MP Materials Corp-A美股招股说明书(2025-07-18版)

11,818,181 Shares Common Stock We are offering 11,818,181 shares of our common stock, par value $0.0001 per share. Our common stock is listed on the New York Stock Exchange (“NYSE”) under the symbol “MP.” On July16, 2025, the last sale price of our commonstock as reported on the NYSE was $58.55 per share. PerShareTotalPrice to the Public$55.00$649,999,955.00Underwriting Discount(1)$1.65$19,499,998.65Proceeds, before expenses, to us$53.35$630,499,956.35 (1)See “Underwriting” for additional information regarding underwriting compensation. We have granted the underwriters the right to purchase, within 30 days of the date of this prospectus supplement and at the public offering price lessunderwriting discount, an additional 1,772,727 shares of common stock, solely to cover over-allotments. See “Underwriting”. Investing in shares of our common stock involves a high degree of risk. Before buying any shares of our common stock,you should carefully consider the risks that we have described in “Risk Factors” beginning on page S-9of thisprospectus supplement and the risk factors under the heading “Risk Factors” contained in PartI, Item1A. in ourAnnual Report onForm10-Kfor the year ended December31, 2024 and PartI, Item1A in our Quarterly Report onForm10-Qfor the three months ended March31, 2025, each of which is incorporated by reference into this prospectussupplement. Neither the United States Securities and Exchange Commission (the “SEC”) nor any state securities commission has approved or disapprovedof these securities or passed upon the adequacy or accuracy of this prospectus supplement or the accompanying prospectus. Any representationto the contrary is a criminal offense. The underwriters expect to deliver the shares of common stock to purchasers on or about July 18, 2025 only in book-entry form through the facilities ofThe Depository Trust Company. Joint Lead Bookrunning Managers J.P. Morgan Goldman Sachs& Co. LLC Bookrunning Manager Morgan Stanley July 16, 2025 TABLE OF CONTENTS Prospectus Supplement ABOUT THIS PROSPECTUS SUPPLEMENTCAUTIONARY NOTES REGARDING FORWARD-LOOKING STATEMENTSWHERE YOU CAN FIND MORE INFORMATIONSUMMARYRISK FACTORSUSE OF PROCEEDSCAPITALIZATIONUNITED STATES FEDERAL INCOME TAX CONSIDERATIONS FORNON-U.S.HOLDERSUNDERWRITINGLEGAL MATTERSEXPERTS Prospectus ABOUT THIS PROSPECTUSMARKET AND OTHER INDUSTRY DATACAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTSMP MATERIALS CORP.RISK FACTORSUSE OF PROCEEDSDESCRIPTION OF CAPITAL STOCKDESCRIPTION OF DEBT SECURITIES ABOUT THIS PROSPECTUS SUPPLEMENT This document is in two parts. The first part is this prospectus supplement, which contains the terms of this offering of common stock. The second partis the accompanying prospectus dated February28, 2025, which was originally filed as part of a Registration Statement onFormS-3that we filed withthe SEC. The accompanying prospectus gives more general information about us, some of which may not apply to this offering. This prospectus supplement may add to, update or change the information in the accompanying prospectus. If information in this prospectus supplementis inconsistent with information in the accompanying prospectus, this prospectus supplement will apply and will supersede that information in theaccompanying prospectus. It is important for you to read and consider all information contained in this prospectus supplement and the accompanying prospectus (and any freewriting prospectus prepared by us or on our behalf in connection with this offering) in making your investment decision. You should also read andconsider the information in the documents to which we have referred you under “Where You Can Find More Information” in this prospectussupplement. We have not, and the underwriters have not, authorized anyone to provide you with any information other than that contained in this prospectussupplement and the accompanying prospectus (and any free writing prospectus prepared by us or on our behalf in connection with this offering). We donot, and the underwriters do not, take any responsibility for, and can provide no assurances as to, the reliability of any information that others mayprovide you. If information in this prospectus supplement is inconsistent with the accompanying prospectus, you should rely on this prospectussupplement. The information in this prospectus supplement and the accompanying prospectus (and any free writing prospectus prepared by us or on ourbehalf in connection with this offering) and the documents incorporated by reference herein and therein is accurate only as of their respective dates orsuch earlier date of any such information as may be stated therein. Our business, financial condition, results of operations, cash flows and prospects mayhave changed since those dates. Neither the delivery of this prospectus supplement and the accompanying prospectus, nor any sale made hereunder,shall under any circumstances create any implication that there has b