Just over 911 million SpaceX shares will be available for trading, representing about 7% of shares outstanding. It's more than the 639 million shares that were sold in the company's record IPO. On Aug. 20, another 319 million shares could unlock, according to the prospectus, followed by roughly 700 million in September and close to that number in October. Musk, the world's richest person, is by far the biggest holder of SpaceX stock with more than 6 billion shares. And prior to the IPO, SpaceX agreed to buy Cursor for $60 billion in a transaction expected to close this quarter.