Arthur J. Gallagher & Co. (AJG) · Insider Trading (Form 4) SEC Filing

=== SEC Form 4 — Statement of Changes in Beneficial Ownership === Document Type: 4 Period of Report: 2026-05-26 10b5-1 Pre-arranged Plan: No --- Issuer --- Name: Arthur J. Gallagher & Co. (AJG) CIK: 0000354190 --- Reporting Owner --- Name: GALLAGHER J PATRICK JR CIK: 0001186006 Role: Director, Officer (CEO) --- Non-Derivative Transactions --- [Transaction #1] Security: Common Stock Date: 2026-05-26 | Code: G (Gift) Shares: -14,698 | Price: $0.00 Shares Owned After: 109,416.9637 | Ownership: D (Direct) --- Holdings --- [Holding #1] Security: Common Stock Ownership: I (Indirect) Footnotes: [F1] Shares held in revocable trust of which my spouse is sole Trustee and as to which I disclaim beneficial ownership. [Holding #2] Security: Common Stock Ownership: I (Indirect) [Holding #3] Security: Common Stock Ownership: I (Indirect) Footnotes: [F2] Held in trust for benefit of children. [Holding #4] Security: Common Stock Ownership: I (Indirect) [Holding #5] Security: Common Stock Ownership: I (Indirect) Footnotes: [F3] Shares held in trust for the benefit of my children of which I am sole Trustee. [Holding #6] Security: Common Stock Ownership: I (Indirect) [Holding #7] Security: Notional Stock Units Ownership: D (Direct) Footnotes: [F4] Each notional stock unit represents a right to receive one share of Gallagher common stock. [F5] The notional stock units become payable following the reporting person's separation from service with Gallagher. [F5] The notional stock units become payable following the reporting person's separation from service with Gallagher. [Holding #8] Security: Phantom Stock Ownership: D (Direct) Footnotes: [F6] Each share of phantom stock represents a right to receive one share of Gallagher common stock. [F7] 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. [F7] 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. [Holding #9] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F8] One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. [Holding #10] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F8] One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. [Holding #11] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F9] One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. [Holding #12] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F8] One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. [Holding #13] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F10] One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. [Holding #14] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F11] One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. [Holding #15] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F8] One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. --- Footnotes (Complete Index) --- F1: Shares held in revocable trust of which my spouse is sole Trustee and as to which I disclaim beneficial ownership. F10: One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. F11: One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. F2: Held in trust for benefit of children. F3: Shares held in trust for the benefit of my children of which I am sole Trustee. F4: Each notional stock unit represents a right to receive one share of Gallagher common stock. F5: The notional stock units become payable following the reporting person's separation from service with Gallagher. F6: Each share of phantom stock represents a right to receive one share of Gallagher common stock. F7: 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. F8: One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. F9: One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. --- Signature --- /s/ /s/ Monica Norzagaray, by power of attorney (2026-05-27)