Before the bell:

U.S. stock futures were under pressure Tuesday after Hewlett-Packard issued a weak outlook and as investors geared up for reports on housing and industrial production.
Hewlett-Packard (HPQ, Fortune 500) reported a 3% increase in sales but warned the current quarter will be hurt by Japanese quake impact and weak PC sales. HP shares fell more than 4% in premarket trade. The company reported ahead of schedule after a memo about its outlook was leaked late Monday.
U.S. stocks ended a choppy session lower Monday as investors remained focused on oil prices and the debt crisis in Europe.
Companies: Dow component Wal-Mart Stores (WMT, Fortune 500) reported quarterly income of $3.4 billion and sales of $103 billion, topping analysts' estimates.
Home Depot (HD, Fortune 500) beat forecasts by a penny, reporting earnings per share of 50 cents. But the home improvement retailer posted sales of $16.8 billion, a 0.2% decrease from the year-earlier period.
Earnings from Dell (DELL, Fortune 500) are due after the closing bell. The company is expected to earn 43 cents per share.
World markets: