Lower stock prices on Thursday set up investors for what would be their third day in a row of declines.
Stocks have risen sharply this year, and some analysts have been wondering if buyers will begin to get more choosy. Also, some investors are worried that a recovering U.S. economy suggests that the Federal Reserve may wind down its stimulus, which has helped to lift stock prices.
About 45 minutes after trading began, the Dow Jones industrial average was down 85 points, or 0.5 percent, at 15,770. The Standard & Poor's 500 index was down five points, or 0.3 percent, at 1,778. The Nasdaq was down five points, or 0.1 percent, at 4,002.
Stocks posted their biggest declines in five weeks on Wednesday, but the Dow is still up more than 20 percent for the year, and the S&P 500 is up almost 25 percent.
In economic news, the number of people seeking unemployment benefits rose to about where it was before the Great Recession.
Also, U.S. shoppers spent more money on appliances, furniture and cars in November. Spending had been muted for months heading into the crucial holiday shopping period, a worrisome sign for investors. Retail sales rose 0.7 percent, the biggest gain in five months. October sales were also revised higher.
Facebook rose $1.62, or 3.3 percent, to $51 after the stock was added to the S&P 500 index.
Lululemon Athletica fell $5.03, or 7.3 percent, to $63.31 after the upscale yoga clothing maker issued a poor sales outlook. Lululemon said a key sales figure will be flat in the next quarter, and revenue for the year will be less than it had predicted.
W.W. Grainger fell after reporting disappointing November sales. The stock fell $5.26, or 2 percent, to $248.70.
Hilton Worldwide jumped $1.49, or 7 percent, to $21.49 on its first day of trading.
Stocks were lower in Europe, too, including a 1.1 percent decline in Britain's FTSE.
The yield on the 10-year Treasury note rose to 2.88 percent, from 2.85 percent on Wednesday.