Spire Inc美股招股说明书(2026-01-07版)

Spire Inc. 6.375% Junior Subordinated Notes due 2086 This is an offering of $200,000,000 principal amount of 6.375% Junior Subordinated Notes due 2086 (the “Notes”) to be issued by Spire Inc. The Notes will bear interest at a rate of6.375% per annum. Interest on the Notes will be payable quarterly in arrears on March1, June1, September1 and December1 of each year (each, an “Interest Payment Date”), beginning onJune1, 2026. The Notes will be issued in registered form and in denominations of $25.00 and integral multiples thereof. The Notes will mature on March1, 2086. We may redeem some or all of the Notes at our option from time to time prior to their maturity at the redemption prices more fully described under “Description of the Notes—Optional Redemption” in this prospectus supplement. We intend to use the net proceeds of this offering, along with other funds, to redeem all of the outstanding shares of our 5.90% Series ACumulative Redeemable Perpetual Preferred Stock (our “Series A Preferred Stock”) with an aggregate $250.0million liquidation preference, upon which the corresponding 10,000,000outstanding depositary shares representing our Series A Preferred Stock will also be redeemed, and for other general corporate purposes. See “Use of Proceeds” in this prospectus supplement.So long as no event of default has occurred and is continuing, we may defer interest payments on the Notes on one or more occasions for up to 40 consecutive quarterly Interest PaymentPeriods (as defined in this prospectus supplement under “Description of the Notes—Interest”) as described in this prospectus supplement. Deferred interest payments will accrue additionalinterest at a rate equal to the interest rate on the Notes, compounded on each Interest Payment Date, to the extent permitted by law. The Notes are a new issue of securities with no establishedtrading market. We intend to apply for listing of the Notes on the New York Stock Exchange. If the application is approved, we expect trading in the Notes to begin within 30 days after thedate that the Notes are first issued. The Notes are expected to trade “flat,” which means that purchasers will not pay, and sellers will not receive, any accrued and unpaid interest on the Notesthat is not reflected in the trading price. Per NoteTotal (1)Plus accrued interest, if any, from the date of issuance, which is expected to be on or about January12, 2026.(2)The underwriting discount will be $0.7875 per Note (or up to a total of $6,300,000 for all Notes), provided that the underwriting discount will be $0.2500 per Note for sales toinstitutions and, to the extent of such institutional sales, the total underwriting discount will be less than, and the proceeds, before expenses, to Spire will be more than, the amount setforth in the above table. As a result of sales to institutions, the total underwriting discount will be $5,624,900 and the total proceeds, before expenses, to Spire will be $194,375,100.The expenses of this offering (excluding the underwriting discount) will be paid by Spire. Investing in the Notes involves certain risks. See “Risk Factors” on pageS-17 of this prospectus supplement. These securities have not been approved or disapproved by the Securities and Exchange Commission (the “SEC”) or any state securities commission, nor has the SEC orany state securities commission determined that this prospectus supplement or the accompanying prospectus is accurate or complete. Any representation to the contrary is acriminal offense. We have granted the underwriters an option, exercisable for 30 days from the date of this prospectus supplement, to purchase up to an additional $30,000,000 in principal amount ofthe Notes at the initial public offering price in order to cover over allotments, if any. If the underwriters exercise this option in full, the total public offering price, underwriting discount andproceeds, before expenses, to Spire Inc. will be $230,000,000, $6,569,900 and $223,430,100, respectively. The underwriters expect to deliver the Notes in book-entry form only through the facilities of The Depository Trust Company for the accounts of its participants, including ClearstreamBanking S.A. and Euroclear Bank SA/NV, as operator of the Euroclear System, on or about January12, 2026. Joint Book-Running Managers Morgan Stanley WellsFargoSecurities BofA Securities Co-Managers Siebert Williams Shank Ramirez & Co., Inc. Table of Contents You should rely only on the information contained in or incorporated by reference in this prospectus supplement, the accompanyingprospectus and any free writing prospectus prepared by or on behalf of us or to which we have referred you. Neither we nor the underwritershave authorized anyone to provide you with different or additional information. We are not, and the underwriters are not, making an offer ofthese securities in any state or jurisdiction where the offer is not permitted. You should not assume that the information contain