Tesla Stock Dropped. History Shows Why That Was a Surprise.

Coming into Friday trading, Tesla stock was up 11% so far this year and up 72% over the past 12 months. (AFP via Getty Images)

Key Points

• Tesla’s third-quarter operating profit was $1.6 billion, a 40% decrease year over year.
• Tesla stock typically rallies two days after earnings, with shares rising 10 out of 12 times in the past three years.
• Investors are focused on Tesla’s future prospects in robotics and robo-taxis, rather than current financial results.

Tesla stock, surprisingly, had a post-earnings rally after weak results. Those gains didn’t extend to Friday, however.

The electric-vehicle maker’s shares clawed back early losses Thursday to close up 2.3% at $448.98. The stock had opened lower and traded as low as $413.90 after reporting a third-quarter operating profit Wednesday afternoon that was disappointing—$1.6 billion, down 40% year over year.

On Friday, the stock dropped 3.4% to $433.72, leaving shares down about $5 over the two days post-earnings. The S&P 500 and Dow Jones Industrial Average added 0.8% and 1%, respectively.

Tesla stock typically rallies two days after earnings.

Elon Musk’s Tesla always reports after the close of trading, so earnings reactions are one day following the report. Over the past three years, Tesla stock has moved about 9% up or down after reporting earnings. Shares rose half the time and fell half the time.

The next day, however, Tesla stock rose 10 times and fell twice. Shares are more likely to go up. Volatility is down as well. The magnitude of the second-day move is closer to 3%.

What happens on one trading day, of course, isn’t all that important in the grand scheme of things. Tesla’s post-earnings move this time tells investors a few things.

For starters, the relatively small move suggests investors didn’t get much new information. Tesla’s robo-taxi plans and the loss of the federal $7,500 EV purchase tax credit that will make selling electric vehicles harder in the fourth quarter are well understood.

Thursday’s trading action confirmed what Barclays analyst Dan Levy wrote in his post-earnings report—investors are focused on the future, excited by the potential for robots and robo-taxis.

Tesla isn’t making significant money from either of those two opportunities yet. That, ideally, comes down the road.

Coming into Friday trading, Tesla stock was up about 11% so far this year and up about 72% over the past 12 months.

Write to Al Root at allen.root@dowjones.com