144 0001993454 XXXXXXXX LIVE 0000354190 Arthur J. Gallagher & Co. 001-09761 2850 GOLF ROAD ROLLING MEADOWS IL 60008-4050 630-773-3800 Arthur J Gallagher Foundation Affiliate COMMON ROBERT W BAIRD & CO

777 E WISCONSIN AVENUE MILWAUKEE WI 53202

10000 3283300.00 255331387 02/27/2025 NYSE COMMON 08/01/2003 PURCHASE ISSUER N 10000 08/01/2003 Cash at time of purchase Y (1) It is anticipated that sales covered by this form will be made within the period beginning 02/28/2025 and ending 05/27/2025 02/27/2025 John Patrick Gallagher Jr