Wall Street stocks declined on Monday as euro zone data signaled the region could be facing a recession, adding to worries about Europe's debt crisis.

Initial optimism about prospects of pro-growth reforms under new governments in Italy and Greece gave way to caution over the huge debt problems still plaguing the euro, which fell against the U.S. dollar.

Industrial production in the euro zone fell in September, the most since early 2009, adding to fears of a sharp contraction by industry and a probable recession. Output at factories in the 17-nation group fell 2.0 percent for the month.

We are not an island. We are dependent ... and Europe's not likely to escape a recession, said Steve Goldman, principal at Goldman Management in Short Hills, New Jersey.

You're seeing further weakness in the banks, and that's acting as a drag, he said.

Financials led the decline on the S&P 500, with the S&P financial index down 1.8 percent. Bank of America shares were down 2.3 percent at $6.07.

Stocks have traded choppily and in tandem with the euro recently in a sign U.S. investors are taking cues from the euro zone's mushrooming debt crisis as bouts of risk aversion are followed by periods of relative optimism.

The Dow Jones industrial average was down 103.80 points, or 0.85 percent, at 12,049.88. The Standard & Poor's 500 Index was down 15.46 points, or 1.22 percent, at 1,248.39. The Nasdaq Composite Index was down 26.79 points, or 1.00 percent, at 2,651.96.

Limiting losses on the Dow, Boeing Co shares rose 1.9 percent to $68.20 after the U.S. planemaker announced an order worth at least $18 billion and said the Middle East will need to recruit and train tens of thousands of new pilots to sustain a massive expansion in long-haul fleets.

(Reporting by Caroline Valetkevitch, additional reporting by Edward Krudy; Editing by Kenneth Barry)