Marsh & McLennan Companies 10-K 2020-12-31

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-K

(Mark One)

For the fiscal year ended December 31, 2020

OR

Commission File No. 1-5998

Marsh & McLennan Companies, Inc.

(Exact name of registrant as specified in its charter)

1166 Avenue of the Americas

New York, New York 10036-2774

(Address of principal executive offices; Zip Code)

(212) 345-5000

Registrant’s telephone number, including area code

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes ý No ¨

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes ¨ No ý

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ý No ¨

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ý No ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer or a smaller reporting Company. See the definitions of "large accelerated filer," "accelerated filer" and "smaller reporting Company" in Rule 12b-2 of the Exchange Act. (Check one):

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant is a shell Company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ý

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. Yes ☒ No ¨

As of June 30, 2020, the aggregate market value of the registrant's common stock held by non-affiliates of the registrant was approximately 53,818,358,381 computed by reference to the closing price of such stock as reported on the New York Stock Exchange on June 30, 2020.

As of February 12, 2021, there were outstanding 508,186,561 shares of common stock, par value $1.00 per share, of the registrant.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of Marsh & McLennan Companies, Inc.’s Notice of Annual Meeting and Proxy Statement for the 2021 Annual Meeting of Stockholders (the "2021 Proxy Statement") are incorporated by reference in Part III of this Form 10-K.

INFORMATION CONCERNING FORWARD-LOOKING STATEMENTS

This Annual Report on Form 10-K contains "forward-looking statements," as defined in the Private Securities Litigation Reform Act of 1995. These statements, which express management's current views concerning future events or results, use words like "anticipate," "assume," "believe," "continue," "estimate," "expect," "intend," "plan," "project" and similar terms, and future or conditional tense verbs like "could," "may," "might," "should," "will" and "would."

Forward-looking statements are subject to inherent risks and uncertainties that could cause actual results to differ materially from those expressed or implied in our forward-looking statements. Factors that could materially affect our future results include, among other things:

• the financial and operational impact of COVID-19 on our revenue and ability to generate new business, our overall level of profitability and cash flow, and our liquidity, including the timeliness and collectability of our receivables;

• the impact from lawsuits, other contingent liabilities and loss contingencies arising from errors and omissions, breach of fiduciary duty or other claims against us, including claims related to pandemic coverage;

• the impact of investigations, reviews, or other activity by regulatory or law enforcement authorities, including the ongoing U.K. FCA review of legacy JLT enhanced transfer value advice;

• the financial and operational impact of complying with laws and regulations where we operate and the risks of noncompliance with such laws, including anti-corruption laws such as the U.S. Foreign Corrupt Practices Act, U.K. Anti-Bribery Act, trade sanctions regimes and cybersecurity and data privacy regulations such as the E.U.’s General Data Protection Regulation;

• our ability to maintain adequate safeguards to protect the security of our information systems and confidential, personal or proprietary information, particularly given the increased risk of supply chain attacks and other cybersecurity attacks or unauthorized dissemination of information caused by remote work arrangements;

• our ability to compete effectively and adapt to changes in the competitive environment, including to respond to technological change, disintermediation, digital disruption and other types of innovation;

• our ability to manage risks associated with our investment management and related services business, particularly in the context of uncertain equity markets, including our ability to execute timely trades in light of increased trading volume and to manage potential conflicts of interest between investment consulting and fiduciary management services;

• our ability to attract and retain industry leading talent;

• our ability to successfully recover if we experience a business continuity problem due to cyberattack, natural disaster, government unrest or otherwise;

• the regulatory, contractual and reputational risks that arise based on insurance placement activities and various insurer revenue streams; and

• the impact of changes in tax laws, guidance and interpretations, or disagreements with tax authorities, particularly due to the change in U.S. presidential administration.

The factors identified above are not exhaustive. Further information concerning Marsh & McLennan Companies and its businesses, including information about factors that could materially affect our results of operations and financial condition, is contained in the Company's filings with the Securities and Exchange Commission, including the "Risk Factors" section in Part I, Item 1A of this report and the "Management’s Discussion and Analysis of Financial Condition and Results of Operations" section in Part II, Item 7 of this report. We caution readers not to place undue reliance on any forward-looking statements, which are based only on information currently available to us and speak only as of the dates on which they are made. We undertake no obligation to update or revise any forward-looking statement to reflect events or circumstances arising after the date on which it is made.

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TABLE OF CONTENTS

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PART I

References in this report to "we", "us" and "our" are to Marsh & McLennan Companies, Inc. and its consolidated subsidiaries (the "Company"), unless the context otherwise requires.

GENERAL

The Company is a global professional services firm offering clients advice in the areas of risk, strategy and people. The Company's 76,000 colleagues advise clients in over 130 countries. With annual revenue of $17 billion, the Company helps clients navigate an increasingly dynamic and complex environment through four market-leading businesses. Marsh advises individual and commercial clients of all sizes on insurance broking and innovative risk management solutions. Guy Carpenter develops advanced risk, reinsurance and capital strategies that help clients grow profitably and pursue emerging opportunities. Mercer delivers advice and technology-driven solutions that help organizations redefine the world of work, reshape retirement and investment outcomes, and unlock health and wellbeing for a changing workforce. Oliver Wyman Group serves as critical strategic, economic and brand advisor to private sector and governmental clients.

The Company conducts business through two segments:

• Risk and Insurance Services** includes risk management activities (risk advice, risk transfer and risk control and mitigation solutions) as well as insurance and reinsurance broking and services. The Company conducts business in this segment through Marsh and Guy Carpenter.

• Consulting** includes health, wealth and career services and products, and specialized management, economic and brand consulting services. The Company conducts business in this segment through Mercer and Oliver Wyman Group.

We describe our current segments in further detail below. We provide financial information about our segments in our consolidated financial statements included under Part II, Item 8 of this report.

OUR BUSINESSES

RISK AND INSURANCE SERVICES

The Risk and Insurance Services segment generated approximately 60% of the Company's total revenue in 2020 and employs approximately 44,100 colleagues worldwide. The Company conducts business in this segment through Marsh and Guy Carpenter.

MARSH

Marsh is the leading global insurance broker and risk advisor, serving companies, institutions and individuals. From its founding in 1871 to the present day, Marsh has demonstrated a commitment to thought leadership, innovation and insurance expertise to meet its clients’ needs. Marsh’s pioneering contributions include introducing the practice of client representation through brokerage, the discipline of risk management, the globalization of risk management services and the development of service platforms that identify, quantify, mitigate and transfer risk.

Currently, approximately 41,000 Marsh colleagues provide risk management, insurance broking, insurance program management services, risk consulting, analytical modeling and alternative risk financing services to a wide range of businesses, government entities, professional service organizations and individuals in more than 130 countries. Marsh generated approximately 50% of the Company's total revenue in 2020.

Insurance Broking and Risk Advisory

In its core insurance broking and risk advisory business, Marsh employs a team approach to identify, quantify and address clients' risk management and insurance needs. Marsh’s product and service offerings include risk analysis, insurance program design and placement, insurance program support and administration, claims support and advocacy, alternative risk strategies and a wide array of risk analysis and risk management consulting services. Clients benefit from Marsh’s advanced analytics, deep technical expertise, specialty and industry knowledge, collaborative global culture and the ability to

develop innovative solutions and products. The firm’s resources also include nearly three dozen specialty and industry practices, including cyber, financial and professional service practices, along with a growing employee health & benefits business.

Marsh provides services to clients of all sizes, including large multinational companies ("Risk Management"), high growth middle-market businesses ("Corporate"), small commercial enterprises and high net-worth private clients, and affinity group members ("Commercial & Consumer"). Marsh's segments are designed to build stronger value propositions and operating models to optimize solutions and services for clients depending on their needs.

Risk Management. Marsh has an extensive global footprint and market-leading advisory and placement services that benefit large domestic and international companies and institutions facing complex risk exposures. These clients are also supported by Marsh’s robust analytics and a growing digital experience.

In addition, Marsh’s largest global clients are serviced by Multinational Client Services, a dedicated team of colleagues from around the world focused on delivering service excellence and insurance solutions to clients wherever they are located. Marsh is digitizing the client experience through tools such as LINQ, Marsh’s account and service application; Blue[i], a suite of analytics tools for clients; and Bluestream, a digital brokerage platform that enables clients to provide insurance to their customers or suppliers in a B2B2C distribution model. Marsh provides global expertise and an intimate knowledge of local markets, helping clients navigate local regulatory environments to address the worldwide risk issues that confront them.

• Marsh JLT Specialty**. Marsh’s specialty unit combined with JLT Specialty to form Marsh JLT Specialty as part of the 2019 acquisition of Jardine Lloyd Thompson Group plc ("JLT"). The new unit offers leading expertise, global service and data-driven insights to clients across seven global specialties: aviation; credit specialties; financial & professional services; private equity & mergers & acquisitions; construction; energy & power; and marine & cargo. These teams of specialist experts are globally committed to delivering consulting, placement, account management and claims solutions to clients who require specialist advice and support. Marsh JLT Specialty has bolstered Marsh’s leadership as a global specialty broker.

Corporate. Middle market clients are served by Marsh’s brokerage operations globally and constitute a substantial majority of clients served by Marsh & McLennan Agency (MMA) in the United States and large portions of Marsh’s international business.

• MMA** offers a broad range of commercial property and casualty products and services, as well as solutions for employee health and benefits, retirement and administration needs and a growing personal lines business in the United States and Canada. Since its first acquisition in 2009, MMA has acquired 82 agencies. MMA provides advice on insurance program structure and market dynamics, along with industry expertise and transactional capability.

Commercial & Consumer. Clients in this market segment typically face less complex risks and are served by Marsh’s innovative product and placement offerings and growing capabilities in digitally enabled distribution.

• Victor Insurance Holdings** is one of the largest underwriting managers of professional liability and specialty insurance programs worldwide. In the United States, Victor Insurance Managers (US) and ICAT Managers deliver risk management and insurance solutions to over 125,000 insureds through a national third-party distribution network of licensed brokers. Through Dovetail Managing General Agency, a small business platform, Victor Insurance Managers (US) deploys cloud-based technology to enable independent insurance agents, on behalf of their small business clients, to obtain online quotes from multiple insurance providers and bind property and casualty and workers compensation insurance policies in real time. Victor Insurance Managers (Canada), a leading managing general agent in Canada with over 43,000 insureds, delivers professional liability and construction insurance, as well as group and retiree benefits programs and claims handling for individuals, organizations and businesses. Victor has a growing business

in the UK (where it was formerly known as Bluefin Underwriting) and in Europe, where new businesses have been launched in the Netherlands, Italy and Germany.

• Marsh Affinity** focuses on insurance programs sold to insureds or vendors through a corporate sponsor using an affinity distribution model.

• High Net Worth (HNW)** Individual high net worth clients and family offices are serviced by MMA and other Marsh personal lines businesses globally. These businesses provide a single-source solution for high net worth clients and are dedicated to sourcing protections across a broad spectrum of risk. Using a consultative approach, Marsh's HNW practices analyze exposures and customizes programs to cover individual clients with complex asset portfolios.

Additional Services and Adjacent Businesses

In addition to insurance broking, Marsh provides certain other specialist advisory or placement services:

Marsh Advisory is a global practice comprising specialists who use data and analytics, including through Marsh’s Blue[i] digital analytics platform, to advise clients about exposures, critical business activities, and risk practices and strategies. Marsh Advisory provides client services in four main areas: Consulting Solutions, Analytics Solutions, Claims Solutions, and Captive Solutions.

