American stocks tumbled, sending the Standard & Poor’s 500 Index to the longest stretch of losses since January, after rising jobless claims heightened concern the economic slump is worsening and a decline in oil pushed energy producers lower.

Caterpillar Inc., Boeing Co., and United Technologies Corp. retreated as much as 5.6% after higher unemployment spurred concern about Friday’s monthly jobs report. Exxon Mobil Corp. dragged energy shares in the S&P 500 to the lowest level since February. Banks and brokerages fell 4.7% after bond investor Bill Gross warned of a “financial tsunami.”

The S&P 500 dropped for a fourth day, decreasing 38.15 points, or 3%, to 1,236.83, sinking the most since June 6. The Dow Jones Industrial Average lost 344.65, or 3%, to 11,188.23. The Nasdaq Composite Index slipped 74.69, or 3.2%, to 2,259.04. Eleven stocks fell for each that rose on the New York Stock Exchange.

“If you look at the data we have on the U.S. and global economy, things are only getting worse and that leads me to believe that demand is going to slow down and slow down pretty quickly,” a New York-based investment strategist at Invesco Ltd., which manages more than $500 billion, Diane Garnick, told Bloomberg Radio.

Stock-index futures started falling after the Labor Department said at 8:30 a.m. New York time that the number of Americans collecting unemployment benefits reached a five-year high. The selling accelerated as oil declined an hour and a half later. The majority of the drop occurred after the S&P 500 slipped below 1,261.16, a one-month intraday low that traders said represented a level of support for the market.

The S&P 500 has lost 16% in 2008 as subprime-related losses at global banks climbed above $500 billion and the American economy teetered on the brink of a recession. This week’s losses pared the rebound in the benchmark stock index to 1.8% from an almost three-year low set on July 15.