Why Tesla's Good News Crashed MP Materials Stock

Shares of rare earth metals miner MP Materials (NYSE: MP) soared after reporting strong earnings last week -- better-than-expected revenues, and profits more than twice the level Wall Street had predicted -- gaining more than 14% over the next two trading days. In early trading Thursday morning, MP Materials is taking a big hit, and indeed is giving back all its post-earnings gains -- down 13.3% through 11:15 a.m. ET -- "thanks" to a revelation made by electric vehicle maker Tesla (NASDAQ: TSLA) last night. In the course of a generally underwhelming investor day, in which Elon Musk failed to announce (as expected) the unveiling of a new budget-priced Model 2 electric car, the electric impresario did have something to announce of importance to rare earth investors: Tesla has invented a permanent magnet motor for electric cars that "does not use any rare earth metals," reports StreetInsider.com.