MP Materials launched a $500M public offering of common stock, and expects to grant a 30-day underwriters option to purchase up to an additional 15% of shares to be sold in the offering.

Shares of MP Materials are surging in early trading Tuesday after Apple said it would invest $500 million in the owner of the U.S.’s only operational rare earths mine.

On Thursday, the United States Department of Defense (DOD) entered a major deal with MP Materials. The DOD agreed to buy $400 million of MP Materials newly created preferred shares stock. The move will make the U.S. military the company’s largest stakeholder. In the hours after the deal, the company’s stock surged more than 50%.