Robotics arms install the front seats to the Tesla Model 3 at the Tesla factory in Fremont, California, on Thursday, July 26, 2018. Mason Trinca | The Washington Post | Getty Images

Tesla's winning streak is unlikely to last much longer, Bernstein analysts found after looking through historical data for what happens after large stocks doubled in under six months. Bernstein analyzed 40 years of trading data, looking at stocks with market values over $20 billion. With Tesla shares up more than 100% in the last six months, the firm wanted to help give investors a better idea of where the stock was headed – even as Elon Musk's electric car maker is almost rising to new record high levels daily. "The track record is mixed – on average, large caps that doubled in the last 6 months subsequently saw a forward 6-month absolute return of just 2.6%," Bernstein analyst Toni Sacconaghi wrote in a note to clients.

The firm excluded time periods of high growth — such as the tech bubble two decades ago or the recovery from the Great Recession — in analyzing stocks that double in under six months. On average, Bernstein found this happened three times a year. Despite Bernstein's mediocre outlook, Tesla shares rose 7% in Tuesday trading to close at $547.20.

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