UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q (Mark One) ☒ Quarterly Report Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 For the quarterly period ended March 31, 2023 ☐ Transition Report Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 For the transition period from to Commission file number 001-31940 F.N.B. CORPORATION (Exact name of registrant as specified in its charter) Pennsylvania 25-1255406 (State or other jurisdictio ...