KeyCorp美股招股说明书(2025-12-23版)

Prospectus Supplement(To Prospectus dated June9, 2023) Common Shares This prospectus supplement supplements our prospectus dated June9, 2023 and registers the resale of an aggregate of 161,968,762 of ourcommon shares, par value $1.00 per share (the “common shares”), issued to the selling shareholder named herein (the “selling shareholder”) under the We are not selling any of our common shares pursuant to this prospectus supplement, and we will not receive any proceeds from the sale of ourcommon shares offered by this prospectus supplement by the selling shareholder. We have agreed to bear the expenses relating to the registration of the You should read this prospectus supplement in conjunction with the accompanying prospectus. This prospectus supplement is not completewithout, and may not be delivered or used except in conjunction with, the prospectus, including any amendments or supplements to it. This prospectus Our common shares are listed on the New York Stock Exchange (“NYSE”), under the symbol “KEY.” The last reported sale price of our commonshares on December22, 2025 was $21.21 per common share. Investing in our common shares involves a high degree of risk. See “Risk Factors” on page 5 of the prospectus andthe “Risk Factors” sections of the documents incorporated by reference into the prospectus before investing in ourcommon shares. Neither the Securities and Exchange Commission (the “SEC”) nor any state securities commission has approved or disapproved of thesesecurities or determined if this prospectus supplement is truthful or complete. Any representation to the contrary is a criminal offense. Prospectus Supplement ABOUT THIS PROSPECTUS SUPPLEMENTFORWARD-LOOKING STATEMENTSWHERE YOU CAN FIND MORE INFORMATION ABOUT THIS PROSPECTUSWHERE YOU CAN FIND MORE INFORMATION Neither we, the selling shareholder nor any underwriters have authorized any other person to provide you with information other than theinformation contained or incorporated by reference in this prospectus supplement and any free writing prospectus prepared by or on behalf of us or towhich we have referred you. Neither we, the selling shareholder nor any underwriters take any responsibility for, or can provide assurance as to thereliability of, any other information that others may give you. You should assume that the information contained in this prospectus supplement or anyfree writing prospectus is accurate as of the date on its respective cover, and that any information incorporated by reference is accurate only as of the Table of Contents ABOUT THIS PROSPECTUS SUPPLEMENT This prospectus supplement relates to a prospectus, dated June9, 2023, which is part of a registration statement that we have filed with the SECusing a “shelf” registration process. Under this shelf registration process, a selling shareholder may, from time to time, offer and sell our common sharesdescribed in this prospectus supplement and in the accompanying prospectus in one or more offerings. This prospectus supplement may add, update orchange information contained in the accompanying prospectus. Please carefully read both this prospectus supplement and the accompanying prospectus The words “Key,” “Company,” “we,” “our,” “ours” and “us” as used herein refer to KeyCorp and its subsidiaries, unless otherwise stated. Table of Contents FORWARD-LOOKING STATEMENTS From time to time, we have made or will make forward-looking statements within the meaning of the Private Securities Litigation Reform Act of1995. These statements do not relate strictly to historical or current facts. Forward-looking statements usually can be identified by the use of words suchas “goal,” “objective,” “plan,” “expect,” “assume,” “anticipate,” “intend,” “project,” “believe,” “estimate,” “will,” “would,” “should,” “could,” or otherwords of similar meaning. Forward-looking statements provide our current expectations or forecasts of future events, circumstances, results oraspirations. Our disclosures in this prospectus supplement and the accompanying prospectus contain forward-looking statements. We may also make Forward-looking statements, by their nature, are subject to assumptions, risks, and uncertainties, many of which are outside of our control. Ouractual results may differ materially from those set forth in our forward-looking statements. There is no assurance that any list of risks and uncertaintiesor risk factors is complete. In addition, no assurance can be given that any plan, initiative, projection, goal, commitment, expectation, or prospect setforth in this prospectus supplement, the accompanying prospectus, or in our other documents filed with or furnished to the SEC can or will be achieved. •the extensive regulation of the U.S. financial services industry;•complex and evolving laws and regulations regarding privacy and cybersecurity;•operational or risk management failures by us or critical third parties; •breaches of security or failures of our technology syst