Ambac and MBIA have been downgraded by Standard & Poorâ??s to double A.

Fitch Ratings had already removed their top-notch status months ago. Moodyâ??s Investors Service is likely to follow Standard & Poorâ??s in the coming weeks.

Without a triple A credit rating, there is no prospect of these bond insurers doing new business again. The entire bond insurance model rests on a triple A credit rating; it is the triple A guarantee that municipal borrowers and structured finance markets have been paying for.

The downgrades may also result in further writedowns for banks who are exposed to monolines.