Stocks set to struggle
Big losses at Delta and Ambac pressure stock futures, offsetting upbeat results from Boeing and Yahoo; more on deck.
NEW YORK (CNNMoney.com) -- Stocks were poised for a mixed open Wednesday as investors weighed a flurry of corporate earnings news including bigger-than-expected losses from both Delta Air Lines and the bond insurer Ambac.
Less than an hour before the start of trading, S&P futures were lower while Nasdaq futures were higher, suggesting a negative start for stocks.
In focus for investors was a devastating loss by Delta (DAL, Fortune 500). The airline blamed exorbitant fuel prices for its massive first-quarter loss of $6.4 billion.
Ambac Financial Group (ABK) also reported a $1.66 billion loss, as it stopped underwriting risky bonds. The bond insurer grabbed headlines earlier this year after rating agencies threatened to strip the company of its sterling AAA rating, which could have sparked another wave of devastating writedowns at the nation's largest financial firms.
"It's all about earnings," said Peter Cardillo, chief market economist at Avalon Partners. "I would suspect perhaps the Ambac report is having an early impact, but the data is young and there is a lot out there."
Offsetting that negative news were better-than-expected results from planemaker Boeing (BA, Fortune 500) which earned $1.2 billion in the first quarter.
Package delivery firm UPS (UPS, Fortune 500) also reported improved results, although the company lowered its earnings guidance for the year.
Investors will be keeping a close eye on tech sector once again Wednesday after Yahoo (YHOO, Fortune 500) reported solid profit and sales that topped Wall Street's estimates just a day earlier. Both Apple (AAPL, Fortune 500) and Amazon.com are due to report after the closing bell.
While Yahoo's results were strong, the company has until Saturday to accept Microsoft's takeover offer or face a proxy fight. It remains unclear whether Microsoft (MSFT, Fortune 500) will be swayed to raise its offer. If it doesn't, the takeover battle could turn ugly.
GM (GM, Fortune 500) is due to release its first-quarter global sales before the market open. Detroit's Big 3 automakers have been battered by slumping sales and are expected to rack up more losses this year.
In other corporate news, the classifieds company Craigslist suggested that eBay (EBAY, Fortune 500), which owns a stake in the privately-held firm, may be attempting a hostile takeover after the online auction house filed a lawsuit against Craigslist on Tuesday.
Oil prices moved slightly lower Wednesday after hitting yet another record high a day earlier. Light, sweet crude for June delivery fell 72 cents to $117.35 in electronic trading on the New York Mercantile Exchange.
Prices could move back up, however, after the latest U.S. oil inventory report, which is due out at 10:30 a.m. ET. The inventory report is one of the few economic readings due out Wednesday other than the weekly reading on mortgage applications.
Meanwhile, retail gasoline prices have hit yet another high, according to auto group AAA. The national average price for a gallon of regular unleaded gasoline has risen to $3.533.
In global trade, Japan stocks gained, led by oil firms. Major markets in Europe fell in midday trading.
The dollar moved higher against the euro and eased versus the yen. 
