SpaceX NASDAQ:SPCX short sellers have made an estimated $3.8 bilion in paper gains after the stock slid below its IPO price during a four-day losing streak.

According to S3 Partners, short interest has climbed to 181 million shares, or about 28% of the company's 646 million-share tradable float. Shares have fallen 11% over the past 4 sessions, touching an intraday low of $132.15 before closing just above their $135 IPO price.

Led by Elon Musk, who is also CEO of Tesla NASDAQ:TSLA, SpaceX designs and launches rockets, operates the Starlink satellite internet network and develops spacecraft for commercial and government customers. The company is also building Starship, its next-generation launch system aimed at missions to the Moon and Mars.

The recent pullback comes as investors wait for 2 major catalysts: SpaceX's 13th Starship test flight and its earnings report, expected in the first week of August.