Monolines, companies that insure against the risk of a bond or other security defaulting, have in the past weeks come under fire from ratings agencies, after concerns grew over their ability to meet the obligations to the bond issuers they insure.

Some, such as ACA, Ambac and SCA, were recently downgraded, raising fears of a domino effect resulting in further downgrades and market losses for the securities they – and other monolines – guarantee.