Marsh Captive Solutions serves more than 1,350 captive facilities, including single-parent captives, reinsurance pools and risk retention groups. The Captive Solutions practice operates in 53 captive domiciles and leverages the consulting expertise within Marsh’s brokerage offices worldwide. The practice includes the Captive Advisory Group, a consulting arm that performs captive feasibility studies and helps to structure and implement captive solutions; the Captive Management Group, an industry leader in managing captive facilities and in providing administrative, consultative and insurance-related services; and the Actuarial Services Group, which is comprised of credentialed actuaries and supporting actuarial analysts.

Torrent Technologies is a service provider to Write Your Own (WYO) insurers participating in the National Flood Insurance Program (NFIP) in the United States. Torrent offers a comprehensive suite of both NFIP and private and excess flood insurance products and services to WYO companies and agents.

Bowring Marsh is an international placement broker primarily for property and casualty risks. Bowring Marsh uses placement expertise in major international insurance market hubs, including Bermuda, Brazil, China, United Arab Emirates, Ireland, Spain, United Kingdom, the United States, Singapore, Japan and Switzerland, and an integrated global network to secure advantageous terms and conditions for its clients throughout the world.

Services for Insurers

Insurer Consulting Group provides services to insurance carriers. Through Marsh's patented electronic platform, MarketConnect, and sophisticated data analysis, Marsh provides insurers with individualized preference setting and risk identification capabilities, as well as detailed performance data and metrics. Insurer consulting teams review performance metrics and preferences with insurers and provide customized consulting services to insurers designed to improve business planning and strategy implementation. Marsh's Insurer Consulting services are designed to improve the product offerings available to clients, assist insurers in identifying new opportunities and enhance insurers’ operational efficiency. The scope and nature of the services vary by insurer and by geography.

GUY CARPENTER

Guy Carpenter, the Company’s reinsurance intermediary and advisor, generated approximately 10% of the Company's total revenue in 2020. Currently, approximately 3,100 Guy Carpenter colleagues provide clients with a combination of specialized reinsurance broking expertise, strategic advisory services and analytics solutions. Guy Carpenter creates and executes reinsurance and risk management solutions for clients worldwide through risk assessment analytics, actuarial services, highly-specialized product knowledge and trading relationships with reinsurance markets. Client services also include contract and claims management and fiduciary accounting.

Acting as a broker or intermediary on all classes of reinsurance, Guy Carpenter places two main types of property casualty and life / health reinsurance: treaty reinsurance, which involves the transfer of a portfolio of risks; and facultative reinsurance, which involves the transfer of part or all of the coverage provided by a single insurance policy.

Guy Carpenter provides reinsurance services in a broad range of centers of excellence and segments, including: Automobile / Motor, Aviation, Crop/Agriculture, Cyber, D&O/Non-Medical Professional, Engineering / Construction, Environmental, GL & Umbrella, Health, Life, Marine and Energy, Medical Professional, Mortgage, Political Risk & Trade Credit, Program Manager Solutions, Property, Public Sector, Retrocessional Reinsurance, Surety, Terror, and Workers Compensation / Employer Liability.

Guy Carpenter also offers clients alternatives to traditional reinsurance, including industry loss warranties and, through its licensed affiliates, capital markets alternatives such as transferring catastrophe risk through the issuance of risk-linked securities. GC Securities, the Guy Carpenter division of MMC Securities LLC and MMC Securities (Europe) Limited, offers corporate finance solutions, including mergers & acquisitions and private debt and equity capital raising, and capital markets-based risk transfer solutions that complement Guy Carpenter's strong industry relationships, analytical capabilities and reinsurance expertise.

Guy Carpenter also provides its clients with reinsurance-related services, including actuarial, enterprise risk management, financial and regulatory consulting, portfolio analysis and advice on the efficient use of capital. Guy Carpenter's Global Strategic Advisory ("GSA") unit helps clients better understand and quantify the uncertainties inherent in their businesses. Working in close partnership with Guy Carpenter account executives, GSA specialists help support clients' critical decisions in numerous areas, including reinsurance utilization, catastrophe exposure portfolio management, new product and market development, rating agency, regulatory and account impacts, loss reserve risk, capital adequacy and return on capital.

Compensation for Services in Risk and Insurance Services

Marsh and Guy Carpenter are compensated for brokerage and consulting services through commissions and fees. Commission rates and fees vary in amount and can depend on a number of factors, including the type of insurance or reinsurance coverage provided, the particular insurer or reinsurer selected, and the capacity in which the broker acts and negotiates with clients. In addition to compensation from its clients, Marsh also receives other compensation, separate from retail fees and commissions, from insurance companies. This other compensation includes, among other things, payments for consulting and analytics services provided to insurers; compensation for administrative and other services (including fees for services provided to or on behalf of insurers relating to the administration and management of quota shares, panels and other facilities in which insurers participate); and contingent commissions, which are paid by insurers based on factors such as volume or profitability of Marsh's placements, primarily driven by MMA and parts of Marsh's international operations.

Marsh and Guy Carpenter receive interest income on certain funds (such as premiums and claims proceeds) held in a fiduciary capacity for others. For a more detailed discussion of revenue sources and factors affecting revenue in our Risk and Insurance Services segment, see Part II, Item 7 ("Management's Discussion and Analysis of Financial Condition and Results of Operations") of this report.

CONSULTING

The Company's Consulting segment generated approximately 40% of the Company's total revenue in 2020 and employs approximately 29,700 colleagues worldwide. The Company conducts business in this segment through Mercer and Oliver Wyman Group.

MERCER

Mercer delivers advice and digital solutions that help organizations meet the health, wealth and career needs of a changing workforce. Mercer has approximately 24,700 colleagues based in 43 countries. Clients include a majority of the companies in the Fortune 1000 and FTSE 100, as well as medium- and small-market organizations, public sector employees and individual customers. Mercer generated approximately 28% of the Company's total revenue in 2020.

Mercer operates in the following areas:

Health. Mercer assists public and private sector employers in the design and management of employee health care programs; administration of health benefits and flexible benefits programs, including benefits outsourcing; employee engagement with their health benefits through a digital experience; compliance with local benefits-related regulations; and the establishment of health and welfare benefits coverage for employees. Mercer provides a range of advice and solutions to clients, which, depending on the engagement, may include: total health and wellness management strategies; global health brokerage solutions; vendor performance and audit; life and disability management; and measurement of healthcare provider performance. These services are provided through traditional fee-based consulting as well as commission-based brokerage services in connection with the selection of insurance companies and healthcare providers. Mercer provides solutions for private active and retiree exchanges in the United States, as well as tools to enhance employee engagement with their health benefits through its DarwinSM platform across the world.

Mercer also provides consulting and actuarial services to U.S. state governments to support the purchase of healthcare through state Medicaid programs. In addition, Mercer provides consulting services to insurance carriers to assist them with improving product offerings available to clients, identifying new opportunities and enhancing insurers’ operational efficiency.

Outside of the U.S., Mercer and Marsh go to market together for Health benefits brokerage and consulting under the Mercer Marsh BenefitsSM (MMB) brand.

Wealth. Through its Wealth business, Mercer assists clients worldwide in the design, governance and risk management of defined benefit, defined contribution and hybrid retirement plans. Mercer provides actuarial consulting, investment consulting, investment management and related services to the sponsors and trustees of pension plans, master trusts, foundations, endowments, and insurance companies as well as wealth management and other financial intermediary firms. Mercer also provides retirement plan outsourcing, including administration and delivery of defined benefit and defined contribution retirement benefits.

Mercer's investment consulting and investment management services (also referred to as “investment solutions,” “delegated solutions,” “fiduciary management” or “outsourced Chief Investment Officer (OCIO) services”) cover a range of stages of the investment process, from strategy, asset allocation and implementation to ongoing portfolio management services. Mercer provides these services primarily to institutional and other sophisticated investors including retirement plans (e.g., defined benefit and defined contribution), master trusts, endowments and foundations and wealth managers and other financial intermediary firms, primarily through manager of manager funds sponsored and managed by Mercer. As of December 31, 2020, Mercer and its global affiliates had assets under management of approximately $357 billion worldwide.

Mercer also provides miscellaneous services to individual retail clients, including financial planning, high net worth risk solutions and other discretionary investment services.

Career. Mercer advises organizations on the engagement, skill assessment, management and reward of employees; the design of executive remuneration programs; people strategies during business transformation; improvement of human resource (HR) effectiveness; and the implementation of digital and cloud-based Human Resource Information Systems. In addition, through proprietary survey data and

decision support tools, Mercer provides clients with human capital information and analytical capabilities to improve strategic human capital decision making. Mercer helps clients plan and implement HR programs and other organizational changes designed to maximize employee engagement, drive desired employee behaviors and achieve improvements in business performance.

OLIVER WYMAN GROUP

With more than 5,000 professionals and offices in 31 countries, Oliver Wyman Group delivers advisory services to clients through three operating units, each of which is a leader in its field: Oliver Wyman, Lippincott and NERA Economic Consulting. Oliver Wyman Group generated approximately 12% of the Company's total revenue in 2020.

Oliver Wyman is a global leader in management consulting. Oliver Wyman combines deep industry knowledge with specialized expertise in strategy, operations, risk management and organization transformation. Industry groups include:

• Automotive

• Aviation, Aerospace & Defense

• Business Services

• Communications, Media & Technology

• Distribution & Wholesale

• Education

• Energy

• Financial Services (including corporate and institutional banking, insurance, wealth and asset management, public policy, and retail and business banking)

• Health & Life Sciences

• Industrial Products

• Public Sector

• Retail & Consumer Products

• Surface Transportation

• Travel & Leisure

Oliver Wyman overlays its industry knowledge with expertise in the following functional specializations:

• Actuarial. Oliver Wyman’s Actuarial Practice uses mathematical and statistical modeling skills and qualitative assessment methodologies to assist clients in evaluating and addressing risk.

• Climate and Sustainability. Oliver Wyman assists clients in cutting through complex climate systems and solving for operational efficiencies. Oliver Wyman helps clients discover new business opportunities, create new pathways, and respond to climate risk, to make needed changes commercially compelling.

• Corporate Finance & Restructuring. Oliver Wyman provides an array of capabilities to support investment decision making by private equity funds, hedge funds, sovereign wealth funds, investment banks, commercial banks, arrangers, strategic investors and insurers.

• Digital. Oliver Wyman partners with clients to address their digital challenges, blending the power of digital with deep industry expertise. By building strong capabilities and culture, Oliver Wyman accelerates and embeds digital transformation, working collaboratively with clients’ leaders, employees, stakeholders, and customers to jointly define, design, and achieve lasting results.

• Operations. Oliver Wyman helps organizations leverage their operations for a competitive advantage using a comprehensive set of capabilities, including performance improvement, digital operations strategy, and risk management.

• Organizational Effectiveness. Oliver Wyman's Organizational Effectiveness capability brings together deep functional expertise and industry knowledge to enable the whole organization to work in service of its strategic vision and to address the most pressing organizational, people, and change issues.

*•*Payments. Oliver Wyman draws on years of industry-shaping work in the Financial Services and Retail industries, deep digital expertise, and renowned research partners in its Celent® business, to help clients - from banks/issuers, to payments providers, to retailers - to build growth strategies, form effective partnerships, optimize costs, and manage risk.

• Pricing, Sales, and Marketing. Oliver Wyman helps organizations drive top-line and margin growth through outstanding strategy and decision making on pricing, marketing optimization, and best practices on sales effectiveness.

• Risk Management. Oliver Wyman works with chief financial officers, chief risk officers, and other senior finance and risk management executives of corporations and financial institutions on risk management solutions. Oliver Wyman provides effective, customized solutions to the challenges presented by the evolving roles, needs and priorities of these individuals and organizations.

• Strategy. Oliver Wyman is a leading provider of corporate strategy advice and solutions in the areas of growth strategy and corporate portfolio; non-organic growth and M&A; performance improvement; business design and innovation; corporate center and shared services; and strategic planning.

