Exhibit 99.1 NEWS RELEASE ARTHUR J. GALLAGHER & CO. ANNOUNCES SECOND QUARTER 2025 FINANCIAL RESULTS ROLLING MEADOWS, IL, July 31, 2025 - Arthur J. Gallagher & Co. (NYSE: AJG) today reported its financial results for the quarter ended June 30, 2025. Management will host a webcast conference call to discuss these results on Thursday, July 31, 2025 at 5:15 p.m. ET/4:15 p.m. CT. To listen to the call, and for printer-friendly formats of this release and the "CFO Commentary" and "Supplemental Quarterly Data," wh ...