Since SpaceX went public in June, Wall Street had been dreading Aug. 6, when the first lockup preventing early investors from selling the stock expired and millions of shares were set to flood the market. They needn't have worried.SpaceX shares have been on a tear since the lockup ended, soaring 35% in just five sessions, adding roughly $500 billion in market capitalisation, and vaulting back over their $135 initial public offering price. The surge bucked concerns about an impending wave of selling and gave investors optimism that future expirations won't be as painful as feared.Read more: Elon Musk discloses 48.4% stake in SpaceX in regulatory filingThis lockup was the biggest one, with 911.5 million shares coming available, more than were sold in the IPO. The next expiration is on Aug 20. Bloomberg