Aon

Aon plc is a global professional services firm whose principal activities are organized around Risk Capital and Human Capital. The company advises businesses, institutions and individuals on how to identify, finance, transfer and manage uncertainty, while also helping employers address health, retirement, wealth and workforce-related challenges. Its best-known activities are insurance brokerage and reinsurance brokerage, but its broader offering includes risk consulting, commercial insurance placement, catastrophe and capital-market advisory, employee health and benefits, retirement and pension consulting, wealth advisory, talent strategy and related technology-enabled services. The modern company was created in Chicago in 1982 when Patrick Ryan’s Ryan Insurance Group merged with the Combined Insurance Company of America, the insurance organization associated with W. Clement Stone. Ryan had entered insurance through auto-credit insurance and expanded into brokerage after acquiring insurance brokerage operations from Esmark in 1976. The holding company adopted the name Aon in 1987. The name was derived from a Gaelic word commonly translated as “one,” reflecting the company’s effort to present a unified global identity. Aon expanded through a long series of acquisitions. Purchases such as Hudig-Langeveldt, The Minet Group, A&A Services and other national brokers built an international insurance-broking network. The acquisition of Benfield in 2008 substantially strengthened reinsurance intermediation and capital advisory. The 2010 acquisition of Hewitt Associates added a major human-resources consulting and outsourcing platform, broadening Aon beyond property-and-casualty and reinsurance brokerage. Aon later sold its employee-benefits outsourcing platform to Blackstone in 2017, creating Alight Solutions, while retaining and developing advisory capabilities in health, retirement, wealth and talent. In its current structure, Risk Capital includes commercial risk solutions and reinsurance solutions. These businesses help clients arrange insurance, reinsurance and alternative risk financing, use analytics to quantify exposures, and respond to issues such as climate volatility, cyber risk, catastrophe loss, litigation, supply-chain disruption and changing regulation. Human Capital includes health solutions and wealth solutions, covering employee benefits, health strategy, retirement plans, pension governance, investment and wealth advice, and workforce or talent-related services. Aon’s model combines specialist advice with global data, benchmarking, analytics and local distribution. The acquisition of NFP, completed in April 2024, expanded Aon’s middle-market presence in the United States and added property-and-casualty brokerage, employee benefits, wealth management and retirement-plan advisory capabilities. Aon also acquired Global Insurance Brokers in India in 2024 and technology assets from Humn.ai to support commercial fleet and mobility solutions. In 2025, Aon reported approximately $17.2 billion in revenue, consisting of about $11.3 billion from Risk Capital and $5.9 billion from Human Capital, according to its annual filing. Aon is incorporated in Ireland, maintains its principal executive office in Dublin and operates its global headquarters from London. Chicago remains a major North American operating center and an important part of the company’s historical identity. Under President and Chief Executive Officer Gregory Case, Aon presents itself as a data- and advice-led firm intended to help clients make better decisions about risk and people. It serves clients in more than 120 countries and remains one of the world’s largest insurance brokers.

