Municipal Bond Credit Rating Access and Retail Investors’ Transaction Costs

In 2010, the Municipal Securities Rulemaking Board proposed a rule change requiring the display of current credit ratings on the EMMA website, a centralized repository of municipal bond information. Prior to the rule change, current credit ratings were freely available on individual rating agencies’ websites or on EMMA if municipalities provided relevant continuing disclosures, making it unclear whether the rule change would benefit investors. A difference-in-difference analysis reveals the rule change is associated with an 8 basis-point decrease in investor transaction costs. This effect is concentrated among the intended beneficiaries (retail investors) when credit risk information demand is high (long-maturity bonds) and current credit rating information on EMMA is low (no continuing disclosure of rating changes was provided on EMMA). The rule change appears to have helped retail investors become aware of current credit ratings by filling a disclosure gap on EMMA for municipalities without continuing disclosures of rating changes.