About 6.22 billion shares changed hands on United States stock exchanges, slightly above the 6.15 billion average for the last 20 sessions.
Investors, who took the North Korea report from Japan in their stride earlier in the day, lost their appetite for risk after Trump's comments to reporters during his vacation at his golf club in New Jersey. Oil prices veered lower as early gains faded. On the week, the Dow Jones lost 0.9 %; the S&P 500 has dropped 1.4 per cent, its biggest weekly decline in more than four months.
The Nasdaq Composite Index, the hardest hit equity gauge on Thursday, climbed 36 points, or 0.6%, to 6,252. Hong Kong's Hang Seng Index plunged by 2 percent, while South Korea's Kospi Index slumped by 1.7 percent.
Late in the session, President Donald Trump said perhaps his threat to unleash "fire and fury" on North Korea "maybe wasn't tough enough".
Top military brass and President Trump are being sued by five US military members that want to keep Trump's transgender ban from becoming a reality - "in any capacity". -North Korea tensions. The VIX, a measure of how much volatility investors expect in stocks, jumped 34.8 percent, the biggest increase since May.
The markets may benefit from bargain hunting, as some traders look to pick up stocks at reduced levels following the pullback seen over the past few sessions. Advanced Micro Devices gave up 50 cents, or 3.9 percent, to $12.33.
The financial sector index gave back gains after news California insurance regulator will probe whether Wells Fargo & Co and an insurance company harmed residents by selling insurance they did not need. MetLife fell 75 cents, or 1.6 percent, to $47.56, while Charles Schwab slid 69 cents, or 1.6 percent, to $41.33.
Disappointing quarterly results from big department store chains also weighed down the market.
Retailers slid after department stores Macy's and Kohl's both said same-store sales continued to decline in the second quarter. Its shares tumbled $11.35 to $61.99.
Nvidia's quarterly revenue in its data center and automotive businesses missed estimates, dragging the chipmaker's shares down 5.43 percent. On the Nasdaq, 1,462 issues rose and 1,227 fell.
The bond market was without direction: the yield of u.s. Treasury bills to 10 years, which evolves to the inverse of the bond price, appears to 2,190 %, compared to 2,198 % Thursday evening, and that bills to 30 years at 2,786 %, compared to 2,773 %.
In commodities trading, crude oil futures are slipping $0.10 to $48.49 a barrel after tumbling $0.97 to $48.59 a barrel on Thursday. It added 39 cents to $49.56 a barrel on Wednesday.
Oil managed to end higher today, after the Energy Information Administration reported a bigger-than-expected decrease in domestic crude inventories last week. Germany's DAX fell 0.9 percent, while the CAC 40 in France lost 0.5 percent.