U.S. stocks ended more than 1 percent lower on Wednesday after rallying the day before, led by declines in Apple shares and in energy companies, which fell with oil prices.
Apple shares ended down 1.9 percent at $110.15 in heavy trading, erasing earlier gains as it launched new products in San Francisco. Chief Executive Tim Cook announced a new version of the Apple TV with an app store and voice-controlled remote control. Some analysts said investors sold Apple shares because expectations were so high heading into the event.
Among Apple's suppliers, Qualcomm shares fell 1.6 percent at $54.32, Skyworks Solutions was down 1.5 percent at $86.42 and Avago Technologies was down 1.5 percent at $127.17. U.S.-traded shares of STMicroelectronics NV fell 6 percent to $7.04.
Energy led declines among S&P 500 sectors, falling 1.9 percent as U.S. oil prices settled down 3.9 percent. Chevron was down 2.5 percent at $74.92.
The volatile session reversed early gains of as much as 1 percent. Indexes had rallied more than 2 percent on Tuesday.
"We had a nice rally yesterday based on an oversold position. There really wasn't anything to create a follow-through, so the buying just kind of ran out of steam," said Bucky Hellwig, senior vice president at BB&T Wealth Management in Birmingham, Alabama. "Investors are still looking for policy developments out of China, and also wary of what might come out of the Fed next week."
The Dow Jones industrial average fell 239.11 points, or 1.45 percent, to 16,253.57, the S&P 500 lost 27.37 points, or 1.39 percent, to 1,942.04 and the Nasdaq Composite dropped 55.40 points, or 1.15 percent, to 4,756.53.
U.S. job openings surged in July, Labor Department data showed, suggesting strength in the economy ahead of the U.S. Federal Reserve's interest rate meeting next week.
Overseas, China's Ministry of Finance said the government will strengthen fiscal policy, boost infrastructure spending and speed up tax reform, adding steps to re-energize growth.
Global financial markets have been rattled in recent weeks by fears that China's slowdown could drag on already sluggish global growth, prompting some investors to bet that the U.S. central bank will delay a hike until the end of the year.