A National Association of Insurance Commissioners proposal for more conservative ratings of insurer holdings of residential and commercial MBS could result in higher risk-based capital requirements on some of these securities, warned analysts. As the proposal currently stands, the changes involve increasing the probability weights assigned to more pessimistic economic scenarios. However, the method by which the economic scenarios are created will not change, according to Barclays Capital analysts monitoring the work of NAIC’s Valuations of Securities Task Force, which was assigned to develop the risk-based capital proposal for insurers’ CMBS and RMBS holdings. The proposed peak-to-trough economic scenarios for RMBS and CMBS consist...