"The market will hold on to its gains for the year. Given the uncertainty I don't see any compelling reasons for an increase," said Brian Gendreau, a market strategist with Cetera Financial Group, a Los Angeles-based broker. "But that could change in a blink. If there's better-than-expected news from these negotiations, the market could pop."
A Chinese government pledge to maintain policies intended to strengthen the world's second-largest economy helped raise optimism about global growth. China's Shanghai Composite Index jumped 2.9 percent to 2,031.91. Hong Kong's Hang Seng ended 2.2 percent higher at 22,270.91.
A private survey showed Wednesday that U.S. businesses added fewer workers in November, in part because Superstorm Sandy shut down factories, retail stores, and other companies. Payroll processor ADP said employers added 118,000 jobs last month. That's below October's total of 157,000, which was revised lower. Investors will also look to the monthly jobs report from the Labor Department Friday for more information about how the economy is doing.
Orders to U.S. factories rose modestly in October, helped by a big gain in demand for equipment that reflects business investment plans. Factory orders edged up 0.8 percent in October, the Commerce Department said Wednesday. That followed a 4.5 percent jump in September.
The yield on the 10-year Treasury note fell 1 basis points to 1.59 percent.
Among other stocks making big moves:
—Freeport-McMoRan Copper & Gold plunged $6.12, or 16 percent, to $32.16 after the mining company said it is buying oil companies Plains Exploration & Production and McMoRan Exploration for about $9 billion.
—Mattress Firm Holding Corp. fell $6.65, or 22 percent, to $23.67 after the mattress retailer said late Tuesday that sales trends were softening.
—Pandora Media, an internet radio company, fell $1.65, or 17.5 percent, to $7.80 after saying it would make a much larger loss in the fourth quarter than analysts had been forecasting.