Morningstar Credit Ratings late last week published new rating criteria for non-agency MBS. While the firm has been active in the commercial MBS sector, the non-agency MBS rating criteria Morningstar released in 2012 never caught on with issuers. “We have taken a fresh, holistic approach to the residential MBS rating process to help investors gauge the relative default risk of a security against its peers,” said Vickie Tillman, president of Morningstar. Tillman joined the rating service in August after more than 30 years at Standard & Poor’s. Morningstar said...