Marsh McLennan

Marsh McLennan is an American professional services group headquartered in New York City. It operates through four principal businesses: Marsh, Marsh Re, Mercer, and Oliver Wyman. Together, these businesses advise organizations on insurance placement, risk financing, catastrophe and reinsurance exposure, employee benefits, retirement programs, investments, workforce strategy, economic analysis, and corporate management. The company traces its origins to the insurance brokerage business established by Henry W. Marsh in Chicago in 1871, after the Great Chicago Fire disrupted the local insurance market. In 1905, Marsh combined his business with that of Donald R. McLennan to create Burroughs, Marsh & McLennan; the company adopted the Marsh & McLennan name in 1906. Its subsequent development combined organic growth with acquisitions in brokerage, reinsurance, investment management, human resources, and strategy consulting. Marsh McLennan's major operating brands have distinct roles. Marsh is its insurance brokerage and risk-advisory business, helping commercial and public-sector clients identify exposures, purchase insurance, structure alternative risk-financing arrangements, and manage claims and risk programs. Marsh Re, historically associated with Guy Carpenter, acts as a reinsurance intermediary and adviser for insurers and other risk carriers. Mercer advises employers, institutions, and investors on health benefits, retirement and pension arrangements, investment matters, workforce transformation, and talent strategy. Oliver Wyman provides management consulting, with work spanning financial services, operations, strategy, public policy, risk, and sector-specific transformation; its group also includes Lippincott and NERA Economic Consulting. The company became publicly traded in 1962 and later adopted a holding-company structure that allowed its operating businesses to retain specialized identities. Its portfolio expanded significantly through the acquisitions of Guy Carpenter, Mercer, Johnson & Higgins, Oliver Wyman, and Jardine Lloyd Thompson. It also exited businesses that were less central to its long-term focus, including Putnam Investments and Kroll. These moves progressively concentrated the group on risk, insurance, people, and management advisory services. Marsh McLennan faced a major reputational and legal crisis in the mid-2000s when its Marsh brokerage unit was accused by New York authorities of bid rigging and conflicts of interest in commercial insurance placement. In 2005, the company agreed to an $850 million settlement and client-compensation arrangement. The episode prompted changes to brokerage practices and accelerated a strategic emphasis on risk and consulting services. The company was deeply affected by the September 11, 2001 attacks: Marsh occupied much of the impact zone in the North Tower of the World Trade Center and lost 295 employees and 63 contractors. A memorial to those killed is located near the company's New York headquarters. In 2021, the corporate identity changed from Marsh & McLennan Companies to Marsh McLennan. The group continued expanding its insurance-brokerage platform, including the acquisition of Jardine Lloyd Thompson in 2019 and McGriff Insurance Services in 2024. In 2025, its subsidiaries were reported as being rebranded under the Marsh name. Marsh McLennan is widely regarded as the world's largest insurance broker and combines a large-scale insurance platform with global consulting capabilities.

