Fear is back in the market.
Investors are worried about slower economic growth in China, a gloomier outlook for US corporate profits and an end to easy money policies in the United States and Europe.
They are also fretting over country-specific troubles around the world - from economic mismanagement in Argentina to political instability in Turkey.
Those fears converged to start a two-day rout in global markets this week, capped by a 318-point drop in the Dow Jones industrial average ysterday.
It was the blue-chip index's worst day since last June. The Dow plunged almost 500 points over the two-day stretch.
The Standard & Poor's 500 index fell 38 points, or 2.1%, to 1,790 yesterday. The Nasdaq composite fell 90 points, or 2.2%, to 4,128.
Despite the sell-off, US stocks remain near all-time highs after surging 30% last year. The S&P 500 is 3% below its record high of 1,848 on January 15.
US stocks have not endured a correction - a drop of 10% or more over time - since October 2011.
The turbulence coincides with a global economic shift: China and other emerging market economies appear to be running into trouble just as the developed economies of the US and Europe finally show signs of renewed strength nearly five years after the end of the Great Recession.
The trouble began on Thursday after a January survey showed a drop in Chinese manufacturing activity. Days earlier, China reported that its economic growth last year matched 2012 for the slowest pace since 1999.
"It is interesting how even a mild tremor in China's growth causes such anxiety around the world," said Eswar Prasad, professor of trade policy at Cornell University.
In Asia yesterday, Japan's Nikkei 225 slipped 1.9% to close at 15,391.56; Hong Kong's Hang Seng shed 1.2% to 22,450.06; and Seoul's Kospi dropped 0.4% to 1,940.56.
Slower growth in China is bad news for countries that supply oil, iron ore and other raw materials to the world's second-biggest economy.
Some of those countries, such as Indonesia and South Africa, were already struggling with an outflow of capital as rising US interest rates drew investors to the United States.