Famed short seller Citron Research is now betting against Mobileye's self-driving car business, Andrew Left told CNBC.
"They're really a one-trick pony," Left told CNBC's "Fast Money: Halftime Report" on Friday. "With autonomous driving, you could even buy Google and get this whole area for free… right now Mobileye is bringing a knife to a gunfight."
"If you want exposure in the area as a short, it's not Nvidia anymore, but rather more of a focus on Mobileye," Left said. "When I initially discussed the Mobileye short, I've always compared it against Nvidia."
Compared to Nvidia, Mobileye has seen more insider selling, spends less on research and development, and has a more pricey valuation, Citron tweeted.
Shares of Mobileye fell about 2 percent mid-day on Friday to about $47 a share. Left's short-term target is $35 a share.
Mobileye declined to comment to CNBC, citing a policy against commenting on individual investors' views.
Mobileye has been an early mover in self-driving cars, Left said. But autonomous driving is becoming more of a competitive space, as heavy-hitters like Uber, Google and major automakers have taken a lead on investments.
"You have to give them credit for saying, 'Autonomous driving is the way of the future,'" Left said. "But since then, everyone has leapfrogged them."
Citron's new position comes amid a rollercoaster week for Nvidia, a high-flying technology company that makes chips for autonomous driving, artificial intelligence and gaming. The stock was downgraded by analysts this week, who said its 217 percent gains over the past year left shares overvalued.
Nvidia hit a 3-month low this week, closer to the $90 price per share that Citron has targeted. With Citron's Nvidia short closed, shares were up about half a percent on Friday.