Lippincott is a creative consultancy specializing in brand and innovation that shapes recognized brands and experiences for clients globally. Lippincott's designers have helped create some of the world's most recognized brands.

NERA Economic Consulting provides economic analysis and advice to public and private entities to achieve practical solutions to highly complex business and legal issues arising from competition, regulation, public policy, strategy, finance and litigation. NERA professionals operate worldwide assisting clients including corporations, governments, law firms, regulatory agencies, trade associations, and international agencies. NERA's specialized practice areas include: antitrust; securities; complex commercial litigation; energy; environmental economics; network industries; intellectual property; product liability and mass torts; and transfer pricing.

Compensation for Services in Consulting

Mercer and Oliver Wyman Group are compensated for advice and services primarily through fees paid by clients. In the majority of cases, Mercer's Health business is also compensated through commissions for the placement of insurance contracts and supplemental compensation from insurers based on such factors as volume, growth of accounts, and total retention of accounts placed by Mercer. Mercer may receive commissions in other parts of its business, such as its Private Client Services business and certain financial advice businesses. Mercer's investments business and certain of Mercer's administration services are compensated typically through fees based on assets under administration or management or fee per member. For a majority of the Mercer-managed investment funds, revenue received from Mercer's investment management clients as sub-advisor fees is reported in accordance with U.S. GAAP, on a gross basis rather than a net basis. For a more detailed discussion of revenue sources and factors affecting revenue in the Consulting segment, see Part II, Item 7 ("Management's Discussion and Analysis of Financial Condition and Results of Operations") of this report.

REGULATION

The Company's activities are subject to licensing requirements and extensive regulation under U.S. federal and state laws, as well as laws of other countries in which the Company's subsidiaries operate. Across most jurisdictions we are also subject to various data privacy laws and regulations that apply to personal information belonging to our clients, their employees and third parties, as well as our own colleagues. In addition, we are subject to various financial crime laws and regulations through our activities, activities of associated persons, the products and services we provide and our business and client relationships. Such laws and regulations relate to, among other areas, sanctions and export control, anti-bribery, anti-corruption, anti-money-laundering and counter-terrorist financing. See Part I, Item 1A

("Risk Factors") below for a discussion of how actions by regulatory authorities or changes in legislation and regulation in the jurisdictions in which we operate may have an adverse effect on our businesses.

Risk and Insurance Services**.** While laws and regulations vary from location to location, every state of the United States and most foreign jurisdictions require insurance market intermediaries and related service providers (such as insurance brokers, agents and consultants, reinsurance brokers and managing general agents) to hold an individual or company license from a government agency or self-regulatory organization. Some jurisdictions issue licenses only to individual residents or locally-owned business entities; in those instances, if the Company has no licensed subsidiary, it may maintain arrangements with residents or business entities licensed to act in such jurisdiction. Such arrangements are subject to an internal review and approval process. Licensing of reinsurance intermediaries is generally less rigorous compared to that of insurance brokers, and most jurisdictions require only corporate reinsurance intermediary licenses.

In 2005, the Insurance Mediation Directive which, as from October 1, 2018 has been superseded by the Insurance Distribution Directive, was adopted by the United Kingdom and 27 other European Union Member States. Its implementation gave powers to the Financial Services Authority ("FSA"), the United Kingdom regulator at the time, to expand its responsibilities in line with the Financial Services and Markets Act (2000), the result of which was the regulation of insurance and reinsurance intermediaries. The enhanced regulatory regime implemented in the United Kingdom created a licensing system based on an assessment of factors which included professional competence, financial capacity and the requirement to hold professional indemnity insurance. In April 2013, the FSA was superseded by the Financial Conduct Authority ("FCA"). In April 2014, the FCA’s responsibilities were expanded further to include the regulation of credit activities for consumers. This included the broking of premium finance to consumers who wished to spread the cost of their insurance. In April 2015, the FCA obtained concurrent competition powers enabling it to enforce prohibitions on anti-competitive behavior in relation to financial services.

Insurance authorities in the United States and certain other jurisdictions in which the Company's subsidiaries do business, including the FCA in the United Kingdom, also have enacted laws and regulations governing the investment of funds, such as premiums and claims proceeds, held in a fiduciary capacity for others. These laws and regulations typically provide for segregation of these fiduciary funds and limit the types of investments that may be made with them, and generally apply to both the insurance and reinsurance business.

Certain of the Company's Risk and Insurance Services activities are governed by other regulatory bodies, such as investment, securities and futures licensing authorities. In the United States, Marsh and Guy Carpenter use the services of MMC Securities LLC, a SEC registered broker-dealer and introducing broker in the United States. MMC Securities LLC is a member of the Financial Industry Regulatory Authority ("FINRA"), the National Futures Association and the Securities Investor Protection Corporation ("SIPC"), primarily in connection with capital markets and other investment banking-related services relating to insurance-linked and alternative risk financing transactions. Also in the United States, Marsh uses the services of MMA Securities LLC, a SEC registered broker-dealer, investment adviser and member of FINRA and SIPC JSL Securities, Inc., a SEC registered broker-dealer and member of FINRA, SIPC and the Municipal Securities Rulemaking Board and Centurion Asset Management LLC, a SEC registered investment adviser, primarily in connection with retirement, executive compensation and benefits consulting and advisory services to qualified and non-qualified benefits plans, companies and executives and personal wealth management. In the United Kingdom, Marsh and Guy Carpenter use the expertise of MMC Securities (Europe) Limited, which is authorized and regulated by the FCA to provide advice on securities and investments, including mergers & acquisitions in the European Union. MMC Securities LLC, MMC Securities (Europe) Limited, MMA Securities LLC, JSL Securities, Inc. and Centurion Asset Management LLC are indirect, wholly-owned subsidiaries of Marsh & McLennan Companies, Inc.

Consulting*.* Mercer's retirement-related consulting and investment services are subject to pension law and financial regulation in many countries. Depending on the country, Mercer may rely on licensed colleagues or registered legal entities to engage in these services, or may utilize other MMC entities or external third parties. In addition, trustee services, investment services (including advice to persons, institutions and other entities on the investment of pension assets and assumption of discretionary

investment management responsibilities) and retirement and employee benefit program administrative services provided by Mercer and its subsidiaries and affiliates are also subject to investment and securities regulations in various jurisdictions, including regulations imposed or enforced by the SEC and the Department of Labor in the United States, the FCA in the United Kingdom, the Central Bank of Ireland and the Australian Prudential Regulation Authority and the Australian Securities and Investments Commission. In the United States, Mercer provides investment services through Mercer Investments LLC, (formerly Mercer Investment Management, Inc.), an SEC-registered investment adviser, which consolidated the activities of each of Mercer’s affiliated investment adviser entities in the United States (including Mercer Investment Consulting LLC and Pavilion Advisory Group) in 2019. Mercer Trust Company, a limited purpose New Hampshire chartered trust bank, may also provide services for certain clients of Mercer’s investment management business in the United States. The benefits insurance consulting and brokerage services provided by Mercer and its subsidiaries and affiliates are subject to the same licensing requirements and regulatory oversight as the insurance market intermediaries described above regarding our Risk and Insurance Services businesses. Mercer provides annuity buy-out support that is subject to regulations (for example, in the U.S., state insurance licensing regulations and ERISA). Mercer uses the services of MMC Securities LLC to provide certain services, including executive benefit and compensation services and securities dealing services.

FATCA**.** Regulations promulgated by the U.S. Treasury Department pursuant to the Foreign Account Tax Compliance Act and related legislation (FATCA) require the Company to take various measures relating to non-U.S. funds, transactions and accounts. The regulations impose on Mercer certain client financial account tracking and disclosure obligations with respect to non-U.S. financial institution and insurance clients.

COMPETITIVE CONDITIONS

The Company faces significant competition in all of its businesses from providers of similar products and services, including competition with regard to identifying and pursuing acquisition candidates. The Company also encounters strong competition throughout its businesses from both public corporations and private firms in attracting and retaining qualified employees. As the Company has clients across various geographies, industries and scale, the competitive landscape is complex and varies across these numerous markets. In addition to the discussion below, see "Risks Relating to the Company Generally — Competitive Risks," in Part I, Item 1A of this report.

Risk and Insurance Services**.** The Company's combined insurance and reinsurance services businesses are global in scope. Our insurance and reinsurance businesses compete principally on sophistication, range, quality and cost of the services and products they offer to clients. The Company encounters strong competition from other insurance and reinsurance brokerage firms that operate on a global, regional, national or local scale, from a large number of regional and local firms in the United States, the United Kingdom, the European Union and elsewhere, from insurance and reinsurance companies that market, distribute and service their insurance and reinsurance products without the assistance of brokers or agents and from other businesses, including commercial and investment banks, accounting firms, consultants and online platforms, that provide risk-related services and products or alternatives to traditional insurance brokerage services. In addition, third party capital providers have entered the insurance and reinsurance risk transfer market offering products and capital directly to the Company’s clients. Their presence in the market increases the competitive pressures that the Company faces.

Certain insureds and groups of insureds have established programs of self-insurance (including captive insurance companies) as a supplement or alternative to traditional third-party insurance, thereby reducing in some cases their need for third-party insurance placements. Certain insureds also obtain coverage directly from insurance providers. There are also many other providers of managing general agency, affinity programs and private client services, including specialized firms, insurance companies and other institutions.

Consulting**.** The Company's consulting businesses face strong competition from other privately and publicly held worldwide and national companies, as well as regional and local firms. These businesses generally compete on the basis of the range, quality and cost of the services and products they provide to clients. Competitors include independent consulting and outsourcing firms, as well as consulting and

outsourcing operations affiliated with accounting, information systems, technology and financial services firms. Mercer's investments business faces competition from many sources, including investment consulting firms (many of which offer delegated services), investment management firms and other financial institutions. In some cases, clients have the option of handling the services provided by Mercer and Oliver Wyman Group internally, without assistance from outside advisors.

Segmentation of Activity by Type of Service and Geographic Area of Operation.

Financial information relating to the types of services provided by the Company and the geographic areas of its operations is incorporated herein by reference to Note 17 to the consolidated financial statements included under Part II, Item 8 of this report.

HUMAN CAPITAL

As a professional services firm, we believe the health of our business relies on the strength of our workforce. Our shared purpose is to make a difference in moments that matter, helping clients meet the challenges of our time. Measurement of our talent outcomes are, therefore, not just a human capital priority, but a business imperative.

For detailed information regarding our human capital management, we encourage investors to visit https://www.mmc.com/about/esg.html for our consolidated environmental, social and governance ("ESG") report to be published in the first quarter 2021. The information on this website, and in the ESG report, does not constitute, and should not be viewed as, incorporation by reference of the information contained on, or available through, the website or the report and does not form part of this Form 10-K.

Our People. As of December 31, 2020, the Company and its consolidated subsidiaries employed 76,000 colleagues worldwide, including approximately 44,100 in Risk and Insurance Services and 29,700 in Consulting. Two-thirds of our global workforce are located in either North America or Europe. While these remain our largest work regions, we have also grown our presence in Asia-Pacific and the Middle East over the last several years. Women comprise more than half of our global enterprise workforce, and approximately 30% of our senior leaders are women. In the United States, where we have the most complete data through workforce self-identification of race and ethnicity, approximately 1 in 4 U.S. colleagues and 14% of U.S. senior leaders identify as non-White.

Our Governance. The Chief People Officer is responsible for developing and executing our enterprise people strategy. This includes the attraction, recruitment, hiring, development and engagement of talent to deliver on our strategy and the design of colleague total rewards programs. The Chief People Officer and the Chief Inclusion & Diversity Officer are responsible for developing and integrating our diversity and inclusion approach into our strategy.

