Wall Street was set for a slightly lower open on Tuesday, pressured by a negative outlook from Hewlett-Packard Co , the world's largest technology company, and weak U.S. housing data.

The shares of a number of tech companies were expected to start lower after HP cut its financial forecasts due to problems stemming from Japan's earthquake, soft PC sales and lowered expectations for its service business. HP's stock was down 5.3 percent at $37.69 in premarket trade.

U.S. housing starts and permits for future home construction fell in April as an overhang of homes on the market discouraged builders from beginning projects, pointing to prolonged weakness in the housing sector.

Housing starts are a continuation of the disappointing data that clouds any U.S. recovery, said Douglas Borthwick, managing director at Faros Trading in Stamford, Connecticut.

S&P 500 futures fell 3 points and were below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration of the contract. Dow Jones industrial average futures lost 48 points while Nasdaq 100 futures fell 9 points.

The weak outlook from HP is likely to push the Nasdaq composite index <.IXIC> lower, which had declined sharply in the previous session as investors sold recent winners in a sign of unease about pockets of U.S. economic weakness.

In other earnings news, Wal-Mart Stores Inc posted a bigger-than-expected jump in quarterly profit on Tuesday, as strength overseas mitigated continued pressure in the United States. Wal-Mart's U.S. same-store sales have now fallen for two years. The stock was down 1.4 percent to $55.25 in premarket trade.

Home Depot Inc shares fell 0.5 percent to $36.78 after the home improvement company reported weaker-than-expected quarterly sales.

The results came the day after its rival, Lowe's Cos , reported weaker-than-expected quarterly sales and earnings and cut its forecast for the year.

HP's rival, computer maker Dell , is due to report quarterly earnings after the bell.

Investors will now be closely looking at other big names like Dell to see if this (the weak results) is a trend (in the industry) or if this is just isolated to certain companies, said Sal Arnuk, co-manager of trading at Themis Trading in Chatham, New Jersey.

New York Attorney General Eric Schneiderman is investigating Bank of America Corp , Morgan Stanley and Goldman Sachs about mortgage-backed securities, the Wall Street Journal said, citing sources.

Mining equipment maker Joy Global is to buy Rowan Cos Inc's drilling and mining gear unit for $1.1 billion in cash.

(Reporting by Angela Moon, Editing by Kenneth Barry)