"You really needed the central banks to come in and force, if you want to call it, the liquidity into the system," Tobias Levkovich, Citigroup Inc.'s chief U.S. equity strategist, told Bloomberg Television. "And they recognize the pressure that was building."

The moves by the central banks fueled speculation that the Fed will cut the discount rate it charges U.S. banks, which has been at 0.75 percent since February 2010, as the changes result in lower borrowing costs for foreign firms.

'Level the Playing Field'

"Be on the lookout for headlines on this front," Dan Greenhaus, chief global strategist at BTIG LLC in New York, wrote in a note to clients. Michael Cloherty, head of U.S. rates strategy at RBC Capital Markets in New York, said in a note that a discount-rate cut would ''level the playing field,'' while Jefferies Group Inc. Chief Financial Economist Ward McCarthy was skeptical the Fed will cut the rate since there is no dollar- funding problem in the U.S.

Today's rally trimmed the sixth monthly decline in seven for the S&P 500, leaving the index down 0.9 percent in November. U.S. equities also advanced after companies added 206,000 workers in November, according to data from ADP Employer Services that bolstered optimism in the labor market before a government jobs report in two days. The median forecast of economists surveyed by Bloomberg News called for an increase of 130,000.

Economic Data

Other data showed business activity in the U.S. expanded in November at the fastest pace in seven months, according to the Institute for Supply Management-Chicago Inc. The index of pending home sales increased 10.4 percent in October, the National Association of Realtors said, the biggest gain since November 2010 and five times the median forecast of economists.

The Fed said the economy expanded at a ''moderate'' pace in 11 of 12 districts, led by gains in manufacturing and consumer spending. The Fed's Beige Book survey reinforced the central bank's view that the economy, while strong enough to skirt a recession, remains too weak to bring down an unemployment rate stuck near 9 percent or higher for more than two years.

Indexes of commodity producers, industrial companies and financial firms jumped at least 4.6 percent to lead gains in all 10 of the main industry groups in the S&P 500. Trading volume of stocks in the index was 26 percent greater than the average at this time of day over the past 10 sessions, according to data compiled by Bloomberg.

Caterpillar Inc., JPMorgan Chase & Co. and General Electric Co. surged at least 6.1 percent as all 30 stocks in the Dow Jones Industrial Average climbed, sending the gauge up as much as 455 points.

Dollar, Commodities