Our ESG Committee and Compensation Committee of the board of directors have oversight of these initiatives. The Compensation Committee has responsibility to review certain key human resource strategic activities, including those relating to diversity, training and recruitment. The Compensation Committee coordinates with the ESG Committee on diversity initiatives and both committees receive reports at least annually on diversity and inclusion from the Company’s Chief People Officer. The Chief Executive Officer and Chief People Officer regularly update our board of directors, the ESG Committee and the Compensation Committee on the Company’s human capital trends and activities.

Diversity & Inclusion. Our Company’s greatest strength is the collective talent of our people. We believe the more diverse our backgrounds and experiences, the more we can achieve together working side by side. We seek capable, creative and fair-minded people who can help us enable client success, find smarter ways to do things and live our Code of Conduct, The Greater Good. We believe that inclusion means more than acceptance—it means belonging. Over the last year, we have taken several concrete actions to further goals, including the formation of a Race Advisory Council to advise our Executive Committee and help amplify diverse perspectives in decision-making. Other initiatives included the design of a new learning and sponsorship program to help underrepresented colleagues strengthen leadership skills, as well as the creation of various forums and networks to promote ongoing candid conversations within the organization.

Talent Development. We strive to create an environment where individuals and teams can perform to their highest potential and where career growth and mobility are encouraged and supported. We are committed to helping colleagues perform at their best by encouraging regular discussions about their

goals, performance, career aspirations and development opportunities. We also recognize the importance of our 13,000 people managers in their crucial roles for reviewing our talent pipeline and have given them increased support and opportunities for promoting the professional and personal growth of their teams. In addition, we offer more than 16,000 individual learning courses as part of continuous learning to help our colleagues grow and develop. In 2020, we published a set of People Manager Practices, centered around managing inclusively, that define what effective people management looks like. Managers also have access to our dedicated People Manager Hub, a one-stop source of information and community for all people managers globally.

Colleague Engagement. Each year we ask our colleagues to share their views on working at Marsh & McLennan through a company-wide engagement survey. Developed internally by our Global Talent Development team, the survey methodology has been consistent since 2011, with updates to specific questions as necessary. A third-party administers our survey in order to maintain confidentiality of responses. In 2020, a record number of colleagues completed the survey. As in the past, we continue to use the survey responses to help inform the ongoing development of a vibrant and inclusive culture.

Health and Wellbeing. As a company, our success depends on the health and wellbeing of our colleagues—we want to support our colleagues with resources, protection and peace of mind to live healthy lives. We offer comprehensive health insurance, including medical coverage and other core health benefits based on the market. We also prioritize our colleagues’ mental wellness, including 24/7 access to an Employee Assistance Program for confidential counselling on personal issues for over 80 percent of our colleagues and their eligible family members, and critical incident support in countries where a disaster has occurred. In addition, we offer competitive time-off benefits, including a paid day off each year to volunteer.

Supporting our colleagues as they navigate the unprecedented challenges of COVID-19 has been our highest priority in 2020 and our teams have responded by working in innovative ways. Refer to "Recent Developments" included in Item 7, "Management’s Discussion and Analysis of Financial Condition and Results of Operations" for information on our response to the COVID-19 pandemic.

Total Rewards. We recognize how important it is to be financially secure through employment, so we offer competitive rewards to help build colleagues’ personal wealth and improve their financial wellbeing. Base pay is just the start. Through our annual bonus program, we encourage performance that aligns with the Company’s interests by providing eligible colleagues with discretionary awards. We also offer various incentives in certain circumstances, such as sales incentives and long-term incentives to roles that have a significant impact on our long-term performance designed to foster the Company’s long-term success. Our robust offerings also include retirement benefits, savings and stock investment plans in certain jurisdictions.

EXECUTIVE OFFICERS OF THE COMPANY

The executive officers and executive officer appointees of the Company are appointed annually by the Company’s Board of Directors. The following individuals are the executive officers of the Company:

Peter J. Beshar, age 59, is Executive Vice President and General Counsel of Marsh & McLennan Companies. In addition to managing the Company’s Legal, Compliance & Public Affairs groups, Mr. Beshar also oversees the Company’s Risk Management group. Before joining Marsh & McLennan Companies in November 2004, Mr. Beshar was a Litigation Partner in the law firm of Gibson, Dunn & Crutcher LLP. Mr. Beshar joined Gibson, Dunn & Crutcher in 1995 after serving as the Assistant Attorney General in charge of the New York Attorney General's Task Force on Illegal Firearms and as the Special Assistant to former U.S. Secretary of State Cyrus Vance in connection with the peace negotiations in the former Yugoslavia.

Paul Beswick, age 46, is Senior Vice President and Global Chief Information Officer (CIO) of Marsh & McLennan Companies. In this role, he manages over 5,000 technologists supporting Marsh & McLennan’s global businesses. Prior to his appointment as Marsh & McLennan CIO in January 2021, Mr. Beswick was a Partner and Global Head of Oliver Wyman Labs and the Digital Practice at Oliver Wyman. During more than two decades with Oliver Wyman, he worked in various sectors, including retail, transportation, telecom, and consumer goods. Before this, Mr. Beswick headed Oliver Wyman's North American Retail Practice. Mr. Beswick holds an MA (first class) in chemical engineering from Cambridge University.

Dominic Burke, age 62, is Vice Chair of Marsh & McLennan Companies. He joined the firm in 2019 with the acquisition of Jardine Lloyd Thompson Group (JLT), after having served as JLT’s Group Chief Executive for more than 13 years. He also serves as Chairman of Marsh JLT Specialty. Mr. Burke has more than three decades of experience in the insurance industry. Prior to serving as JLT’s Group Chief Executive, Mr. Burke held various roles at JLT including Group Chief Operating Officer and prior to that, CEO of JLT’s U.K. Retail and Employee Benefits business. Mr. Burke joined JLT in 2000, when it acquired the company he founded, Burke Ford Insurance Group. Mr. Burke serves as the Chairman of Newbury Racecourse plc and is a Director for the charity Injured Jockeys Fund in the U.K.

John Q. Doyle, age 57, is Vice Chair, Marsh & McLennan Companies and President and Chief Executive Officer of Marsh. He oversees all of Marsh’s businesses and operations globally. Mr. Doyle was named CEO of Marsh in July 2017, having joined Marsh & McLennan Companies as President of Marsh in April 2016. Prior to that, he was Chief Executive Officer of AIG’s commercial insurance businesses. Mr. Doyle began his career at AIG in 1986 and held several senior executive positions, including President and Chief Executive Officer of AIG property and casualty in the U.S., President and Chief Executive Officer of National Union Fire Insurance Company, and President of American Home Assurance Company.

Martine Ferland, age 59, is Vice Chair, Marsh & McLennan Companies and President and Chief Executive Officer of Mercer, a role she assumed in March 2019. Previously, she was Mercer’s Group President, responsible for leading the firm’s regions and Global Business Solutions. She joined Mercer in 2011 as Retirement Business Leader for the Europe and Pacific region, and has served as Europe and Pacific Region President and Co-President, Global Health. Ms. Ferland began her career as a pension actuary and consultant at Willis Towers Watson, where she spent 25 years and held various leadership positions in Montreal and New York. Ms. Ferland is a Fellow of the Society of Actuaries and of the Canadian Institute of Actuaries.

Carmen Fernandez, age 47, is Senior Vice President and Chief People Officer for Marsh & McLennan Companies. Prior to her current role, Ms. Fernandez held positions within Marsh & McLennan for 15 years, most recently Deputy CHRO, CHRO of Guy Carpenter, and HR leadership roles at Mercer, including North America HR Leader, Global HR Leader for the Career business and Chief of Staff in the Office of the CEO. Before joining Marsh & McLennan, Ms. Fernandez worked in investment banking at Bank of America and Goldman Sachs. She began her career as a consultant with Pricewaterhouse Coopers.

Daniel S. Glaser, age 60, is President and Chief Executive Officer of Marsh & McLennan Companies. Prior to starting his current role in January 2013, Mr. Glaser served as Group President and Chief Operating Officer of the Company. He rejoined Marsh & McLennan Companies in December 2007 as Chairman and Chief Executive Officer of Marsh, returning to the firm where he had begun his career right out of university in 1982. Mr. Glaser is an insurance industry veteran who has held senior positions in commercial insurance and insurance brokerage, working in the United States, Europe and the Middle East. Mr. Glaser serves as the Chairman of the U.S. Federal Advisory Committee on Insurance (FACI). He is a member of: the Board of Trustees for The Institutes and the Board of Directors for the Partnership for New York City. He is also Co-Chair of the International Advisory Board for BritishAmerican Business.

Peter Hearn, age 65, is Vice Chair, Marsh & McLennan Companies and President and Chief Executive Officer of Guy Carpenter. Previously, he was Global Chairman of Willis Re from March 2011 to June 2015. Prior to that, Mr. Hearn served as the company’s Global CEO from February 2005 to March 2011, during which time he was also a member of the Willis Group Executive Committee. Mr. Hearn began his reinsurance career in 1978 with Willis Faber and Dumas, working in the North American casualty, facultative, marine, and North American reinsurance divisions until 1981, when he joined Towers Perrin Forster and Crosby. Mr. Hearn joined Willis Re as a Senior Vice President in 1994.

Scott McDonald, age 54, is Vice Chair, Marsh & McLennan Companies and President and Chief Executive Officer of Oliver Wyman Group. Prior to assuming this role in January 2014, Mr. McDonald was President of Oliver Wyman. Before becoming President of Oliver Wyman in 2012, Mr. McDonald was the Managing Partner of Oliver Wyman's Financial Services practice and has held a number of senior positions, including the Global head of the Corporate & Institutional Banking Practice. Before joining Oliver Wyman in 1995, he was an M&A investment banker with RBC Dominion Securities in Toronto.

Mark McGivney, age 53, is Chief Financial Officer of Marsh & McLennan Companies. Prior to assuming this role in January 2016, Mr. McGivney held a number of senior financial management positions since joining the Company in 2007. Most recently he was Senior Vice President, Corporate Finance of Marsh & McLennan, and was responsible for leading and directing the Company’s Corporate Development, Treasury and Investor Relations functions from 2014 until 2016. Prior to that, he served as Chief Financial Officer of Marsh, and Chief Financial Officer and Chief Operating Officer of Mercer. His prior experience includes senior positions at The Hanover Insurance Group, including serving as Senior Vice President of Finance, Treasurer, and Chief Financial Officer of the Property & Casualty business, as well as positions with Merrill Lynch and Price Waterhouse.

AVAILABLE INFORMATION

The Company is subject to the information reporting requirements of the Securities Exchange Act of 1934. In accordance with the Exchange Act, the Company files with, or furnishes to, the SEC its annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K and proxy statement for its annual shareholders' meeting. The Company makes these reports and any amendments to these reports available free of charge through its website, www.mmc.com, as soon as reasonably practicable after they are filed with or furnished to the SEC. The SEC also maintains a website at www.sec.gov that contains reports, proxy and information statements and other information regarding issuers, like the Company, that file electronically with the SEC.

The Company also posts on its website certain governance and other information for investors.

The Company encourages investors to visit these websites from time to time, as information is updated and new information is posted. Website references in this report are provided as a convenience and do not constitute, and should not be viewed as, incorporation by reference of the information contained on, or available through, the websites. Therefore, such information should not be considered part of this report.

You should consider the risks described below in conjunction with the other information presented in this report. These risks have the potential to materially adversely affect the Company's business, results of operations or financial condition.

