Municipal bond insurance

Coverage that guarantees bond­holders against default by a municipality. This form of financial guar­antee was introduced in the early 1970s and became a runaway success. Municipalities embraced it because their offerings took on the credit rating of the company that wrote the insurance, rather than their own ratings. It meant that most municipal bond offerings were ele­vated to Triple-A, and municipalities could raise money at a lower rate of interest. For investors, it made municipal bonds less risky.