Mortgage underwriting standards have loosened in recent years, led by the jumbo market and reduced overlays on agency mortgages, according to the Mortgage Bankers Association. However, underwriting standards aren’t nearly as lenient as they were in the early 2000s, prompting some to call for further loosening. The MBA’s Mortgage Credit Availability Index has trended up since the beginning of 2012. “Most of the action in terms of loosening has been on the jumbo side,” said Michael Fratantoni, MBA chief economist, at a talk hosted this week by the Urban Institute’s Housing Finance Policy Center. Separately, he noted...