Bill Ackman's Pershing Square Holdings ends 2015 down 20.5%

Thomson Reuters BOSTON — Billionaire investor Bill Ackman's Pershing Square Holdings hedge fund ended 2015 with a 20.5% loss after Valeant Pharmaceuticals, a top holding, was battered in the second half of the year. Pershing Square, one of the industry's most closely watched hedge funds, told investors in an update that the fund, one of several portfolios run by the firm, ended December nearly flat with a 0.3% gain for the month. News of the sharp drop wasn't a surprise since Ackman told inves...