ONE Gas Inc美股招股说明书(2026-08-12版)

$375,000,000 5.45% Notes due 2036 We are offering $375,000,000 aggregate principal amount of 5.45% Notes due 2036 (the “notes”). The notes will mature on September1, 2036. The notes will bear interest at a rate of 5.45% per year from, and including, the date of issuance. See “Description of the Notes—Terms of theNotes.” We will pay interest on the notes semi-annually in arrears on March 1 and September 1 of each year, beginning on March1, 2027. We mayredeem the notes, in whole or in part, at any time at the redemption prices described under the caption “Description of the Notes—OptionalRedemption.” The notes will be senior unsecured obligations of ours and will be equal in right of payment with all of our unsecured and unsubordinatedindebtedness. The notes will be issued in minimum denominations of $2,000 and integral multiples of $1,000 in excess thereof. Investing in the notes involves risks. See “RiskFactors” beginning on pageS-6 of this prospectus supplement andon page6 of the accompanying base prospectus. (1)Plus accrued interest, if any, from August13, 2026, if settlement occurs after that date. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities ordetermined if this prospectus supplement or the accompanying base prospectus is truthful or complete. Any representation to the contrary is acriminal offense. The notes will not be listed on any national securities exchange. Currently, there is no public market for the notes. We expect that the notes will be ready for delivery in registered book-entry form only through the facilities of TheDepository Trust Company forthe accounts of its participants, including Clearstream Banking S.A., and Euroclear Bank SA/NV, as operator of the Euroclear System, against paymentin New York, New York, on or about August13, 2026. Joint Book-Running Managers TABLE OF CONTENTS Prospectus Supplement PROSPECTUS SUPPLEMENT SUMMARYRISK FACTORSUSE OF PROCEEDSCAPITALIZATIONDESCRIPTION OF THE NOTESU.S. FEDERAL INCOME TAX CONSIDERATIONS FOR NON-U.S. HOLDERSUNDERWRITING (CONFLICTS OF INTEREST)LEGAL MATTERSEXPERTSCAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTSWHERE YOU CAN FIND MORE INFORMATION ABOUT THIS PROSPECTUSWHERE YOU CAN FIND MORE INFORMATIONINCORPORATION BY REFERENCEFORWARD-LOOKING STATEMENTSABOUT ONE GASRISK FACTORSUSE OF PROCEEDSDESCRIPTION OF DEBT SECURITIES This document is in two parts. The first part is this prospectus supplement, which describes the specific terms of this offering. The second part isthe accompanying base prospectus, which gives more general information, some of which may not apply to this offering of notes. Generally, when werefer only to the “prospectus,” we are referring to both parts combined. If information varies between this prospectus supplement and the accompanyingbase prospectus, you should rely on the information in this prospectus supplement. Any statement made in this prospectus supplement, the accompanying base prospectus or in a document incorporated into this prospectussupplement or the accompanying base prospectus will be deemed to be modified or superseded for purposes of this prospectus supplement to the extentthat a statement contained in this prospectus supplement, the accompanying base prospectus or in any other subsequently filed document that is alsoincorporated by reference into this prospectus supplement modifies or supersedes that statement. Any statement so modified or superseded will not bedeemed, except as so modified or superseded, to constitute a part of this prospectus supplement or the accompanying base prospectus. Please read“Where You Can Find More Information” and “Incorporation by Reference” in this prospectus supplement and the accompanying base prospectus. We and the underwriters have not authorized anyone else to provide you with information different from that contained in or incorporated byreference into this prospectus supplement and the accompanying base prospectus, including any free writing prospectus. We and the underwriters takeno responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. We and the underwriters arenot making an offer to sell or a solicitation of an offer to purchase these notes in any jurisdiction where the offer or sale is not permitted. You should notassume that the information contained in this prospectus supplement, the accompanying base prospectus or any free writing prospectus authorized by usis accurate as of any date other than the date on the front cover of such document or that the information incorporated by reference herein or therein isaccurate as of any date other than the date of such document incorporated by reference or, in each case, as of any earlier date as of which suchinformation is given. PROSPECTUS SUPPLEMENT SUMMARY This summary highlights certain information about ONE Gas. It is not complete and