Arthur J. Gallagher & (AJG)

=== SEC Form 4 — Statement of Changes in Beneficial Ownership === Document Type: 4 Period of Report: 2026-08-19 10b5-1 Pre-arranged Plan: No --- Issuer --- Name: Arthur J. Gallagher & Co. (AJG) CIK: 0000354190 --- Reporting Owner --- Name: Mead Christopher E CIK: 0001737644 Role: Officer (VICE PRESIDENT) --- Non-Derivative Transactions --- [Transaction #1] Security: Common Stock Date: 2026-08-19 | Code: M (Exercise of derivative) Shares: +3,500 | Price: $86.17 Total Value: $301,595.00 Shares Owned After: 25,723.4077 | Ownership: D (Direct) [Transaction #2] Security: Common Stock Date: 2026-08-19 | Code: S (Open market sale) Shares: -3,500 | Price: $257.02 Total Value: $899,587.50 Shares Owned After: 22,223.4077 | Ownership: D (Direct) --- Derivative Transactions --- [Transaction #1] Security: Non-qualified Stock Option Date: 2026-08-19 | Code: M (Exercise of derivative) Shares: -3,500 | Price: $0.00 Exercisable: N/A | Expires: 2027-03-12 Shares Owned After: 7,590 | Ownership: D (Direct) Footnotes: [F1] One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. --- Holdings --- [Holding #1] Security: Common Stock Ownership: I (Indirect) [Holding #2] Security: Phantom Stock Ownership: D (Direct) Footnotes: [F2] Each share of phantom stock represents a right to receive one share of Gallagher common stock. [F3] 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. [F3] 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 #3] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F4] One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. [Holding #4] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F1] One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. [Holding #5] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F1] One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. [Holding #6] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F5] Closing price of Gallagher common stock on February 28, 2025. [F1] One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. [Holding #7] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F6] One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. [Holding #8] 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 #9] Security: Notional Stock Units Ownership: D (Direct) Footnotes: [F8] Each notional stock unit represents a right to receive one share of Gallagher common stock. [F9] The notional stock units become payable in July 2026 and following the reporting person's separation from service with Gallagher. [F9] The notional stock units become payable in July 2026 and following the reporting person's separation from service with Gallagher. --- Footnotes (Complete Index) --- F1: One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. F2: Each share of phantom stock represents a right to receive one share of Gallagher common stock. F3: 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. F4: One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. F5: Closing price of Gallagher common stock on February 28, 2025. F6: One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. F7: One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. F8: Each notional stock unit represents a right to receive one share of Gallagher common stock. F9: The notional stock units become payable in July 2026 and following the reporting person's separation from service with Gallagher. --- Signature --- /s/ /s/ Monica Norzagaray, by power of attorney (2026-08-20)