X0609 4 2026-09-08 0000354190 Arthur J. Gallagher & Co. AJG 0001186006 GALLAGHER J PATRICK JR false 2850 GOLF ROAD ROLLING MEADOWS IL 60008-4002 1 1 CEO 0 Common Stock 2026-09-08 4 G 0 49988 0 D 0 I By Corporation Common Stock 5328 I By Spouse's Trust Common Stock 128447.9697 D Common Stock 244860 I By Irrevocable Trust Common Stock 302764 I By Spouse Common Stock 219955 I By Trust Common Stock 491.142 I Gallagher 401(k) plan account Notional Stock Units 0 Common Stock 153788.107 153788.107 D Phantom Stock Common Stock 139553.727 139553.727 D Non-qualified Stock Option 127.90 2028-03-16 Common Stock 76975 76975 D Non-qualified Stock Option 86.17 2027-03-12 Common Stock 68550 68550 D Non-qualified Stock Option 228.20 2033-03-01 Common Stock 48449 48449 D Non-qualified Stock Option 158.56 2029-03-15 Common Stock 35825 35825 D Non-qualified Stock Option 337.74 2032-03-01 Common Stock 22727 22727 D Non-qualified Stock Option 243.54 2031-03-01 Common Stock 27210 27210 D Non-qualified Stock Option 177.09 2030-03-15 Common Stock 30029 30029 D This transaction represents a gift for estate planning purposes. Shares held in trust for the benefit of my children of which I am sole Trustee. Shares held in trusts of which my spouse is sole trustee and as to which I disclaim beneficial ownership. Held in trust for benefit of children. Each notional stock unit represents a right to receive one share of Gallagher common stock. The notional stock units become payable in July 2026 and following the reporting person's separation from service with Gallagher. 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. One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. /s/ Monica Norzagaray, by power of attorney 2026-09-10