Travel and media companies led USA stocks lower in afternoon trading Wednesday as some rare earnings disappointments weighed on the market.
At 12:36 p.m. ET (1636 GMT), the Dow Jones Industrial Average was down 158.98 points, or 0.72 percent, at 21,889.72 and the S&P 500 was down 27.37 points, or 1.11 percent, at 2,446.65. The Nasdaq added 39.68 points, or 0.6 percent, to 6,256.56.
The Russell 2000 index of smaller companies gave up 24.40 points, or 1.7 percent, to 1,372.54.
Emerging market stocks lost 1.28 percent.
Overnight, MSCI's broadest index of Asia-Pacific shares outside Japan had skidded 1.55 percent, its biggest one-day loss since mid-December, to leave it down 2.5 percent for the week.
Stock market falls can hit pension values, but savers who are not set to take their savings for a number of years typically don't need to worry, as losses are usually recouped over the longer term. Silver also rose, gaining 47 cents, or 2.8 percent, to $16.86 an ounce.
The major averages have slid firmly into negative territory, with the Dow and the S&P 500 pulling back further off Monday's record closing highs.
Sterling was last trading at $1.3009, up 0.27 percent on the day.
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The NASDAQ Composite Index and Dow started the day lower but regained strength and recovered some losses as the day progressed.
France's CAC 40 extended losses to hit a session low, down 1.2 percent after the auto incident in Paris.
'Stock markets in Europe are still under pressure because of the heightened tensions surrounding North Korea, ' said David Madden, market analyst at CMC Markets UK.
Away from the geopolitical drama, US inflation data is due at 1330 GMT.
The Chinese volatility gauge jumped by the most since January 2016, to its highest level in more than seven months. It is poised to end the week down 1.9 percent.
"In the event that war should break out, and that leads to an acceptance of further loose monetary and fiscal policy in the USA, we would expect a falling U.S. dollar real yield environment, giving renewed, and sustainable, impetus to monetary metals prices".
Update: The FTSE 100 has slumped further into the red amid persisting fears over North Korea tensions, with the sell-off accelerated by a slump in U.S. markets. US gold futures gained 0.26 percent to $1,293.50 an ounce.
The September crude contract was up 20 cents to US$49.76 per barrel and the September natural gas contract was up seven cents to US$2.95 per mmBTU. A separate Labour Department report showed initial claims for state unemployment benefits rose 3,000 to a seasonally adjusted 244,000 for the week ended August 5.