Tesla stock was quiet ahead of its Cybercab event in Austin, Texas.

Shares of the electric-vehicle maker were down 0.2% in premarket trading at $355.30, while S&P 500 and Dow Jones Industrial Average futures were down 0.2% and 0.1%.

It's been an interesting week for the stock. Shares rose 5.5% on Monday only to fall 3.2% on Tuesday. The volatility seems to be tied to robo-taxis. Tesla is hosting a Cybercab event on Thursday.

Investors can't be sure exactly what to expect. The event likely marks the introduction of Cybercabs, Tesla's purpose-built robo-taxi with no steering wheel that it began producing early this year, into its robo-taxi fleet. There could be some tidbits for investors about costs, service expansion, and regulatory hurdles to Cybercab introduction in different areas of the country.

Tesla launched a robo-taxi service in Austin, Texas, in June 2025 using Model Y vehicles. Growth, however, has been slow. Tesla now operates, perhaps, hundreds of taxis in a few cities, including Miami and Dallas. (Tesla hasn't responded to requests for comment about fleet size.) Alphabet's Waymo operates thousands of robo-taxis in more than a dozen U.S. cities.

Cybercab is part of Tesla's plan to catch and pass other providers, including Waymo. It's a lower-cost two-seat vehicle with camera-only sensors. Waymo uses a suite of sensors, including lidar, which is essentially laser-based radar.

Lower costs matter to any business. Today, robo-taxi rides are priced against services from the likes of Uber Technologies, which have higher costs because of the human driver. When enough robo-taxis are in operation, robo-taxis will be priced against one another. The low-cost provider should win the majority of market share, assuming all the robo-taxis are equally reliable and safe.

A lot is riding on the robo-taxi business. Americans drive more than three trillion miles each year, and low robo-taxis costs mean that it could be better to ride than own a car. If robo-taxi costs fall to even 50 cents per mile, there is a trillion-dollar opportunity for someone. Based on its trillion-dollar valuation, investors expect Tesla to be that someone.