S&P moved into negative territory for 2011 (ext)

NEW YORK (CNNMoney) -- Stocks closed down more than 1% Wednesday, as investors continued to fret over how Europe could solve its debt troubles in 2012. Selling intensified ahead of the close.

On a light trading week, investors have few other economic or corporate indicators to mull before 2011 ends.

Still, traders and analysts said the low volumes led to more pronounced swings, and some of the moves are coming from year-end portfolio rebalancing rather than convictions over the trajectory of all stocks or a particular stock.

"I don't know what to read into today," said Peter Boockvar, equity strategist at Miller Tabak + Co. "There's nothing going on in the U.S. market. It's a holiday week."

The S&P fell back into negative territory for the year.

Despite Wednesday's sell-off, the Dow remains up 5% for 2011.

Some traders still hope to close the year poised for a January bounce. To get there, some say 1260 would be the magic number for the S&P to clear on Friday.

"If we could clear 1,260 by the end of the week, we could see a strong rally in January," said Joe Bell, senior equity analyst at Schaeffer's Investment Research.

U.S. stocks have been buoyed recently by signs of improvement in the US economy, including declines in weekly claims for unemployment benefits and an uptick in new home construction.

But investors say the market remains vulnerable as the debt crisis in Europe continues to threaten the outlook for the global economy and financial markets.

One bright spot for Europe on Wednesday was an Italian auction of 3- and 24-month bonds that drew strong demand and yields half as high as the previous month's auctions. The results helped lift European equities and banks.

Investors will be more closely watching Thursday's auction of Italian 10-year bonds, which have seen yields continue to flirt with the 7% danger zone. That level is worrisome because it flashed the first warning signs for Ireland, Portugal and Greece, which all eventually needed bailouts.

Oil prices eased off the previous sessions spike, slipping $1.64 to $99.70 a barrel. On Tuesday, crude prices jumped 2% after Iran threatened to choke off the flow of oil passing through the Strait of Hormuz.

Gold futures for February delivery fell $31.40 to $1,564.10 an ounce.

The dollar fell against the British pound and the Japanese yen but edged higher against the euro.