8-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): December 23, 2025

KeyCorp

(Exact name of registrant as specified in charter)

(216) 689-3000

Registrant’s telephone number, including area code:

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

Securities Registered Pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

On December 23, 2025, KeyCorp (the “Company”) filed a prospectus supplement to its Registration Statement on Form S-3 (No. 333-272573) (the “Registration Statement”) filed with the U.S. Securities and Exchange Commission under the Securities Act of 1933, as amended, with respect to the registration of 161,968,762 common shares, par value $1.00 per share, of the Company that were issued to The Bank of Nova Scotia (“BNS”) pursuant to the Investment Agreement, dated as of August 12, 2024, by and between the Company and BNS. Pursuant to the terms of the Investment Agreement, the Company was required to file this prospectus supplement no later than December 27, 2025.

In connection with the filing of the prospectus supplement, the Company is filing a legal opinion as Exhibit No. 5.1 to this Current Report on Form 8-K, which is incorporated by reference into the Registration Statement.

(d) Exhibits

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

EX-5.1

Exhibit 5.1

December 23, 2025

KeyCorp

127 Public Square

Cleveland, Ohio 44114

Ladies and Gentlemen:

We have acted as special counsel to KeyCorp, an Ohio corporation (the “Company”). Our opinion has been requested as to certain matters in connection with the registration for resale of up to 161,968,762 of the Company’s common shares, par value $1.00 per share (the “Shares”), originally issued to Scotiabank (the “Selling Shareholder”) pursuant to the Investment Agreement dated as of August 12, 2024 by and between the Company and the Selling Shareholder (the “Investment Agreement”). The Shares have been registered for resale pursuant to the Company’s Registration Statement on Form S-3 (File No. 333-272573) (the “Registration Statement”) filed on June 9, 2023 with the Securities and Exchange Commission (the “Commission”) pursuant to the Securities Act of 1933, as amended (the “Securities Act”), including the base prospectus dated June 9, 2023 (the “Base Prospectus”), and the prospectus supplement dated December 23, 2025 (the “Prospectus Supplement,” together with the Base Prospectus, the “Prospectus”) filed by the Company with the Commission on December 23, 2025 pursuant to Rule 424(b) of the rules and regulations under the Securities Act.

We have examined such documents, including the Registration Statement, the Prospectus, the Investment Agreement, the articles of incorporation of the Company, as amended through the date hereof (the “Articles”), the code of regulations of the Company, as amended through the date hereof (the “Regulations”) and of the Company’s Board of Directors or duly authorized committee thereof. We have also examined originals, or copies of originals certified to our satisfaction, of such agreements, documents, certificates and statements of the Company and have examined such questions of law as we have considered relevant and necessary as a basis for this opinion letter. In rendering our opinion set forth below, we have assumed the authenticity of all documents submitted to us as originals, the genuineness of all signatures and the conformity to authentic originals of all documents submitted to us as copies. We have also assumed the legal capacity for all purposes relevant hereto of all natural persons and, with respect to all parties to agreements or instruments relevant hereto other than the Company, that such parties had the requisite power and authority (corporate or otherwise) to execute, deliver and perform such agreements or instruments, that such agreements or instruments have been duly authorized by all requisite action (corporate or otherwise), executed and delivered by such parties and that such agreements or instruments are the valid, binding and enforceable obligations of such parties. As to questions of fact material to our opinion, we have relied upon certificates of officers of the Company and of public officials.

Squire Patton Boggs (US) LLP

KeyCorp

December 23, 2025

Page 2

Based on the foregoing, and having regard for such legal considerations as we have deemed relevant, we are of the opinion that the Shares are validly issued, fully paid and non-assessable.

Our opinion expressed above is limited to the laws of the State of Ohio and the federal laws of the United States of America, and we are expressing no opinion as to the effect of any other laws. We assume no obligation to advise you of changes in matters of fact or law which may thereafter occur, and we do not opine with respect to any law, regulation, rule or governmental policy which may be enacted or adopted after the date hereof.

We hereby consent to the filing of this opinion as an exhibit to a Current Report on Form 8-K of the Company filed with the Commission on December 23, 2025, and thereby incorporated by reference into the Registration Statement, and to the use of our name in the Prospectus under the caption “Validity of Securities.” In giving this consent, we do not admit that we are within the category of persons whose consent is required under Section 7 of the Securities Act and the rules and regulations thereunder.