Citron Research’s Andrew Left, a vocal long-term shorter of Tesla, drove up shares today as he performed a surprise U-turn and said he’s now long on the company.

“As much as you can’t believe you are reading this, we can’t believe we are writing this!” Left -- who is also suing Tesla and its leader Elon Musk for inflating its stock -- said in a report today. “The Model 3 is a proven hit and many of the TSLA warning signs have proven not to be significant.”

Citron also tweeted that it made its determination after reviewing all recent information on Tesla "dominating its categories."

Citron has held a long-term short position on the company, saying in March that "supply and demand problems" should lower the company’s stock price to US$100 by year-end. Tesla’s shares rose as much as 7.5 per cent after the report today, to US$280.60.

"While the media has been focused on Elon Musk’s eccentric, outlandish and at times offensive behavior, it has failed to notice the legitimate disruption of the auto industry," he wrote. "Plain and simple -- Tesla is destroying the competition."