Stock futures pointed to a lower Friday opening as investors worried that a massive power outage that swept across swaths of the eastern United States and Canada Thursday afternoon would disrupt business on Friday.

The mammoth power outage left sections of New York, Detroit, Cleveland and Toronto without electricity.

The New York Stock Exchange told Fox News late Thursday that it planned to open for normal trading on Friday at 9:30 a.m. EDT even if it had to operate on a generator, and that no data from Thursday's trading session had been lost.

Fears of civil unrest -- if power is not restored quickly -- could be hurting futures, traders said.

"I don't think people are fearing terrorism. I think they are fearing massive looting in cities like New York and Detroit if the power doesn't come back up before it gets dark out," said Keith Keenan, vice president of institutional trading at brokerage Wall Street Access. "Obviously, that creates economic problems. I think that's the reason why you're probably seeing the futures market move lower after hours."

In the regular session, the blue-chip Dow Jones industrial average added 38.80 points, or 0.42 percent, to finish at 9,310.56. The broader Standard & Poor's 500 Index rose 6.48 points, or 0.66 percent, to 990.51. The technology-laced Nasdaq Composite Index gained 13.73 points, or 0.81 percent, to finish at 1,700.34, based on the latest available data.

Early Thursday, government data showed signs of job market stability and a sharp narrowing in the U.S. trade gap after the biggest export surge in three years.

The data pointed to the economic rebound investors had been betting on since early spring. Wall Street's reaction was muted early in the day, but stocks cut early losses and crawled higher as the session progressed.

The market also got a boost after a report that an Indonesian man known as "Hambali," suspected mastermind of the Bali bombings and the more recent JW Marriott hotel blast in Jakarta, has been captured.

People feel "the threat of further terrorist attacks is somewhat reduced," said Tim Heekin, director of trading at investment bank Thomas Weisel Partners. "It's a victory for the U.S., so it is a little bit of a relief pop."

Hambali was the most wanted man in Southeast Asia and was seen as the bridge between the militant group Jemaah Islamiah and Osama bin Laden's al Qaeda, blamed for the Sept. 11 attacks in 2001.

Rising bond yields kept a lid on stock price gains. U.S. Treasury prices fell for a fourth straight session, sending the yield on the benchmark 10-year note to a 1-year high near 4.67 percent. Some investors fear that rising bond yields could choke economic growth by raising borrowing costs.

But after the power outage, Treasury prices jumped. The 10-year note's price rose 9/32, while its yield fell to 4.53 percent.

The number of Americans filing first-time claims for jobless benefits edged up slightly last week, the government said Thursday. But the number held below 400,000 for the fourth consecutive week, which economists say indicates some job creation.

Initial claims for state unemployment benefits rose a slim 2,000 to 398,000 in the week ending Aug. 9, the Labor Department said.

A separate report showed the U.S. trade gap at a smaller-than-expected $39.5 billion in June, down from $41.5 billion in May on the biggest surge in exports in three years.

A third government report showed the overall U.S. Producer Price Index, a gauge of inflation at the wholesale price level, crept up 0.1 percent in July, helping keep deflation fears at bay without sparking inflation concerns.

Intel (INTC) , the world's largest maker of computer chips, rose 43 cents, or 1.7 percent, to $25.14 and ranked as the Nasdaq's most active share. Web gear giant Cisco Systems Inc. (CSCO) added 21 cents to $17.80.

International Paper (IP) climbed $1.11 to $40.80, and aluminum producer Alcoa Inc. rose 78 cents to $27.80. Both led the Dow higher.

But McDonald's Corp. (MCD) dragged on the blue-chip gauge with a loss of 22 cents to $22.95. Wachovia Securities cut the fast-food company to "market perform" from "outperform," saying the shares are "near fully valued."

Diversified manufacturer 3M Co. (MMM) added more pressure to the Dow, skidding $2.36 or 1.63 percent to $142.14. Smith Barney cut its rating on 3M to "in-line" from "outperform" to "reflect its recent strong upward move."

Target (TGT) dropped $2.24 to $37.70 on second-quarter earnings that missed analysts' expectations by a penny a share.

The Russell 2000 index, which tracks smaller company stocks, rose 3.75, or 0.8 percent, to 471.22.

Overseas, Japan's Nikkei stock average finished Thursday up 1.7 percent. In Europe, Britain's FTSE 100 rose 1.4 percent, while France's CAC-40 and Germany's DAX index each climbed 1.7 percent.

Reuters and the Associated Press contributed to this report.