Ratings agency DBRS addressed some of the risks underlying certain residential mortgage-backed securities transactions this past week. The agency reviewed 417 RMBS transactions, confirming the ratings on 4,059 classes from 412 deals and downgrading 173 RMBS classes from 89 transactions. Meanwhile, seven classes from one particular RMBS transaction were upgraded, and 47 classes from 27 deals were discontinued after borrowers repaid their notes. Most of the transactions impacted by downgrades were supported by residential mortgages from pre-2006 vintages, with most of the collateral backed by subprime, prime and Alt-A mortgages, according to DBRS data. Underlying loans pressured some of the deals as delinquency and loss trends on mortgages continued toward the negative. DBRS concluded that the upgraded transaction “has exhibited positive performance trends and experienced increases in credit support sufficient to withstand stresses at their new rating level.” Write to: Kerri Panchuk.