What happened

Shares of electric-car company Tesla (NASDAQ:TSLA) popped on Tuesday, rising as much as 7.5%. As of 11:14 a.m. EDT, the stock was up 5.6%.

The stock's rise comes after the electric-car company scheduled its earnings report about a week earlier than usual with just two days' notice, leading to some speculation that the automaker may have achieved its goal to become profitable during the quarter. However, another catalyst propelling the stock on Tuesday is a prominent short-seller's reversal on the electric-car company's stock.

Model 3 interior

Model 3. Image source: Tesla.

So what

Citron Research, which had previously encouraged investors to short Tesla stock, is now reversing its stance on the stock.

"The story has become too compelling to ignore," Citron said in a note to investors on Tuesday.

Citron's Andrew Left cites fast-growing sales of Model 3 and lack of notable competition as key reasons for his bullishness. Explaining how he changed his mind, Left said:

The most challenging part of being a short seller is to constantly check your thesis to make sure nothing has changed. You must let all predispositions and prejudices disappear and stay focused on only the facts.

Now what

Investors, of course, should take any analyst's opinion with a grain of salt, leaning instead on their own due diligence.

Investors will get some concrete details on Tesla's recent performance when the automaker reports its third-quarter results after market close on Wednesday.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.