The Dow Jones industrial average lost 3.18 points, 0.02 percent, to end the trading session at 12,807.36.
The Nasdaq dropped 9.46 points to 2,864.08, a loss of 0.33 percent .
The Standard & Poor's 500 closed at 1,361.22 points, down 2.39, or 0.18 percent.
Stocks began their retreat after European Central Bank Vice President Victor Constancio said a Greek debt restructuring wasn't an option, renewing concerns about the euro zone's ability to manage its financially trouble countries.
"After [an] earnings season, people tend to focus on the bigger-picture issues, and they're often more worrisome," Karl Mills, president and chief investment officer at Jurika Mills & Keifer, told The Wall Street Journal reported.
Mills said investors were watching public-private financial interaction, saying there was a "private-sector plane where things are getting better, and a public-sector plane where you see things getting worse. The current trajectory of public debt relative to revenues is alarming."
The U.S. manufacturing sector slowed a bit in April, although not as much as expected while U.S. construction spending rose in March after three straight months of decline.
The listed volume on the New York Stock Exchange was 4.2 billion shares. Declines outnumbered advancers 1,747 to 1,242.
The 10-year treasury note was at 3.28 percent.
The euro was $1.4816, up from Friday's $1.4807. Against the yen, the dollar was 81.26 yen, compared to Friday's 81.2203 yen.
In London, the FTSE 100 closed at 6,069.90, up 1.74, or 0.03 percent.
In Tokyo, the Nikkei closed up 154.46 points at 10,004.20, or 1.57 percent.