NEW YORK (CNN/Money) - Stocks weakened Thursday morning as rising energy prices trumped any positive corporate news or economic readings.

The Dow Jones industrial average (down 4.46 to 10,468.63, Charts), the Standard & Poor's 500 (down 2.83 to 1,214.06, Charts) index and the Nasdaq composite (down 3.63 to 2,111.77, Charts) all retreated in the early going.

Stocks have had a particularly volatile week as investors have juggled concerns about energy prices and the economy. Meanwhile, the last week of the quarter has meant increased trading volume, usually to the upside, as money managers make last-minute changes to their portfolios.

Those concerns remained in play Thursday.

Oil prices continued to climb on fears and confusion about the impact of the recent hurricanes on the U.S. oil infrastructure. U.S. light crude oil for November delivery rose 65 cents to $67 a barrel in electronic trading.

A pair of economic reports released in the morning were fairly upbeat, but neither reflected the full impact of hurricanes Katrina and Rita.

Weekly jobless claims plunged by a greater-than-expected 79,000 last week, but do not fully incorporate the fallout from Rita.

Meanwhile, the government said that gross domestic product growth (GDP) in the second quarter grew at 3.3 percent annualized pace, unchanged from an earlier read and in line with forecasts.

Among stock movers, PepsiCo (up $1.69 to $56.75, Research) rose after reporting improved quarterly earnings that topped forecasts Thursday morning. The beverage and snack producer also boosted its full-year earnings forecast.

Shares of Research in Motion (down $5.95 to $71.30, Research) slipped despite the company's improved quarterly earnings and forecast. The company makes the BlackBerry wireless device.

Treasury prices eased, raising the yield on the 10-year note to about 4.29 percent from 4.25 percent late Wednesday. Treasury prices and yields move in opposite directions.

The dollar gained modestly against the euro and the yen.

COMEX gold fell 50 cents to $472.60 an ounce.

In global trade, major Asian markets rose, while European markets were mixed at midday.