Level Global Investors, currently under investigation along with three other hedge funds for insider trading by federal authorities, told investors on Friday that it would shut down. It cited the investigation and investor withdrawals as the cause. At the same time, Diamondback Capital, which was also raided by investigators, has been asked by investors to return some $722 million by the end of March. This amounts to 12.3% of the company’s capital.

According to Reuters, David Ganek, one of the founders of Level Global, said in a letter to investors, “The government has commenced what may be a lengthy inquiry with no set timeline. This process, even when it leads to the positive outcome that counsel expects, nonetheless threatens to undermine our ability to meet our fiduciary responsibility to our investors.” The letter went on to say, “With the continuing cloud of uncertainty, we understand why investors might elect to redeem in the current environment.”

After emphasizing that the firm is “not a target” of the investigation and has retained outside counsel to review its practices, Ganek added in the letter, “I remain highly confident that my conduct in leading the firm and its investment process was lawful and ethical at all times.”

The company, along with Diamondback Capital, Loch Capital Management and Barai Capital Management, were all raided by the FBI in November. Of all the firms, only one, Barai Capital Management, has seen anyone charged with anything: Samir Barai was arrested on Tuesday and charged with insider trading. His fund had already shut down.

Anthony Chiasson, the other cofounder of Level Global, and who is the company’s director of research, did not sign the letter sent to investors on Friday. He and Ganek both came from Steven Cohen’s SAC Capital Advisors, a $12 billion hedge fund. Also on Tuesday, two former SAC Capital employees were charged with insider trading while at the fund. Noah Freeman, one of the employees, is cooperating with the investigation.

Level Global’s fund, which used a long/short equity strategy, says that since inception its return has been 88.9% as of Dec. 31, compared with an S&P 500 benchmark return for the same period of 27%. Both Level Global and Diamondback were used by pension funds to invest their holdings.