Bond insurance is a type of insurance that a bond issuer purchases that guarantees the repayment of the principal and all associated interest payments to the bondholders in the event of default. Bond issuers buy insurance to enhance their credit rating in order to reduce the amount of interest that it needs to pay.
Bond insurance is also known as financial guaranty insurance.
The rating of a debt instrument takes into account the creditworthiness of the issuer. The riskier an issuer is deemed to be, the lower its credit rating and, thus, the higher the yield that investors expect from investing in the debt security. Such issuers are faced with a higher cost of borrowing than companies that are estimated to be stable and less risky. In order to obtain a more favorable rating and to attract more investors to a bond issue, companies may undergo a credit enhancement.