MP Materials Corp-A美股招股说明书(2025-07-16版)

Preliminary Prospectus Supplement Common Stock We are offering shares of our common stock, par value $0.0001 per share, with an aggregate offering price of $500,000,000. Investing in shares of our common stock involves a high degree of risk. Before buying any shares of beginning on page S-9of this prospectus supplement and the risk factors under the heading “RiskFactors” contained in PartI, Item1A. in our Annual Report onForm10-Kfor the year endedDecember31, 2024 and PartI, Item1A in our Quarterly Report on Form10-Qfor the three monthsended March31, 2025, each of which is incorporated by reference into this prospectus supplement. Joint Lead Bookrunning Managers J.P. MorganGoldman Sachs& Co. LLCBookrunning Manager Prospectus Supplement UNITED STATES FEDERAL INCOME TAX CONSIDERATIONS FORNON-U.S.HOLDERS CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS WHERE YOU CAN FIND MORE INFORMATION is 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. in which such an offer or solicitation is not authorized or to any person to whom it is unlawful to make such an offer or solicitation. See “Underwriting.”In this prospectus supplement and the accompanying prospectus, unless otherwise stated, references to “we,” “us,” and “our” refer to MP MaterialsCorp. and its subsidiaries on a consolidated basis. Capitalized terms used herein and not defined have the meanings ascribed thereto in theaccompanying prospectus.S-ii Certain statements included or incorporated by reference in this prospectus supplement and the accompanying prospectus that are not historical facts areforward-looking statements for purposes of the safe harbor provisions under the United States Private Securities Litigation Reform Act of 1995.Forward-looking statements may be identified by the use of the words such as “estimate,” “plan,” “will,” “shall,” “may,” “project,” “forecast,” “intend,” offering; the use of proceeds from the DoD Transactions (as defined in “Summary—Recent Developments”); the timing and consummation of futurephases of the DoD Transactions, our and the Department of Defense’s future obligations related to the DoD Transactions; the expected impact of theDoD Transactions on our business and the broader industry; the availability of government appropriations, funding and support for the DoDTransactions; the availability of additional or replacement funding for our development projects and operations; the financial and accounting assessment our engagement with industry and the government and outcomes related to this engagement; the price and market for rare earth materials, the continueddemand for rare earth materials and the market for rare earth materials generally; future demand for magnets; estimates and forecasts of our results ofoperations and other financial and performance metrics, including neodymium-praseodymium (“NdPr”) oxide production and shipments and expectedNdPr oxide production and shipments; and our mining and magnet projects, including the fact that the our ability to expand our separation capabilities toinclude samarium is conditioned upon the Department of Defense extending the Samarium Project Loan in accordance with the Transaction Agreement,to develop the 10X Facility (as defined in “Summary—Recent Developments”) and to achieve run rate production of separated rare earth materials andproduction of commercial metal and magnets; expectations and benefits of a long-term agreement with Apple Inc. (“Apple”) and our ability to supplyU.S.-produced rare earth magnets; our ability to achieve technological advancements and supply chain objectives and the timing thereof; the timing forcompletion of a rare earth recycling line at Mountain Pass; our ability to expand the capacity at our Independence Facility (as defined in “Summary”)and commence magnet shipments, and timing thereof; the estimated revenues to be received by us under the agreement with Apple; the impact and beyond our control.These forward-looking statements are subject to a number of risks and uncertainties, including:•risks related to the authorization of funding of and continued support for the DoD Transactions, to challenges thereto and to our ability, asneeded, to obtain additional or replacement funding on terms acceptable to us or at all; •risks related to our long-term agreement with Apple Inc. and our ability to meet the obligations thereunder, including risks related to ourability to construct, develop and scale our facilities, technology and production; •our ability to consummate this offering or other future financings on terms acceptable to us, or at all;•risks related to changes in trade policy in the United States, China or other countries, including the implementation of new tariffs, and thematerial adverse impact on our bu