X0609 4 2026-08-16 0000354190 Arthur J. Gallagher & Co. AJG 0001795399 Bloom Mark H. false 2850 GOLF ROAD ROLLING MEADOWS IL 60008 1 Vice President 0 Common Stock 2026-08-16 4 M 0 1280.485 0 A 5023.485 D Common Stock 2026-08-16 4 F 0 606.814 251.21 D 4416.671 D Common Stock 193.263 I Gallagher 401(k) plan account Phantom Stock 2026-08-16 4 M 0 1280.485 0 D Common Stock 1280.485 6017.051 D Non-qualified Stock Option 228.20 2033-03-01 Common Stock 13331 13331 D Non-qualified Stock Option 337.74 2032-03-01 Common Stock 6887 6887 D Non-qualified Stock Option 243.54 2031-03-01 Common Stock 5777 5777 D Non-qualified Stock Option 158.56 2029-03-15 Common Stock 4900 4900 D Non-qualified Stock Option 177.09 2030-03-15 Common Stock 4673 4673 D Notional Stock Units Common Stock 962.2459 962.2459 D 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 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. Grant date of 3/15/2022. 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. The transactions in this report relate solely to the withholding of shares to cover applicable income and employment taxes with respect to the distribution of an award under the Age 62 Plan. /s/ Monica Norzagaray, by power of attorney 2026-08-18