Ratings agency Moody's has lowered the insurance financial strength rating of Travelers Property Casualty (P&C)Corporation to Aa3 from Aa2.
Moody's said the rating downgrades were prompted by Travelers' $1.3bn (£810m) charge in connection with the company's revised estimate of its exposure to asbestos liabilities.
The charge will lead to an increase in the company's asbestos reserves to $3.4bn after reinsurance recoverables.
Moody's added that the strong capitalisation and annual dividend capacity of the principal insurance subsidiaries, continued to support a higher rating than would be expected under current conditions.