Aon’s history combines the development of Combined Insurance with Patrick Ryan’s expansion of insurance brokerage. W. Clement Stone entered the insurance business through a small Detroit agency acquired by his mother. He later founded the Combined Registry Company and built a direct-writing business focused on low-cost accident and health insurance. Combined expanded through acquisitions, including American Casualty Insurance Company of Dallas in 1939, and consolidated its operations as Combined Insurance Company of America in 1947. Patrick Ryan came from an automobile-dealing family in Wisconsin and began his own insurance business in 1964 as an auto-credit insurer. In 1976, Ryan acquired insurance-brokerage operations from Esmark and shifted the business toward commercial brokerage and higher-value insurance products. In 1982, Ryan Insurance Group merged with Combined Insurance Company of America. The transaction created the corporate foundation of Aon and transferred effective leadership to Ryan. The holding company adopted the Aon name in 1987, using a Gaelic term associated with unity or “one.” During the late 1980s and 1990s, Aon pursued international scale. It acquired Dutch broker Hudig-Langeveldt in 1992, sold its remaining direct life-insurance holdings to General Electric in 1995, and acquired The Minet Group and A&A Services in 1997. The latter transaction also helped return the Howden family name to the insurance market. Further purchases expanded Aon in Spain, Italy and Asia. The rapid acquisition program created integration costs and pressured profitability, encouraging the company to introduce fee-disclosure policies and reorganize around more integrated operating structures. Aon continued to adjust its portfolio in the 2000s. It acquired insurance and benefits consulting assets, reduced its workforce during a 2000 restructuring and supported the creation of Endurance Specialty, a Bermuda-based underwriting business. After the September 11, 2001 attacks, Aon suffered the deaths of 176 employees who worked in the South Tower of the World Trade Center. The company later moved its New York operations and continued expanding its brokerage and consulting businesses. Regulatory scrutiny became a major feature of the period. In 2004 and 2005, Aon and other large brokers faced investigations into contingent commissions paid by insurers. Aon agreed to a $190 million settlement in 2005 without admitting wrongdoing. In 2007, it sold Combined Insurance Company of America to ACE Limited and Sterling Life Insurance Company to Munich Re, reducing exposure to capital-intensive underwriting. In 2008, the acquisition of Benfield for approximately $1.75 billion strengthened reinsurance brokerage and capital advisory. The 2010 acquisition of Hewitt Associates for approximately $4.9 billion transformed Aon’s Human Capital business. Hewitt brought large-scale employee benefits, retirement, human-resources consulting and outsourcing expertise, as well as roughly 23,000 colleagues. Aon subsequently sold the employee-benefits outsourcing platform to Blackstone in 2017, creating Alight Solutions, while maintaining advisory operations in health, retirement, wealth and talent. Aon announced in 2012 that its corporate headquarters would move to London, while Chicago remained a major North American operating center. The company expanded into specialized areas including cyber risk, flood insurance processing, technology consulting, assessments and investment management. In 2021, Aon agreed to combine with Willis Towers Watson, but the transaction was terminated after regulatory objections. The failed merger was followed by continued organic and acquisitive development of Aon’s two-division model. In 2024, Aon completed the acquisition of NFP, a major middle-market provider of risk, benefits, wealth and retirement-plan advisory services. The deal added thousands of colleagues and broadened Aon’s distribution among middle-market clients. Aon also completed the acquisition of Global Insurance Brokers in India and acquired Humn.ai technology assets for fleet and mobility applications. By 2025, Aon reported $17.2 billion in revenue across Risk Capital and Human Capital and continued to position itself as a global data-, analytics- and advice-led professional services firm.

1. 2025Risk Capital and Human Capital revenue model reported

   Aon reported 2025 revenue of approximately $17.2 billion, divided between Risk Capital and Human Capital.

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2. 2024NFP acquisition completed

   Aon completed the acquisition of NFP, adding middle-market risk, benefits, wealth and retirement capabilities.

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3. 2024Global Insurance Brokers acquired in India

   Aon completed the acquisition of Global Insurance Brokers to expand its Indian insurance-broking platform.

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4. 2021Proposed Willis Towers Watson merger terminated

   The proposed combination was ended after regulatory concerns prevented the transaction from proceeding.

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5. 2017Employee-benefits outsourcing platform sold

   Aon sold its human-resources outsourcing platform to Blackstone, creating Alight Solutions.

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6. 2012Headquarters moved to London

   Aon announced the relocation of its headquarters to London while retaining Chicago as a major North American operating center.

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7. 2010Hewitt Associates acquired

   The approximately $4.9 billion transaction substantially expanded Aon’s human-capital consulting and outsourcing capabilities.

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8. 2008Benfield acquired

   The approximately $1.75 billion acquisition strengthened Aon’s reinsurance brokerage and capital advisory capabilities.

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9. 2005Contingent-commission settlement

   Aon agreed to a $190 million settlement connected with regulatory investigations into contingent commissions.

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10. 2001Endurance Specialty established

    Aon helped establish Endurance Specialty, a Bermuda-based underwriting operation, with other investors.

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11. 2001World Trade Center tragedy

    Aon lost 176 employees in the September 11 attacks at its South Tower offices in New York.

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12. 1997Minet Group and A&A Services acquired

    The transactions expanded Aon’s international brokerage platform and briefly made it the world’s largest insurance broker.

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13. 1995Direct life-insurance holdings sold

    Aon sold its remaining direct life-insurance operations to General Electric and concentrated more heavily on brokerage and consulting.

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14. 1992Hudig-Langeveldt acquired

    The Dutch broker acquisition strengthened Aon’s international insurance-broking network.

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15. 1987Holding company renamed Aon

    The company adopted the Aon name as its unified global identity.

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16. 1982Ryan Insurance Group merges with Combined Insurance

    The merger created the corporate foundation of Aon and transferred effective leadership to Patrick Ryan.

