Do Municipalities Pay More to Issue Unrated Bonds?

Abstract

Approximately 34% of local municipal bond issues were issued without ratings during 1998 to 2017. We study the circumstances that affect the decision to obtain a rating and whether unrated bonds, controlling for observable risk factors, are more expensive to issue than rated bonds. Results show that issuers are less likely to obtain ratings for smaller issues, negotiated offerings, and bonds with high proxies for risk such as coming from areas with low personal income. We estimate the effect of forgoing a rating on offering yields using a doubly-robust Inverse Probability Weighted Regression Adjustment that controls for confounding that arises from risk and other characteristics affecting both the choice to obtain a rating and the yield. We separately analyze revenue bonds, general obligation bonds, bank qualified, and not bank qualified bonds and find ratings decrease offering yields by 47, 49, 60, and 42 basis points respectively. The higher offering yields cost municipalities $22.5B in higher interest expense during our sample period. We find the choice of issuers to forgo ratings despite the substantial potential savings appears to be influenced by the dual underwriters who also work as advisors to the issuer. These underwriters benefit from not obtaining a rating because it lowers the price investors are willing to pay from the bond, but also lowers the price the underwriter must pay the issuer and thus increases the underwriter’s profit.