Wall Street declined, while US Treasuries and gold rose, after reports that a Malaysian passenger jet with 295 people on board had been shot down over Ukraine.
Ukraine said pro-Russian rebels shot down the plane, while separatists denied the claims. The crash comes just as the US and the European imposed fresh, and their toughest yet, sanctions on Russia for stoking unrest in eastern Ukraine.
In late afternoon trading in New York, the Dow Jones Industrial Average dropped 0.51 percent, the Standard & Poor's 500 index slid 0.65 percent, while the Nasdaq Composite Index retreated 0.88 percent.
Earlier in the day, the Dow set an intraday record high of 17,151.56.
US Treasuries rose, pushing yields on the 10-year benchmark note five basis points lower to 2.47 percent, as investors sought the perceived safety of fixed-income securities.
Gold, another typical safe-haven investment, also advanced. Gold futures for August delivery rose 1.3 percent to settle at US$1,316.90 an ounce on the Comex in New York.
"The market is really acute to geopolitical risk," Todd Lowenstein, a fund manager at Highmark Capital Management in Los Angeles, told Bloomberg News. "Given where valuations are and the move lately amid all the M&A activity, when you have some geopolitical shocks, people will look for a reason to sell."
Declines in shares of Intel and Caterpillar, down 2.2 percent and 1.6 percent respectively, led the drop in the Dow. Bucking the trend were shares of UnitedHealth, up 2.6 percent as well as those of Microsoft, up 1.5 percent.
Microsoft said it will slash up to 18,000 jobs as part of a restructuring of the tech giant. The cuts represent about 14 percent of its workforce and most of the jobs to be eliminated were employees inherited in Microsoft's acquisition of Finnish phone maker Nokia.
In Europe, the Stoxx 600 Index shed 0.9 percent from the previous close. The UK's FTSE 100 Index dropped 0.7 percent, Germany's DAX fell 1.1 percent, while France's CAC 40 declined 1.2 percent.
The latest US economic data were mixed. Jobless claims unexpectedly dropped by 3,000 to 302,000 in the week ended July 12, while the Philadelphia Federal Reserve Bank's business activity index rose to 23.9 in July, the highest level in more than three years.
Even so, housing starts posted a surprise drop, sliding 9.3 percent to an 893,000 annualised rate in June, down from a 985,000 rate in May.
Analysts pointed to the good news.
"We should focus on jobless claims data," Joel Naroff, chief economist at Naroff Economic Advisers in Holland, Pennsylvania, told Reuters. "The labour market is tightening, firms are not cutting workers and people are finding jobs."
In a speech to a business group in Kentucky, St Louis Fed chief James Bullard said inflation in the US "seems to be rising again", adding to his forecast that interest rates may need to rise sooner than the central bank currently is thinking.
"If macroeconomic conditions continue to improve at the current pace, the normalisation process may need to begin sooner rather than later," he said in his prepared remarks. "The objective is to execute policy normalisation over the next few years without creating excessive inflation or substantial financial stability risks."