The firms have all collapsed or been propped up by the US government over the past three weeks as a result of their exposure to sub-prime debt.
FBI agents are now looking to see if the businesses deceived borrowers by providing “misinformation” about the terms of sub-prime loans.
Robert Mueller, director of the FBI, told the US Congress that the agency is looking into 26 lenders regarding corporate fraud related to the collapse of the of the US mortgage lending industry.
He says: “The allegations would be that there are misstatements of assets.”
A spokesman from the US Justice Department, says: “As part of our investigative responsibility the FBI conducts corporate fraud investigations. However we do not discuss which companies may or may not be the subject of an investigation.”