Trader Stephen Guilfoyle, center, works on the floor of the...

Trader Stephen Guilfoyle, center, works on the floor of the New York Stock Exchange. (Aug. 2, 2011) Credit: AP

Stocks fell for the eighth straight day Wednesday as worries about the economy deepen. The S&P 500 index was headed for its longest losing streak since the peak of the financial crisis in October 2008.

Investors are growing increasingly concerned about the economy. Shortly after the market opened, the Institute of Supply Management said its index measuring the service sector of the U.S. economy grew at the weakest pace in 17 months in July. Economists had expected a slight increase.

The report was the latest sign that the U.S. economy may be slowing. Over the last week, investors have reacted to reports that consumers are cutting back spending, a slowdown in manufacturing, and that the U.S. economy did not grow as much as previously thought in the first three months of the year.

The Dow Jones industrial average lost 129 points, or 1.1 percent, to 11,738 in late morning trading. The S&P 500 was down 17 points, or 1.3 percent, to 1,236. The Nasdaq composite fell 41, 1.6 percent, to 2,626.

The yield on the 10-year Treasury note fell to another low for the year of 2.57 percent, from 2.62 percent Tuesday, as investors moved money into assets that hold up better during economic downturns. Gold, another traditional safe haven, rose nearly 2 percent to $1,671 an ounce.

All but one of the 30 companies in the Dow lost ground. Companies that outperform in expanding economies fell the most. Caterpillar Inc., Boeing Co. and Chevron Corp. led the Dow lower with losses of 2 percent or more.

Several large U.S. companies reported earnings before the market opened. MasterCard rose nearly 6 percent after the company beat analysts' estimates. Clorox fell 2 percent after the company said higher commodity costs were eating into its income.

Before the market opened, payroll processor ADP said private companies added 114,000 jobs last month. The number was within Wall Street's forecasts, but still well below the rate of growth that signifies a healthy jobs market. ADP's employment figures do not always predict the government's broader employment report, which will be released Friday morning. Last month, for example, ADP reported that private employers added 157,000 jobs in June. The government later said that private companies added just 57,000 jobs.

Analysts predict that the unemployment rate was 9.2 percent in July, unchanged from the month before.

A report that consumers cut their spending in June for the first time in nearly two years led to a broad sell-off on the stock market Tuesday. The Standard & Poor's 500 index lost 33 points, or 2.6 percent, turning the widely used market indicator negative for the year. The Dow Jones industrial average fell 266 points, or 2.2 percent.

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