UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

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Marsh & McLennan Companies, Inc.

(Name of Registrant as Specified in its Charter)

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Exercise Your Right to Vote Important Notice Regarding the Availability of Proxy Materials for the Stockholder Meeting to Be Held on May 16, 2019. MARSH & McLENNAN COMPANIES, INC. MARSH & McLENNAN COMPANIES, INC. 1166 AVENUE OF THE AMERICAS NEW YORK, NY 10036 Meeting Information Meeting Type: Annual Meeting For holders as of: March 18, 2019 Date: May 16, 2019 Time: 10:00 A.M. EDT Location: Marsh & McLennan Companies, Inc. 1166 Avenue of the Americas New York, NY 10036 You are receiving this communication because you hold shares in the company named above. This is not a ballot. You cannot use this notice to vote these shares. This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. You may view the proxy materials online at www.proxyvote.com or easily request a paper copy (see reverse side). We encourage you to access and review all of the important information contained in the proxy materials before voting. See proxy the materials reverse and side voting of this instructions notice to obtain .

Before You Vote How to Access the Proxy Materials Proxy Materials Available to VIEW or RECEIVE: NOTICE AND PROXY STATEMENT ANNUAL REPORT How to View Online: Have the information that is printed in the box marked by the arrow (located on the following page) and visit: www.proxyvote.com. How to Request and Receive a PAPER or E-MAIL Copy: If you want to receive a paper or e-mail copy of these documents, you must request one. There is NO charge for requesting a copy. Please choose one of the following methods to make your request: 1) BY INTERNET: www.proxyvote.com 2) BY TELEPHONE: 1-800-579-1639 3) BY E-MAIL*: sendmaterial@proxyvote.com * If requesting materials by e-mail, please send a blank e-mail with the information that is printed in the box marked by the arrow (located on the following page) in the subject line. Requests, instructions and other inquiries sent to this e-mail address will NOT be forwarded to your investment advisor. Please make the request as instructed above on or before May 2, 2019 to facilitate timely delivery. How To Vote Please Choose One of the Following Voting Methods Vote By Internet: To vote now by Internet, go to www.proxyvote.com. Have the information that is printed in the box marked by the arrow (located on the following page) available and follow the instructions. Vote By Mail: You can vote by mail by requesting a paper copy of the materials, which will include a proxy card. Vote In Person: Many stockholder meetings have attendance requirements including, but not limited to, the possession of an attendance ticket issued by the entity holding the meeting. Please check the meeting materials for any special requirements for meeting attendance. At the meeting, you will need to request a ballot to vote these shares.

Voting Items The Board of Directors recommends you vote FOR the following directors: Item 1 Election of Directors 1a. Anthony K. Anderson 1b. Oscar Fanjul 1c. Daniel S. Glaser 1d. H. Edward Hanway 1e. Deborah C. Hopkins 1f. Elaine La Roche 1g. Steven A. Mills 1h. Bruce P. Nolop 1i. Marc D. Oken 1j. Morton O. Schapiro 1k. Lloyd M. Yates 1l. R. David Yost The Board of Directors recommends you vote FOR the following proposals: Item 2 Advisory (Nonbinding) Vote to Approve Named Executive Officer Compensation Item 3 Ratification of Selection of Independent Registered Public Accounting Firm