Tesla (TSLA) posted its biggest single-day gain in over a year on June 29, surging more than 8% after the company began rolling out a major software update to millions of older vehicles.
The catalyst was Full Self-Driving (FSD) v14 Lite, a new version of Tesla’s self-driving software built for older cars that had gone more than 14 months without a meaningful update.
Why Did Tesla Stock Jump?
Tesla sold millions of cars with the promise that they would eventually gain self-driving capabilities. Delivering a meaningful upgrade to that existing fleet, without requiring owners to buy a new car, signals that Tesla can keep older customers engaged.
It also gives those owners a reason to subscribe to Tesla’s $99-per-month FSD service, which represents a growing revenue stream for the company. The rally on June 29 also coincided with rising expectations ahead of Tesla’s second-quarter delivery report.
Morgan Stanley raised its Q2 delivery estimate to 413,000 vehicles, above the Wall Street consensus, citing recovering sales in Europe and China.
Investors tracking the broader Elon Musk investment picture have also watched how sentiment shifts between Tesla and SpaceX since its June IPO.
What Is FSD v14 Lite?
FSD is Tesla’s driver-assistance system. It handles much of the driving, lane changes, traffic lights, and parking, but still requires the driver to stay alert and in control at all times.
The v14 Lite update targets cars built with Tesla’s older Hardware 3 (HW3) chip, sold from around 2019 onward. Those vehicles had been running on FSD version 12.6 since early 2025. Meanwhile, newer Tesla models moved ahead with version 14, gaining features like automatic parking and gear-shifting.
Tesla VP of AI, Ashok Elluswamy, announced the rollout on X on June 29. He said the build “distills the driving behavior from AI4’s v14 series” into the older hardware, with “significantly improved safety” as the headline upgrade
Whether the stock holds these gains will likely depend on Tesla’s delivery numbers, due later this week, and on early performance data from the FSD v14 Lite rollout.