At least 46 vintage non-agency MBS took principal forbearance-related losses in March, according to industry analysts. The losses are a concern for investors because they were taken without warning, based on forbearance that happened well before March. Most of the deals taking retroactive forbearance losses in March were issued by Bear Stearns from 2005 through 2007 and were largely serviced by JPMorgan Chase, according to analysts at Bank of America Merrill Lynch and Barclays Capital. Write-downs on the deals were as high as 6.8 percent for a single month. “When a servicer recognizes losses on loans previously modified with forbearance, it could significantly impact...