Uber Technologies (UBER) stock surged for a second day Friday, as billionaire hedge fund manager Bill Ackman said he had amassed a more than $2 billion stake in the ride-hail and food-delivery company. The gains added to a rally that started Thursday and pushed Uber up to its highest levels since October.

In a post on X, Ackman said his Pershing Square Capital Management fund began amassing a position in Uber in January and now holds 30.3 million shares.

"We believe that Uber is one of the best managed and highest quality businesses in the world," Ackman wrote on X. "Remarkably, it can still be purchased at a massive discount to its intrinsic value. This favorable combination of attributes is extremely rare, particularly for a large cap company."

On Friday, Uber stock is up 6.6% at 74.6.

Uber Stock Battling Robotaxi Worries

Last year, Uber stock fell about 2% in 2024 after rallying 150% in 2023. While the company's run of profit growth has impressed Wall Street analysts, the stock was held back by concerns about robotaxis.

The growth of Waymo's self-driving-taxi service and Elon Musk's pledge to create an "Airbnb-meets-Uber" business at Tesla (TSLA) have sparked fears about competition.

Meanwhile, Uber has pitched itself as a partner to AV developers, connecting their cars to the Uber app's 171 million active users. The company opened up a waitlist Wednesday for Austin riders who want to take a robotaxi ride through Waymo. Uber is also partnered with Waymo in Phoenix and for the Google-backed startup's upcoming expansion to Atlanta. But Waymo has announced expansion elsewhere without Uber, including most recently Miami.

Shares fell 7.5% Wednesday after Uber reported fourth-quarter earnings that included a lower-than-expected bookings forecast. But Uber stock has bounced back since with Friday's jump and an 8.2% gain on Thursday.

Uber is now ahead more than 20% so far this year. Shares are in a 17-week-long consolidation pattern with a buy point of 87, according to MarketSurge.

Friday's gain places Uber stock well ahead of its 200-day moving average after shares retook the long-term trendline Thursday.