Fitch Ratings has placed Converium's Insurer Financial Strength 'BBB-'(BBB minus) rating on Rating Watch Negative.
The rating comes following the company's announcement that it is to delay publication of its third quarter results pending the restatement of its financial accounts.
Fitch said the ratings have been put on watch as Fitch cannot rely on previously published financial statements until the restated accounts have been published in mid-December.
The ratings agency said the restatement of Converium's accounts could potentially result in deterioration in the group's overall financial profile and damage its franchise in advance of the forthcoming renewal season.
Fitch said that should this prove to be the case, it would likely downgrade Converium's ratings.
Conversely, Fitch added, the ratings are likely to be affirmed if the restatement does not materially affect the group's financial profile or ability to access business.