Arthur J. Gallagher & (AJG)

=== SEC Form 4 — Statement of Changes in Beneficial Ownership === Document Type: 4 Period of Report: 2026-03-31 10b5-1 Pre-arranged Plan: No --- Issuer --- Name: Arthur J. Gallagher & Co. (AJG) CIK: 0000354190 --- Reporting Owner --- Name: CARY RICHARD C CIK: 0001185998 Role: Officer (Controller, CAO) --- Non-Derivative Transactions --- [Transaction #1] Security: Common Stock Date: 2026-03-31 | Code: M (Exercise of derivative) Shares: +471.698 | Price: $215.95 Total Value: $101,863.18 Shares Owned After: 50,958.487 | Ownership: D (Direct) [Transaction #2] Security: Common Stock Date: 2026-03-31 | Code: F (Payment of exercise/tax) Shares: -139 | Price: $215.95 Total Value: $30,017.05 Shares Owned After: 50,819.487 | Ownership: D (Direct) Footnotes: [F1] The transactions in this report relate solely to the distribution of vested shares under the Age 62 Plan and the withholding of shares to cover applicable income and employment taxes. --- Derivative Transactions --- [Transaction #1] Security: Phantom Stock Date: 2026-03-31 | Code: M (Exercise of derivative) Shares: -471.698 | Price: $0.00 Shares Owned After: 160.685 | 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. --- Holdings --- [Holding #1] Security: Common Stock Ownership: I (Indirect) [Holding #2] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F4] One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. [Holding #3] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F4] One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. [Holding #4] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F5] One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. [Holding #5] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F4] One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. [Holding #6] Security: Notional Stock Units Ownership: D (Direct) Footnotes: [F6] Each notional stock unit represents a right to receive one share of Gallagher common stock. [F7] The notional stock units become payable following the reporting person's separation from service with Gallagher. [F7] The notional stock units become payable following the reporting person's separation from service with Gallagher. --- Footnotes (Complete Index) --- F1: The transactions in this report relate solely to the distribution of vested shares under the Age 62 Plan and the withholding of shares to cover applicable income and employment taxes. 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 exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. F5: One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. F6: Each notional stock unit represents a right to receive one share of Gallagher common stock. F7: The notional stock units become payable following the reporting person's separation from service with Gallagher. --- Signature --- /s/ /s/ Monica Norzagaray, by power of attorney (2026-04-01)