Filed Pursuant to Rule 424(b)(7)
Registration No. 333-251239
PROSPECTUS SUPPLEMENT
(To Prospectus dated
December 28, 2020)
MP MATERIALS CORP.
Up to 111,147,154 Shares of Common Stock
This prospectus supplement, as
previously supplemented on May 3, 2021 and May 13, 2021, supplements and amends the selling securityholder information contained in the prospectus, dated December 28, 2020 (the “Prospectus”), which forms a part of the
registration statement on Form S-1 (No. 333-251239) filed by MP Materials Corp., a Delaware corporation (“we,” “our”), with the Securities and
Exchange Commission relating to the possible resale from time to time of up to 111,147,154 shares of our common stock, par value $0.0001 per share (“Common Stock”). This prospectus supplement is being filed solely for the purpose of
designating additional selling securityholders and updating information with respect to Fortress Acquisition Sponsor LLC and does not register any additional shares of Common Stock. The additional selling securityholders received their shares upon a
transfer from Fortress Acquisition Sponsor LLC effected on December 31, 2020. The selling securityholders may use the Prospectus, as amended by this prospectus supplement, to resell from time to time the shares of our Common Stock
referenced therein.
You should read this prospectus supplement in conjunction with the Prospectus, including any amendments or supplements to it. This
prospectus supplement is not complete without, and may not be delivered or used except in conjunction with, the Prospectus, including any amendments or supplements to it. This prospectus supplement is qualified by reference to the Prospectus, except
to the extent that the information provided by this prospectus supplement supersedes information contained in the Prospectus. You should not assume that the information provided in this prospectus supplement, the Prospectus or any prior prospectus
supplement is accurate as of any date other than their respective dates. Neither the delivery of this prospectus supplement, the Prospectus or any prior prospectus supplement, nor any sale made hereunder or thereunder, shall under any circumstances
create any implication that there has been no change in our affairs since the date of this prospectus supplement, or that the information contained in this prospectus supplement, the Prospectus or any prior prospectus supplement is correct as of any
time after the date of that information.
The registration of the shares of our Common Stock covered by the Prospectus as amended by this prospectus
supplement does not necessarily mean that any of the selling securityholders will offer or sell any of their shares.
Our common stock is listed on the
New York Stock Exchange under the symbol “MP.” On June 21, 2021, the last reported sale price of our Common Stock was $30.81 per share.
Investing in our Common
Stock involves risks. See “Risk Factors” beginning on page 8 of the Prospectus dated December 28, 2020, as updated and supplemented by the section entitled “Risk Factors” included in our Annual Report for the year ended
December 31, 2020 and the section entitled “Risk Factors” included in our Quarterly Report for the quarter ended March 31, 2021.
Neither the United States Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed
upon the adequacy or accuracy of this prospectus supplement or the accompanying prospectus. Any representation to the contrary is a criminal offense.
The date of this prospectus supplement is June 22, 2021.