Tesla shares broke above $250 on Tuesday for the first time this year ahead of the company's annual shareholders meeting.
At the gathering, CEO Elon Musk said it seemed likely that the company would maintain an average annual growth rate of roughly 50 percent for the next several years.
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CNBC's "Fast Money" trader Dan Nathan said Tesla's stock has traded off a lot of good news recently and investors who haven't jumped in yet might be late too to the party.
"If you're getting onto this story right now," the risk is to the downside, Nathan said.
Fellow "Fast Money" trader Guy Adami disagreed. "I would say the potential risk is to the upside," he said. Although Tesla shares have climbed significantly since the end of March, they've gone up in a pretty orderly fashion, Adami added. He sees it possibly trading up to the $290s.
When asked about the rumors on Tuesday, GM CEO Mary Barra said she doesn't think a merger with Fiat would make sense in terms of scale.
Naturally, the GM-Fiat news sparked a debate on how to trade a potential merger between GM and a competitor, which led to a game of "who'd you rather," with the choices being GM and its long-time competitor Ford.
"Just on valuation alone, I think you start dipping your toes into the letter F," Adami said, citing Ford's upbeat auto sales figures in May.
On the other hand, Najarian said he has his money on GM in the long run. "The upside comes from GM," he said.
GM shares tumbled last year, mostly on a slew of auto recalls, but it has since recovered to trade around $35 a share.
"I think this is a stock that could very easily hit $40 again… it trades really inexpensive and could go to the upside, " Najarian said.