Economic security

Oil, stocks off on weak data; Europe shares up

The U.S. Federal Reserve is widely expected to raise interest rates for the first time in nearly a decade before the end of the year. If Chinese weakness seeps into the U.S. economy, the Fed could reassess its plan to hike rates and markets would have to balance between more support from the central bank and the expectation for slower growth.

"The slowdown in China [is] feeding into a slowdown in Asia, and the question becomes how much of that is feeding into the U.S.?" said Quincy Krosby, market strategist at Prudential Financial in Newark, New Jersey.