=== SEC Form 4 — Statement of Changes in Beneficial Ownership ===
Document Type: 4
Period of Report: 2026-08-24
10b5-1 Pre-arranged Plan: No
--- Issuer ---
Name: Arthur J. Gallagher & Co. (AJG)
CIK: 0000354190
--- Reporting Owner ---
Name: Bay Walter D.
CIK: 0001410235
Role: Officer (General Counsel)
--- Non-Derivative Transactions ---
[Transaction #1]
Security: Common Stock
Date: 2026-08-24 | Code: S (Open market sale)
Shares: -12,000 | Price: $270.08
Total Value: $3,240,972.00
Shares Owned After: 71,292.092 | Ownership: D (Direct)
Footnotes:
[F1] The price reported is an average weighted price. The shares were sold in multiple transactions on 8/24/2026 at prices ranging from $270.01 to $270.17. The reporting person will provide to the Securities and Exchange Commission staff, the issuer, or any security holder of the issuer, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
--- Holdings ---
[Holding #1]
Security: Common Stock
Ownership: I (Indirect)
[Holding #2]
Security: Non-qualified Stock Option
Ownership: D (Direct)
Footnotes:
[F2] 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:
[F2] 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:
[F3] 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:
[F2] 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:
[F4] Closing price of Gallagher common stock on February 28, 2025.
[F2] 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 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:
[F6] 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:
[F7] Each notional stock unit represents a right to receive one share of Gallagher common stock.
[F8] The notional stock units become payable in July 2026 and following the reporting person's separation from service with Gallagher.
[F8] The notional stock units become payable in July 2026 and following the reporting person's separation from service with Gallagher.
[Holding #10]
Security: Phantom Stock
Ownership: D (Direct)
Footnotes:
[F9] Each share of phantom stock represents a right to receive one share of Gallagher common stock.
[F10] 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 in the year they attain age 62, or after a one-year period for participants who have attained age 61.
[F10] 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 in the year they attain age 62, or after a one-year period for participants who have attained age 61.
--- Footnotes (Complete Index) ---
F1: The price reported is an average weighted price. The shares were sold in multiple transactions on 8/24/2026 at prices ranging from $270.01 to $270.17. The reporting person will provide to the Securities and Exchange Commission staff, the issuer, or any security holder of the issuer, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
F10: 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 in the year they attain age 62, or after a one-year period for participants who have attained age 61.
F2: One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date.
F3: One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date.
F4: Closing price of Gallagher common stock on February 28, 2025.
F5: One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date.
F6: One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date.
F7: Each notional stock unit represents a right to receive one share of Gallagher common stock.
F8: The notional stock units become payable in July 2026 and following the reporting person's separation from service with Gallagher.
F9: Each share of phantom stock represents a right to receive one share of Gallagher common stock.
--- Signature ---
/s/ /s/ Monica Norzagaray, by power of attorney (2026-08-26)
