The effect of this is to raise the rating of the bond to the rating of the insurer; accordingly, a bond insurer's credit rating must be almost perfect. The premium requested for insurance on a bond is a measure of the perceived risk of failure of the issuer.

The economic value of bond insurance to the governmental unit, agency, or company offering bonds is a saving in interest costs reflecting the difference in yield on an insured bond from that on the same bond if uninsured. Insured securities ranged from municipal bonds and structured finance bonds to collateralized debt obligations (CDOs) domestically and abroad. [citation needed]

Government bonds are almost never insured. [citation needed]Municipal bond insurance was introduced in the US in 1971 by AMBAC, the first of the so-called 'financial guaranty corporations' (also called 'monoline insurers') to get involved. By 2002 over 40% of municipal bonds were insured, often by a procedure involving payment of a single premium at the purchase of the bond. [citation needed] However, the financial crisis of 2007-2010 negatively impacted the monolines to the point where their continued existence is in doubt.