Moody’s Investors Service is working to correct errors it made when rating a significant number of interest-only tranches on non-agency MBS dating back to at least 2015. At the end of August, Moody’s placed ratings of IO tranches from 953 MBS on review. While such reviews generally indicate whether an upgrade or downgrade is possible, the rating service said it wasn’t sure which direction ratings would go for many deals included in the review. The effort covers...