Fitch Ratings placed the A- issuer default rating of Allied World Assurance Co. Holdings AG and the A+ insurer financial strength ratings of Allied World Assurance Co. Ltd., Allied World Assurance Co. (U.S.) Inc., Allied World National Assurance Co. and Allied World Insurance Co. on Rating Watch Negative.

The ratings action follows the announcement that Fairfax Financial Holdings Ltd. plans to acquire Allied World.

Fitch said the Rating Watch Negative reflects the uncertainty whether ownership by Fairfax will constrain Allied World's ratings. Resolution of the Rating Watch Negative will consider the rating agency's view on the consolidated credit strength of Fairfax and the future strategic importance of Allied World within Fairfax.