U.S. stocks fell for a sixth day as unprecedented interest-rate cuts by six central banks failed to convince investors the global economy will avoid a recession.

Alcoa Inc., the largest U.S. aluminum producer, tumbled 16 percent as a reduction in manufacturing caused by the credit crisis left the company with earnings that trailed analyst estimates. J.C. Penney Co. dropped as much as 8.3 percent after same-store sales slumped in September. Russia, Indonesia, Ukraine and Romania shut their exchanges and Brazil's benchmark index fell to the lowest level in two years in the worst week for emerging markets in at least two decades.

The Standard & Poor's 500 Index lost 16.86 points, or 1.7 percent, to 979.37 at 12:21 p.m. in New York. The Dow Jones Industrial Average slid 175.94, or 1.9 percent, to 9,271.17. The Nasdaq Composite Index decreased 1.5 percent to 1,727.86. Four stocks fell for each that rose on the New York Stock Exchange.

"The uncomfortable reality is that this mess is going to take more time than anyone wants to come to grips with," said Matthew Kaufler, a fund manager at Rochester, New York-based Clover Capital Management Inc., which oversees $2.6 billion. "For the first time in couple of decades, we have the prospect of a consumer recession."

The S&P 500's six-day stretch of declines is the longest since April 2002. The gauge's 15 percent slide from Sept. 30 through yesterday was its third-steepest on record, according to Bespoke Investment Group LLC, a Harrison, New York-based research firm. The bigger declines from five straight losses occurred in 1932.

Global Slump

The MSCI World Index of 23 developed markets extended its five-day retreat to more than 14 percent, the worst since the market crash of 1987.

The dollar weakened and 10-year Treasury yields exceeded two-year notes by the most since 2004, signaling investors remain cautious about economic prospects.

The Fed, European Central Bank and four other central banks lowered interest rates in an unprecedented, emergency coordinated bid to ease the economic effects of the financial crisis. The Fed cut its benchmark rate by a half point to 1.5 percent and said the ECB and central banks of the U.K., Canada, Sweden and Switzerland are also reducing borrowing costs.

'More Symbolic'

"It's more symbolic than anything else," said Peter Sorrentino, a money manager at Huntington Asset Advisors in Cincinnati, which oversees $16.5 billion. "It's the availability of credit, not the price of credit that's the problem."