Stocks were volatile session, with the Dow and the S&P 500 hovering around the unchanged mark as bank shares fell but gain sin technology stocks drove up the Nasdaq. In Europe, stocks snapped a three-day losing streak as mining shares rose on a bright outlook for metals, offsetting declines in bank shares.

But news that Spain's central bank on Saturday had taken over savings bank CajaSur after a failed merger weighed heavily on sentiment across financial markets.

Wall Street opened lower on the euro-zone fears, with the Dow losing 1 percent at one point, but trimmed losses later.

The Dow Jones Industrial Average was down 38.40 points, or 0.38 percent, at 10,154.99 around 1640 GMT. The Standard & Poor's 500 Index dipped 1.37 points, or 0.13 percent, to 1,086.32, but the Nasdaq Composite Index rose 11.78 points, or 0.53 percent, to 2,240.82.

Bank shares were mostly lower following, with the Standard & Poor's financial index down 0.8 percent. Shares of Citigroup, gained 3.7 percent after Goldman upgraded the bank to "buy" from "neutral."

The FTSEurofirst 300 finished 0.33 percent higher, after sliding as much as 0.7 percent earlier.

Global stocks as measured by MSCI were practically flat, after last week's 4.8 percent loss.

But emerging markets stocks rose 0.8 percent, as rising prices of oil and other raw materials supported the outlook for commodity-exporting countries.

The euro fell broadly on Monday, as persistent concerns about the euro-zone debt situation threatened the future of the single currency.

The news wiped out last week's short-covering rally in the euro, which had been spurred by talk European monetary officials might intervene to prop up the beleaguered single currency.

The euro was down 1.54 percent at $1.2376. Last week, it reached a four-year low of $1.2143.

Data showing US existing home sales rose more than expected in April briefly pushed the euro to session lows against the dollar at $1.2345, according to EBS data.

Meanwhile, US crude rose on Monday, struggling in choppy trading to stay above $70 a barrel despite high oil inventories and continued worries that Europe's debt problems may keep demand growth curbed.

US crude rose 40 cents to $70.44 a barrel at 12:48 p.m. EDT (1648 GMT), having traded in a range from $69.57 to $70.96. Brent crude was down 11 cents at $71.57.