SUMMARY RISK FACTORS

Some of the factors that could materially and adversely affect our business, financial condition, results of operations or prospects, include the following:

• The COVID-19 pandemic could have a material adverse effect on our business operations, results of operations, cash flows and financial position;

• Our results of operations and investments could be adversely affected by macroeconomic conditions, political events and market conditions;

• Our business performance and growth plans could be negatively affected if we are not able to develop and implement improvements in technology or respond effectively to the threat of digital disruption and other technological change;

• We could incur significant liability or our reputation could be damaged if our information systems are breached or we otherwise fail to protect client or Company data or information systems;

• The costs to comply with, or our failure to comply with, U.S. and foreign laws related to privacy, data security and data protection, such as the E.U. General Data Protection Regulation (GDPR) and the California Consumer Privacy Act (CCPA), could adversely affect our financial condition, operating results and our reputation;

• We are subject to significant uninsured exposures arising from errors and omissions, breach of fiduciary duty and other claims;

• We cannot guarantee that we are or will be in compliance with all current and potentially applicable U.S. federal and state or foreign laws and regulations, and actions by regulatory authorities or changes in legislation and regulation in the jurisdictions in which we operate could have a material adverse effect on our business;

• Our business or reputation could be harmed by our reliance on third-party providers or introducers;

• The loss of members of our senior management team or other key colleagues could have a material adverse effect on our business;

• Failure to maintain our corporate culture could damage our reputation;

• Increasing scrutiny and changing expectations from investors, clients and our colleagues with respect to our environmental, social and governance (ESG) practices may impose additional costs on us or expose us to new or additional risks;

• We face significant competitive pressures in each of our businesses, including from disintermediation, as our competitive landscape continues to evolve;

• We rely on a large number of vendors and other third parties to perform key functions of our business operations and to provide services to our clients. These vendors and third parties may act in ways that could harm our business;

• Our inability to successfully recover should we experience a disaster or other business continuity or data recovery problem could cause material financial loss, loss of human capital, regulatory actions, reputational harm or legal liability;

• We face risks when we acquire businesses;

• If we are unable to collect our receivables, our results of operations and cash flows could be adversely affected;

• We may not be able to obtain sufficient financing on favorable terms;

• Our defined benefit pension plan obligations could cause the Company's financial position, earnings and cash flows to fluctuate;

• Our significant non-U.S. operations expose us to exchange rate fluctuations and various risks that could impact our business;

• Our quarterly revenues and profitability may fluctuate significantly;

• Credit rating downgrades would increase our financing costs and could subject us to operational risk;

• We have significantly increased our debt as a result of the JLT acquisition, which could adversely affect our financial flexibility;

• The current U.S. tax regime makes our results more difficult to predict;

• We are exposed to multiple risks associated with the global nature of our operations;

• Results in our Risk and Insurance Services segment may be adversely affected by a general decline in economic activity;

• Volatility or declines in premiums and other market trends may significantly impede our ability to grow revenues and profitability;

• Adverse legal developments and future regulations concerning how intermediaries are compensated by insurers or clients, as well as allegations of anti-competitive behavior or conflicts of interest more broadly, could have a material adverse effect on Marsh’s business, results of operations and financial condition;

• Mercer’s Investments business is subject to a number of risks, including risks related to third-party investment managers, operational risk, conflicts of interest, asset performance and regulatory compliance, that, if realized, could result in significant damage to our business;

• Revenues for the services provided by our Consulting segment may decline for various reasons, including as a result of changes in economic conditions, the value of equity, debt and other asset classes, our clients’ or an industry's financial condition or government regulation or an accelerated trend away from actively managed investments to passively managed investments;

• Factors affecting defined benefit pension plans and the services we provide relating to those plans could adversely affect Mercer; and

• The profitability of our Consulting segment may decline if we are unable to achieve or maintain adequate utilization and pricing rates for our consultants.

RISKS RELATING TO THE COMPANY GENERALLY

Macroeconomic Risks

The COVID-19 pandemic could have a material adverse effect on our business operations, results of operations, cash flows and financial position.

Global health concerns relating to the ongoing COVID-19 pandemic and related government actions taken to reduce the spread of the virus have had a dramatic impact on the macroeconomic environment, and the outbreak continues to materially increase economic uncertainty and reduce economic activity.

The outbreak has resulted in authorities implementing numerous measures to try to contain the virus, such as travel bans and restrictions, quarantines, shelter in place or total lock-down orders and business limitations and shutdowns. Such measures have significantly contributed to decreased levels of business activity of our clients and the industries and markets that we serve. Governments around the globe have taken steps to mitigate some of the more severe anticipated economic effects of the virus, but there can be no assurance that such steps will be effective or achieve their desired results in a timely fashion.

The outbreak has adversely impacted and is likely to further adversely impact our workforce and operations and the operations of our clients, third-party vendors and business partners. The spread of COVID-19 has caused us to modify our business practices (including transitioning substantially all of our colleagues to a remote work environment, restricting colleague travel, developing social distancing plans for our colleagues and cancelling physical participation in meetings, events and conferences), and we

may take further actions as may be required by government authorities or as we determine are in the best interests of our colleagues, clients and business partners. There is no certainty how long such policies will remain in effect or that such measures will be sufficient to mitigate the risks posed by the virus or will otherwise be satisfactory to government authorities.

The ongoing impacts of COVID-19 may affect our ability to generate new business, our overall level of profitability and cash flow, and our liquidity due to a number of macroeconomic and operational factors. Such factors may include:

• in our Risk and Insurance Services segment, a reduction in demand, pricing and commission

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There are no unresolved comments to be reported pursuant to Item 1B.

The Company maintains its corporate headquarters in New York City. We also maintain other offices around the world, primarily in leased space. In certain circumstances we may have space that we sublet to third parties, depending upon our needs in particular locations.

The Company and certain of its subsidiaries own, directly and indirectly through special purpose subsidiaries, a 58% condominium interest covering approximately 900,000 square feet of office space in a 44 story condominium in New York City. This real estate serves as the Company's headquarters and is occupied primarily by the Company and its subsidiaries for general corporate use. The condominium interests are financed by a 30-year mortgage loan that is non-recourse to the Company unless the Company (i) is downgraded below B (stable outlook) by S&P or Fitch or B2 (stable outlook) by Moody's and such downgrade is continuing or (ii) an event of default under the mortgage loan has occurred. The mortgage is secured by a first priority assignment of leases and rents, including the leases which the Company and certain of its subsidiaries entered into with their affiliated special purpose subsidiaries which own the mortgaged condominium interests. The net rent due under those leases in effect services the mortgage debt.

We and our subsidiaries are party to a variety of other legal, administrative, regulatory and government proceedings, claims and inquiries arising in the normal course of business.

Additional information regarding certain legal proceedings and related matters is set forth in Note 16 to the consolidated financial statements appearing under Part II, Item 8 ("Financial Statements and Supplementary Data") of this report.

Not applicable.

PART II

For information regarding dividends paid and the number of holders of the Company’s common stock, see the table entitled "Selected Quarterly Financial Data and Supplemental Information (Unaudited)" below on the last page of Part II, Item 8 ("Financial Statements and Other Supplementary Data") of this report.

The Company’s common stock is listed on the New York, Chicago and London Stock Exchanges. The following table indicates the high and low prices (NYSE composite quotations) of the Company’s common stock during 2020 and 2019 and each quarterly period thereof:

There were no repurchases of the Company's common stock during 2020. In November 2019, the Board of Directors of the Company authorized the Company to repurchase up to $2.5 billion in shares of the Company's common stock, which superseded any prior authorizations. As of December 31, 2020, the Company remained authorized to repurchase up to approximately $2.4 billion in shares of its common stock. There is no time limit on the authorization.

Marsh & McLennan Companies, Inc. and Subsidiaries

FIVE-YEAR STATISTICAL SUMMARY OF OPERATIONS

(a)Includes the impact of net restructuring costs of $89 million, $112 million, $161 million, $40 million, and $44 million in 2020, 2019, 2018, 2017 and 2016, respectively, and JLT integration, restructuring and acquisition related costs of $305 million, $485 million and $12 million in 2020, 2019 and 2018, respectively. 2020 also includes a $161 million JLT legacy E&O provision.

(b)Income tax expense in 2017 includes a $460 million provisional charge related to the enactment of U.S. tax reform.

See "Management’s Discussion and Analysis of Financial Condition and Results of Operations", appearing under Part II, Item 7 of this report, for discussion of significant items affecting the results of operations in 2020 and 2019.

General

Marsh & McLennan Companies, Inc. and its consolidated subsidiaries (the "Company") is a global professional services firm offering clients advice in the areas of risk, strategy and people. The Company’s 76,000 colleagues advise clients in over 130 countries. With annual revenue over $17 billion, the Company helps clients navigate an increasingly dynamic and complex environment through four market-leading businesses. Marsh advises individual and commercial clients of all sizes on insurance broking and innovative risk management solutions. Guy Carpenter develops advanced risk, reinsurance and capital strategies that help clients grow profitably and pursue emerging opportunities. Mercer delivers 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. Oliver Wyman Group serves as critical strategic, economic and brand advisor to private sector and governmental clients.

The Company conducts business through two segments:

• Risk and Insurance Services** includes risk management activities (risk advice, risk transfer and risk control and mitigation solutions) as well as insurance and reinsurance broking and services. The Company conducts business in this segment through Marsh and Guy Carpenter.

• Consulting** includes health, wealth and career consulting services and products, and specialized management, economic and brand consulting services. The Company conducts business in this segment through Mercer and Oliver Wyman Group.

We describe the primary sources of revenue and categories of expense for each segment below, in our discussion of segment financial results. A reconciliation of segment operating income to total operating income is included in Note 17 to the consolidated financial statements included in Part II, Item 8 in this report.

Acquisitions and dispositions impacting the Risk and Insurance Services and Consulting segments are discussed in Note 5 to the consolidated financial statements.

For information on fiscal 2018 results and similar comparisons, see "Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations" of our Form 10-K for the fiscal year ended December 31, 2019.

This MD&A contains forward-looking statements as that term is defined in the Private Securities Litigation Reform Act of 1995. See "Information Concerning Forward-Looking Statements" at the outset of this report.

Business Update Related To COVID-19

In March 2020, the World Health Organization declared the Coronavirus (COVID-19) a pandemic. The pandemic has impacted essentially every geography in which the Company operates. Governments implemented various restrictions around the world, including closure of non-essential businesses, travel, shelter-in-place requirements for citizens and other restrictions. The Company has taken a number of precautionary steps to safeguard its businesses and colleagues from COVID-19, including implementing travel restrictions, arranging work from home capabilities and flexible work policies.

In the second and third quarters of 2020, the Company began re-opening offices in various locations around the world, while ensuring that it continued to adhere to guidelines and orders issued by national, state and local governments. The timing of additional office re-openings will vary based on the conditions and restrictions in each location. In the fourth quarter, there was a surge in COVID-19 infections in many parts of the world, leading to renewed lock-downs and increased government restrictions. The safety and well-being of our colleagues continues to be our first priority. Several vaccines have been or are in various stages of approval. However, the speed of distribution and the impact on colleagues' ability to return to the office remains uncertain. The vast majority of the Company’s colleagues have continued and will continue working in a remote work environment for most of 2021. The Company expects it will continue its ability to service clients effectively while colleagues remain in a remote work environment.

For the year ended December 31, 2020, the COVID-19 pandemic had an adverse impact on the Company’s revenue growth, primarily in our businesses that are discretionary in nature, which was partly mitigated through disciplined expense management by implementing restrictions on travel and other cost containment measures. However, the ultimate extent of the COVID-19 impact to the Company will depend on numerous evolving factors and future developments that it is not able to predict. Factors that could adversely affect the Company’s financial statements related to the financial and operational impact of COVID-19 are outlined in the "Risk Factors” section of this report.

