Bill Ackman's Pershing Square Takes 5% Stake In Valeant Pharmaceuticals By: Benzinga via Benzinga March 09, 2015 at 15:02 PM EDT Bill Ackman, founder and CEO of hedge fund Pershing Square Capital Management, acquired a $3.3 billion stake in Valeant ... Read More >> Related Stocks: Valeant Pharmaceuticals International, Inc.