Letter Agreement Amendment, dated February 22, 2024, between Marsh & McLennan Companies, Inc. and Dean M. Klisura

February 22, 2024

Dean Klisura

Hand Delivery

Subject: Terms of Employment

Dear Dean,

This first amendment to the Letter Agreement, dated December 1, 2021, between you and Marsh & McLennan Companies, Inc. (the “Letter Agreement”), revises the terms and conditions of your employment as President and Chief Executive Officer of Guy Carpenter & Company LLC (“Guy Carpenter”) and Vice Chair, Marsh McLennan. The Letter Agreement will continue to govern your employment except as specified below:

1.This position reports to the President and Chief Executive Officer of Marsh & McLennan Companies, Inc. (“Marsh McLennan”).

2.Exhibit A to the Letter Agreement shall be deleted and replaced in its entirety with the attached Exhibit A.

The terms of this amendment are effective as of February 22, 2024. Please acknowledge your agreement with the terms of the Letter Agreement, as further amended by this third amendment, by signing and dating this and the enclosed copy and returning one to me.

Sincerely,

/s/ John Q. Doyle

John Q. Doyle

President and Chief Executive Officer

Marsh McLennan

Accepted and Agreed:

(Signature)

(Date)