Einhorn's Greenlight Capital hedge fund bet against Tesla shares during the first three months of year, racking up losses on its short position. Greenlight did not disclose its current position on Tesla.

The fund's basket of shorts against what it considers to be bubble stocks, including Tesla, hurt its performance during the quarter, Einhorn said on an earnings conference call for Greenlight Capital Re Ltd, the insurer where he oversees its investment portfolio.

Einhorn also discussed General Motors Co, its biggest long position, but the automaker's shares rose just 1.5 percent during the first three months of this year. "GM trades at a significant discount to its intrinsic value despite the company's strong operating performance," Einhorn said.

In March, Greenlight announced a plan for GM to "unlock substantial shareholder value" by splitting its common into two classes of common equity.

Einhorn said by placing what Greenlight believes are conservative valuations on each component, "it's easy to get a value that is 27 percent to 79 percent higher than the current share price."

"We generally avoid public activism, but in this case management has misrepresented our idea, and we think our fellow shareholders deserve an opportunity of new way the merits of our plan for themselves," Einhorn said.

For its part, Einhorn suggested that Tesla remained a short position for Greenlight.

"For the time being, investors remain hypnotized by Tesla's CEO," Einhorn said. "We're skeptical that the company will be able to mass market its Model 3 at volumes and margins and justify the current valuation."

Model 3, Tesla's third-generation car, is on track for volume production by September, Musk said in February. He expects the rollout to help Telsa deliver five times its current annual sales volume, a key target in the automaker's efforts to stop burning cash.

Overall, Einhorn has had company in Tesla: Traders short-selling Tesla's soaring stock have lost $3.7 billion this year, eclipsing the combined losses of traders shorting Apple Inc, Amazon.com and Netflix.

(Reporting By Jennifer Ablan; Editing by Richard Chang)

By Jennifer Ablan