The acquisition was intended to expand Marsh McLennan's global insurance-brokerage and risk-advisory scale.

  What changed. Marsh McLennan acquired Jardine Lloyd Thompson for £4.3 billion.

  Aftermath. The transaction expanded the group's international insurance and specialty-risk footprint.

  Acquisition consideration. £4.3 billion (2019)

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• 2010Divest KrollM&A

  The group was reducing exposure to businesses outside its central risk and consulting portfolio.

  What changed. Marsh McLennan sold Kroll, its corporate intelligence and investigations unit, to Altegrity.

  Aftermath. The divestiture continued the company's concentration on core insurance, risk, human-capital, and consulting services.

  Sale consideration. $1.13 billion (2010)

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• 2007Sell Putnam InvestmentsM&A

  Marsh McLennan chose to concentrate on risk, insurance, and human-capital activities rather than retain its investment-management business.

  What changed. The company sold Putnam Investments to Power Financial.

  Aftermath. The divestiture simplified the portfolio and increased the strategic emphasis on the group's insurance and consulting operations.

  Sale consideration. $3.9 billion (2007)

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• 2005Reorganize after the insurance-practices settlementStrategy

  The bid-rigging and broker-compensation controversy created legal, regulatory, and reputational pressure on Marsh's brokerage model.

  What changed. Marsh McLennan reorganized its activities and refocused the group around insurance services and consulting.

  Aftermath. The company paid $850 million to settle the lawsuit and compensate affected clients, while continuing to develop its risk and consulting businesses.

  Settlement and client compensation. $850 million (2005)

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• 2004Insurance bid-rigging and broker-compensation controversyControversy

  Marsh's insurance-brokerage business became a central subject of an investigation into bid rigging and contingent compensation practices affecting the insurance industry. New York Attorney General Eliot Spitzer alleged that Marsh's arrangements and placement practices could prevent it from acting as an unbiased broker and could increase client costs while increasing Marsh's revenue. The company agreed in early 2005 to pay $850 million to settle the lawsuit and compensate commercial-insurance clients whose policies had been arranged between 2001 and 2004. The controversy led to internal reorganization and a renewed focus on insurance services and consulting.

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• 2001September 11 World Trade Center lossesControversy

  Marsh occupied eight floors of the North Tower of the World Trade Center, including floors 93 through 100. The aircraft impact destroyed or blocked the stairways and elevators serving the impact area. The company lost 295 employees and 63 contractors. A memorial to those killed is located near the company's New York headquarters.

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• 2025Marsh McLennan reports a diversified 2025 operating portfolio

  Reference material attributed approximately 54% of 2025 revenue to Marsh, 10% to Marsh Re, 23% to Mercer, and 13% to Oliver Wyman.

  Other
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• 2025Marsh McLennan rebrands subsidiaries under Marsh

  The group's subsidiaries were rebranded under the Marsh name, with the former Guy Carpenter business identified as Marsh Re.

  Other
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• 2024Marsh McLennan agrees to acquire McGriff Insurance Services

  The company acquired McGriff Insurance Services for $7.75 billion, strengthening its insurance-distribution platform.

  M&A
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• 2023John Doyle becomes chief executive of Marsh McLennan

  John Doyle, previously president and chief executive of Marsh, succeeded Dan Glaser as president and chief executive of the parent group on January 1, 2023.

  Leadership change
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• 2021Marsh & McLennan Companies rebrands as Marsh McLennan

  The company adopted Marsh McLennan as its corporate brand, linking the parent identity more closely with its best-known operating business.

  Other
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• 2019Marsh McLennan completes acquisition of Jardine Lloyd Thompson

  The group acquired insurance broker and adviser Jardine Lloyd Thompson for £4.3 billion, materially expanding its brokerage and risk-services scale.

  M&A
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• 2010Marsh McLennan sells Kroll

  The company sold its corporate intelligence and investigations unit, Kroll, to Altegrity, continuing the divestment of non-core activities.

  M&A
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• 2007Marsh receives approval to operate a wholly owned insurance brokerage in China

  Marsh received the first license for a wholly owned foreign insurance-brokerage company to operate in China.

  Regulation
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• 2007Marsh McLennan sells Putnam Investments

  The group sold Putnam Investments to Power Financial as part of a strategy to concentrate on risk, insurance, and human-capital businesses.

  M&A
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1. Marsh McLennan