Acquisition of JLT

On April 1, 2019, the Company completed the acquisition (the "Transaction") of all of the outstanding shares of Jardine Lloyd Thompson Group plc ("JLT"), a public company organized under the laws of England and Wales. In accordance with the terms of the Transaction, JLT shareholders received £19.15 in cash for each JLT share, which valued JLT’s existing share capital at approximately £4.3 billion (or approximately $5.6 billion based on the exchange rate of U.S. $1.31:£1) on the Transaction closing date. As of December 31, 2020, the Company has substantially integrated JLT into all of its business operations.

After the acquisition of JLT, the Company assumed the legal liabilities of JLT’s litigation and regulatory exposures as of April 1, 2019. Please see the "Risk Factors" section of this Annual Report on Form 10-K for risks associated with the acquisition and Note 16 to the consolidated financial statements which discusses certain errors and omission matters related to the acquisition.

JLT's results of operations for the period April 1, 2019 through December 31, 2019 are included in the Company’s results of operations for 2019. In accordance with applicable accounting guidance, JLT's results of operations for the period January 1 through March 31, 2019 and for the year ended 2018 are not included in the Company's results of operations and therefore, affect comparability. The Company’s results for the years ended December 31, 2020 and 2019 were impacted by JLT related acquisition, restructuring and integration costs as well as legacy MMC restructuring programs as discussed in Note 14 to the consolidated financial statements.

Consolidated Results of Operations

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Market Risk and Credit Risk

Certain of the Company’s revenues, expenses, assets and liabilities are exposed to the impact of interest rate changes and fluctuations in foreign currency exchange rates and equity markets.

Interest Rate Risk and Credit Risk

Interest income generated from the Company’s cash investments as well as invested fiduciary funds will vary with the general level of interest rates.

The Company had the following investments subject to variable interest rates:

Based on the above balances, if short-term interest rates increased or decreased by 10%, or 3 basis points, over the full year, annual interest income, including interest earned on fiduciary funds, would increase or decrease by approximately $2 million.

In addition to interest rate risk, our cash investments and fiduciary fund investments are subject to potential loss of value due to counter-party credit risk. To minimize this risk, the Company and its subsidiaries invest pursuant to a Board approved investment policy. The policy mandates the preservation of principal and liquidity and requires broad diversification with counter-party limits assigned based primarily on credit rating and type of investment. The Company carefully monitors its cash and fiduciary fund investments and will further restrict the portfolio as appropriate to market conditions. The majority of cash and fiduciary fund investments are invested in short-term bank deposits and liquid money market funds.

Foreign Currency Risk

The translated values of revenue and expense from the Company’s international operations are subject to fluctuations due to changes in currency exchange rates. The non-U.S. based revenue that is exposed to foreign exchange fluctuations is approximately 53% of total revenue. We periodically use forward contracts and options to limit foreign currency exchange rate exposure on net income and cash flows for specific, clearly defined transactions arising in the ordinary course of business. Although the Company has significant revenue generated in foreign locations which is subject to foreign exchange rate fluctuations, in most cases both the foreign currency revenue and expenses are in the functional currency of the foreign location. As such, under normal circumstances, the U.S. dollar translation of both the revenues and expenses, as well as the potentially offsetting movements of various currencies against the U.S. dollar, generally tends to mitigate the impact on net operating income of foreign currency risk. However, there have been periods where the impact was not mitigated due to external market factors, and external macroeconomic events may result in greater foreign exchange rate fluctuations in the future. If foreign exchange rates of major currencies (Euro, Sterling, Australian dollar and Canadian dollar) moved 10% in the same direction against the U.S. dollar compared with the foreign exchange rates in 2020, the Company estimates net operating income would increase or decrease by approximately $39 million. The Company has exposure to approximately 80 foreign currencies overall. In Continental Europe, the largest amount of revenue from renewals for the Risk & Insurance Services segment occurs in the first quarter.

Equity Price Risk

The Company holds investments in both public and private companies as well as private equity funds, including investments of approximately $72 million that are valued using readily determinable fair values and approximately $33 million of investments without readily determinable fair values. The Company also has investments of approximately $280 million that are accounted for using the equity method. The investments are subject to risk of decline in market value, which, if determined to be other than temporary for assets without readily determinable fair values, could result in realized impairment losses. The

Company periodically reviews the carrying value of such investments to determine if any valuation adjustments are appropriate under the applicable accounting pronouncements.

At December 31, 2020, the Company owns approximately 14% of the common stock of AF, a South African company listed on the Johannesburg Stock Exchange. The investment in AF is accounted at fair value, with unrealized gains and losses recorded as investment income in the consolidated statement of income. The fair value of this investment at December 31, 2020 was approximately $54 million.

Other

A number of lawsuits and regulatory proceedings are pending. See Note 16 ("Claims, Lawsuits and Other Contingencies") to the consolidated financial statements included in this report.

MARSH & McLENNAN COMPANIES, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF INCOME

The accompanying notes are an integral part of these consolidated statements.

MARSH & McLENNAN COMPANIES, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

The accompanying notes are an integral part of these consolidated statements.

MARSH & McLENNAN COMPANIES, INC. AND SUBSIDIARIES

CONSOLIDATED BALANCE SHEETS

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None.

Disclosure Controls and Procedures. Based on their evaluation, as of the end of the period covered by this annual report on Form 10-K, the Company’s chief executive officer and chief financial officer have concluded that the Company’s disclosure controls and procedures (as defined in Rules 13a-15(e) or 15d-15(e) under the Securities Exchange Act of 1934) are effective.

Internal Control over Financial Reporting.

(a)Management’s Annual Report on Internal Control Over Financial Reporting

MANAGEMENT’S ANNUAL REPORT ON INTERNAL CONTROL OVER FINANCIAL REPORTING

The management of Marsh & McLennan Companies, Inc. is responsible for establishing and maintaining adequate internal control over financial reporting for the Company. The Company’s internal control over financial reporting is designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles.

The Company’s internal control over financial reporting includes those policies and procedures relating to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the Company; the recording of all necessary transactions to permit the preparation of the Company’s consolidated financial statements in accordance with generally accepted accounting principles; the proper authorization of receipts and expenditures in accordance with authorizations of the Company’s management and directors; and the prevention or timely detection of the unauthorized acquisition, use or disposition of assets that could have a material effect on the Company’s consolidated financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

Management evaluated the effectiveness of the Company’s internal control over financial reporting as of December 31, 2020 under the supervision and with the participation of the Company’s principal executive and principal financial officers. In making this evaluation, management used the criteria set forth by the Committee of Sponsoring Organizations of the Treadway Commission (COSO) in Internal Control—Integrated Framework issued in 2013. Based on its evaluation, management determined that the Company maintained effective internal control over financial reporting as of December 31, 2020.

Deloitte & Touche LLP, the Independent Registered Public Accounting Firm that audited and reported on the Company’s consolidated financial statements included in this annual report on Form 10-K, also issued an audit report on the effectiveness of the Company’s internal control over financial reporting as of December 31, 2020.

(b)Audit Report of the Registered Public Accounting Firm.

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Shareholders and the Board of Directors of Marsh & McLennan Companies, Inc.

Opinion on Internal Control over Financial Reporting

We have audited the internal control over financial reporting of Marsh & McLennan Companies, Inc. and subsidiaries (the “Company”) as of December 31, 2020, based on criteria established in Internal Control — Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO). In our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2020, based on criteria established in Internal Control — Integrated Framework (2013) issued by COSO.

We have also audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the consolidated financial statements as of and for the year ended December 31, 2020, of the Company and our report dated February 17, 2021, expressed an unqualified opinion on those financial statements.

Basis for Opinion

The Company’s management is responsible for maintaining effective internal control over financial reporting and for its assessment of the effectiveness of internal control over financial reporting, included in the accompanying Management’s Annual Report on Internal Control Over Financial Reporting. Our responsibility is to express an opinion on the Company’s internal control over financial reporting based on our audit. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audit in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether effective internal control over financial reporting was maintained in all material respects. Our audit included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, testing and evaluating the design and operating effectiveness of internal control based on the assessed risk, and performing such other procedures as we considered necessary in the circumstances. We believe that our audit provides a reasonable basis for our opinion.

Definition and Limitations of Internal Control over Financial Reporting

A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

/s/ Deloitte & Touche LLP

New York, New York

February 17, 2021

(c)Changes in Internal Control Over Financial Reporting

There were no changes in the Company’s internal control over financial reporting identified in connection with the evaluation required by Rules 13a-15(d) or 15d-15(d) under the Securities Exchange Act of 1934 that occurred during the quarter ended December 31, 2020 that have materially affected, or are reasonably likely to materially affect, the Company’s internal control over financial reporting.

None.

PART III

Information as to the directors and nominees for the board of directors of the Company is incorporated herein by reference to the material set forth under the heading "Item 1: Election of Directors" in the 2021 Proxy Statement.

The executive officers and executive officer appointees of the Company are Peter J. Beshar, Paul Beswick, Dominic Burke, John Q. Doyle, Martine Ferland, Carmen Fernandez, Daniel S. Glaser, Peter Hearn, Scott McDonald and Mark C. McGivney. Information with respect to these individuals is provided in Part I, Item 1 above under the heading "Executive Officers of the Company".

The information set forth in the 2021 Proxy Statement in the sections "Corporate Governance—Codes of Conduct", "Board of Directors and Committees—Committees—Audit Committee" and "Additional Information—Transactions with Management and Others" is incorporated herein by reference.

The information set forth in the sections "Additional Information—Director Compensation" and "Executive Compensation—Compensation of Executive Officers" in the 2021 Proxy Statement is incorporated herein by reference.

The information set forth in the sections "Additional Information—Stock Ownership of Directors, Management and Certain Beneficial Owners" and "Additional Information—Equity Compensation Plan Information" in the 2021 Proxy Statement is incorporated herein by reference.

The information set forth in the sections "Corporate Governance—Director Independence", "Corporate Governance—Review of Related-Person Transactions" and "Additional Information—Transactions with Management and Others" in the 2021 Proxy Statement is incorporated herein by reference.

The information set forth under the heading "Item 3: Ratification of Selection of Independent Registered Public Accounting Firm—Fees of Independent Registered Public Accounting Firm" in the 2021 Proxy Statement is incorporated herein by reference.

PART IV

The following documents are filed as a part of this report:

(1)Consolidated Financial Statements:

Consolidated Statements of Income for each of the three years in the period ended December 31, 2020

Consolidated Statements of Comprehensive Income for each of the three years in the period ended December 31, 2020

Consolidated Balance Sheets as of December 31, 2020 and 2019

Consolidated Statements of Cash Flows for each of the three years in the period ended December 31, 2020

Consolidated Statements of Shareholders Equity for each of the three years in the period ended December 31, 2020

Notes to Consolidated Financial Statements

Report of Independent Registered Public Accounting Firm

Other:

Selected Quarterly Financial Data and Supplemental Information (Unaudited) for fiscal years 2020 and 2019

Five-Year Statistical Summary of Operations

(2)All required Financial Statement Schedules are included in the Consolidated Financial Statements or the Notes to Consolidated Financial Statements.

(3)The following exhibits are filed as a part of this report:

(2.1)Stock Purchase Agreement, dated as of June 6, 2010, by and between Marsh & McLennan Companies, Inc. and Altegrity, Inc. (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2010)

(2.2) Rule 2.7 Announcement, dated as of September 18, 2018 (incorporated by reference to the Company’s Current Report on Form 8-K dated September 18, 2018)

**†**As permitted by Item 601(b)(4)(iii)(A) of Regulation S-K, the Company has not filed with this Form 10-K certain instruments defining the rights of holders of long-term debt of the Company and its subsidiaries becauce the total amount of securities authorized under any of such instruments does not exceed 10% of the total assets of the Company and its subsidiaries on a consolidated basis. The Company agrees to furnish a copy of any such agreement to the Commission upon request.