Marsh McLennan developed from an insurance brokerage founded by Henry W. Marsh in Chicago in 1871. Marsh established the business after the Great Chicago Fire disrupted the insurance market and caused many insurers to fail. In 1905, Henry W. Marsh and Donald R. McLennan combined their businesses to form Burroughs, Marsh & McLennan. The company was renamed Marsh & McLennan in 1906. The group broadened its insurance capabilities through the 1923 acquisition of Guy Carpenter, a reinsurance intermediary founded the previous year. Mercer was acquired in 1959, adding human-resources and employee-benefits consulting. Marsh & McLennan became a public company through an initial public offering in 1962. In 1969, it reorganized as a holding company, allowing its businesses to operate under specialized identities while sharing ownership and strategic direction. The company entered investment management in 1970 through the acquisition of Putnam Investments. It later expanded its management-consulting activities by acquiring Temple, Barker & Sloane in 1987 and merging with Strategic Planning Associates in 1989. Those consulting operations were combined in 1990 to form Mercer Management Consulting. In 1997, the $1.8 billion acquisition of Johnson & Higgins substantially increased the scale of the insurance-brokerage business and helped Marsh & McLennan regain the position of the world's largest insurance broker. Mercer acquired Delta Consulting Group in 2000 for organizational-development and change-management expertise. The September 11 attacks had a devastating effect on the company: Marsh occupied eight floors of the World Trade Center's North Tower, including the floors across the aircraft impact zone. The company lost 295 employees and 63 contractors. A memorial is located beside the group's New York headquarters. In 2003, Marsh & McLennan acquired Oliver Wyman, a consulting firm with a strong financial-services practice. In 2004, its Marsh brokerage operation became involved in a major insurance-industry bid-rigging and contingent-commission controversy. New York Attorney General Eliot Spitzer alleged that Marsh had not acted as an impartial broker and that the arrangements could raise client costs while increasing broker revenue. In early 2005, Marsh agreed to an $850 million settlement and compensation program. The crisis led to operational changes and reinforced the group's focus on insurance services and consulting. The company received a significant regulatory milestone in China in 2007, when Marsh obtained the first license reported for a wholly owned foreign insurance-brokerage company there. That year, three Mercer consulting units were combined into Oliver Wyman. Marsh & McLennan also sold Putnam Investments to Power Financial for $3.9 billion, emphasizing its core risk and human-capital activities. In 2010, it sold Kroll to Altegrity for $1.13 billion after divesting several smaller Kroll operations. Brian Duperreault became chief executive in 2008. John Doyle led Marsh as president and chief executive from 2017 to 2022 and became chief executive of the parent company on January 1, 2023, succeeding Dan Glaser. The group expanded through the acquisition of Jardine Lloyd Thompson in 2019, a transaction valued at £4.3 billion in the available reference material. In April 2021, Marsh & McLennan Companies adopted Marsh McLennan as its corporate name and brand identity. The group subsequently acquired McGriff Insurance Services in November 2024 for $7.75 billion. The available reference material also reports a 2025 rebranding of subsidiaries under the Marsh name. By this period, the business consisted principally of Marsh, Marsh Re, Mercer, and Oliver Wyman. The insurance and risk businesses remained the largest part of the group, while consulting provided a substantial second platform. Marsh McLennan continues to operate as a global professional services company and is identified as the world's largest insurance broker.

• 2025

  Subsidiary brands consolidated under Marsh

  [1]Marsh McLennanen.wikipedia.org

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

• 2024

  McGriff Insurance Services is acquired

  [1]Marsh McLennanen.wikipedia.org

  In November 2024, the group acquired McGriff Insurance Services for $7.75 billion, further expanding its insurance-distribution platform.

• 2023

  John Doyle becomes chief executive of the parent company

  [1]Marsh McLennanen.wikipedia.org

  John Doyle, who led Marsh as president and chief executive from 2017 to 2022, became chief executive of the parent company on January 1, 2023, succeeding Dan Glaser.

• 2021

  Corporate rebrand to Marsh McLennan

  [1]Marsh McLennanen.wikipedia.org

  In April 2021, the corporate name changed from Marsh & McLennan Companies to Marsh McLennan.

• 2019

  Jardine Lloyd Thompson is acquired

  [1]Marsh McLennanen.wikipedia.org

  The acquisition, valued at £4.3 billion, expanded the group's international insurance brokerage and employee-benefits businesses. Marsh McLennan acquired Jardine Lloyd Thompson for £4.3 billion.

• 2010

  Kroll is sold

  [1]Marsh McLennanen.wikipedia.org

  Kroll was sold to Altegrity for $1.13 billion after several smaller Kroll operations had been divested, as part of the group's portfolio concentration strategy.

• 2008

  Brian Duperreault becomes chief executive

  [1]Marsh McLennanen.wikipedia.org

  Brian Duperreault became chief executive of Marsh & McLennan.

• 2007

  Putnam Investments is sold

  [1]Marsh McLennanen.wikipedia.org

  The company sold Putnam to Power Financial for $3.9 billion and refocused on risk, insurance, and human-capital services.

• 2007

  China brokerage license and consulting consolidation

  [1]Marsh McLennanen.wikipedia.org

  Marsh obtained the first license reported for a wholly owned foreign insurance-brokerage company in China, while three Mercer consulting units were combined into Oliver Wyman.

• 2005

  Insurance-brokerage settlement

  [1]Marsh McLennanen.wikipedia.org

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

Showing the 10 most recent.

