UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

__________________________

Form 8-K

__________________________

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

~~January~~March 296, 2026

Date of Report: (Date of earliest event reported)

__________________________

ARTHUR J. GALLAGHER & CO.

(Exact name of registrant as specified in its charter)

__________________________

Delaware

1-09761

36-2151613

(State or other jurisdiction of
incorporation or organization)

(Commission
File Number)

(I.R.S. Employer
Identification Number)

2850 Golf Road, Rolling Meadows, Illinois 60008, (630) 773-3800

(Address, including zip code and telephone number, including area code, of registrant’s principal executive offices)

Not Applicable

(Former name or former address, if changed since last report)

__________________________

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐o Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) o Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) o Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class

Trading
Symbol(s)

Name of each exchange
on which registered

Common Stock, $1.00 par value

AJG

New York Stock Exchange

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 2 5.02. Departure ~~Results~~of Directors or Certain Officers; Election of ~~Operations~~Directors; ~~and~~Appointment ~~Financial~~of ~~Condition~~Certain Officers; Compensatory Arrangements of Certain Officers

On ~~January 29~~March 6, 2026, Sherry Barrat informed Arthur J. Gallagher & Co. (the “Company”) ~~issued~~that ashe ~~press~~has ~~release~~decided ~~setting~~to ~~forth~~retire from the ~~Company’s~~Board ~~financial~~of ~~results~~Directors ~~for~~ (the ~~quarter~~“Board”). ~~ended~~Her ~~December~~retirement 31will be effective on May 12, ~~2025~~2026 upon the election of directors at the 2026 Annual Meeting of Stockholders (the ~~Earnings~~“2026 ~~Release~~Annual Meeting”). AAccordingly, ~~copy~~Ms. ofBarrat will not stand for reelection at the ~~Earnings~~2026 ~~Release~~Annual Meeting. Ms. Barrat’s decision is ~~attached~~not ~~hereto~~related asto ~~Exhibit 99~~any disagreement with the Company on any matter relating to the Company's operations, policies or practices.1 Effective at the conclusion of the 2026 Annual Meeting, the size of the Board will be reduced from ten to nine members. The Board thanks Ms. Barrat for her years of dedicated service and many contributions to the Company.

Item 7.01. Regulation FD Disclosure

In connection with the filing of the Earnings Release, the Company made materials entitled “Supplemental Quarterly Data” and “CFO Commentary” available through the investor relations page of its website. The CFO Commentary includes certain estimates relating to 2026 and other future results.

Item 9.01. Financial Statements and Exhibits

99.1		Press release, dated January 29, 2026, issued by Arthur J. Gallagher & Co.
104		The cover page from this Current Report on Form 8-K, formatted in Inline XBRL.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

			~~Arthur J. Gallagher & Co.~~	Arthur J. Gallagher & Co.
Date: January 29, 2026		By:	/s/ Douglas K. Howell
Date: March 12, 2026	By:			/s/ Walter D. Bay
			Douglas K. HowellVice President and Chief Financial Officer
				Walter D. BayVice President, General Counsel and Secretary

Filing Compare · Arthur J. Gallagher & Co.