The Pershing Square CEO said he's admired the ridesharing giant since actor Edward Norton introduced him to the app in its early days.

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.

Bill Ackman said his hedge fund Pershing Square Capital Management owns 30.3 million shares of Uber Technologies Inc., citing the strength of the rideshare company’s management and saying that its stock is undervalued.