Fears of a China-led global economic slowdown drove Wall Street to its steepest one-day drop in nearly four years on Friday and left the Dow industrials more than 10 percent below a May record.
Wall Street's selloff this week suggested investors are growing nervous about paying high prices for stocks at a time of minimal earnings growth, tumbling energy prices and an expected rate hike by the U.S. Federal Reserve that could gradually usher the end of almost a decade of easy money.
Stocks have seen few large moves this year, staying in a narrow range throughout 2015, but volatility spiked this month once China surprisingly devalued its currency. Weak Chinese manufacturing data on Friday, and another drop in China's stock market, rattled investors' nerves and led to Friday's tumble.
While this month's selloff has been swift, many analysts feel the declines may be close to being exhausted, with a turnaround possibly starting as soon as next week.
"You're definitely witnessing a perfect storm in terms of China timing, people on vacation that affects liquidity, and you've got a lot of questions on the Fed and people are obviously focused on oil," said Andrew Frankel, co-president of Stuart Frankel & Co in New York.
"If you're buying a stock, you're dipping a toe in here."
The Dow Jones industrial average .DJI closed down 530.94 points, or 3.12 percent, to 16,459.75, the S&P 500 .SPX lost 64.84 points, or 3.19 percent, to 1,970.89 and the Nasdaq Composite .IXIC dropped 171.45 points, or 3.52 percent, to 4,706.04.
Next week, investors will focus on housing data, which has been strong of late, and the preliminary reading of second-quarter GDP, which could lead investors back towards riskier assets if they point to an improving U.S. economy.
The Russell 2000 .RUT index of small-cap stocks also confirmed a move into correction territory, marking a 10-percent decline from its most recent closing high on June 23.
The CBOE Volatility index .VIX, Wall Street's so-called fear gauge, touched its highest since October and notched its biggest-ever weekly percentage gain.
The S&P slumped 5.8 percent for the week, its biggest weekly decline since September 2011. The index lost more than $1 trillion of its value this week, according to S&P Dow Jones Indexes. Only 10 S&P 500 components advanced on Friday.
The selloff was broad, with all 10 major sectors in the red. The energy index .SPNY dropped 2.6 percent as U.S. crude oil CLc1 dipped below $40 a barrel for the first time since the 2009 financial crisis.
Many investors still anticipate the U.S. central bank will begin raising interest rates by the end of the year, but fewer of them expect a September hike after reading minutes from the Fed's July meeting on Wednesday.
Apple (AAPL.O), still by far the most valuable U.S. company, fell 4.6 percent to $107.44, the biggest drag on the S&P and the Nasdaq.
For the week, the Dow dropped 5.8 percent and the Nasdaq tumbled 6.8 percent.
The drag from Apple pushed the technology .SPLRCT sector down 4.2 percent. The consumer staples index .SPLRCS fell 2.6 percent, moving into the red for the year. Eight of the 10 S&P sectors are now in negative territory for the year.
Six stocks fell for every one that closed higher on the NYSE; on the Nasdaq, the ratio was about 2-1/2 decliners for every 1 advancer.
The S&P 500 posted no new 52-week highs for the first time since Aug. 8, 2011, after S&P downgraded the U.S. credit rating, while there were 75 new lows; the Nasdaq recorded 13 new highs and 276 new lows.
Volume was heavy, with about 10.6 billion shares traded on U.S. exchanges, well above the 6.75 billion average this month, according to BATS Global Markets.