The Basel Committee on Banking Supervision recently proposed replacing credit ratings with loan-characteristic metrics for determining capital requirements on bank holdings of residential MBS and commercial MBS. Federal regulators in the U.S. note that the proposal is preliminary and any changes to U.S. capital requirements will go through a notice and comment process separate from the BCBS’ activity. The current standardized approach established by Basel for determining capital requirement riskweights prescribes the use of external credit ratings for residential MBS and commercial MBS, among other holdings by banks subject to capital requirements. “While acknowledging that credit rating agencies play an important role in financial markets and that external credit assessments provide valuable information that may assist in the analysis of credit risk exposures, the hard-wiring of external credit assessments into standards, laws and regulations may often lead...