Should I buy Tesla stock for my ISA in 2026?

Tesla (NASDAQ:TSLA) stock has a long track record of proving the doubters wrong. And there have been plenty of those over the years, ranging from Charlie Munger to countless analysts and short sellers.

But any investor who believed in CEO Elon Muskâs vision for the EV company has likely made incredible returns over the past decade. In this time, the stock has skyrocketed more than 3,000%, making Tesla the eighth-largest company in the S&P 500 today.

However, that’s all in the past. The only question I have now is, should I invest in the stock today?

Innovation machine

Letâs start with the positives I see here. First off, thereâs Tesla’s relentless innovation, with robotaxis, the Tesla Bot (Optimus), and various other projects going on at the company.

Musk said recently that Optimus robots will be doing household chores, walking dogs, and even carrying out surgery within the next few years. While we might scoff at that likelihood, and certainly the timeline in which it might happen, the vision is nonetheless exciting.

This is certainly not Ford or Peugeot we’re looking at here!

Also, Tesla has a thriving energy generation and storage business that rarely gets talked about. In Q3, revenue here jumped 44% year on year to just over $3bn. This is scaling independently of the automotive segment, and Iâm bullish on its long-term global growth potential.

Meanwhile, after years of missed deadlines, robotaxis are finally on the road. Granted, they still face regulatory hurdles, but it’s worth noting that a Robotaxi iOS app is now available in the US and Canada. Anyone can download it to join the waitlist.

So this robotaxi dream is much closer to becoming reality.

What about the stock?

Turning to things I donât like, Tesla’s core EV business is struggling. In 2025, it delivered approximately 1.64m cars, which represented a 9% drop on the year before.

Also, China’s BYD has become the worldâs top seller of EVs. So while Tesla is struggling to grow sales, rivals are gaining ground, especially in Europe.

Will robotaxis scale fast enough to offset declining EV sales? Possibly, but I canât be sure, and this uncertainty worries me.

Meanwhile, Musk continues to polarise opinion with his outspoken online presence. While this doesnât seem to do the share price any harm â it has doubled in two years — it must still be hurting EV sales.

After all, politics is tribal and many people/potential customers now associate the brand squarely with Musk.

According to a study by economists at Yale University, Tesla lost between 1m and 1.26m vehicle sales in the US between late 2022 and early 2025 due to Musk’s political activism.

By the first quarter of 2025, we found that Tesla sales would have been about 125% higher than they were without the Musk partisan effect.
Yale University

Finally, we have the valuation, with Tesla stock trading at 193 times forward earnings. As I see it, this valuation assumes itâs game, set, and match for Teslaâs robotaxis business.

In reality though, it will face an increasing amount of competition worldwide, including from Nvidia indirectly (it’s arming carmakers with an open-source autonomous driving platform).

Putting all this together, Iâm not keen to invest in Tesla stock today. I see better tech opportunities elsewhere.

The post Should I buy Tesla stock for my ISA in 2026? appeared first on The Motley Fool UK.

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Ben McPoland has positions in Nvidia. The Motley Fool UK has recommended Nvidia and Tesla. Views expressed on the companies mentioned in this article are those of the writer and therefore may differ from the official recommendations we make in our subscription services such as Share Advisor, Hidden Winners and Pro. Here at The Motley Fool we believe that considering a diverse range of insights makes us better investors.