U.S. stocks ended little changed in a low-volume session, on Monday, after Moody's downgrade of Greece's government bond ratings to junk status, citing the risks in the joint euro-zone and IMF rescue package for the debt-laden country, took the wind out of the market's sails. While not unexpected, the downgrade weighed on a market that had rallied on earlier data showing euro-zone industrial output surged in April, achieving the biggest year-on-year percentage gain in almost two decades. So the Dow Jones industrial average slipped 20 points, or 0.2 percent, to 10,191. And the Standard & Poor's 500 Index shed 2 points, or 0.2 percent, to 1,090. But the Nasdaq Composite Index ended flat, at 2,244. During the trading day, yesterday, the euro had come within a breath of 1.23 dollars, its highest level since early June, as investors seemed comfortable taking on more risk, but then pared gains following Moody's downgrade. But the CBOE volatility index fell 0.7 percent to 28.58. Another note from Moody's Investors Service, this time on the oil sector, highlighted the uncertainty created by BP's oil spill. Moody's said the spill has created an unprecedented financial, legal, regulatory and environmental crisis for companies that operate in the Gulf of Mexico. U.S. President Barack Obama plans to press the company to set up an escrow account to pay damage claims by individuals and businesses hurt by BP's oil spill in the Gulf of Mexico.The British company said the cost of the spill hit 1.6 billion dollars.