(Reuters) - Shares of XL Fleet Corp, which provides electric drive systems to enhance vehicle fuel economy, fell as much at 19.5% on Wednesday after U.S. short-selling firm Muddy Waters said it has taken a short position in the company’s stock. Muddy Waters founder Carson Block said that after talking to former XL Fleet employees, he believed the company significantly exaggerated its order backlog, that the return on investment for the company’s products was likely negative, and that it would not be able to compete with big car makers on electrification. "We don"t see that this company has a future, we just think of this as a bubble stock that everybody is trying to cash out of as soon as they"re able to," he said here on his streaming video channel. XL Fleet did not immediately respond to a request for comment. The company’s shares were down 13.6% at $13.78 late on Wednesday. On Dec. 23, short seller Citron Research took a bullish view on XL Fleet and said it was long the shares, estimating the company’s total available market was over $1 trillion. XL Fleet, which provides electrified power-train solutions for commercial fleet vehicles built by companies including Ford Motor Co and General Motors, went public in late December through a merger with a blank check company in a deal that valued it at $1 billion. Block said he did not think the company was worth anything near $1 billion. When asked if he was worried that retail traders would begin buying the company’s shares in an attempt to drive their value up to punish short sellers, as happened with GameStop Corp , Block said he did not think a “short squeeze” was imminent. “We wouldn’t be touching this if we felt that the technicals made this squeezy,” he said.