The unveiling was originally planned for August 8, but Tesla has pushed the event back until October to give teams more time, Bloomberg News reported, citing people familiar with the decision.

Shares of Tesla fell 6.4 percent in afternoon trading.

Before Thursday, Tesla shares had risen 11 straight days in a move partly attributed to the robotaxi event, which Musk has described as a platform for the company's ambitious autonomous driving technology.

The outspoken Musk has a history of making bold predictions about the prospects for autonomous vehicles, saying conventional autos will one day be as obsolete as a horse and buggy and using a flip phone.

But Musk has fallen short of projections about the timeframe for self-driving technology, after previously predicting the company would achieve the breakthrough by 2018.

Analyst Dan Ives of Wedbush said that while Thursday's "kneejerk" market reaction to the delay was a negative, the later timeframe "could just make the actual Robotaxi event and prototypes even better and more eye popping."

Tesla would not be the first entrant in the autonomous taxi sector, with companies such as Waymo already operating vehicles in several US cities.