US stocks gained sharply and ended near session high on Friday after Federal Reserve Chairman Ben Bernanke said the central bank would take actions if the economy deteriorates significantly.

The Dow Jones industrial average rallied 164.84 points, or 1.65 percent, to 10,150.65. The Standard & Poor’s 500 index gained 17. 37 points, or 1.66 percent, to 1,064.59 and the Nasdaq jumped 34. 94 points, or 1.65 percent, to 2,153.63.

However, major indexes were still in the red for the week despite of Friday’s surge.

In remarks kicking off a two-day meeting of the world’s top central bankers, Bernanke admitted the economic recovery is “less vigorous than we expected,” but he believed the economy would pick up next year.

He reassured investors by saying the Fed still had tools to help support economic activity and guard against disinflation.

“I believe that additional purchases of longer-term securities should the FOMC (Federal Open Market Committee) choose to undertake them, would be effective in further easing financial conditions,” said Bernanke.

Bernanke’s remarks came after the government data showed the U. S. economy was rebounding at a much slower pace than previously forecasted.

According to the Commerce Department, U.S. gross domestic product, the broadest measure of the economy’s output, grew at a 1. 6 percent annual rate in the second quarter. The reading showed a significant plunge from the initial estimate of 2.4 percent last month, but it was higher than market expectation.

The U.S. economy grew 3.7 percent in the first quarter, however, the rebound slowed afterwards due to the largest surge in imports in 26 years and a slowdown in companies’ restocking of goods.

In currencies, the U.S. dollar rose against the yen after Bernanke pledged to boost the recovery, while the euro traded up 0. 2 percent at 1.2731 dollars after see-sawing.

Light, sweet crude oil for October delivery extended its rally to the third day on Friday, climbing 1.81 dollars to settle at 75. 17 dollars a barrel on the New York Mercantile Exchange.

In London, Brent crude jumped 1.63 dollars to settle at 76.65 dollars a barrel on the ICE futures exchange.