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
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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
1. Name and Address of Reporting Person *
Gallagher Patrick Murphy

(Last) (First) (Middle)
2850 GOLF ROAD

(Street)
ROLLING MEADOWS IL 60008

(City) (State) (Zip)
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)
Chief Operating Officer
3. Date of Earliest Transaction (Month/Day/Year)
03/15/2026
4. If Amendment, Date of Original Filed (Month/Day/Year)
6. Individual or Joint/Group Filing (Check Applicable Line)
X Form filed by One Reporting Person
Form filed by More than One Reporting Person
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 (restricted) 03/15/2026   A   4,620 (1) A $ 0 4,620 D  
Common Stock (restricted) 03/15/2026   M   4,620 D $ 0 0 D  
Common Stock 03/15/2026   M   4,620 A $ 0 41,062.6637 D  
Common Stock 03/15/2026   F   1,962 D $ 207.93 39,100.6637 D  
Common Stock 03/16/2026   F (2)   525 D $ 207.93 38,575.6637 D  
Common Stock               10,560 I By Spouse as Trustee (3)
Common Stock               491.136 I Gallagher 401(k) plan account
Common Stock               53,262 I By Spouse's Trust (4)
Common Stock               83,407.25 I By Trust
Common Stock               21,032 I By Trust (5)
Common Stock               55,109 I By Irrevocable Trust
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 $ 228.2               (6) 03/01/2033 Common Stock 17,775   17,775 D  
Phantom Stock (7)               (8)   (8) Common Stock 17,594.638   17,594.638 D  
Non-qualified Stock Option $ 337.74 (9)               (10) 03/01/2032 Common Stock 11,901   11,901 D  
Non-qualified Stock Option $ 243.54               (11) 03/01/2031 Common Stock 11,386   11,386 D  
Non-qualified Stock Option $ 127.9               (10) (12) 03/16/2028 Common Stock 7,255   7,255 D  
Non-qualified Stock Option $ 86.17               (10) (13) 03/12/2027 Common Stock 6,270   6,270 D  
Non-qualified Stock Option $ 177.09               (14) 03/15/2030 Common Stock 6,160   6,160 D  
Notional Stock Units (15)               (16)   (17) Common Stock 907.072   907.072 D  
Phantom Stock (7)               (18)   (18) Common Stock 3,804.562   3,804.562 D  
Non-qualified Stock Option $ 158.56               (10) (19) 03/15/2029 Common Stock 5,510   5,510 D  
Explanation of Responses:
1. Performance share units (awarded on March 15, 2023) earned and vested as of March 15, 2026.
2. Shares withheld to cover applicable tax obligations relating to the vesting of restricted stock units.
3. Shares held in trusts, for the benefit of the reporting person's children, of which his wife is sole trustee.
4. Shares held in a revocable trust and an irrevocable trust of which the reporting person's spouse is sole Trustee and as to which he disclaims beneficial ownership
5. Shares held in trust for the benefit of the reporting person's children, of which he is a trustee.
6. One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date.
7. Each share of phantom stock represents a right to receive one share of Gallagher common stock.
8. 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.
9. Closing price of Gallagher common stock on February 28, 2025.
10. One-third of this stock option becomes exerciseable on each of the 3rd, 4th, and 5th anniversaries of the grant date.
11. One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date.
12. Grant date of 3/16/2021.
13. Grant date of 3/12/2020.
14. One-third of this stock option becomes exercisable on each of the 3rd, 4th, and 5th anniversaries of the grant date.
15. Each notional stock unit represents a right to receive one share of Gallagher common stock.
16. The notional stock units become payable following the reporting person's separation from service with Gallagher.
17. The notional stock units become payable following the reporting person's separation from service with Gallagher.
18. These shares represent awards under the Deferred Cash Participation Plan, a nonqualified deferred compensation plan of the Company, which have been deemed invested in Company common stock at the election of the participant. These awards are payable in a lump sum on the six-month anniversary of the reporting person's separation from service.
19. Grant date of 3/15/2022.
/s/ Monica Norzagaray, by power of attorney 03/17/2026
** Signature of Reporting Person Date
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