Tesla Inc. (TSLA), the most-bet-against stock in the U.S., has gained another high-profile short seller on fears that the electric vehicle maker will not be able to sustain production of its new mass-market vehicle without raising additional cash. (See also: The Street Responds to Tesla’s Slide.)

Steve Eisman was one of the few investors who successfully predicted and profited on the fall of the subprime mortgage security frenzy during the 2008 financial crisis. He was the main character of Michael Lewis' best-selling book "The Big Short" and was depicted by actor Steve Carell in the feature film based on the book.

In an interview with Bloomberg TV on Friday, the Neuberger Berman portfolio manager indicated that while Tesla's CEO and founder Elon Musk is "a very smart man," his "execution problems" are of concern to investors. "He's nowhere in autonomous driving, as far as I can tell, and big competition is coming in his space next year," said Eisman.

Model 3 Goals Attained—Does it Matter?

Tesla, which has yet to turn a profit, has been under fire recently as it finally reached its production targets for the Model 3. While bulls cheered the accomplishment, skeptics are doubtful that the Palo Alto, California-based automaker can sustain operations and reach profitability the end of 2018 as Musk promised.

Meanwhile the billions of cash that the firm has burned through remains a concern for the bears. Earlier this week, shares took a tumble on a Wall Street Journal report citing a Tesla memo that asked a supplier to return a "meaningful amount of money of its payments since 2016" in efforts to reach profitability.

Tesla bulls, including analyst at Baird, saw the sell-off as a buying opportunity and viewed that report as "a further step in TSLA's progression towards profitability rather than as a necessity to strengthen the company's balance sheet." Others, including analysts at Morgan Stanley, viewed the series of headlines surrounding Tesla and Musk as adding a layer of risk to evaluating the carmaker's stock in the short term.

Tents and Tentativeness

Eisman was dismissive of Tesla building cars in a massive tent outside of its Fremont, California, assembly plant, as reported by Bloomberg. He also cited the high turnover rate at Tesla, noting that "the company has lost an enormous number of executives over the last two years."

As for Musk's ability to prove his haters wrong, the short seller suggested, "we'll see—maybe he pulls a rabbit out of the hat and gets the company going better. So far, the jury's out." (See also: Tesla to $400 and Beyond, Say Street Bulls.)