The yield on the US Treasury's 10-year bond hit an all-time record low and the dollar reached a nearly two-year high against the euro as investors sought safety from Europe's troubles.
The Dow Jones Industrial Average sank 160.83 points, or 1.28 percent, to finish the session at 12,419.86.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
The S&P 500 index, a broad measure of the markets, tumbled 19.10 (1.43 percent) to 1,313.32, while the tech-rich Nasdaq dropped 33.63 (1.17 percent) to 2,837.36.
"There is nothing that can be considered bullish news from Europe today, so the bearish news on Spain is (in the) forefront," said Dick Green at Briefing.com.
"The bottom line is that the mess in Europe remains a mess. There is no consensus across countries on how to address the credit crisis and the political institutions to deal with EU matters are still feeling their way."
Twenty-nine of the Dow's 30 blue-chip stocks closed in the red, with Intel bucking the sell-off with a fractional gain.
Alcoa skidded 3.5 percent, Caterpillar lost 2.5 percent, General Electric was down 1.6 percent and JPMorgan Chase shed 2.0 percent.
ExxonMobil and Chevron both plunged 2.6 percent amid sharp falls in crude oil prices.
Shares in struggling BlackBerry maker Research In Motion plummeted 7.1 percent after the company warned after markets closed Tuesday that it expected an operating loss in the current quarter and had hired investment banks to weigh its options.
Facebook fell 2.3 percent to $28.19, almost $10 below its May 18 market debut price of $38.
Monsanto was a rare bright spot, up 2.2 percent after raising its earnings outlook on strong seed sales.
So was Apple, up 1.2 percent after chief executive Tim Cook hinted that products on the horizon could come in the area of television.
With fear sweeping the Street, nervous investors awaited a series of US economic data, capped Friday by the keenly awaited May jobs report.
"With so little news flow today many participants anxiously await the second reading on first-quarter GDP, which is due tomorrow along with weekly initial jobless claims and the latest monthly ADP Employment Change," said Briefing.com analysts.
The bond market rallied sharply. The yield on the 10-year Treasury bond dropped to 1.63 percent from 1.73 percent Tuesday, an all-time low, while the 30-year fell to 2.72 percent from 2.84 percent.
Bond prices and yields move in opposite directions.
