UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Title of each class Trading Symbol(s) Name of each exchange on which registered Common Stock, par value $1.00 per share AJG New York Stock Exchange Securities registered pursuant to Section 12(g) of the Act: None FORM 10-K ☒ Annual Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the fiscal year ended December 31, 2023 ☐ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of ...