The remaining public money SAC managed as of the end of 2013 (a figure that, at its peak, was roughly $16 billion) has largely been returned to outside investors, with the exception of some ancillary investments that are less easily liquidated, according to the memo.
The firm is undergoing a reorganization that includes shrinking the employee base to 850 from more than 1,000 and establishing four streamlined units: long-short equities, a division that once included three separate desks; macro, or globally themed, trading; quantitative trading; and a separate unit devoted to managing Cohen's private investments.
(Read more: SAC still on hook in insider trading probe: Source)
As part of the reorganization, SAC's stock-trading desk will be co-headed by Mike Ferrucci, who previously ran SAC's London office, and Phil Villhauer, who had led the firm's "execution," or trade completion, desk and who recently testified in the insider-trading trial of former SAC portfolio manager Mathew Martoma. (Martoma was convicted on three counts of securities fraud and conspiracy, and awaits sentencing.)
To bolster compliance at SAC's soon-to-be established family office, which will manage only private capital belonging to Cohen, his family members and certain senior employees, the company will establish what the memo refers to as a "chief surveillance officer."
SAC has also hired Doug Haynes, the memo adds, a veteran of McKinsey and General Electric, to "focus on all aspects of human capital development."
SAC's memo did not put a figure on the assets under management it expects to oversee, but people familiar with the firm's operations expect it to be roughly $9 billion.
—By CNBC's Kate Kelly