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: 2026-07-01 10b5-1 Pre-arranged Plan: No --- Issuer --- Name: Arthur J. Gallagher & Co. (AJG) CIK: 0000354190 --- Reporting Owner --- Name: Pesch Michael Robert CIK: 0002022545 Role: Officer (Vice President) --- Non-Derivative Transactions --- [Transaction #1] Security: Common Stock Date: 2026-07-01 | Code: M (Exercise of derivative) Shares: +355.801 | Price: $229.57 Total Value: $81,681.24 Shares Owned After: 44,832.7289 | Ownership: D (Direct) --- Derivative Transactions --- [Transaction #1] Security: Notional Stock Units Date: 2026-07-01 | Code: M (Exercise of derivative) Shares: -355.801 | Price: $0.00 Shares Owned After: 6,134.526 | Ownership: D (Direct) Footnotes: [F2] Each notional stock unit represents a right to receive one share of Gallagher common stock. [F3] Portions of these notional stock units are payable to the reporting person in shares of common stock in July of 2026, 2027 and 2028 and following the reporting person's separation from service. [F4] Portions of these notional stock units are payable to the reporting person in shares of common stock in July of 2026, 2027 and 2028 and following the reporting person's separation from service. --- Holdings --- [Holding #1] Security: Common Stock Ownership: I (Indirect) [Holding #2] Security: Common Stock Ownership: I (Indirect) Footnotes: [F1] Shares held in irrevocable trust, of which his spouse is sole Trustee. [Holding #3] Security: Common Stock Ownership: I (Indirect) [Holding #4] Security: Phantom Stock Ownership: D (Direct) Footnotes: [F5] Each share of phantom stock represents a right to receive one share of Gallagher common stock. [F6] 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. [F6] 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 #5] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F7] One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. [Holding #6] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F8] Grant date of 3/12/2020. [F9] One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. [Holding #7] 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. [F10] Grant date of 3/16/2021. [Holding #8] 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. [F11] Grant date of 3/15/2022. [Holding #9] 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. [F12] Grant date of 3/15/2023. --- Footnotes (Complete Index) --- F1: Shares held in irrevocable trust, of which his spouse is sole Trustee. F10: Grant date of 3/16/2021. F11: Grant date of 3/15/2022. F12: Grant date of 3/15/2023. F2: Each notional stock unit represents a right to receive one share of Gallagher common stock. F3: Portions of these notional stock units are payable to the reporting person in shares of common stock in July of 2026, 2027 and 2028 and following the reporting person's separation from service. F4: Portions of these notional stock units are payable to the reporting person in shares of common stock in July of 2026, 2027 and 2028 and following the reporting person's separation from service. F5: Each share of phantom stock represents a right to receive one share of Gallagher common stock. F6: 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: One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. F8: Grant date of 3/12/2020. 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 (2026-07-06)