Many expected that SAC would not be able to survive the criminal charge, which the United States attorney's office in Manhattan brought against the firm in July. Yet SAC has withstood the indictment largely because Wall Street banks, like JPMorgan Chase and Goldman Sachs, have continued to trade with the firm and provide financing for its operations.
In trying to reach a settlement, Mr. Cohen wants to save his once-celebrated hedge fund, which has been brought low by a raft of criminal charges against former employees. Though SAC has said it has never encouraged or tolerated insider trading, it would have difficulty exonerating itself at trial, legal specialists have said.
As long as prosecutors can show that SAC traders acted "on behalf of and for the benefit of" the fund when trading illegally, then a jury is permitted to impute liability to SAC itself. Several former traders have pleaded guilty and are expected to testify against the fund.
Talks between SAC and the government will continue as two former SAC portfolio managers prepare for separate criminal trials. On Tuesday, one of those trials, the insider trading case against Mathew Martoma, was delayed for two months. In a hearing at Federal District Court in Manhattan, Judge Paul G. Gardephe postponed the start of Mr. Martoma's trial to Jan. 6 from Nov. 4.
Richard M. Strassberg, Mr. Martoma's lawyer, requested the extension because of a conflict with another trial. He is representing Bank of America in a trial that began on Tuesday and could last six weeks.
Federal prosecutors have charged Mr. Martoma with trading on confidential data he received from two doctors about drugs being developed by the pharmaceutical companies Elan and Wyeth. Prosecutors contend that the tips Mr. Martoma received about clinical tests allowed SAC to earn profits and avoid losses totaling $276 million.
The second trial, of the former SAC portfolio manager Michael S. Steinberg, is scheduled for Nov. 18 and no delay is expected. Prosecutors have charged him with being part of a vast insider trading ring that illegally traded the stocks of Dell and Nvidia.
Mr. Martoma and Mr. Steinberg are two of 11 former SAC employees who have been charged with or implicated in illegal trading while at the fund; five of them have admitted guilt.
SAC hoped it had resolved its troubles related to insider trading six months ago. In March, the fund agreed to pay a $616 million penalty to the S.E.C. to resolve two civil actions connected to trading by Mr. Martoma and Mr. Steinberg. Mr. Cohen's legal team has argued that any additional financial penalty should take into account that this payment, which effectively came out of Mr. Cohen's pocket, has already been made.
Despite agreeing to that record fine, the authorities continued to press their case. In July, Preet Bharara, the United States attorney in Manhattan, brought criminal charges against SAC, citing the many prosecutions of SAC's former employees and calling the fund "a magnet for market cheaters." Also that month, the S.E.C. filed its lawsuit against Mr. Cohen, accusing him of failing to reasonably supervise his employees, including Mr. Martoma and Mr. Steinberg. Mr. Cohen, 57, who has not been charged criminally, has denied the government's accusations and said that he has acted appropriately at all times.
Though SAC has survived, the government's cases have severely hobbled the fund, which managed about $15 billion at the beginning of the year.
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Virtually all of the firm's outside investors have asked for their money back, about $6 billion in assets. The roughly $9 billion left in the fund will be mostly Mr. Cohen's, with a small percentage belonging to his employees.