MPLX LP美股招股说明书(2026-08-11版)

$1,250,000,000 4.700% Senior Notes due 2029$500,000,000 5.000% Senior Notes due 2032$500,000,000 5.500% Senior Notes due 2036 MPLX LP is offering $1,250,000,000 aggregate principal amount of 4.700% Senior Notes due 2029, which we refer to as the “2029 notes,” $500,000,000 aggregate principalamount of 5.000% Senior Notes due 2032, which we refer to as the “2032 notes,” and $500,000,000 aggregate principal amount of 5.500% Senior Notes due 2036, which we refer to as the“2036 notes.” We collectively refer to the 2029 notes, the 2032 notes and the 2036 notes as the “notes.” We will pay interest on the notes semi-annually in arrears on May 1 and November 1 of each year they are outstanding, commencing on May 1, 2027. Interest on the notes willbe paid to holders of record of the notes as of the close of business on the April 15 and October 15 immediately preceding the respective interest payment date. We have the option to redeem some or all of the notes of any series at any time and from time to time, as described under the heading “Description of the Notes—Optional The notes will be unsecured and unsubordinated obligations of MPLX LP and will rank equally with all of MPLX LP’s other existing and future unsecured and unsubordinatedindebtedness from time to time outstanding, but will be effectively junior to MPLX LP’s secured indebtedness, if any, to the extent of the value of the relevant collateral. The notes will not bethe obligation of any of MPLX LP’s subsidiaries and will be structurally subordinated to all indebtedness and other obligations of MPLX LP’s subsidiaries. Each series of notes is a new issue of securities with no established trading market. We do not intend to apply to list the notes on any securities exchange or to have the notes (1)Plus accrued interest, if any, from August 24, 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 or determined if thisprospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense. Delivery of the notes offered hereby in book-entry form will be made only through the facilities of The Depository Trust Company for the accounts of its participants, includingEuroclear Bank, SA/NV and Clearstream Banking,société anonyme, on or about August 24, 2026, which is the tenth business day following the date of the pricing of the notes (suchsettlement cycle being referred to as “T+10”). See “Underwriting (Conflicts of Interest).” Table of Contents TABLE OF CONTENTS ABOUT THIS PROSPECTUS SUPPLEMENTWHERE YOU CAN FIND MORE INFORMATIONINFORMATION WE INCORPORATE BY REFERENCEDISCLOSURES REGARDING FORWARD-LOOKING STATEMENTSSUMMARYRISK FACTORSUSE OF PROCEEDSCAPITALIZATIONDESCRIPTION OF OTHER INDEBTEDNESSDESCRIPTION OF THE NOTESMATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCESCERTAIN ERISA CONSIDERATIONSUNDERWRITING (CONFLICTS OF INTEREST)LEGAL MATTERSEXPERTS ABOUT THIS PROSPECTUSWHERE YOU CAN FIND MORE INFORMATIONINFORMATION WE INCORPORATE BY REFERENCEDISCLOSURES REGARDING FORWARD-LOOKING STATEMENTSTHE COMPANYRISK FACTORSUSE OF PROCEEDS Table of Contents ABOUT THIS PROSPECTUS SUPPLEMENT We provide information to you about this offering in two parts. The first part is this prospectus supplement which describes the specificterms of this offering and adds to, updates and changes information contained in the accompanying prospectus. The second part is the accompanyingprospectus, which provides general information, some of which may not apply to this offering. This prospectus supplement should be read inconjunction with the accompanying prospectus. To the extent the information contained in this prospectus supplement is inconsistent with theinformation in the accompanying prospectus, you should rely on the information in this prospectus supplement. You should rely only on the information contained or incorporated by reference in this prospectus supplement, in the accompanyingprospectus, or in any free writing prospectus that we may provide to you. We have not, and the underwriters have not, authorized anyone to provide youwith different information. We are not, and the underwriters are not, making offers to sell the notes in any jurisdiction in which an offer or solicitation isnot authorized or in which the person making such offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make an offer orsolicitation. You should not assume that the information contained in this prospectus supplement, the accompanying prospectus, or any documentincorporated by reference is accurate as of any date other than the date on the cover page of those respective documents. Our business, financialcondition, results of operations and prospects may have changed since those respective dates. Except as otherwise indicated, references in this prospectus supplement to “MPLX,” the