Chip Somodevilla / Getty Warren Buffett's Berkshire Hathaway has lost Bill Ackman as an investor. The hedge-fund manager revealed the sale of his Pershing Square fund's $1 billion Berkshire stake in a conference call on Wednesday. Pershing sold Berkshire in the last few weeks to free up cash so it can capitalize if prices fall again, Ackman said on the call. The move is surprising as Ackman boosted his Berkshire holdings by more than a third in the first quarter. Visit Business Insider's homepage for more stories. Warren Buffett's Berkshire Hathaway has lost billionaire hedge-fund manager Bill Ackman as an investor. Ackman revealed the sale of his Pershing Square fund's $1 billion stake in Berkshire, and its exit from much smaller positions in Blackstone and Park Hotels & Resorts, in a conference call on Wednesday.