UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 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 1934 For the Transition Period from to Commission File Number 001-35077 Wintrust Financial Corporation (Exact name of registrant as specified in its charter) Illinois 36-3873352 (State or other jurisdiction of inc ...