Investors betting against Tesla were up nearly $800 million Thursday after the electric carmaker gave Model 3 production figures that fell way short of estimates and as the company's chief executive officer entered federal court in Manhattan to defend against claims that he violated an October settlement with the U.S. government.

Tesla sank more than 8 percent Thursday to around $267 per share, giving short sellers betting against the stock $763 million in mark-to-market profits so far on the day, estimates S3 Analystics. Tesla's short interest is now at $9.04 billion, with about 30 million shares shorted (25% of float) making it one of the most shorted stocks in the U.S. market, according to S3′s Ihor Dusaniwsky.