Fannie Mae and Freddie Mac’s regulator may identify as much as $30bn of debt included in mortgage bonds that the companies can force sellers to repurchase, according to Joshua Rosner, an analyst who in 2007 predicted the collapse in the market for the securities. The Federal Housing Finance Agency this month said it issued 64 subpoenas seeking loan files and other documents related to so-called non-agency mortgage securities bought by the two government-supported companies. The US is trying to determine whether misrepresentations might require issuers to repurchase debt, producing funds from firms that may include Wall Street’s largest banks to help repay taxpayer money.