Shares of Aurora (NASDAQ:AUR) fell by as much as 28% on Thursday after disclosing a four-month delay in the commercial launch of its self-driving truck.

In explaining the reason for the delay, CEO Chris Urmson said during the company’s Q3 earnings call that additional safety measures need to be completed before he feels comfortable launching the vehicle.

“We want to have extremely high confidence in the system as we go forward,” Urmson said on the call, adding that “while this is modestly later than we had intended, this timing remains within the margin of error we have anticipated and conveyed throughout 2024.”

Aurora (AUR) plans to launch the Aurora Drive with a “crawl, walk, run” approach, by deploying up to 10 driverless trucks in commercial operations during the launch, beginning with just one driverless truck before transitioning the balance to all driverless.

In the second half of 2025, Aurora’s (AUR) focus will be expanding product capabilities, adding new lanes, and increasing capacity to tens of trucks by the end of the year.

The company expects to earn a profit by 2026.