Prosecutors last year charged Mathew Martoma, a former SAC employee, with having earned millions for the firm, thanks to well-timed trades in drug companies Elan Corp. and Wyeth Inc., now part of Pfizer, in 2008 after he allegedly received non-public negative information about drug trial results. Martoma pleaded not guilty and his trial is set to begin in November.
Since launching its investigation into SAC, the government has charged or implicated nine former or current SAC employees in insider trading cases. Neither the firm nor Cohen have been charged with any wrongdoing.
In March SAC agreed to pay a $601.7 million fine to the U.S. Securities and Exchange Commission to settle allegations arising from the Elan and Wyeth trades.
(Read More: SAC Capital Redemptions $2 to $3 Billion: Exclusive)
The Journal also reported that the SEC's ongoing investigation of Cohen could lead to civil charges against him, citing an unnamed source close to that investigation.
While the conventional wisdom on Wall Street has been that the clock is running out on prosecutors making a case by the July deadline, continuing investigations into allegations of insider trading in at least two other stocks, first reported by Reuters in December, could extend the deadline to file charges for three more years, people familiar with the SAC probe told Reuters.
A source familiar with the investigation told Reuters that authorities were reluctant to charge the firm if they couldn't charge Cohen himself.
In a bid to keep outside investors happy, SAC recently stepped up its compliance policies and offered clients greater flexibility to pull their money out. Clients submitted redemption notices for billions of dollars at the June 3 deadline.
In May, the firm said it would no longer cooperate unconditionally in the insider trading investigations.
Despite its legal woes, SAC managed to sidestep dramatic market selloffs which took a bite out of many rivals' performance last month.
SAC gained 1.5 percent in June, leaving its main funds up 8.25 percent for the year.