At one point — about 3 p.m. — the Dow dropped almost 200 points in almost a split-second, reports CBS News correspondent Anthony Mason.
That split-second dive, in part, happened because of a computer glitch that kept some trades from being immediately reflected in the index of 30 blue-chip stocks.
But what started the massive meltdown? It was not some bad piece of economic news here at home.
A 9 percent slide in Chinese stocks, which came a day after investors sent Shanghai's benchmark index to a record high close, set the tone for U.S. trading. The Dow began the day falling sharply, and the decline accelerated throughout the course of the session before stocks took the huge plunge in late afternoon as computer-driven sell programs kicked in.
The Dow fell 546.02, or 4.3 percent, to 12,086.06 before recovering some ground in the last hour of trading to close down 416.02, or 3.29 percent, at 12,216.24. Because the worst of the plunge took place after 2:30 p.m., the New York Stock Exchange's trading limits, designed to halt such precipitous moves, were not activated.
"What we're seeing here in the U.S. is something that happened globally overnight," Eugene Peroni of Claymore Advisors told CBS News Radio. "We're seeing most markets lower, so one can't make the case that this is really just particular to the U.S. market."
The decline was the Dow's worst since Sept. 17, 2001, the first trading day after the terror attacks, when the blue chips closed down 684.81, or 7.13 percent.
The drop hit every sector of stocks across the market. Riskier issues such as small-cap and technology stocks suffered the biggest declines.
There are 500 stocks in the Standard & Poor's 500 Index, adds Mason; all but three of then went down.
But analysts who have been expecting a pullback after a huge rally that began last October and sent the Dow to a series of record highs, were unfazed by Tuesday's drop.
"This corrective consolidation phase isn't just going to be one day, but we don't believe this is going to be a bear market," said Bob Doll, BlackRock's global chief investment officer of equities.
Some investors also tried to put Tuesday's slide into a longer-term perspective.
"All who invest should feel grateful that we've had a great run for the last 12 to 18 months," said Joel Kleinman, a Washington, D.C. attorney, adding that he has learned to not read too much into any short-term ups and downs. "This is another day in the market."
Still, traders' dwindling confidence was knocked down further by data showing that the economy may be decelerating more than anticipated. A Commerce Department report that orders for durable goods in January dropped by the largest amount in three months exacerbated jitters about the direction of the U.S. economy, just a day after former Federal Reserve Chairman Alan Greenspan said the United States may be headed for a recession.
"It looks more and more like the economy is a slow growth economy," said Michael Strauss, chief economist at Commonfund. "Moderate economic growth is good — an abrupt stop in economic growth scares people."
The market had been expecting the government on Wednesday to revise its estimate of fourth-quarter GDP growth down to an annual rate of about 2.3 percent from an initial forecast of 3.5 percent, and grew increasingly nervous on Tuesday that the figure could come in even lower.
The housing market, which the Street had been hoping had bottomed out, also looked far from recovery after a Standard & Poor's index indicated that single-family home prices across the nation were flat in December. A later report from the National Association of Realtors said existing home sales climbed in January by the largest amount in two years, but the data didn't erase housing-related concerns, as median home prices fell for a sixth straight month.