Company: WTFCN
Filing Date: 2025-05-09
Form Type: 424B5
Source: 0001104659-25-046769
Chunk: 5

Company: WINTRUST FINANCIAL CORP
Filing Date: 2025-05-09
Form: 424B5
Chunk 5
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4 filed with the SEC on February 28, 2025;

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our Quarterly Report on Form 10-Q for the quarter ended March 31, 2025 filed with the SEC on May 5, 2025; and

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those portions of our Definitive Proxy Statement on Schedule 14A filed with the SEC on April 3, 2025incorporated by reference in our Annual Report on Form 10-K for the year ended December 31, 2024.

You may request a copy of these filings, other than an exhibit to a filing unless that exhibit is specifically incorporated by reference into that filing, at no cost, by writing to us at the following address or calling us at the following telephone number:

<div align='center'>Wintrust Financial Corporation 
 9700 W. Higgins Road, Suite 800 
 Rosemont, Illinois 60018 
 Attention: Investor Relations 
 (847) 939-9000</div>

We will provide to each person, including any beneficial owner, to whom a copy of this prospectus supplement and the accompanying prospectus is delivered a copy of any or all of the information that

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TABLE OF CONTENTS

has been incorporated by reference in this prospectus supplement and the accompanying prospectus but not delivered with this prospectus supplement and the accompanying prospectus. We will provide this information upon written or oral request at no cost to the requester. You should direct your requests to us at the address or telephone number above.

You should rely only on the information incorporated by reference or provided in this prospectus supplement or the accompanying prospectus. We have not authorized anyone else to provide you with different information or to make any representations other than as contained in this prospectus or in any prospectus supplement. This document may only be used where it is lawful to sell these securities. We are not making any offer of these securities in any state where the offer is not permitted.

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### SPECIAL NOTE CONCERNING FORWARD-LOOKING STATEMENTS
This prospectus supplement, the accompanying prospectus, the documents incorporated by reference or deemed incorporated by reference into this prospectus supplement or the accompanying prospectus and any other written or oral statements made by us from time to time may contain forward-looking statements within the meaning of the federal securities laws. Forward-looking information can be identified through the use of words such as “intend,” “plan,” “project