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.

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

Shares of Uber Technologies jumped to a three-month high on Friday after billionaire hedge fund manager Bill Ackman announced that he had taken a stake worth about $2.3 billion in the ride-sharing platform.