(2.3) Co-operation Agreement, dated as of September 18, 2018, by and among Marsh & McLennan Companies, Inc., MMC Treasury Holdings (UK) Limited and Jardine Lloyd Thompson Group plc. (incorporated by reference to the Company’s Current Report on Form 8-K dated September 18, 2018)

(3.1) Restated Certificate of Incorporation of Marsh & McLennan Companies, Inc. (incorporated by reference to the Company’s Current Report on Form 8-K dated July 17, 2008)

(3.2) Amended and Restated By-Laws of Marsh & McLennan Companies, Inc. (incorporated by reference to the Company’s Current Report on Form 8-K dated January 12, 2017)

(4.1)Indenture dated as of June 14, 1999 between Marsh & McLennan Companies, Inc. and State Street Bank and Trust Company, as trustee (incorporated by reference to the Company’s Registration Statement on Form S-3, Registration No. 333-108566)

(4.2) Third Supplemental Indenture dated as of July 30, 2003 between Marsh & McLennan Companies, Inc. and U.S. Bank National Association (as successor to State Street Bank and Trust Company), as trustee (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2003)

(4.3) Indenture dated as of March 19, 2002 between Marsh & McLennan Companies, Inc. and State Street Bank and Trust Company, as trustee (incorporated by reference to the Company’s Registration Statement on Form S-4, Registration No. 333-87510)

(4.4) Indenture, dated as of July 15, 2011, between Marsh & McLennan Companies, Inc. and The Bank of New York Mellon, as trustee (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2011)

(4.5) First Supplemental Indenture, dated as of July 15, 2011, between Marsh & McLennan Companies, Inc. and The Bank of New York Mellon, as trustee (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2011)

(4.6) Form of Third Supplemental Indenture between Marsh & McLennan Companies, Inc. and The Bank of New York Mellon, as trustee (incorporated by reference to the Company’s Current Report on Form 8-K dated September 24, 2013)

(4.7) Form of Fourth Supplemental Indenture between Marsh & McLennan Companies, Inc. and The Bank of New York Mellon, as trustee (incorporated by reference to the Company’s Current Report on Form 8-K dated May 27, 2014)

(4.8) Form of Fifth Supplemental Indenture between Marsh & McLennan Companies, Inc. and The Bank of New York Mellon, as trustee (incorporated by reference to the Company’s Current Report on Form 8-K dated September 10, 2014)

*Management contract or compensatory plan or arrangement required to be filed as an exhibit pursuant to Item 15(b) of Form 10-K.

(4.9) Sixth Supplemental Indenture, dated as of March 6, 2015, between Marsh & McLennan Companies, Inc. and The Bank of New York Mellon, as trustee (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2015)

(4.10) Seventh Supplemental Indenture, dated as of September 14, 2015, between Marsh & McLennan Companies, Inc. and The Bank of New York Mellon, as trustee (incorporated by reference to the Company's Current Report on Form 8-K filed on September 14, 2015)

(4.11) Eighth Supplemental Indenture, dated as of March 14, 2016, between Marsh & McLennan Companies, Inc. and The Bank of New York Mellon, as trustee (incorporated by reference to the Company's Quarterly Report on Form 10-Q filed on May 2, 2016)

(4.12) Ninth Supplemental Indenture, dated as of January 12, 2017, between Marsh & McLennan Companies, Inc. and The Bank of New York Mellon, as trustee (incorporated by reference to the Company's Annual Report on Form 10-K filed on February 24, 2017)

(4.13) Tenth Supplemental Indenture, dated as of March 1, 2018, between Marsh & McLennan Companies, Inc. and The Bank of New York Mellon, as trustee (incorporated by reference to the Company's Current Report on Form 8-K filed on March 1, 2018)

(4.14) Eleventh Supplemental Indenture, dated January 15, 2019, between Marsh & McLennan Companies, Inc. and The Bank of New York Mellon, as trustee (incorporated by reference to the Company's Current Report on Form 8-K filed on January 15, 2019)

(4.15) Twelfth Supplemental Indenture, dated March 21, 2019, between Marsh & McLennan Companies, Inc. and The Bank of New York Mellon, as trustee (incorporated by reference to the Company's Current Report on Form 8-K filed on March 21, 2019)

(4.16) Thirteenth Supplemental Indenture, dated May 7, 2020, between Marsh & McLennan Companies, Inc. and The Bank of New York Mellon, as trustee (incorporated by reference to Company’s Current Report on Form 8-K dated May 7, 2020)

(4.17) Description of Marsh & McLennan Companies, Inc.’s Securities Registered Pursuant to Section 12 of the Securities Exchange Act of 1934 (incorporated by reference to the Company's Annual Report on Form 10-K for the year ended December 31, 2019)

(10.1)*Marsh & McLennan Companies, Inc. U.S. Employee 1996 Cash Bonus Award Voluntary Deferral Plan (incorporated by reference to the Company's Annual Report on Form 10-K for the year ended December 31, 1996

*Management contract or compensatory plan or arrangement required to be filed as an exhibit pursuant to Item 15(b) of Form 10-K.

(10.2)*Marsh & McLennan Companies, Inc. U.S. Employee 1997 Cash Bonus Award Voluntary Deferral Plan (incorporated by reference to the Company's Annual Report on Form 10-K for the year ended December 31, 1997)

(10.3)*Marsh & McLennan Companies, Inc. U.S. Employee 1998 Cash Bonus Award Voluntary Deferral Plan (incorporated by reference to the Company's Annual Report on Form 10-K for the year ended December 31, 1998)

(10.4)*Marsh & McLennan Companies, Inc. 2000 Senior Executive Incentive and Stock Award Plan (incorporated by reference to the Company’s Annual Report on Form 10-K for the year ended December 31, 1999)

(10.5)*Amendments to Marsh & McLennan Companies, Inc. 2000 Senior Executive Incentive and Stock Award Plan and the Marsh & McLennan Companies, Inc. 2000 Employee Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2005)

(10.6)*Form of Awards under the Marsh & McLennan Companies, Inc. 2000 Senior Executive Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2004)

(10.7)*Additional Forms of Awards under the Marsh & McLennan Companies, Inc. 2000 Senior Executive Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2005)

(10.8)*Marsh & McLennan Companies, Inc. 2000 Employee Incentive and Stock Award Plan (incorporated by reference to the Company’s Annual Report on Form 10-K for the year ended December 31, 2001)

(10.9)*Form of Awards under the Marsh & McLennan Companies, Inc. 2000 Employee Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2004)

(10.10)*Additional Forms of Awards under the Marsh & McLennan Companies, Inc. 2000 Employee Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2005)

(10.11)*Form of Long-term Incentive Award under the Marsh & McLennan Companies, Inc. 2000 Senior Executive Incentive and Stock Award Plan and the Marsh & McLennan Companies, Inc. 2000 Employee Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2006)

*Management contract or compensatory plan or arrangement required to be filed as an exhibit pursuant to Item 15(b) of Form 10-K.

(10.12)*Form of 2007 Long-term Incentive Award under the Marsh & McLennan Companies, Inc. 2000 Senior Executive Incentive and Stock Award Plan and the Marsh & McLennan Companies, Inc. 2000 Employee Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2007)

(10.13)*Form of 2008 Long-term Incentive Award under the Marsh & McLennan Companies, Inc. 2000 Senior Executive Incentive and Stock Award Plan and the Marsh & McLennan Companies, Inc. 2000 Employee Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2008)

(10.14)*Form of 2009 Long-term Incentive Award under the Marsh & McLennan Companies, Inc. 2000 Senior Executive Incentive and Stock Award Plan and the Marsh & McLennan Companies, Inc. 2000 Employee Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2009)

(10.15)*Form of 2010 Long-term Incentive Award under the Marsh & McLennan Companies, Inc. 2000 Senior Executive Incentive and Stock Award Plan and the Marsh & McLennan Companies, Inc. 2000 Employee Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2010)

(10.16)*Form of 2011 Long-term Incentive Award under the Marsh & McLennan Companies, Inc. 2000 Senior Executive Incentive and Stock Award Plan and the Marsh & McLennan Companies, Inc. 2000 Employee Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2011)

(10.17)*Form of 2011 Long-term Incentive Award dated as of June 1, 2011 under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2011)

(10.18)*Form of 2012 Long-term Incentive Award under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2012)

(10.19)*Form of 2013 Long-term Incentive Award under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2013)

(10.20)*Form of 2014 Long-term Incentive Award under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2014)

*Management contract or compensatory plan or arrangement required to be filed as an exhibit pursuant to Item 15(b) of Form 10-K.

(10.21)*Form of 2015 Long-term Incentive Award under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2015)

(10.22)*Form of 2016 Long-term Incentive Award under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2016)

(10.23)*Form of Deferred Stock Unit Award, dated as of February 24, 2012, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2012)

(10.24)*Form of Deferred Stock Unit Award, dated as of March 1, 2013, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2013)

(10.25)*Form of Deferred Stock Unit Award, dated as of March 1, 2014, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2014)

(10.26)*Form of Deferred Stock Unit Award, dated as of March 1, 2015, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2015)

(10.27)*Form of Deferred Stock Unit Award, dated as of March 1, 2016 under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2016)

(10.28)*Form of Deferred Stock Unit Award, with grant dates from March 1, 2017 through February 1, 2018, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended March 31, 2017)

(10.29)*Form of Deferred Stock Unit Award, with grant dates from March 1, 2018 through February 1, 2019, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended March 31, 2018)

(10.30)*Form of Deferred Stock Unit Award, with grant dates from March 1, 2019 through February 1, 2020, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended March 31, 2019)

*Management contract or compensatory plan or arrangement required to be filed as an exhibit pursuant to Item 15(b) of Form 10-K.

(10.31)*Form of Deferred Stock Unit Award, with grant dates from May 1, 2019 through February 1, 2020, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan - Form A (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended June 30, 2019)

(10.32)*Form of Deferred Stock Unit Award, with grant dates from May 1, 2019 through February 1, 2020, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan - Form B (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended June 30, 2019)

(10.33)Form of Deferred Stock Unit Award, with grant dates from March 1, 2020 through February 1, 2021, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended March 31, 2020)

(10.34)*Form of Restricted Stock Unit Award, dated as of April 1, 2016 under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2016)

(10.35)*Form of Restricted Stock Unit Award, dated as of February 22, 2017 under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2017)

(10.36)*Form of Restricted Stock Unit Award, dated as of February 21, 2018 under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2018)

(10.37)*Form of Restricted Stock Unit Award, dated as of February 19, 2019, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended March 31, 2019)

(10.38)*Form of Restricted Stock Unit Award, dated as of May 1, 2019, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan - Form A (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended June 30, 2019)

(10.39)*Form of Restricted Stock Unit Award, dated as of May 1, 2019, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan - Form B (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended June 30, 2019)

*Management contract or compensatory plan or arrangement required to be filed as an exhibit pursuant to Item 15(b) of Form 10-K.

(10.40)*Form of Restricted Stock Unit Award, dated as of May 1, 2019, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan - Form C (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended June 30, 2019)

(10.41)*Form of Restricted Stock Unit Award, dated as of February 19, 2020, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended March 31, 2020)

(10.42)*Form of Performance Stock Unit Award, dated as of February 22, 2017, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended March 31, 2017)

(10.43)*Form of Performance Stock Unit Award, dated as of February 21, 2018, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended March 31, 2018)

(10.44)*Form of Performance Stock Unit Award, dated as of February 19, 2019, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended March 31, 2019)

(10.45)*Form of Performance Stock Unit Award, dated as of May 1, 2019, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended June 30, 2019)

(10.46)*Form of Performance Stock Unit Award, dated as of February 19, 2020, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended March 31, 2020)

(10.47)*Form of Stock Option Award, dated as of February 22, 2017, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended March 31, 2017)

(10.48)*Form of Stock Option Award, dated as of February 21, 2018, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended March 31, 2018)

(10.49)*Form of Stock Option Award, dated as of February 19, 2019, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended March 31, 2019)

*Management contract or compensatory plan or arrangement required to be filed as an exhibit pursuant to Item 15(b) of Form 10-K.

