X0508 4 2025-08-20 0000354190 Arthur J. Gallagher & Co. AJG 0001589933 GALLAGHER THOMAS JOSEPH 2850 GOLF ROAD ROLLING MEADOWS IL 60008-4002 1 President 0 Common Stock 2025-08-20 4 G 0 875 0 D 308046.08 D Common Stock 2025-08-20 4 G 0 375 0 A 119175 I By wife as trustee Common Stock 2025-08-21 4 G 0 30000 0 D 32428 I By wife Common Stock 2025-08-21 4 G 0 30000 0 A 96709 I By Irrevocable Trust Common Stock 62295 I By grantor retained annuity trust Common Stock 418.7 I Gallagher 401(k) plan account The reporting person disclaims beneficial ownership of these shares, and this report shall not be deemed an admission that the reporting person is the beneficial owner of these shares for purposes of Section 16 or for any other purpose. These shares are held in trusts, for the benefit of the reporting person's children, of which his wife is a trustee. The reporting person's spouse transferred these shares of common stock to an irrevocable trust for no consideration. The reporting person is trustee of the trust, and the reporting person and his children are the sole beneficiaries of the trust. The reporting person remains the beneficial owner of the securities held by the trust. /s/ Monica Norzagaray, by power of attorney 2025-08-22