Bylaw Amendment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C.  20549 _____________________ FORM 8-K   CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934   Date of report (Date of earliest event reported) January 14, 2026 Marsh & McLennan Companies, Inc. (Exact Name of Registrant as Specified in its Charter) Delaware 1-5998 36-2668272 (State or Other Jurisdiction of Incorporation) (Commission File Number) (IRS Employer Identification No.) 1166 Avenue of the Americas, New York, NY 10036 (Address of Principal Executive Offices) (Zip Code) Registrant’s telephone number, including area code (212) 345-5000     Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:   ☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)   ☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)   ☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))   ☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))     Securities registered pursuant to Section 12(b) of the Act: Title of each class Trading symbol(s) Name of exchange on which registered Common Stock, par value $1.00 per share MRSH New York Stock Exchange NYSE Texas     Indicate by check mark whether the registrant is an emerging growth company as defined in as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). Emerging growth company ☐ 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.   ☐ Item 5.03 Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year On and effective January 14, 2026, the Board of Directors of Marsh & McLennan Companies, Inc. (the “Company”) approved amended and restated bylaws of the Company (the “Amended and Restated Bylaws”). Among other things the amendments (i) update and conform various provisions to reflect the latest amendments to the Delaware General Corporation Law (the “DGCL”), including related to the stockholder list and quorum for committee meetings, (ii) update certain procedural and informational requirements under the advance notice provisions related to director nominations and other proposals, including related to the requirement to provide certain disclosures and information to the Company, the number of nominees the stockholder can nominate and reflecting the universal proxy rules under Rule 14a-19, (iii) clarify the voting standard for matters submitted to the stockholders and (iv) clarify the authority of the chair of the meeting of stockholders. The Amended and Restated Bylaws also make other clarifications, updates and conforming changes. This summary is qualified in its entirety by reference to the Amended and Restated Bylaws, a copy of which is attached hereto as Exhibit 3.1 and incorporated herein by reference. Item 9.01        Financial Statements and Exhibits   (d)        Exhibits   3.1        Amended and Resta ted Bylaws of Marsh & McLennan Companies, Inc. 2 SIGNATURES     Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.   MARSH & McLENNAN COMPANIES, INC.         By: /s/ Connor Kuratek      Name: Connor Kuratek   Title: Deputy General Counsel and Corporate Secretary     Date:    January 14, 2026 3