Interest shortfalls in the residential MBS space continued to drift higher across different collateral types, tranche types and vintages throughout 2013, according to Morningstar Credit Ratings. “As of the December 2013 remittance cycle, nearly one out of five deals (19.1 percent) in our sample experienced a shortfall in at least one tranche,” Morningstar said in a recent report. Interest shortfalls take place...