X0609 4 2026-08-19 0000354190 Arthur J. Gallagher & Co. AJG 0001737644 Mead Christopher E false 2850 GOLF ROAD ROLLING MEADOWS IL 60008-4002 1 VICE PRESIDENT 0 Common Stock 2026-08-19 4 M 0 3500 86.17 A 25723.4077 D Common Stock 2026-08-19 4 S 0 3500 257.025 D 22223.4077 D Common Stock 491.098 I Gallagher 401(k) plan account Non-qualified Stock Option 86.17 2026-08-19 4 M 0 3500 0 D 2027-03-12 Common Stock 3500 7590 D Phantom Stock Common Stock 21943.184 21943.184 D Non-qualified Stock Option 228.20 2033-03-01 Common Stock 12344 12344 D Non-qualified Stock Option 127.90 2028-03-16 Common Stock 11725 11725 D Non-qualified Stock Option 158.56 2029-03-15 Common Stock 8420 8420 D Non-qualified Stock Option 337.74 2032-03-01 Common Stock 8264 8264 D Non-qualified Stock Option 243.54 2031-03-01 Common Stock 7368 7368 D Non-qualified Stock Option 177.09 2030-03-15 Common Stock 7009 7009 D Notional Stock Units Common Stock 1982.8313 1982.8313 D One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. 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 exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. Closing price of Gallagher common stock on February 28, 2025. 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. 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. /s/ Monica Norzagaray, by power of attorney 2026-08-20