“Clearly, our investment in Valeant was a huge mistake,” Ackman wrote in his annual letter to Pershing Square shareholders, published Tuesday night. “In retrospect, we misjudged the prior management team and this contributed to our loss. We deeply regret this mistake, which has cost all of us a tremendous amount, and which has damaged the record of success of our firm.”

Ackman took a larger share of blame for the Valeant (VRX) misstep than he has seemed to do in the past. Previously, Ackman has largely danced around the issue, or said that Pershing’s mistake with Valeant was not being more actively involved in the company’s operations.

Valeant stock, a one-time Wall Street darling, has shed 95% of its value since it first came under fire for hiking drug prices in the summer of 2015, contributing to Pershing’s two years of consecutive losses.

Yet as other major investors bailed on Valeant last year, Ackman dug his heels in pledging to help fix the company, and continued to buy more of the stock. Ackman even joined Valeant’s board himself in the hope of boosting shareholder confidence in the management team. But after losing what amounted to $7.7 million every day the market was open for the two years he owned the stock, the hedge funder said in mid-March that he had sold his entire stake in the troubled company.

“My approach to mistakes is that I personally assume 100% of the responsibility on behalf of the firm while sharing the credit for our successes,” Ackman wrote in the letter, noting that he and other Pershing Square employees, as the fund’s largest investors, had personally borne the brunt of the Valeant losses. “It is much more painful to lose our shareholders’ money, and for this I deeply and profoundly apologize,” he continued.

But the letter also threw some shade at Valeant’s former executive team, which includes onetime CEO Michael Pearson. The ex-CEO filed a lawsuit this week against his former employer seeking some three million shares in compensation he says he is still owed, but which Valeant’s board decided it was “not in a position” to pay, the company said in a recent filing.

Ackman, who remains on Valeant’s board, said in the letter that “the highly acquisitive nature of Valeant’s business required flawless capital allocation and operational execution”—something, the hedge fund manager suggested, the former management team had lacked.

And while Ackman reiterated his opinion of Valeant’s new CEO Joe Papa as hardworking, he noted that it could be a while before the company is worthy of investment.

“While Valeant has made significant progress and we expect management to continue to do so, there is still a lot of work to be done,” Ackman wrote.

Pershing recorded losses of 20.5% in 2015, and 13.5% in 2016.

The question remains whether Valeant’s other big investors, including hedge fund Paulson & Co., which has also fallen on hard times recently, will stick it out or also call its quits on Valeant. Paulson added to its stake in Valeant in past quarters, boosting it to almost 4% of his entire portfolio at the end of 2016. That contributed to some $3 billion in losses the hedge fund suffered last year, according to Bloomberg.