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17. 1976Ryan acquires Esmark brokerage operations

    The acquisition accelerated Ryan’s move toward insurance brokerage and broader commercial insurance products.

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18. 1964Patrick Ryan starts an insurance business

    Ryan founded a company focused initially on auto-credit insurance, later expanding into commercial insurance brokerage.

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19. 1947Combined Insurance Company of America formed

    Combined consolidated earlier insurance acquisitions and continued its direct accident and health insurance model.

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20. 1939American Casualty Insurance Company acquired

    Stone acquired American Casualty Insurance Company of Dallas, an important step in building the Combined Insurance organization.

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21. 1918W. Clement Stone enters the insurance business

    Stone joined the small Detroit insurance agency acquired by his mother, beginning the business lineage that later became associated with Combined Insurance.

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A global, advice-led professional services firm that integrates insurance brokerage, reinsurance, risk analytics and human-capital consulting for multinational, middle-market and institutional clients.

• Commercial Risk SolutionsInsurance brokerage and risk consulting

  Aon’s commercial risk business advises companies on risk identification, insurance program design, brokerage placement, claims strategy and risk financing. Its work spans property, casualty, specialty, cyber, marine, trade credit, political risk, construction, energy and other commercial exposures. The business combines local brokerage with global market access, benchmarking and analytics for multinational and middle-market clients.

• Reinsurance SolutionsReinsurance brokerage and capital advisory

  Reinsurance Solutions helps insurers manage underwriting volatility and capital requirements by arranging treaty and facultative reinsurance, catastrophe protection, retrocession and alternative capital. The business also provides catastrophe modeling, portfolio analytics, capital advisory and insurance-linked securities expertise through Aon Securities and related platforms.

• Health SolutionsEmployee health and benefits advisory

  Health Solutions advises employers on employee health insurance, benefits strategy, wellbeing, healthcare cost management, benefits administration and related workforce programs. It uses market benchmarking and analytics to help organizations design competitive benefits while managing affordability, compliance and employee experience across countries.

• Wealth SolutionsRetirement, pension and wealth advisory

  Wealth Solutions provides retirement-plan consulting, pension governance, actuarial advice, investment consulting, fiduciary support and wealth-related services. Its clients include employers, pension sponsors, trustees, institutions and individuals seeking to manage long-term financial obligations, investment decisions and retirement outcomes.

• Talent and workforce advisoryHuman-capital consulting

  Aon’s talent-related services address workforce strategy, rewards, compensation, talent assessment, leadership, organizational effectiveness and employee experience. These capabilities originated in the company’s broader human-resources consulting heritage, including Hewitt, and are integrated with health, retirement and people analytics offerings.

• Aon Data & AnalyticsRisk and human-capital analytics

  Aon develops and applies data, modeling and analytics to insurance pricing, catastrophe exposure, cyber risk, workforce decisions, health costs, retirement liabilities and other complex business questions. The platform-oriented approach is intended to connect specialist advice with actionable benchmarks and decision support.

• 2023Aon and PGA TOUR analytics partnership

  United States · Global

  Aon and the PGA TOUR developed a partnership centered on real-time analytics, decision-making and the Aon Risk Reward Challenge. The program connected the brand’s advisory positioning with golf strategy and performance data.

  Outcome. The partnership continued to feature the Aon Trophy and a prize associated with the Risk Reward Challenge.

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• 2021Aon at Manchester United training facilities

  United Kingdom · Global

  Aon extended its Manchester United relationship beyond the shirt by holding naming rights to the club’s training center and sponsoring training kits. The activation associated Aon with preparation, performance measurement and decision-making.

  Outcome. The training-center naming-rights and training-kit relationship ended in 2021.

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• 2009Manchester United shirt sponsorship

  United Kingdom · Global

  Aon signed a four-year sponsorship agreement with Manchester United and replaced AIG as the club’s principal shirt sponsor from the 2010–11 season. The partnership placed the Aon name prominently on the club’s playing shirts and linked the brand with global sport, performance and risk themes.

  Outcome. Aon’s shirt sponsorship continued through the 2014–15 season, after which Chevrolet became the shirt sponsor. Aon subsequently held naming rights to the Trafford Training Centre and sponsored Manchester United training apparel through 2021.

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• 2024Acquisition of NFPM&A

  Aon sought to deepen its reach in the middle market and combine risk, benefits, wealth and retirement capabilities.

  What changed. Aon completed a cash-and-stock acquisition of NFP on April 25, 2024.

  Aftermath. NFP became an Aon company and expanded Aon’s distribution and advisory capabilities among middle-market clients.

