Valeant's collapse — from Clinton's tweet to Ackman's exit (VRX)

Bill Ackman has officially quit Valeant Pharmaceuticals.
The founder of the hedge fund Pershing Square on Monday sold his investment in the company and announced his plan to step down from the board. Valeant's shares were down 9% Tuesday morning.
Once a stock market darling, Valeant has been falling since September 2015 after the company began to face scrutiny over its pricing strategy and its use of a secret specialty pharmacy called Philidor. When Philidor's existence — which had been ke