A global, multi-specialist professional services group that combines insurance intermediation and risk expertise with human-capital, investment, economic, and management consulting. Its positioning is centered on helping organizations understand uncertainty, transfer or finance risk, manage workforces, and make complex strategic decisions. 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.

• Insurance brokerage and risk management

  Marsh

  Marsh is the group's principal insurance brokerage and risk-advisory business. It helps companies, governments, and institutions identify and quantify exposures, arrange commercial insurance, design insurance programs, manage claims, use analytical models, and structure alternative risk-financing solutions. It is the largest operating business in the group and represents the core of Marsh McLennan's global insurance platform. The business accounted for approximately 54% of group revenue in the 2025 figures cited in the reference material. 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.

• Reinsurance brokerage and advisory · 1922

  Marsh Re

  Marsh Re is the group's reinsurance intermediary and advisory business, historically known as Guy Carpenter. It works with insurers and other risk carriers on reinsurance placement, capital and risk strategy, catastrophe exposure, analytics, and the design of structures that transfer or finance insurance risk. The business represented approximately 10% of 2025 group revenue according to the cited reference material. 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.

• Human-capital and investment consulting

  Mercer

  Mercer advises employers, pension sponsors, institutions, and investors on health benefits, retirement and pension programs, investment strategy, workforce transformation, talent, rewards, and organizational effectiveness. It provides the group's principal human-capital and employee-benefits platform and complements Marsh's corporate risk expertise. 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. 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.

• Management consulting · 1984

  Oliver Wyman

  Oliver Wyman is the group's global management-consulting business. Its work includes corporate and business-unit strategy, financial-services consulting, risk, operations, organizational transformation, public-sector advice, and sector-specific performance improvement. The broader platform includes Lippincott and NERA Economic 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. Oliver Wyman is the group's global management-consulting business. Its work includes corporate and business-unit strategy, financial-services consulting, risk, operations, organizational transformation, public-sector advice, and sector-specific performance improvement. The broader 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.

• Economic and regulatory consulting

  NERA Economic Consulting

  NERA Economic Consulting provides economic analysis, competition and regulatory advice, litigation support, financial analysis, and expert testimony. It operates within the Oliver Wyman consulting platform and serves clients facing complex legal, policy, market, and regulatory questions. The cited material identifies NERA as part of Oliver Wyman without supplying separate product-launch information. 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.

• Brand and design consulting

  Lippincott

  Lippincott is a brand and design consultancy associated with Oliver Wyman. Its work covers brand strategy, identity, customer experience, innovation, and the design of market-facing experiences for companies and institutions. 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. 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.

• 2005

  Settlement and client compensation

  Marsh agreed to pay $850 million to resolve the New York lawsuit and compensate eligible clients for commercial insurance arranged during the relevant period, including policies arranged between 2001 and 2004. The matter contributed to changes in the company's brokerage practices and strategic organization.

  Source

• 2004

  Marsh insurance-brokerage bid-rigging controversy

  New York Attorney General Eliot Spitzer accused Marsh's brokerage operation of failing to act as an impartial intermediary and of participating in bid-rigging and compensation practices that could increase costs for commercial-insurance clients. The allegations formed part of a wider insurance-industry controversy involving other brokers and insurers. 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.

  Source

• 2001

  September 11 World Trade Center losses

  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.

  Source

Read more

• 2025

  Rebrand subsidiaries under MarshStrategy

  Background

  The group continued simplifying its brand architecture after adopting the Marsh McLennan corporate identity.

  Action taken

  The company's subsidiaries were reported as being rebranded under the Marsh name.

  Aftermath

  The change further emphasized Marsh as the common identity across the group's insurance-related businesses.

  Source

• 2025

  Consolidate subsidiary branding under MarshStrategy

  Background

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

  Action taken

  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.

  Source

• 2024

  Acquire McGriff Insurance ServicesM&A

  Background

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

  Action taken

  The company acquired McGriff Insurance Services.

  Aftermath

  The acquisition added scale to the company's insurance-brokerage operations. The transaction strengthened the group's insurance-brokerage presence.

