Six federal regulators approved a final rule this week setting risk-retention requirements for residential MBS transactions, exempting the entire agency MBS universe and non-agency securities backed by qualified mortgages. There is not that much left. The risk-retention requirements for residential mortgages will take effect one year after the final rule is published in the Federal Register, which is expected shortly. Regulators opted to align the definition for qualified-residential mortgages with the standards established by the Consumer Financial Protection Bureau for QMs. The sponsor of a non-agency MBS that includes non-QRMs will have to retain at least 5.0 percent of the balance of the security, as required by the Dodd-Frank Act. In 2011, federal regulators proposed...