Cover and table of contents

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-Q

(Mark One)

For the quarterly period ended March 31, 2024

OR

For the transition period from________ to________.

Marsh & McLennan Companies, Inc.

1166 Avenue of the Americas

New York, New York 10036

(212) 345-5000

Commission file number 1-5998

State of Incorporation: Delaware

I.R.S. Employer Identification No. 36-2668272

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

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 and posted 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 and post such files). Yes ý No ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of "large accelerated filer," "accelerated filer," "smaller reporting company," and "emerging growth company" in Rule 12b-2 of the Exchange Act.

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

As of April 15, 2024, there were outstanding 492,724,025 shares of common stock, par value $1.00 per share, of the registrant.

INFORMATION CONCERNING FORWARD-LOOKING STATEMENTS

This Quarterly Report on Form 10-Q 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 impact of geopolitical or macroeconomic conditions on us, our clients and the countries and industries in which we operate, including from multiple major wars, escalating conflict throughout the Middle East and rising tension in the South China Sea, slower GDP growth or recession, lower interest rates, capital markets volatility and inflation;

• the increasing prevalence of ransomware, supply chain and other forms of cyber attacks, and their potential to disrupt our operations, or the operations of our third party vendors, and result in the disclosure of confidential client or company information;

• the impact from lawsuits or investigations arising from errors and omissions, breaches of fiduciary duty or other claims against us in our capacity as a broker or investment advisor, including claims related to our investment business’ ability to execute timely trades;

• the financial and operational impact of complying with laws and regulations, including domestic and international sanctions regimes, anti-corruption laws such as the U.S. Foreign Corrupt Practices Act, U.K. Anti Bribery Act and cybersecurity, data privacy and artificial intelligence regulations;

• our ability to attract, retain and develop industry leading talent;

• our ability to compete effectively and adapt to competitive pressures in each of our businesses, including from disintermediation as well as technological change, digital disruption and other types of innovation such as artificial intelligence;

• our ability to manage potential conflicts of interest, including where our services to a client conflict, or are perceived to conflict, with the interests of another client or our own interests;

• the impact of changes in tax laws, guidance and interpretations, such as the implementation of the Organization for Economic Cooperation and Development international tax framework, or the increasing number of disagreements with and challenges by tax authorities in the current global tax environment; and

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

The factors identified above are not exhaustive. Marsh & McLennan Companies, Inc., and its consolidated subsidiaries (the "Company") operate in a dynamic business environment in which new risks emerge frequently. Accordingly, 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. The Company undertakes no obligation to update or revise any forward-looking statement to reflect events or circumstances arising after the date on which it is made.

Further information concerning the Company, 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 and the "Management’s Discussion and Analysis of Financial Condition and Results of Operations" section of this Quarterly Report on Form 10-Q and our most recently filed Annual Report on Form 10-K.

TABLE OF CONTENTS

PART I. FINANCIAL INFORMATION