"The market is going to open sharply lower in a spill-over from the Chinese decline and geopolitical concerns," said Peter Cardillo, chief market economist at Avalon Partners.

A steeper-than-expected drop in durable goods orders in January also fueled growth concerns. At 10 a.m., the market will get an update on the housing market, with the release of January existing home sales.

"The market is still at very high levels and we're also getting a long list of economic data. Investors are going to be playing quite close to the vest while bonds are going to be the big beneficiary today," said Cardillo.

Futures for the Dow Jones Industrial Average were down 107 points at 12,547, while those for the S&P 500 index fell 15 points to 1,437.

Nasdaq 100 futures fell 30 points to 1,807.

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"Crude oil getting back above $61 is a bit of a concern," said Owen Fitzpatrick, head of U.S. equity at Deutsche Bank. "Tech has been on the run and we're also seeing some profit-taking there, especially money flowing out of semiconductors."

The Dow Jones Industrial Average gave up early gains to close down 15 points at 12,632, with 17 of its 30 components finishing in negative territory.

The Dow rose to 12,662 in early action but quickly gave up its gains, weighed by the likes of Boeing Co., Hewlett-Packard and IBM.

The S&P 500 fell 1.8 points to 1,449, marking the first four-session losing streak for the broad market index since August of 2006. Participants who follow market technicals may see the move as indicative of a long-awaited pull-back, after the market's uninterrupted run since July of last year.

The Nasdaq Composite dropped 10 points to close at 2,504.

Overnight comments from former Federal Reserve Chairman Alan Greenspan, who warned of a possible recession in the U.S. before year end, as he cited "stabilizing" profit margins, also fueled concerns about growth.

"We got off to a stronger start than maybe was warranted," said Art Hogan, chief market strategist at Jefferies & Co. "We've got the biggest leveraged buy-out in history and signs of more to come, but how does that really affect the macro picture?"

"At the same time, we're getting an increase in the price of oil, the market's worried about inflation, subprime mortgages, housing and the economy slowing down."

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Investors will also be keeping a wary eye on Federal Reserve Chairman Ben Bernanke when he speaks on U.S. fiscal policy and, in a separate speech, globalization and inflation. In addition, the markets will be hit with February car sales, which may offer further evidence of trouble in the beleaguered U.S. car industry, and a few high-profile corporate earnings reports.

"This could be a critical test week for the market," said Philip Dow, director of equity strategy at RBC Dain Rauscher. "We've had back-to-back down days...you've got key reports that could be viewed by some as conclusive [about economic conditions] in the short term. So, the market could be vulnerable."

Corporate earnings reports from American International Group and Dell Inc. will be among the last high-profile events of the quarterly earnings season.

General Motors has a regulatory deadline of Friday to report its fourth-quarter results. However, the automaker, which delayed the report as it conducts an accounting review, has said it may seek an extension until March 16.

Other companies putting out results include XM Satellite Radio and Sirius Satellite Radio, which agreed last week to merge.

The recent rise of crude oil prices -- which have now hit their highest levels of the year -- following a higher-than-expected uptick in consumer price inflation last week will put investors on edge as they await the core personal consumption expenditure price index, the Fed's favored gauge of inflation.

"That could be a number that takes the market down a percent if it's too hot," said Dow.

More generally, investors who have begun to expect the economy will come in for a soft landing marked by steady growth and contained inflation may react negatively if economic news casts doubt on that scenario.

"We're all focused on this Goldilocks scenario...anything that's outside of that or doesn't meet that expectation...will create a little bit of selling," said John Hughes, managing director of Epiphany Equity Research. "We would expect sideways to a slightly lower (direction) at this point."

Key to assessing the likelihood of the soft landing will be figures on sales of existing and new homes, due Tuesday and Wednesday. The numbers will provide insight on "how the individual consumer is holding up, and how are they approaching the (real estate) market," particularly in light of the recent flare-up in worries about the deterioration of the subprime loan market, said Joe Sunderman, director of research at Schaeffer Research.

Economists expect existing home sales to rise to 6.35 million from 6.22 million, while sales of new homes are expected to decline to 1.12 million from 1.2 million.

Other high-profile data include the Institute of Supply Management's report on manufacturing activity, scheduled for Wednesday. The index for February is expected to tick up to 50 from 49.3 in January. A reading above 50 signals expansion.

Durable goods orders for January will be delivered Tuesday, with economists expecting a decline of 5.7% compared with a rise of 2.9%.

Also to come Wednesday will be remarks on the subject of liquidity and financial markets by New York Federal Reserve President Timothy Geithner, a voting member of the central bank's rate-setting body.

Investors will get a look at the final reading on fourth-quarter gross domestic product from the Commerce Department on Wednesday. Economists surveyed by MarketWatch expect the annual growth rate to come in at 2.2%, easing back from the faster-than-expected surge of 3.5% reported in January.

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A mid-morning report from the International Atomic Energy Agency took the momentum out of the market that had stemmed from, among other things, news that Whole Foods Market Inc. agreed to buy smaller rival Wild Oats Markets.

According to Mike Malone, trading analyst at Cowen & Co., the release of the IAEA report might have served as a trigger for the market to consolidate recent gains.

"The news out of Iran shouldn't be much of a surprise to the market, but we were hitting technical resistance," he said.

The Dow Jones Industrial Average closed down 52 points at 12,686, with 22 of its 30 components in negative territory.

"It's a nondescript kind of market, right now," said Paul Nolte, director of investments at Hinsdale Investments. "The market looks heavy at this point, but investors continue to buy the dips, and the dips remain very shallow."

The S&P 500 fell 1.2 points to 1,456, while the Nasdaq Composite erased earlier losses to close up 6.5 points at 2,524.

Market sentiment also absorbed crude-oil futures approaching $61 a barrel, amid the tensions surrounding Iran and following weekly U.S. inventories data. Crude oil gained 88 cents to close at $60.95, after earlier trading as high as $61.25.

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But minutes from the Federal Reserve's last meeting on interest rates, released in afternoon trade, showed that the Fed wasn't overly concerned about inflation at the end of January, and somewhat soothed the market's worries.

"The minutes had a bit of a calming effect on the market," said Jay Suskind, director of trading at Ryan, Beck & Co. "They show the Fed seems to be on the fence about both inflation and a slowing economy, just like the markets are."

The Dow Jones Industrial Average fell 48 points to close at 12,738, with 20 of its 30 components in negative territory. The Dow earlier fell to a low of 12,707.

The S&P 500 closed down 2 points at 1,457, while the tech-heavy Nasdaq Composite reversed early weakness to close up 5.3 points at 2,518.

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