The Price of Safety: The Evolution of Municipal Bond Insurance Value

Economic theory predicts that bond insurance lowers issuers’ financing costs by resolving asymmetric information and mitigating credit risk. With comprehensive data over the last 36 years, we find increasingly diminished empirical support for these models. The value of insurance in resolving asymmetric information beyond that resolved by credit ratings and other observable bond characteristics is economically minimal. The average gross value of insurance ranges from 4 to 14 bps when bond insurers offer Aaa-rated coverage. However, this gross value becomes insignificant after 2008 when Aaa-rated insurance no longer exists. Evidence suggests that the lack of insurance benefit in the postcrisis period is attributable to the deteriorated creditworthiness of insurance companies. Examining noninterest saving explanations for the continued use of insurance in the no-Aaa insurance market, we find evidence that issuers purchase insurance out of habit (with insurance value most diminished for habitual purchasers with low governance quality) and for the convenience it affords in default, but no evidence that insurance improves secondary market liquidity. This paper was accepted by Gustavo Manso, finance. Supplemental Material: The data files and online appendix are available at https://doi.org/10.1287/mnsc.2023.4813 .