Electric car maker Tesla surprised investors with profits for the third quarter of 2019, Reuters reports.

The announcement led to a boom in Elon Musk's company stock, which rose by 21% to $ 307.12 per share. This is the first time Tesla's stock has gone above the $ 300 limit for more than 7 months.

Tesla reported a profit of $ 1.86 per share, a significantly better result than what the experts expected. Their forecast was a loss of $ 0.46 per share for the quarter.

However, market analysts warn that the company has not yet proven that it is able to maintain a stable performance.

Tesla had a similar jump in stock value about a year ago, when it rose 31 percent.

But throughout 2019, unit value has fallen as a result of questions about whether the company is managed properly, whether it can fight much better-developed auto industry companies, and whether demand for the Key Model 3 is actually high enough.

Tesla now claims to produce the Model 3 much more efficiently and expect their new SUV, called the Model Y, to be produced in Shanghai, to generate more profits for each car sold.

Here are the key numbers, outlined by Markets Insider: