Fitch rates U.S. credit AAA

Fitch Ratings Tuesday affirmed its AAA credit rating for the United States and said the outlook is stable, citing the nation's central role in the global financial system and the flexible, diverse economy.

Fitch had put the rating under review after lawmakers reached a compromise Aug. 2 on a debt-limit agreement that prevented a U.S. default.  It gave the triple-A rating with a mild warning.

U.S. credit may be placed on negative outlook, indicating more than a 50 percent probability that the nation will be downgraded in the next two years, should weaker than estimated economic growth or a failure by a congressional committee to enact $1.2 trillion in budget cuts spur projected debt levels to rise more than estimated, Fitch said Tuesday in a statement.

Lawmakers' agreed on Aug. 2 put in place a plan to enforce $2.4 trillion in spending reductions over the next 10 years.

Standard & Poor's on Aug. 5 cut its U.S. credit rating to AA+ from AAA, saying lawmakers failed to cut spending enough to reduce record deficits.

Moody's Investors Service affirmed its top U.S. ranking last week.

"The Fitch reassessment of waiting to see what the committee comes up with is prudent and also appropriate given the mandate of the" committee, said Christian Cooper, head of U.S. dollar derivatives trading in New York at Jefferies Group. The market is concerned about whether the congressional super committee  will  be able to put what is still a very recent partisan fight aside and come to some agreement,  Cooper said.

Marketable U.S. government debt  has risen to $9.4 trillion from $4.34 trillion in mid-2007 as the government borrowed to bail out the nation's banking system and lift the economy out of recession.

The U.S. budget  went from surpluses averaging $139.7 billion from 1998 through 2001 to a deficit of $1.29 trillion last year, Bloomberg data show. That hasn't raised the country's borrowing costs. Average debt yields of 1.5 percent in July compare with 6.54 percent in 2000.

The Aug. 2 law is to reduce the deficit by a minimum of $4.1 trillion in the coming decade, such that the fully implemented plan "would bring U.S. public finances materially closer to a sustainable path," Fitch said.

"The Treasury Department continues to believe that Treasury securities are AAA investments," Treasury spokesman Anthony Coley said Tuesday in an email. "Today's report underscores the importance of Congress taking additional actions to address our long-term fiscal challenges."