By Agence France-Presse
The Nasdaq and Dow suffered their worst weeks since the start of the global financial crisis as the US-China trade dispute returning to the forefront, and amid continued concerns about the Federal Reserve's plans for interest rate increases.
"It has been a remarkably terrible trading week for financial markets amid concerns over rising US interest rates, decelerating global growth, Brexit uncertainty and chaos in Washington," said Lukman Otunuga, a research analyst at FXTM.
The Dow Jones Industrial Average finished the week with a loss of nearly seven percent, after losing 1.8 percent or more than 400 points Friday, to close at 22,445.37.
Markets elsewhere were mixed, with European bourses flat or rising slightly, while Tokyo slid.
The Wall Street decline came as Washington teetered towards a likely government shutdown as US President Donald Trump dug in on threats to close if congressional Democrats continue to refuse his demand for funds to build a wall on the border of Mexico.
Thousands of US government employees could be furloughed without a paycheck right before the end-of-year holidays if Trump and congressional Democrats fail to strike a deal by midnight (0500 GMT Saturday).
With that deadline looming, investors received another jolt in the final hour of trading when White House advisor Peter Navarro delivered hardline comments on the ongoing trade talks with China.
"China is basically trying to steal the future of Japan, the US and Europe, by going after our technology," Navarro, a longtime China hawk, told the Japan's Nikkei news agency in an interview conducted Thursday but published Friday.
And he said China must address all US concerns about its trade policies, saying there are "no half-measures."
Investors also have been anxious over the surprise resignation of Defense Secretary Jim Mattis, who laid out significant policy disagreements with the US president in his letter to Trump which he made public.
"We are in a fragile environment," said Gregori Volokhine of Meeschaert Financial Services.
"The extremist position is winning in the Trump administration, not just on trade but on everything."
Investors have been unnerved by the Federal Reserve's decision to raise interest rates this week, and projecting it would continue to raise next year.
New York Federal Reserve Bank President John Williams on Friday tried to tamp down market concerns, opening the door to a more benign monetary policy in 2019, saying the Fed was listening to the fears about the risks and will "be ready to reassess and re-evaluate our views and our policy stance."
Stocks briefly rallied on Williams remarks, but fell quickly back into the red.
Key figures around 2130 GMT
New York - Dow: DOWN 1.8 percent at 22,445.37 (close)
New York - S&P 500: DOWN 2.1 percent at 2,416.58 (close)
New York - Nasdaq: DOWN 3.0 percent at 6,332.99 (close)
London - FTSE 100: UP 0.1 percent at 6,721.17 (close
Frankfurt - DAX 30: UP 0.2 percent at 10,633.82 (close)
Paris - CAC 40: FLAT at 4,694.38 (close)
EURO STOXX 50: FLAT at 3,000.61 (close)
Tokyo - Nikkei 225: DOWN 1.1 percent at 20,166.19 (close)
Hong Kong - Hang Seng: UP 0.5 percent at 25,753.42 (close)
Shanghai - Composite: DOWN 0.8 percent at 2,516.25 (close)
Euro/dollar: DOWN at $1.1365 from $1.1446 at 2200 GMT
Dollar/yen: DOWN at 111.23 yen from 111.28 yen
Pound/dollar: DOWN at $1.2634 from $1.2656
Oil - Brent Crude: DOWN 53 cents at $53.82 per barrel
Oil - West Texas Intermediate: DOWN 29 cents at $45.59 per barrel.