Spire Inc美股招股说明书(2025-11-19版)

Spire Inc. $450,000,000 6.250% Series A Junior Subordinated Notes due 2056$450,000,000 6.450% Series B Junior Subordinated Notes due 2056 This is an offering of $450,000,000 principal amount of 6.250% Series A Junior Subordinated Notes (the “Series A Notes”) and $450,000,000 principal amount of 6.450% Series BJunior Subordinated Notes (the “Series B Notes” and, collectively, the “Notes”) to be issued by Spire Inc. The Series A Notes will bear interest (i)from and including the date of originalissuance to, but excluding, June1, 2031, at an annual rate of 6.250% and (ii)from and including June1, 2031 during each Series A Interest Reset Period (as defined herein) at an annual rateequal to the Five-Year Treasury Rate (as defined herein) as of the most recent Series A Reset Interest Determination Date (as defined herein) plus 2.556%; provided that the interest rate duringany Series A Interest Reset Period will not reset below 6.250%. The SeriesB Notes will bear interest (i)from and including the date of original issuance to, but excluding, June1, 2036, at anannual rate of 6.450% and (ii)from and including June1, 2036 during each Series B Interest Reset Period (as defined herein) at an annual rate equal to the Five-Year Treasury Rate (asdefined herein) as of the most recent Series B Reset Interest Determination Date (as defined herein) plus 2.327%; provided that the interest rate during any Series B Interest Reset Period willnot reset below 6.450%. Interest on the Notes will be payable semi-annually in arrears on June1 and December1 of each year beginning on June1, 2026. The Notes will be issued inregistered form and in denominations of $2,000 and integral multiples of $1,000 in excess thereof. The Series A Notes will mature on June1, 2056. The Series B Notes will mature on June1,2056. We may redeem some or all of the Notes at our option from time to time prior to their maturity at the applicable redemption prices more fully described under “Description of theNotes—Optional Redemption” in this prospectus supplement. We intend to use the net proceeds of this offering, together with other funds, to finance the Piedmont Acquisition (as definedherein). 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 either (or both) series of theNotes on one or more occasions for up to 10 consecutive years as described in this prospectus supplement. Deferred interest payments with respect to either (or both) series will accrueadditional interest at a rate equal to the interest rate on the notes, compounded on each interest payment date, to the extent permitted by law. Each series of the Notes is a new issue ofsecurities with no established trading market. We do not intend to apply for listing of the Notes on any securities exchange and cannot assure the holders that an active after-market for theNotes will develop or be sustained or that holders of the Notes will be able to sell them at favorable prices or at all. Investing in the Notes involves certain risks. See “Risk Factors” on page S-18 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. 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 November 24, 2025. BMO Capital MarketsMizuhoBofA Securities Wells Fargo SecuritiesRBC Capital MarketsTD Securities 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 contained in orincorporated by reference in this prospectus supplement, the accompanying prospectus or any free writing prospectus is accurate as of any dateother than the date on the front of this prospectus supplement, the date of the accompanying prospectus or the date of such free writingprospectus, as applicable. Our business, financial condition, results of operations and prospects may have changed since those respective dates. TABLE OF CONTENTS Prospectus Supplement ABOUT THIS PROSPECTUS SUPPLEMENTFORWARD-LOOKING STATEMENTSPROSPECTUS SUPPLEMENT SUMMARYSU