U.S. stocks closed

U.S. stocks tumbled toward the worst levels of last month's selloff as global equities slid amid a rout in commodity and biotechnology shares.

The Standard & Poor's 500 Index fell 2.6 percent to 1,881.85 at 4 p.m. in New York, down for a fifth consecutive session to a one-month low. The Russell 2000 Index slumped 2.9 percent to an 11-month low.

"We are in a chaotic market, lots of volatility but not making much progress in either direction," said James Gaul, a portfolio manager at Boston Advisors LLC, which oversees $2.8 billion. "Earnings are going to be really important this quarter considering the macro backdrop and general global fears as well as the concerns about the Fed potentially raising interest rates as early as next month."

The S&P 500 is down 8.8 percent in the third quarter, poised for its worst fall since 2011. The benchmark is almost 12 percent below its all-time high set in May. The Chicago Board Options Exchange Volatility Index has closed above 20 for the past 26 sessions, the longest streak since January 2012.

Equity markets have been turbulent in recent weeks amid confusion over the Federal Reserve's tightening policy and concern over a slowdown in Asia. Data today showed profits of Chinese industrial companies fell the most since the country's government began compiling data in 2011. Biotechnology shares tumbled on Friday, offsetting gains fueled by Fed Chair Janet Yellen's reassurances that turbulence in emerging markets won't harm U.S. growth.

Federal Reserve Bank of New York President William C. Dudley said today the central bank will "probably" raise interest rates later this year despite uncertainties over global growth. "I think that the economy is doing pretty well," Dudley said at an event in New York. He said he expected growth in the second half will be "a little bit weaker" than in the first half.

A report today showed household spending climbed more than forecast in August and incomes also rose as the biggest part of the U.S. economy continued to power past a global slowdown. Separate data showed contract signings to purchase previously owned U.S. homes unexpectedly declined in August for just the second time this year, signaling residential real estate might have difficulty building on recent momentum.

The Nasdaq Biotech Index slid into a bear market on Friday amid its worst weekly decline in four years. The rout was sparked by a tweet last Monday from Democratic presidential hopeful Hillary Clinton suggesting there may be "price gouging" in the market for prescription drugs. The group had rallied 56 percent from an October low to an all-time high on July 20, and has since plunged 27 percent.

Stocks fell after the Fed's decision to hold off raising rates on Sept. 17 raised questions about the impact of a global growth slowdown on the U.S. Despite Yellen signaling last week that the economy is sturdy enough to handle higher raise rates in 2015, traders are pricing in a 41 percent probability of the event in December and a 48 percent chance in January.