By Akane Otani
NEW YORK (Reuters) - Stocks ended lower on Thursday, continuing a recent streak of weakness as Russia's surprisingly harsh retaliatory measures in response to Western sanctions raised concerns about global growth.
In addition to Moscow's ban on imports of many Western foods, following sanctions imposed for Russia's support of rebels in eastern Ukraine, investors worried that the conflict between Russian and Ukraine is escalating, with the downing of a Ukrainian fighter jet.
The declines briefly dragged the Dow below its 200-day moving average in afternoon trading. The S&P 500 is now nearly 4 percent below the record closing high it set last month
While the full extent of the sanctions are still unknown, escalating tensions in Russia could continue to spur selling in stocks, analysts said.
"Before this point, U.S. investors have always thought of geopolitical concerns as being largely no more than a 24-hour event. Now, the growing concern is that the outlook for global growth is pointing down," said Andrew Wilkinson, chief market analyst at Interactive Brokers Group in Greenwich, Connecticut.
"To that extent, investors seem more prone to selling, and asking questions later rather than buying the dip as they had become accustomed to doing in the past."
All but one of the S&P 500's industry sectors ended down on the day, backtracking from brief gains in the morning. Consumer staples shares (.SPCOMS), the bright spot of trading on Wednesday, slipped 0.8 percent on Thursday, while utilities (.SPCOMU) shares posted the sole sector gains.
Health insurer stocks were poor performers, dipping after Goldman Sachs downgraded Aetna (AET.N) to "neutral" and cut earnings estimates on a number of its peers. Aetna (AET.N) shares slid 4.0 percent to $75.22, UnitedHealth Group (UNH.N) shares lost 2.7 percent to $79.26 and Cigna shares (CI.N) fell 3.0 percent to $88.75.
The Dow Jones industrial average (.DJI) fell 75.07 points, or 0.46 percent, to 16,368.27, the S&P 500 (.SPX) ended down 10.67 points, or 0.56 percent, to 1,909.57, and the Nasdaq Composite (.IXIC) lost 20.09 points, or 0.46 percent, to 4,334.97.
Twenty-First Century Fox (FOXA.O) surged 5.1 percent to $33.97 after the company's quarterly profit beat Wall Street's expectations.
Jobless claims reports lent optimism to the market in the morning as the four-week claims average fell to its lowest level since February 2006, suggesting labor market conditions are continuing to improve.
About 5.5 billion shares traded on all U.S. platforms, according to BATS exchange data, compared with the five-day average of 6.9 billion.
(Editing by Leslie Adler)