Speaking at the Fed’s annual retreat in Jackson Hole, Wyoming, Bernanke did not offer new measures to boost the economy but said it was critical for the economy’s health to reduce long-term joblessness.

US stocks jumped more than 1 percent, reversing initial losses of as much as 2 percent, while Treasuries, whose yields are at near-historic lows, cut initial gains.

Bernanke said the central bank’s policy panel would meet for two days in September instead of one to discuss additional monetary stimulus, offering some hope to investors for further action down the road.

“He didn’t give the market the green light for QE3 — he also didn’t give the market the red light for QE3,” said Kevin Caron, market strategist at Stifel, Nicolaus in Florham Park, New Jersey, referring to the Fed’s quantitative easing program.

“By implying that inflation is viewed as not a concern, it leaves the possibility for something down the road,” he added.

The speech follows several turbulent weeks for markets, with investors facing concerns about another US recession and escalating euro zone debt troubles, as well as a downgrade of the top-tier US credit rating.

Analysts said the very choppy trade in many markets after Bernanke spoke reflected that concern about the US economy, as well as a realization that US interest rates will stay at record lows for years to come.

World stocks as measured by the MSCI world equity index were up 1 percent, but are down 11.1 percent since the start of the month, while Brent crude was last up 81 cents at $111.43 a barrel.

Bernanke’s speech last year laid the groundwork for the Fed’s $600 billion bond-buying program to revive the economy under the rubric “QE2” for the Fed’s second round of stimulus, or quantitative easing.

The dollar gained on the euro after the speech but later shed those gains, with the euro last up 0.8 percent at $1.4494. The dollar was also down 0.7 percent against a basket of currencies.

An increase of money supply, such as the QE2 program, tends to erode the value of the dollar relative to other currencies.

On Wall Street, the Dow Jones Industrial Average was up 122.27 points, or 1.10 percent, at 11,272.09. The Standard & Poor’s 500 Index was up 15.63 points, or 1.35 percent, at 1,174.90. The Nasdaq Composite Index was up 56.08 points, or 2.32 percent, at 2,475.71.

Wall Street scrambled to raise cash in case Hurricane Irene causes major disruption in trading for thousands of traders who live in the New York, New Jersey and Connecticut.

The repurchase market, a major source of cash for Wall Street to fund trades and operations, showed an increase in interest rates on loans that mature on Monday, a sign markets are worried there could be disruptions — however temporary — as a result of the hurricane.

Interest rates on loans backed by Treasury bonds that expire on Monday rose by several hundredths of a percentage point from late Thursday to about 0.08 percent in the $1.6 trillion repurchase market.

In the US Treasury market, benchmark 10-year Treasury notes were trading 11/32 higher in price to yield 2.19 percent, down from 2.21 percent late on Thursday.

“I think that seeing Treasuries come off a little bit here, you’re seeing some bets being unwound in the market,” said Rich Bryant, a Treasury trader at MF Global Securities in New York.

Gold was higher, fueled by safe-haven buying. Spot gold was up 0.9 percent at $1,786.20 an ounce.