  Acquisition value. $7.75 billion (November 2024)

  Source

• 2021

  Adopt the Marsh McLennan corporate brandStrategy

  Background

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

  Action taken

  Marsh & McLennan Companies changed its corporate name and brand identity to Marsh McLennan.

  Aftermath

  The new identity positioned the group under a shorter, more recognizable corporate brand while its specialist businesses continued operating in their respective markets.

  Source

• 2019

  Acquire Jardine Lloyd ThompsonM&A

  Background

  The acquisition was intended to expand the group's international brokerage and employee-benefits capabilities.

  Action taken

  Marsh McLennan acquired Jardine Lloyd Thompson for £4.3 billion.

  Aftermath

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

  Acquisition value. £4.3 billion (2019)

  Source

• 2010

  Divest KrollM&A

  Background

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

  Action taken

  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)

  Source

• 2007

  Sell Putnam InvestmentsM&A

  Background

  The group was concentrating on risk, insurance, and human-capital businesses rather than maintaining a broad investment-management portfolio.

  Action taken

  Marsh & McLennan sold Putnam Investments to Power Financial.

  Aftermath

  The divestiture reduced the group's exposure to mutual funds and supported a more focused professional-services strategy. The divestiture simplified the portfolio and increased the strategic emphasis on the group's insurance and consulting operations.

  Sale value. $3.9 billion (2007)

  Source

• 2005

  Reorganize after the insurance-practices settlementStrategy

  Background

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

  Action taken

  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)

  Source

• 1997

  Acquire Johnson & HigginsM&A

  Background

  The insurance-brokerage sector was consolidating and Johnson & Higgins was a major competitor.

  Action taken

  Marsh & McLennan acquired Johnson & Higgins for $1.8 billion.

  Aftermath

  The transaction materially enlarged the brokerage operation and helped the company move ahead of Aon as the world's largest insurance broker.

  Acquisition value. $1.8 billion (1997)

  Source

• 1969

  Create a holding-company structureStrategy

  Background

  The company had developed several specialized operating activities and sought a structure that would preserve distinct business identities.

  Action taken

  Marsh & McLennan reorganized under a holding-company model with separately managed operating companies.

  Aftermath

  The structure became a foundation for later expansion across insurance, reinsurance, human-capital, investment, and management consulting.

  Source

• 2025

  Marsh McLennan subsidiary brands are reported as being rebranded under Marsh[1]Marsh McLennanen.wikipedia.org

  Other

  The company was reported as rebranding its subsidiaries under the Marsh name, extending the corporate brand architecture across the group.

• 2025

  Marsh McLennan reports a diversified 2025 operating portfolio[1]Marsh McLennanen.wikipedia.org

  Other

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

• 2025

  Marsh McLennan rebrands subsidiaries under Marsh[1]Marsh McLennanen.wikipedia.org

  Other

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

• 2024

  Marsh McLennan acquires McGriff Insurance Services[1]Marsh McLennanen.wikipedia.org

  M&A

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

• 2023

  John Doyle becomes chief executive of Marsh McLennan[1]Marsh McLennanen.wikipedia.org

  Leadership change

  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.

• 2021

  Marsh & McLennan adopts the Marsh McLennan corporate identity[1]Marsh McLennanen.wikipedia.org

  Other

  The company rebranded from Marsh & McLennan Companies to Marsh McLennan, creating a unified corporate identity while retaining major operating brands.

• 2021

  Marsh & McLennan Companies rebrands as Marsh McLennan[1]Marsh McLennanen.wikipedia.org

  Other

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

• 2019

  Marsh McLennan completes acquisition of Jardine Lloyd Thompson[1]Marsh McLennanen.wikipedia.org

  M&A

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

• 2010

  Marsh & McLennan sells Kroll to Altegrity[1]Marsh McLennanen.wikipedia.org

  M&A

  The company sold its corporate intelligence and investigative unit Kroll to Altegrity, continuing a program of divestitures outside its core advisory businesses.

• 2007

  Marsh receives first wholly owned foreign insurance-brokerage license in China[1]Marsh McLennanen.wikipedia.org

  Regulation

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

Showing the 10 most recent.

1. 1Marsh McLennanen.wikipedia.org
2. 2Marsh McLennan corporate websitemarshmclennan.com
3. 3http://www.mmc.com/mmc.com