David Einhorn's $5.5 billion Greenlight Capital hedge fund lost 18.3% in the first half of 2018 while the benchmark S&P 500 was positive. Tesla was the firm's "second biggest loser" he said, thanks to its 29% jump in the same period. Einhorn is swapping his Tesla Model S for a Jaguar I-PACE SUV, he told investors Tuesday. Elon Musk responded on Twitter, saying he will "send Einhorn a box of short shorts to comfort him." Follow Tesla's stock price in real-time here. Billionaire hedge fund manager David Einhorn hasn't had a fun year.