The hedge fund manager said his fund began buying Uber shares in early January and has amassed 30.3 million shares, worth $2.3 billion.

Uber stock hit its highest level since October after Ackman disclosed his Pershing Square hedge fund accumulated a 1.4% stake in the ride hailer.

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