The agency said in a statement that the decision "follows decisions by MBIA and Ambac's managements to cease providing substantive non-public portfolio information used in Fitch's capital analysis model, to discontinue previous full interactive dialogue with Fitch analysts, and to request withdrawal of Fitch's ratings".
Fitch criticised the companies' "reactive strategic and capital management planning", adding that the recent downgrades from Standard & Poor's and Moody's made the prospects of the insurers uncertain. It could resume coverage based on publicly available information only, if investors requested it, Fitch added.
Ambac and MBIA have both requested Fitch to drop coverage - Ambac on June 18 and MBIA in March this year - after Fitch was the first of the agencies to downgrade the monolines from AAA. The other agencies followed suit earlier this month.
As of yesterday, Fitch rated both insurers A.