Fitch reiterates warning over U.S. debt.

Fitch has again warned it will formally review the U.S.'s AAA rating if the debt ceiling isn't raised, although the agency believes that the risk of a default "remains extremely low." Even if the U.S. averts a default, however, Fitch could still downgrade the country later in the year if Washington fails to formulate a medium-term plan to cut the deficit and restore confidence.