Tesla stock rose on Friday as speculation circulated online that the EV manufacturer could take a stake in SpaceX in conjunction with an initial public offering by the rocket company.

Shares of the electric-vehicle maker traded as high as $439.88 and closed at $430.41, up 3.3%, while the S&P 500 and Dow Jones Industrial Average both lost about 0.4%. Friday's gains left Tesla stock down about $1 from where it was before the company reported fourth-quarter numbers on Wednesday evening.

Elon Musk is CEO of both Tesla and SpaceX. Tesla disclosed a $2 billion investment in Musk's AI company xAI on Wednesday.

Friday's move also came after Electrek reported that Tesla's robo-taxis crash at a higher rate than human drivers, citing data reported to the National Highway Traffic Safety Administration.

The data is publicly available, and Tesla has reported 10 incidents, ranging from hitting other cars to hitting a cyclist. Tesla didn't respond to a request for comment.

Parsing safety data is always difficult. National safety statistics include a lot of highway driving, while Tesla robo-taxis operate in a city. A lot of minor incidents involving humans go unreported.

Alphabet's Waymo has reported 41 incidents over the same span as Tesla's 10, but Waymo also has more robo-taxis in Austin than Tesla. It has no human safety monitors in its vehicles to help avoid some incidents.

The goal, of course, is fewer accidents and increased safety. Waymo reports a roughly 80% to 90% reduction in accidents versus comparable driving by humans.

Exactly how good robo-taxis are and will be is hard to say precisely. What is certain is that investors are going to have to get used to reading robo-taxi safety reports

Tesla stock fell 3.5% on Thursday, following better-than-expected fourth-quarter earnings that, for the most part, encouraged Wall Street. Automotive profit margins were improved, and Tesla outlined plans to add more cities to its robo-taxi service, including Dallas, Houston, Phoenix, Miami, Orlando, Tampa, and Las Vegas.

While shares dropped, it wasn't too severe for a Tesla earnings report. Options markets implied shares would move about 5%, up or down, following earnings. The fact that shares moved less than that shows investors that nothing truly surprising happened.

Analysts and investors agree that Tesla is morphing from a car company into an AI company. "Big picture, the goal now is clearly to build a foundation for a new era of growth driven by physical AI," wrote Deutsche Bank analyst Edison Yu on Thursday, noting that Tesla plans a $20 billion increase in capital spending in 2026, which will help build the AI future.

The jump in spending might have been the biggest reason for the Thursday decline. In the past, Tesla often spent less than $10 billion a year on new plants and equipment.