As investors digest a recent spate of rating downgrades for the bond insurers, concerns have surfaced about risks that could affect the last remaining insurers with triple-A credit ratings and further darken the outlook for the troubled industry.

Together with heavy losses on subprime mortgage-related bonds they guaranteed, bond insurers such as Ambac and MBIA are exposed to problems in their so-called “guaranteed investment contracts” (GIC) businesses. These problems could result in additional claims on capital at a time when they can least sustain them.