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: GALLAGHER THOMAS JOSEPH CIK: 0001589933 Role: Officer (President) --- Non-Derivative Transactions --- [Transaction #1] Security: Common Stock Date: 2026-07-01 | Code: M (Exercise of derivative) Shares: +351.945 | Price: $229.57 Total Value: $80,796.01 Shares Owned After: 323,743.025 | Ownership: D (Direct) --- Derivative Transactions --- [Transaction #1] Security: Notional Stock Units Date: 2026-07-01 | Code: M (Exercise of derivative) Shares: -351.945 | Price: $0.00 Shares Owned After: 13,345.6345 | Ownership: D (Direct) Footnotes: [F3] Each notional stock unit represents a right to receive one share of Gallagher common stock. [F4] Portions of these notional stock units are payable to the reporting person in shares of common stock in July of 2026 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 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) [Holding #3] Security: Common Stock Ownership: I (Indirect) [Holding #4] Security: Common Stock Ownership: I (Indirect) Footnotes: [F1] 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. [F2] These shares are held in trusts, for the benefit of the reporting person's children, of which his wife is a trustee. [Holding #5] Security: Common Stock Ownership: I (Indirect) [Holding #6] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F5] 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: [F5] One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. [Holding #8] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F6] One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. [Holding #9] Security: Phantom Stock Ownership: D (Direct) Footnotes: [F7] Each share of phantom stock represents a right to receive one share of Gallagher common stock. [F8] 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] 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 #10] Security: Non-qualified Stock Option Ownership: D (Direct) Footnotes: [F5] 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: [F10] Closing price of Gallagher common stock on February 28, 2025. [F5] 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: [F11] One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. --- Footnotes (Complete Index) --- F1: 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. F10: Closing price of Gallagher common stock on February 28, 2025. F11: One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date. F2: These shares are held in trusts, for the benefit of the reporting person's children, of which his wife is a trustee. F3: Each notional stock unit represents a right to receive one share of Gallagher common stock. F4: Portions of these notional stock units are payable to the reporting person in shares of common stock in July of 2026 and following the reporting person's separation from service. F5: One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. F6: One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date. F7: Each share of phantom stock represents a right to receive one share of Gallagher common stock. F8: 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. 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)