(10.50)*Form of Stock Option Award, dated as of May 1, 2019, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended June 30, 2019)

(10.51)*Form of Stock Option Award, dated as of February 19, 2020, under the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended March 31, 2020)

(10.52)*Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company’s Registration Statement on Form S-8 dated August 5, 2011, Registration No. 333-176084)

(10.53)*Amendment to the Marsh & McLennan Companies, Inc. 2011 Incentive and Stock Award Plan (incorporated by reference to the Company’s Annual Report on Form 10-K for the year ended December 31, 2018)

(10.54)*Marsh & McLennan Companies, Inc. 2020 Incentive and Stock Award Plan (incorporated by reference from Exhibit C to the Company’s Definitive Proxy Statement on Schedule 14A filed on April 3, 2020)

(10.55)*Amendments to Certain Marsh & McLennan Companies Equity-Based Awards Due to U.S. Tax Law Changes Affecting Equity-Based Awards granted under the Marsh & McLennan Companies, Inc. 2000 Senior Executive Incentive and Stock Award Plan and the Marsh & McLennan Companies, Inc. 2000 Employee Incentive and Stock Award Plan, effective January 1, 2009 (incorporated by reference to the Company’s Annual Report on Form 10-K for the year ended December 31, 2008)

(10.56)*Section 409A Amendment Document, effective as of January 1, 2009 (incorporated by reference to the Company’s Annual Report on Form 10-K for the year ended December 31, 2008)

(10.57)*Section 409A Amendment Regarding Payments Conditioned Upon Employment-Related Action to Any and All Plans or Arrangements Entered into by the Marsh & McLennan Companies, Inc., or any of its Direct or Indirect Subsidiaries, that Provide for the Payment of Section 409A Nonqualified Deferred Compensation, effective December 21, 2012 (incorporated by reference to the Company’s Annual Report on Form 10-K for the year ended December 31, 2012)

*Management contract or compensatory plan or arrangement required to be filed as an exhibit pursuant to Item 15(b) of Form 10-K.

(10.58)*Marsh & McLennan Companies Supplemental Savings & Investment Plan (formerly the Marsh & McLennan Companies Stock Investment Supplemental Plan) Restatement, effective January 1, 2012 (incorporated by reference to the Company’s Annual Report on Form 10-K for the year ended December 31, 2012)

(10.59)*First Amendment to the Marsh & McLennan Companies Supplemental Savings & Investment Plan Restatement effective January 1, 2012 (incorporated by reference to the Company's Annual Report on Form 10-K for the year ended December 31, 2016)

(10.60)*Second Amendment to the Marsh & McLennan Companies Supplemental Savings & Investment Plan Restatement effective January 1, 2012 (incorporated by reference to the Company's Annual Report on Form 10-K for the year ended December 31, 2017)

(10.61)*Third Amendment to the Marsh & McLennan Companies Supplemental Savings & Investment Plan Restatement effective January 1, 2012 (incorporated by reference to the Company’s Annual Report on Form 10-K for the year ended December 31, 2018)

(10.62)Fourth Amendment to the Marsh & McLennan Companies Supplemental Savings & Investment Plan Restatement effective January 1, 2012

(10.63)*Marsh & McLennan Companies Benefit Equalization Plan and Marsh & McLennan Companies Supplemental Retirement Plan as Restated, effective January 1, 2012 (incorporated by reference to the Company’s Annual Report on Form 10-K for the year ended December 31, 2012)

(10.64)*First Amendment to the Marsh & McLennan Companies Benefit Equalization Plan and Marsh & McLennan Companies Supplemental Retirement Plan as Restated effective January 1, 2012 (incorporated by reference to the Company's Annual Report on Form 10-K for the year ended December 31, 2016)

(10.65)*Second Amendment to the Marsh & McLennan Companies Benefit Equalization Plan and Marsh & McLennan Companies Supplemental Retirement Plan as Restated effective January 1, 2012 (incorporated by reference to the Company's Annual Report on Form 10-K for the year ended December 31, 2016)

*Management contract or compensatory plan or arrangement required to be filed as an exhibit pursuant to Item 15(b) of Form 10-K.

(10.66)*Marsh & McLennan Companies, Inc. Senior Executive Severance Pay Plan (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the Quarter ended March 31, 2008)

(10.67)*Amendment to the Marsh & McLennan Companies, Inc. Senior Executive Severance Pay Plan, effective December 31, 2009 (incorporated by reference to the Company’s Annual Report on Form 10-K for the year ended December 31, 2009)

(10.68)*Marsh & McLennan Companies, Inc. Senior Management Incentive Compensation Plan (incorporated by reference to the Company’s Annual Report on Form 10-K for the year ended December 31, 1994)

(10.69)*Marsh & McLennan Companies, Inc. Directors' Stock Compensation Plan - May 31, 2009 Restatement (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2009)

(10.70)*Marsh & McLennan Companies International Retirement Plan As Amended and Restated Effective January 1, 2009 (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2014)

(10.71)*Description of compensation arrangements for independent directors of Marsh & McLennan Companies, Inc. effective June 1, 2016 (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2016)

(10.72)*Letter Agreement, effective as of March 20, 2013, between Marsh & McLennan Companies, Inc. and Daniel S. Glaser (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended September 30, 2013)

(10.73)*Non-Competition and Non-Solicitation Agreement, effective as of September 18, 2013, between Marsh & McLennan Companies, Inc. and Daniel S. Glaser (incorporated by reference to the Company's Quarterly Report on Form 10-Q for the quarter ended September 30, 2013)

(10.74)*Letter Agreement, effective as of May 14, 2014, between Marsh & McLennan Companies, Inc. and Daniel S. Glaser (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2014)

*Management contract or compensatory plan or arrangement required to be filed as an exhibit pursuant to Item 15(b) of Form 10-K.

(10.75)*Letter Agreement, effective as of February 22, 2016, between Marsh & McLennan Companies, Inc. and Daniel S. Glaser (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2016)

(10.76)*Letter Agreement, effective as of February 22, 2017, between Marsh & McLennan Companies, Inc. and Daniel S. Glaser (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2017)

(10.77)*Letter Agreement, dated as of September 18, 2019, between Marsh & McLennan Companies, Inc. and Daniel S. Glaser (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2019)

(10.78)*Letter Agreement, effective as of January 1, 2016, between Marsh & McLennan Companies, Inc. and Mark C. McGivney (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2015)

(10.79)*Non-Competition and Non-Solicitation Agreement, effective as of January 1, 2016, between Marsh & McLennan Companies, Inc. and Mark C. McGivney (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2015)

(10.80)*Letter Agreement, effective as of January 17, 2018, between Marsh & McLennan Companies, Inc. and Mark C. McGivney (incorporated by reference to the Company's Annual Report on Form 10-K for the year ended December 31, 2017)

(10.81)Letter Agreement, effective as of January 16, 2019, between Marsh & McLennan, Inc. and Mark C. McGivney (incorporated by reference to the Company’s Annual Report on Form 10-K for the year ended December 31, 2018)

(10.82)*Letter Agreement, effective as of July 5, 2017, between Marsh & McLennan Companies, Inc. and John Q. Doyle (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2018)

(10.83)*Non-Competition and Non-Solicitation Agreement, dated as of February 25, 2016, between Marsh & McLennan Companies, Inc. and John Q. Doyle (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2018)

*Management contract or compensatory plan or arrangement required to be filed as an exhibit pursuant to Item 15(b) of Form 10-K.

(10.84)*Letter Agreement, effective as of January 15, 2020, between Marsh & McLennan Companies, Inc. and John Q. Doyle (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2020)

(10.85)*Letter Agreement, effective as of March 1, 2019, between Marsh & McLennan Companies, Inc. and Martine Ferland (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2020)

(10.86)*Non-Competition and Non-Solicitation Agreement, effective as of March 1, 2016, between Marsh & McLennan Companies, Inc. and Martine Ferland (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2020)

(10.87)*Letter Agreement, effective as of July 1, 2019, between Marsh & McLennan Companies, Inc. and Dominic J. Burke (incorporated by reference to the Company's Current Report on Form 8-K filed on April 29, 2020)

(10.88)*Non-Competition and Non-Solicitation Agreement, effective as of April 1, 2019, between Marsh & McLennan Companies, Inc. and Dominic J. Burke (incorporated by reference to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2020)

(10.89)*Letter Agreement, effective as of April 29, 2020, between Marsh & McLennan Companies, Inc. and Dominic J. Burke (incorporated by reference to the Company's Current Report on Form 8-K filed on April 29, 2020)

(10.90)Calculation Agency Agreement, dated as of January 15, 2019, between Marsh & McLennan Companies, Inc. and The Bank of New York Mellon, as calculation agent (incorporated by reference to the Company's Current Report on Form 8-K filed on January 15, 2019)

(10.91)Paying Agency Agreement, dated as of March 21, 2019, between Marsh & McLennan Companies, Inc. and The Bank of New York Mellon, London Branch, as paying agent (incorporated by reference to the Company's Current Report on Form 8-K filed on March 21, 2019)

(10.92)Shareholder Undertaking, dated as of September 18, 2018 (incorporated by reference to the Company’s Current Report on Form 8-K dated September 18, 2018)

(10.93)Form of Director Undertaking, dated as of September 18, 2018 (incorporated by reference to the Company’s Current Report on Form 8-K dated September 18, 2018)

*Management contract or compensatory plan or arrangement required to be filed as an exhibit pursuant to Item 15(b) of Form 10-K.

(10.94)Bridge Loan Agreement, dated as of September 18, 2018 by and between Marsh & McLennan Companies, Inc., the lenders party thereto and Goldman Sachs Bank USA, as administrative agent (incorporated by reference to the Company’s Current Report on Form 8-K dated September 18, 2018)

(10.95)Calculation Agency Agreement, dated as of January 15, 2019, between Marsh & McLennan Companies, Inc. and The Bank of New York Mellon, as calculation agent (incorporated by reference to the Company's Current Report on Form 8-K filed on January 15, 2019)

(14.1)Code of Ethics for Chief Executive and Senior Financial Officers (incorporated by reference to the Company’s Annual Report on Form 10-K for the year ended December 31, 2002)

(21.1)List of Subsidiaries of Marsh & McLennan Companies, Inc.

(23.1)Consent of Independent Registered Public Accounting Firm

(24.1)Power of Attorney (included on signature page)

(31.1)Rule 13a-14(a)/15d-14(a) Certification of Chief Executive Officer

(31.2)Rule 13a-14(a)/15d-14(a) Certification of Chief Financial Officer

(32.1)Section 1350 Certifications

101.INSXBRL Instance Document

101.SCHXBRL Taxonomy Extension Schema

101.CALXBRL Taxonomy Extension Calculation Linkbase

101.DEFXBRL Taxonomy Extension Definition Linkbase

101.LABXBRL Taxonomy Extension Label Linkbase

101.PREXBRL Taxonomy Extension Presentation Linkbase

104.Cover Page Interactive Data File (formatted as inline XBRL and contained in Exhibit 101)

*Management contract or compensatory plan or arrangement required to be filed as an exhibit pursuant to Item 15(b) of Form 10-K.

None.

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Each person whose signature appears below hereby constitutes and appoints Katherine J. Brennan and Connor Kuratek, and each of them singly, such person’s lawful attorneys-in-fact and agents, with full power to them and each of them to sign for such person, in the capacity indicated below, any and all amendments to this Annual Report on Form 10-K filed with the Securities and Exchange Commission.

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities indicated this 17th day of February, 2021.