NEW YORK (CNNMoney.com) - Stocks fell at the open Friday after disappointing earnings from General Electric and Citigroup along with rising oil prices raised concerns on Wall Street.

The Dow Jones industrial average (Charts) tumbled about 0.7 percent as of 10 a.m. ET. The S&P 500 index (down 2.56 to 1,282.48, Charts) and the Nasdaq composite (down 5.10 to 2,296.71, Charts) fell more moderately.

Oil prices jumped near $67 a barrel on concern over the latest audio tapes that surfaced Thursday warning of new al Qaeda attacks. And Nigerian oil unions said Friday they would withdraw from facilities in the oil-rich delta region if violence persisted, raising more fears of supply disruption.

In earnings news, shares of Dow component Citigroup (down $1.02 to $46.92, Research) slipped 2 percent after the bank said fourth-quarter earnings from continuing operations fell 3 percent.

GE (down $0.55 to $34.13, Research) reported fourth-quarter profit fell 46 percent, in line with Wall Street expectations, and raised the lower end of its 2006 guidance. But revenue for the quarter was below forecasts and shares fell over 1 percent.

Motorola (Research) added to earnings worries. The world's second-largest mobile phone maker reported fourth-quarter earnings up about 86 percent from last year but indicated that first quarter earnings and revenue will fall.

Treasury prices were higher, lowering the yield on the 10-year note to 4.35 percent from 4.37 percent late Thursday. The dollar was lower against the euro and the yen.

Asian markets were largely flat, with Tokyo's Nikkei closing virtually unchanged after a week of market slides due to the investigation into the high-flying Internet company Livedoor. European stocks traded just below 4-1/2-year highs.