Arthur J. Gallagher & Co. — Proxy Solicitation & Information Statement 2026

Mar 23, 2026

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

(Rule 14a-101)

Information Required In Proxy Statement

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No. __ )

Filed by the Registrant x Filed by a Party other than the Registrant ☐

Check the appropriate box:

o	Preliminary Proxy Statement
o	Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))
o	Definitive Proxy Statement
x	Definitive Additional Materials
o	Soliciting Material Pursuant to §240.14a-12

ARTHUR J. GALLAGHER & CO.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

x	No fee required.
o	Fee paid previously with preliminary materials.
o	Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11.