Six months ago, MP Materials (MP 7.24%) investors got some excellent news. The U.S. government -- specifically, the Department of Defense -- would invest $400 million in MP Materials preferred convertible stock. Today, worries are rising that the price guarantee might go away, and this is taking a toll on MP Materials stock price, now down 9.4% at 1:15 p.m. The guarantees given to MP Materials, in contrast, appear to be written into the contract already. Expand NYSE : MP MP Materials Today's Change ( -7.24 %) $ -4.85 Current Price $ 62.16 Key Data Points Market Cap $12B Day's Range $ 58.28 - $ 65.20 52wk Range $ 18.64 - $ 100.25 Volume 17M Avg Vol 9.4M Gross Margin -2627.54 %Is MP Materials stock a buy?