NEW YORK (CNNMoney.com) - U.S. stock indexes were poised for a mixed opening at Wednesday's open, after a disappointing outlook from Dow component DuPont as well as a downgrade of Yahoo! took some of the steam out of the market.

U.S.stock futures were mixed with the Nasdaq under water. Merrill Lynch reportedly downgraded Yahoo (Research) to neutral from buy, putting pressure on the tech sector.

DuPont (Research) cut its fourth-quarter earnings outlook to 10 cents a share from 20 to 25 cents a share, citing operational disruptions related to last year's hurricanes and lower-than-expected performance in three business segments.

"DuPont's guidance is going to make investors question the Dow components," following Alcoa's hurricane-related earnings miss Tuesday, said Art Hogan, market strategist at Jefferies & Co. "Corporate news will dominate the minds of investors as we're starting to kick off with earnings season."

He added that the impact from rising energy costs as consumers start to see higher heating bills should also impact the market, particularly in the first quarter.

Investors will be paying close attention to the weekly crude oil inventory report, due after the open, as energy prices remain high despite a wave of unseasonably warm weather in the Northeast.

Oil prices reversed course after earlier gains. The February light crude futures contract for NYMEX fell 18 cents to $63.19 a barrel in electronic trading, while the February contract for Brent crude dropped 16 cents to $61.76.

Treasury prices edged lower, with the yield on the 10-year note rising to 4.43 percent fron 4.42 percent late Tuesday. Bond prices and yields move in opposite directions.

The dollar was virtually unchanged against the euro but lost some ground against the yen

Asian markets ended mostly higher with Tokyo's Nikkei index up following a rally in property and chip stocks. European markets were also higher.

In corporate news, Genentech (Research) reported higher quarterly earnings from a year earlier, in line with analysts' estimates. However, sales of its cancer colon treatment Avastin were short of estimates, which is expected to put pressure on the stock.

And Guidant (Research) was in the spotlight after the New York Times reported that Johnson & Johnson (Research) made a last minute effort to negotiate a new deal to buy the company following a $25 billion bid from Boston Scientific (Research). The Times, citing people familiar with the matter, said it was unclear if Johnson & Johnson had actually made a higher formal bid, but Guidant is expected to announce its decision Wednesday.

For a more detailed look at the markets before the open, click here.