Mortgages included in jumbo mortgage-backed securities in 2014 showed some shifting characteristics while maintaining strong underwriting overall, according to a new analysis by Inside Nonconforming Markets. Looser underwriting on jumbo mortgages has largely been at the fringes: some MBS have included a cluster of mortgages with combined loan-to-value ratios of 80 percent, a few borrowers with credit scores below 680 and ... [Includes one data chart]