  U.S. GAAP purchase price. Approximately $9.1 billion in the finalized purchase accounting disclosure; public announcement materials also described approximately $13.0 billion including cash, assumed liabilities and equity (April 25, 2024)

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• 2024Acquisition of Global Insurance BrokersM&A

  Aon wanted to expand its insurance-broking presence and capabilities in India.

  What changed. Aon completed the acquisition of Global Insurance Brokers and planned integration with Aon India Insurance Brokers subject to the applicable corporate process.

  Aftermath. The transaction expanded Aon’s Indian platform and local distribution capabilities.

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• 2024Acquisition of Humn.ai technology assetsOther

  Aon sought technology and analytics capabilities for commercial fleet and mobility risk.

  What changed. Aon acquired selected technology assets and intellectual property from Humn.ai.

  Aftermath. The transaction was intended to strengthen Aon’s commercial fleet proposition and insight-driven risk services.

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• 2021Termination of proposed Willis Towers Watson mergerM&A

  Aon and Willis Towers Watson proposed a combination intended to create a larger global professional services and insurance-broking group, but regulators raised competition concerns.

  What changed. The parties terminated the merger agreement after regulatory opposition, including U.S. Department of Justice action.

  Aftermath. Aon continued as an independent company and pursued organic growth and smaller acquisitions instead of the proposed mega-merger.

  • Willis Towers Watson — Willis Towers Watson proceeded independently after the merger agreement was terminated.
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• 2017Sale of employee-benefits outsourcing platformM&A

  Aon evaluated its human-resources outsourcing platform as less central to its long-term advisory strategy.

  What changed. Aon sold the platform to Blackstone for approximately $4.8 billion, creating Alight Solutions.

  Aftermath. Aon concentrated its Human Capital activities more heavily on advisory services in health, retirement, wealth and talent.

  Sale consideration. Approximately $4.8 billion (2017)

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• 2010Acquisition of Hewitt AssociatesM&A

  Aon sought to expand from insurance brokerage into human-resources, employee-benefits and retirement consulting.

  What changed. Aon acquired Hewitt Associates in a cash-and-stock transaction valued at approximately $4.9 billion.

  Aftermath. The deal added substantial human-capital consulting capacity, approximately 23,000 colleagues and more than $3 billion in revenue at the time.

  Acquisition consideration. Approximately $4.9 billion (2010)

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• 2008Acquisition of BenfieldM&A

  Aon wanted to expand its reinsurance brokerage and capital advisory capabilities.

  What changed. Aon acquired Benfield Group for approximately $1.75 billion, including assumed debt.

  Aftermath. The transaction strengthened Aon’s position in reinsurance intermediation and alternative capital markets.

  Acquisition consideration. Approximately $1.75 billion (2008)

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• 1987Adopted the Aon nameStrategy

  The company sought a unified identity after the Ryan Insurance Group and Combined Insurance businesses were combined.

  What changed. The holding company was renamed Aon, a name associated with the Gaelic word for “one.”

  Aftermath. The Aon identity became the basis for the company’s international expansion and later corporate rebranding.

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• 2011Foreign Corrupt Practices Act resolutionControversy

  Aon paid a $1.76 million criminal penalty to the U.S. Department of Justice and an additional civil penalty reported by the Securities and Exchange Commission to resolve FCPA-related matters. The case concerned improper payments and inadequate books, records and controls involving subsidiaries and intermediaries in several countries.

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• 2009UK regulatory breach involving bribery controlsControversy

  The UK Financial Services Authority fined Aon £5.69 million after finding that the company had inadequate systems and controls for assessing bribery and corruption risks in dealings with overseas firms and individuals. The regulator did not find that money had reached illegal organizations. Aon said the conduct was not deliberate and reported that it had strengthened its controls.

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• 2005Contingent commissions investigation and settlementControversy

  Aon was among major insurance brokers investigated over contingent commissions paid by insurers. Regulators argued that such payments could create conflicts of interest by influencing broker placement decisions. Aon agreed to a $190 million settlement without admitting wrongdoing.

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1. Aon plc — Wikipedia
2. Aon plc 2025 Form 10-K
3. Aon Leadership and Governance
4. Aon Corporate Information
5. Aon completes acquisition of NFP
6. Aon completes acquisition of Global Insurance Brokers in India
7. U.S. Department of Justice FCPA resolution
8. Aon and PGA TOUR analytics partnership
9. U.S. GAAP purchase price