Even after SAC Capital Advisors LP received billions of dollars in withdrawal requests this week, founder Steven A. Cohen isn’t about to give up managing other people’s money.

SAC President Tom Conheeney, in a June 4 e-mail to employees, said the hedge-fund firm has no plans to become a family office even after it received “significant” redemptions requests for the second quarter, according to two people who saw the contents of the e-mail. SAC doesn’t see significant staff reductions, Conheeney wrote.

SAC employees had expected that clients, who faced a June 3 redemption deadline, would take back most of the $4 billion they haven’t already marked for redemptions by early next year, people familiar with the firm said earlier this week. Investors are exiting as the U.S. government intensifies its probe of insider trading at the Stamford, Connecticut-based firm, once one of the best in the industry, with returns averaging 25 percent since 1992.

“We don’t like losing capital, but even with the investors that are leaving, we still have a stable capital base and have been performing well this year,” Conheeney said in the e-mail. Even if the firm ended this year with assets close to where it was four years ago, “we will still be a good-sized firm.”

At the beginning of 2010 the firm managed about $10 billion. Cohen and employees currently account for about $9 billion of the firm’s assets.

A spokesman for SAC declined to comment on the e-mail.

“Cohen is taking a defiant stance that will make the government more determined to pursue charges and more difficult for Cohen to settle if the heats get too high,” said Erik Gordon, a business and law professor at the University of Michigan in Ann Arbor.

The mood at the red-brick headquarters has darkened in recent weeks after Cohen and the other employees were subpoenaed to appear before a grand jury. Some workers have started putting out feelers for new jobs, and Cohen has reduced his own trading to the lower end of his normal $2 billion to $3 billion range to spend time with lawyers, said people with knowledge of the firm.

While it would be a logical step for Cohen to focus on managing his own wealth, two people who know Cohen said his decision not to throw in the towel is in keeping with his personality. Cohen doesn’t want to let the government get the best of him and is seeking to defend a reputation as one of the most successful hedge-fund managers ever, said the people, who asked not to be named because the information is private.

Cohen’s desire to continue as clients flee isn’t completely unrealistic. A few investors have called SAC asking to put money into its funds, according to two people familiar with the situation. Some key investors have told the firm they may reconsider their redemption requests once they have greater clarity of legal issues surrounding the firm, Conheeney told employees in the e-mail.