SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
	Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person* Bay Walter D. (Last) (First) (Middle) 2850 GOLF ROAD (Street) ROLLING MEADOWS ILLINOIS 60008-4002 (City) (State) (Zip) UNITED STATES (Country)	2. Issuer Name and Ticker or Trading Symbol Arthur J. Gallagher & Co. [ AJG ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director 10% Owner X Officer (give title below) Other (specify below) General Counsel
	2a. Foreign Trading Symbol
	3. Date of Earliest Transaction (Month/Day/Year) 08/24/2026	6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person
	4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	08/24/2026		S		12,000	D	$270.081(1)	71,292.092	D
Common Stock								491.129	I	Gallagher 401(k) plan account

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Non-qualified Stock Option	$127.9							(2)	03/16/2028	Common Stock	24,500		24,500	D
Non-qualified Stock Option	$86.17							(2)	03/12/2027	Common Stock	17,630		17,630	D
Non-qualified Stock Option	$228.2							(3)	03/01/2033	Common Stock	16,952		16,952	D
Non-qualified Stock Option	$158.56							(2)	03/15/2029	Common Stock	11,405		11,405	D
Non-qualified Stock Option	$337.74(4)							(2)	03/01/2032	Common Stock	11,350		11,350	D
Non-qualified Stock Option	$243.54							(5)	03/01/2031	Common Stock	10,884		10,884	D
Non-qualified Stock Option	$177.09							(6)	03/15/2030	Common Stock	9,452		9,452	D
Notional Stock Units	$0(7)							(8)	(8)	Common Stock	5,828.5456		5,828.5456	D
Phantom Stock	(9)							(10)	(10)	Common Stock	4,007.175		4,007.175	D

Explanation of Responses:

1. 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.

2. One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date.

3. One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date.

4. Closing price of Gallagher common stock on February 28, 2025.

5. One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date.

6. One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date.

7. Each notional stock unit represents a right to receive one share of Gallagher common stock.

8. The notional stock units become payable in July 2026 and following the reporting person's separation from service with Gallagher.

9. Each share of phantom stock represents a right to receive one share of Gallagher common stock.

10. 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.

	/s/ Monica Norzagaray, by power of attorney	08/26/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)