Also named as defendants are Patricia Cook, Freddie Mac's former executive vice president; Donald Bisenius, ex-senior vice president at Freddie Mac; Enrico Dallavecchia, who was chief risk officer for Fannie Mae; and Thomas Lund, Fannie's Mae's former executive vice president.

Mudd, now CEO of Fortress Investment Group LLC, was ousted when Fannie Mae and Freddie Mac were seized by regulators in September 2008. In a statement, he said the federal government and investors were aware of "every piece of material data about loans held by Fannie Mae."

"The government reviewed and approved the company's disclosures during my tenure, and through the present," Mudd said today in the statement. "Now it appears that the government has negotiated a deal to hold the government, and government-appointed executives who have signed the same disclosures since my departure, blameless -- so that it can sue individuals it fired years ago."

Mark Hopson, Syron's attorney at Sidley Austin LLP in Washington, didn't return a call seeking comment.

'Did Not Mislead'

Michael Levy, Lund's attorney at Bingham McCutchen LLP in Washington, said his client "did not mislead anyone. During a period of unprecedented disruption in the housing market, nobody worked more diligently or honestly to serve the best interests of both investors and homeowners."

Dallavecchia is now chief risk officer at PNC Financial Services Group. A phone call to Laurie Miller, his attorney at Nixon Peabody LLP, wasn't immediately returned.

During Mudd's tenure as CEO of Fannie Mae, from 2004 through its government takeover in 2008, the firm ramped up its business with lower-quality mortgages. Mudd said in a 2006 interview that he planned to expand the companies' holdings to include more higher-risk loans. Anything else would be "counterproductive," he told investors in March of that year.

In April 2007, Mudd said in testimony before lawmakers that the firm's exposure to subprime loans "remains minimal, less than 2.5 percent of our book."

At the same hearing, Syron said his firm hadn't "been heavily involved in subprime all along."