Last week, the stock of Uber Technologies went on a wild ride, falling hard after Uber reported earnings on Feb. 5, only to rocket higher toward the end of the week. On earnings, while revenue and earnings per share actually beat expectations,

Uber’s stock extends its surge as hedge funder Ackman says he’s amassed a 30.3-million-share stake since early January.

Bill Ackman has a stake worth $2.3 billion in Uber stock. He says UBER is currently trading at a massive discount.