X0508 4 2026-02-28 0000062709 MARSH & MCLENNAN COMPANIES, INC. MRSH 0002016426 Tomlinson Patrick 1166 AVENUE OF THE AMERICAS NEW YORK NY 10036 1 President and CEO, Mercer 0 Common Stock 2026-02-28 4 M 0 2219 0 A 4794 D Common Stock 2026-02-28 4 F 0 1139 186.74 D 3655 D Restricted Stock Units 2026-02-28 4 M 0 2219 0 D Common Stock 2219 6082 D Vesting and distribution to reporting person of 2,219 shares underlying restricted stock units of which 1,134 were withheld by Marsh & McLennan Companies to cover applicable taxes. These 2,219 shares underlying restricted stock units relate to 610 restricted stock units that were granted on February 23, 2023 and 1,609 restricted stock units relating to performance stock units that were granted on February 23, 2023 for the performance period 2023-2025. The security converts to Marsh & McLennan Companies common stock on a 1-for-1 basis. Not applicable. /s/ Tessa Patti, Attorney-in-fact 2026-03-03