US stocks plunged Wednesday led by tech shares as a key oil stockpiles report and the Federal Reserve's Beige Book pointed to more sluggish US economic growth.
The blue-chip Dow Jones Industrial Average lost 364.81 points, or 2.2 percent, to 16,151.41.
The S&P 500 sank 48.40, or 2.5 percent, to 1,890.28, while the Nasdaq Composite lost 159.85 (3.4 percent) at 4,526.06.
There was no clear catalyst for the selloff, after Wall Street opened with a buoyancy that gave hope to a third straight gain.
But it came as investors remained cautious at the opening of the fourth-quarter earnings season, and with China's economic troubles still far from over.
The Beige Book, the Fed's regional survey of economic conditions, was somewhat less buoyant than December's, but was not downbeat.
A bearish US crude and fuel stockpiles report took the wind out of a rebound in oil prices and that spilled over into equities again, said Michael James at Wedbush Securities.
"Oil is a key determinant of economic strength and as long as we continue to have imbalances in supply and demand, until demand starts to pick up, you're not going to have an increase in the price of oil," he said.
"A majority of traders are using the lack of increased demand for oil as a read-through for global growth in general," he said.
The losses were heavy across the board. Tech-sector leaders Amazon, the foundation of the S&P 500's gains last year, fell 5.8 percent while Twitter (Xetra: A1W6XZ - news) lost 4.8 percent. Alphabet (Google) gave up 3.5 percent and Apple (LSE: 0R2V.L - news) 2.6 percent.
Losses were also heavy across the biotech sector; the Nasdaq (NasdaqGS: NDAQ - news) biotech index lost 5.3 percent.
Banks slid on the eve of the first quarterly reports from the sector. Citigroup (NYSE: C - news) dropped 3.6 percent and Wells Fargo (Hanover: NWT.HA - news) 3.2 percent.
Of the Dow blue chips, Home Depot (Swiss: HD.SW - news) was the worst performer, down 4.8 percent, and Goldman Sachs (NYSE: GS-PB - news) followed, off 4.1 percent.
Most oil sector shares also sank but, in a move to safety within the sector, investors moved to the largest firm, ExxonMobil, making it ironically the only gainer on the Dow, up 0.6 percent.
General Motors (NYSE: GM - news) was also a gainer, rising 0.6 percent, after it lifted its 2016 earnings forecast, raised its dividend by six percent, and boosted its share repurchase program by $4 billion to $9 billion.
Rival Ford though lost 5.1 percent after it announced, by comparison, a special one-time dividend and projected 2016 earnings only in line with 2015.
Railroad CSX, one of the first companies to deliver fourth-quarter and full-year 2015 earnings results, lost 5.7 percent and dragged down other transport stocks as it reported a 13 percent fall in income in the final quarter, largely due to a slump in coal shipments.
Rival rail carrier Union Pacific (Swiss: UNP.SW - news) fell 3.2 percent and Norfolk Southern lost 5.9 percent.