NEW YORK — Fitch Ratings said today it will keep its rating on U.S. debt at the highest grade, AAA, and issued a “stable” outlook, meaning it expects the rating to stay there.

That’s better than the other two main ratings agencies: Moody’s lists the U.S. debt at AAA but says its outlook is negative. And Standard & Poor’s set off a maelstrom in the stock market last week after it took its rating on the U.S. down to the second-highest grade, AA-plus, for the first time.

In Washington, the Obama administration welcomed the announcement from Fitch but said it would be important for Congress to take the steps called for in the budget agreement.

“The Treasury Department continues to believe that Treasury securities are AAA investments. Today’s report underscores the importance of Congress taking additional actions to address our long-term fiscal challenges,” Treasury spokesman Anthony Coley said.