Tesla (TSLA 3.49%) stock is posting big gains in Friday's trading thanks to robotaxi news. The company's share price was up 4.6% as of 1:30 p.m. ET and had been up as much as 6% earlier in the session.

Tesla told employees yesterday that it will be rolling out its robotaxi service in San Francisco this weekend. The company's robotaxi rides in the city will initially also have a human driver behind the wheel for safety purposes.

A chart line moving up over a hundred-dollar bill.

Image source: Getty Images.

Tesla's valuation gains today follow a bigger sell-off in yesterday's trading that was spurred by disappointing second-quarter results and comments from management suggesting that performance headwinds could continue in the near term. The company's share price has seen some big swings in 2025, and is down roughly 21% year to date with today's pop.

Is Tesla stock a buy right now?

Tesla launched robotaxi operations in Austin, Texas last month, and the rollout of the service in San Francisco is happening quicker than previously anticipated. While that's a bullish development for the company, challenges facing the core auto business still make the stock a risky buy right now.

Tesla's automotive revenue sank 16% year over year to land at $16.7 billion in the second quarter, and CEO Elon Musk said that the company could face a few quarters of relatively weak performance due to the impact of tariffs and the expiration of subsidies for the electric vehicle (EV) market. Despite big declines for its sales and earnings, the EV company is still valued at roughly 11 times this year's expected sales and 185 times expected earnings. While Tesla's robotaxi and robotics initiatives could potentially start being meaningful sales contributors within the next year, challenges facing the core auto business suggest that investors may be able to wait for a better buy-in point.