Billionaire hedge fund manager William A. Ackman conceded that his big wager on Valeant Pharmaceuticals (VRX) was "a huge mistake" that has cost his hedge fund firm, Pershing Square Capital Management, "a tremendous amount."
"I deeply and profoundly apologize," Ackman said in his annual letter to investors, The New York Times reported.
Ackman sold his entire stake in Valeant earlier in March, suffering a loss of about $4 billion. He bought the stake in early 2015.
In his annual letter to investors, released on Tuesday evening, Ackman took the blame for the bad bet, acknowledging that the investment had "damaged the record of success of our firm," the Times reported.
"My approach to mistakes is that I personally assume 100% of the responsibility on behalf of the firm while sharing the credit for our success," he added.
Pershing Square posted losses in 2015 and 2016, largely because of the firm's position in Valeant.