The Standard & Poor's 500 Index trimmed its worst quarterly decline since 2011, as health-care shares rebounded from their longest losing streak in four years.

The S&P 500 Index rose 0.1 percent to 1,884.03, at 4:03 in New York, and is down 4.5 percent in September, following August's 6.3 percent retreat. The Nasdaq Composite Index lost 0.6 percent as Apple Inc. sank 3 percent.

Stocks have been volatile in recent weeks amid confusion over the Federal Reserve's rate-tightening policy while concern lingers that an economic slowdown in Asia will curb demand for commodities and crimp global growth. The S&P 500 is poised for its worst quarter since 2011, down 9 percent. The benchmark is 12 percent below its all-time high set in May.

The turbulence underscores the disparity between investors confident in the U.S. economy and those concerned about sliding commodity prices and slowing Chinese growth. Fed officials insist the recovery has sufficient momentum to cope with higher interest rates. Still, the selloff in U.S. shares has prompted at least two of the bull market's biggest cheerleaders to cut their year-end forecasts for the S&P 500 by as much as 9.7 percent.

Goldman Sachs chief U.S. equity strategist David Kostin also lowered his year-end price target for the equity benchmark. He now estimates a level of 2,000, down from 2,100 earlier, because of slower than anticipated growth from the world's two biggest economies and lower-than-expected oil prices.

A report today showed consumer confidence unexpectedly gained this month as persistent job gains helped Americans shake off the effects of tumbling stock prices. Another report showed home prices in 20 U.S. cities rose 5 percent in July from the same month a year earlier, propelled by improving demand and limited supply.

Traders are split on whether the Fed will raise rates this year. They are pricing in about a 38 percent chance of an increase in December, and a 47 percent probability in January.