Stocks in retreat again

NEW YORK (CNNMoney.com) -- U.S. stocks opened lower Thursday as weak retail sales and a dismal outlook from Cisco Systems weighed on investors.

The Dow Jones industrial average lost 0.2 percent. The Nasdaq composite index slipped 0.9 percent. The Standard & Poor's 500 index was 0.3 percent lower.

Among companies in the news at Tuesday's open:

Wal-Mart Stores: The No. 1 retailer reported January sales at stores that were much weaker than expected. Stock (WMT, Fortune 500)

Cisco Systems: The leading network equipment maker posted fiscal second-quarter sales and earnings that met Wall Street's estimates, but warned revenue would only grow below expectations in its next quarter. Stock (CSCO, Fortune 500)

Delta Air Lines, Northwest Airlines: The two companies are reported to be inching closer to a combination that would create the nation's largest carrier, with a deal possibly coming next week. Delta (DAL, Fortune 500) Northwest (NWA, Fortune 500)

PepsiCo: The world's second-largest soft drink maker said its fourth-quarter profit fell 30% from results a year ago that included a tax benefit. Stock (PEP, Fortune 500)

D.R. Horton: The nation's largest homebuilder swung to a loss in its fiscal first quarter, due to hefty charges to write off inventory and land values as the housing slump continues to worsen. Stock (DHI, Fortune 500)

On the economic front: Initial filings for unemployment claims fell by 22,000 last week, but the government's 4-week average was the highest in a month. Details

-- from staff and wire reports