The FBI is investigating Fannie Mae, Freddie Mac, Lehman Brothers Holdings and insurer American International Group and their senior executives for potential mortgage fraud, according to reports in the US.
The FBI did not provide specifics but said the inquiries were part of a broader probe.
The bureau is trying to determine whether anyone in those financial institutions, including their senior executives, had any responsibility for providing 'misinformation,' the reports said.
'As part of our investigative responsibility, the FBI conducts corporate fraud investigations. The number of cases fluctuates over time, however we do not discuss which companies may or may not be the subject of an investigation,' said Justice Department spokesman Brian Roehrkasse.
A federal law enforcement official confirmed the FBI is now looking at 26 cases of potential corporate fraud related to the collapse of the US mortgage lending industry.
FBI Director Robert Mueller told the US Congress a week ago that 24 cases of potential corporate fraud were under investigation, up from 21 disclosed by the bureau in July.
In testimony before the House of Representatives Judiciary Committee, the FBI chief also vowed to pursue corporate executives if necessary in mortgage fraud cases.