With the Standard & Poor's 500 Index near record highs, investors are trying to weigh the positive outlook for the US economy with concern about signs of economic trouble in China and the ongoing Ukrainian crisis.
In afternoon trading in New York, the Dow Jones Industrial Average dropped 0.21 percent, as did the Standard & Poor's 500 Index. The Nasdaq Composite Index eked out a 0.07 percent gain.
Slides in shares of Coca-Cola and those of Boeing, down 1.3 percent and 1 percent respectively, led the Dow lower.
"Everybody's kind of on edge when you're at all-time highs," Walter Todd, chief investment officer of Greenwood Capital Associates in Greenwood, South Carolina, told Bloomberg News.
The latest US data prompted some economists to boost their optimism for the world's largest economy. JPMorgan economist Daniel Silver said fourth-quarter growth was likely to be revised higher after services industry data on Wednesday suggested a much stronger pace of consumer spending than the government had previously assumed, according to Reuters.
In Europe, the Stoxx 600 Index ended the session with a 1.1 percent drop from the previous close. The UK's FTSE 100 and France's CAC 40 gave up 1 percent, while Germany's DAX retreated 1.3 percent.
As Ukraine's Crimea region prepares for a referendum about its status on March 16, Group of 7 leaders warned they would not recognise the outcome of such a vote.
"We call on the Russian Federation to immediately halt actions supporting a referendum on the territory of Crimea regarding its status, in direct violation of the Constitution of Ukraine," according to the G-7 statement. "Any such referendum would have no legal effect."
The statement said it represented the leaders of Canada, France, Germany, Italy, Japan, the United Kingdom, the United States, the President of the European Council and the President of the European Commission. The top US and Russian foreign ministers are set to meet later this week.
The uncertainty underpinned the appeal of perceived safe-haven investments including US Treasuries and gold. Ten-year Treasuries rose, pushing yields 5 basis points lower to 2.72 percent.
Ireland government bonds have also become more enticing to investors. Yields on the country's 10-year note dropped to a record low, a day before the country will hold its first bond auction since 2010, according to Bloomberg News.
"Ireland has seen its fundamentals improve hugely but the rally has been driven by the more general market environment," Jan Von Gerich, a fixed-income strategist at Nordea Bank in Helsinki, told Bloomberg. "The auction will go well. Ireland is going to have more frequent market access going forward and increase liquidity."