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): October 8, 2026

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:

Securities registered pursuant to Section 12(b) of the Exchange Act (only applicable to Spire Inc.):

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. ☐

Item 8.01 Other Events.

On October 8, 2026, Spire Missouri Inc. (“Spire Missouri”), a wholly owned subsidiary of Spire Inc., issued $350 million in aggregate principal amount of its First Mortgage Bonds, 6.200% Series due 2036 (the “Bonds”) pursuant to an Underwriting Agreement dated October 5, 2026, between Spire Missouri and the several underwriters named therein, for whom BofA Securities, Inc., TD Securities (USA) LLC, Regions Securities LLC, and U.S. Bancorp Investments, Inc. acted as representatives.

The Bonds were issued pursuant to Spire Missouri’s registration statement on Form S-3 (Registration Number 333-287024-01) filed with the Securities and Exchange Commission on May 7, 2025 (the “Registration Statement”), the base prospectus dated May 7, 2025, the preliminary prospectus supplement dated October 5, 2026 and the prospectus supplement dated October 7, 2026. The Bonds will be governed by the Mortgage and Deed of Trust, dated as of February 1, 1945, between Spire Missouri and Regions Bank, as successor trustee, as amended and supplemented by all supplemental indentures thereto, the latest of which is the Forty-Second Supplemental Indenture relating to the Bonds, dated as of October 8, 2026.

Spire Missouri intends to use the net proceeds for general corporate purposes, which may include repayment of other short-term indebtedness.

This Current Report on Form 8-K is being filed to report as exhibits certain documents in connection with the offering and sale of the Bonds for incorporation by reference into the Registration Statement.

Item 9.01 Financial Statements and Exhibits.

(b) Exhibits:

SIGNATURES

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