X0306 4 2023-03-10 0000354190 Arthur J. Gallagher & Co. AJG 0001665268 Cavaness Joel D 2850 GOLF ROAD ROLLING MEADOWS IL 60008-4002 1 Vice President Common Stock (restricted) 2023-03-12 4 A 0 9580 0 A 9580 D Common Stock (restricted) 2023-03-12 4 M 0 9580 0 D 0 D Common Stock 2023-03-12 4 M 0 9580 0 A 148990 D Common Stock 2023-03-12 4 F 0 4142 182.76 D 144848 D Common Stock (restricted) 1650 I By Spouse Common Stock 2022.63 I By Spouse Common Stock 214.63 I Gallagher 401(k) plan account Phantom Stock 2023-03-10 4 I 0 3226.7 185.95 A Common Stock 3226.7 124294.951 D Performance share units (awarded on March 12, 2020) earned and vested as of March 12, 2023. Each share of phantom stock represents a right to receive one share of Gallagher common stock. These shares represent awards under the Age 62 Plan, a nonqualified deferred compensation plan of the Company, which have been deemed invested in Company common stock at the election of the reporting person. Participants vest in these awards when they attain age 62, or after a one-year period for participants who have attained age 61. /s/ Seth Diehl, by power of attorney 2023-03-14