MP Materials said on Wednesday it would sell $500 million of its common stock, a day after the U.S. rare earths miner inked a supply deal with Apple .

MP Materials stock has risen 255% after a $400 million deal from the Pentagon and a $500 million magnet contract with Apple. Is MP stock too high?

Shares of MP Materials were up 26% in midday trading at $61.19, putting the stock on pace for a record closing high. Apple stock was up 0.6%, while the S&P 500 was flat and the Dow Jones Industrial Average was down 0.6%.