Tesla Is Down 13% in 2026 While the S&P 500 Is Up. Here’s the 1 Catalyst Left This Year That Could Flip That.

Tesla's (NASDAQ:TSLA) stock decline this year is partially due to the same reason it could yet turn positive. Specifically, it's the sluggish robotaxi rollout, including the dedicated robotaxi, Cybercab. Simply put, management's previous statements on the timing and scale of the rollout proved overly optimistic for 2026. However, there is a pathway to recovery.

Tesla's robotaxi rollout

The robotaxi metrics that investors were encouraged to follow, namely robotaxi fleet size and city deployments, have failed to impress. Or rather, they failed to impress relative to expectations.

Image source: Tesla.

To be fair, management has made some effort to try and reset these expectations, not least by emphasizing a commitment to safety and the importance of refining its next major upgrade of full self-driving (FSD) software, v15, before scaling the robotaxi fleet, and the need to learn and improve operational matters relating to running a robotaxi fleet.

It's easy and tempting to think that Tesla can just tweak some software and push a few buttons in a factory to produce more Cybercabs and send them out into service, but the reality is very different. As such, investors should focus on what really matters: the iterative process of building a microcosm of a robotaxi service that can be scaled later.

Scaling robotaxi isn't easy

The importance and complexity of this can't be overstated. After all, if you scale a robotaxi service with significant imperfections, say safety issues, then the absolute number of high-profile safety incidents will increase in line with the scaling. These increased safety incidents would inevitably create political and regulatory issues, and more such incidents would increase unit costs.

Moreover, if the scaling involves geographic expansion, it could introduce new edge cases and disproportionately magnify safety issues. At the same time, Tesla obviously wants to expand into new geographies to train its neural networks so they can operate without geofencing in the future -- a major advantage of Tesla's approach compared to Waymo's need for geofencing.

Tesla has a massive data advantage over Waymo and others in gathering data from consumer vehicles, but it also needs miles under unsupervised robotaxi operation, notably Cybercab.

Furthermore, there's the question of whether Tesla's management will gain operational experience with the robotaxi fleet to reduce unit costs (the key to beating competitors like Waymo over the long term) as it scales.

How Tesla stock can outperform

Taken together, this points to the necessity of iteratively refining a robotaxi service before scaling, and the good news is that Tesla has reported progress on this in 2026. Cybercab is in operation, with unsupervised miles under robotaxi growing at a double-digit percentage weekly rate in the third quarter.

Image source: Getty Images.

On that note, the key catalyst for the stock in late 2026 could be the release of v15 FSD, even if it's a limited access release. Early versions of it are already running in the robotaxi fleet, and in October management confirmed, "Pretty soon, we'll be able to release the same software as part of the v15 release to customers." Given that it's the same software used to run robotaxis and Cybercab, it suggests Tesla's software is ready to scale robotaxi and Cybercab next year. An early release would focus investors on the likelihood of massive scaling in 2027, and the stock would likely be rewarded.

Lee Samaha has no position in any of the stocks mentioned. The Motley Fool has positions in and recommends Tesla. The Motley Fool has a disclosure policy.