(Read more: Up big, this fund poaches talent from SAC, others)
Those charges include at least one count of securities fraud, but the settlement will not include an admission of promoting insider trading within the firm, people familiar with the matter said.
In addition to the plea, which will at least temporarily halt SAC's run as a hedge fund managing public money, the company will be fined $1.8 billion—about $600 million of which has already been paid as part of a prior case's resolution, added this person. The figure would appear to be a record amount for the Manhattan U.S. Attorney, and a large amount for the Justice Department overall.
A spokesman for SAC declined comment on the matter and spokesmen for the Southern District of New York U.S. Attorney's Office, which is handling the case, didn't respond to a request for comment.
SAC will not immediately settle separate civil charges, levied this past summer by the Securities and Exchange Commission, that company founder Steve Cohen failed to supervise employees who engaged in insider trading, said one of the people familiar with the matter.
(Read more: SAC retrenches as insider trading probe drains firm)
Nonetheless, as part of the deal, SAC will lose the right to manage public money, by surrendering its investment-advisor registration with the SEC, this person said.
The details of how that conversion will work are still being determined. After a brief grace period in which it will redeem the rest of the public money it currently manages, SAC will convert to a family office that manages at least $9 billion, said the person familiar with the matter.
Staff layoffs in addition to the ones it has already made in the U.S. and London are possible, this person said.
—Follow Kate Kelly on Twitter @KateKellyCNBC. Reuters contributed to this report.