Westlake Corp美股招股说明书(2025-11-05版)

$600,000,000 5.550% Senior Notes due 2035$600,000,000 6.375% Senior Notes due 2055 We are offering $600,000,000 aggregate principal amount of our 5.550% Senior Notes due 2035 (the “2035 notes”) and $600,000,000 aggregate principal amount of our6.375% Senior Notes due 2055 (the “2055 notes” and, together with the 2035 notes, the “notes”). The 2035 notes will mature on November15, 2035, and the 2055 notes will mature on November 15, 2055. The 2035 notes will accrue interest at a rate of 5.550% perannum, and the 2055 notes will accrue interest at a rate of 6.375% per annum. Interest on each series of the notes will accrue from November 6, 2025 and will be payablesemi-annually in arrears on May15 and November15 of each year, beginning May15, 2026. We may redeem the notes at our option, in whole or in part, at any time prior to their maturity at the applicable redemption price described under “Description of theSenior Notes—Optional Redemption.” If a change of control triggering event as described under “Description of the Senior Notes—Change of Control Triggering Event”occurs, we will be required, unless we have exercised our right to redeem the notes, to offer to purchase the notes from the holders. The notes will be our senior unsecured obligations and will rank equally in right of payment with all of our other senior unsecured indebtedness from time to timeoutstanding. The notes will be effectively subordinated to any secured indebtedness to the extent of the value of the assets securing such indebtedness and to theindebtedness and other liabilities of our subsidiaries. The notes will be issued only in registered form in minimum denominations of $2,000 and integral multiples of $1,000 in excess thereof in book-entry form only. Investing in the notes involves risks. See “Risk Factors” beginning onpageS-6of this prospectus supplement, as well as the risksset forth in our filings with the Securities and Exchange Commission that are incorporated by reference into this prospectussupplement, to read about important factors you should consider carefully before investing in the notes. (1)Plus accrued interest, if any, from November 6, 2025, if settlement occurs after that date. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if thisprospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense. We do not intend to apply for listing of the notes of either series on any securities exchange or for inclusion of the notes of either series on any automated dealerquotation system. We expect that delivery of the notes, in book-entry form only through the facilities of The Depository Trust Company for the accounts of itsparticipants, including Euroclear Bank S.A./N.V., as operator of the Euroclear System, and Clearstream Banking,sociétéanonyme, will be made on or aboutNovember6, 2025. BofASecuritiesBarclays PNCCapitalMarketsLLC TDSecurities This prospectus supplement is part of a registration statement we filed with the Securities and Exchange Commission (the “SEC”). In making yourdecision whether to participate in this offering, you should rely only on the information contained in or incorporated by reference into this prospectussupplement and the accompanying prospectus. We have not, and the underwriters have not, authorized any person to provide you with any additional ordifferent information. We and the underwriters take no responsibility for, and can provide no assurance as to the reliability of, any information thatothers may give you. This prospectus supplement and the accompanying prospectus may only be used where it is legal to offer and sell the notes, andthis prospectus supplement and the accompanying prospectus are not an offer to sell or a solicitation of an offer to purchase the notes in any jurisdictionwhere such an offer, solicitation or sale would be unlawful. The information contained in this prospectus supplement or the accompanying prospectus iscurrent only as of the date of this prospectus supplement or the accompanying prospectus, as the case may be, and any information incorporated byreference is current only as of the date of the document incorporated by reference. Our business, financial condition, results of operations and prospectsmay have changed since those respective dates. We expect that delivery of the notes will be made to investors on or about November6, 2025, which will be the second business day following the dateof pricing the notes (such settlement being referred to as “T+2”). Under Rule15c6-1under the Securities Exchange Act of 1934, as amended (the“Exchange Act”), trades in the secondary market generally are required to settle in one business day unless the parties to any such trade expressly agreeotherwise. Accordingly, purchasers who wish to trade the notes on any date prior to the business day before de