Wall Street gained overnight after Federal Reserve Chairman Janet Yellen reassured investors that the central bank remained committed to bolstering the US jobs market, consumer spending, corporate investment and the nascent housing recovery.
"One reason why I believe it is appropriate for the Federal Reserve to continue to provide substantial help to the labour market, without adding to the risks of inflation, is because of the evidence I see that there remains considerable slack in the economy and the labour market," Yellen said in prepared remarks for a speech in Chicago, Illinois.
"I think this extraordinary commitment is still needed and will be for some time, and I believe that view is widely shared by my fellow policymakers at the Fed," Yellen said.
Yellen's comments eased concern sparked earlier this month when she suggested US interest rates might rise as early as the first half of 2015.
In afternoon trading in New York, the Dow Jones Industrial Average gained 0.82 per cent, the Standard & Poor's 500 Index rose 0.88 per cent, while the Nasdaq Composite Index climbed 1.27 per cent.