The rating agency retained its top triple-A credit rating on US government debt.
Such a lower rating could cost US taxpayers if borrowers start demanding higher interest rates on Treasury bills and notes, global newswires reported.
''In the context of higher interest rates, without effective fiscal policy measures to reduce government spending or increase revenues, Moody's expects that the US's fiscal deficits will remain very large, significantly weakening debt affordability,'' the rating agency said in a statement.
The US administration criticised Moody's decision. ''While the statement by Moody's maintains the United States' Aaa rating, we disagree with the shift to a negative outlook,'' deputy treasury secretary Wally Adeyemo said.
Fibre2Fashion News Desk (DS)