NEW YORK, Sept. 16 -- U.S. stocks dropped on Friday as the market remained volatile amid concerns about the pace of central bank tightening.

The Dow Jones Industrial Average fell 139.40 points, or 0.45 percent, to 30,822.42. The S&P 500 was down 28.02 points, or 0.72 percent, to 3,873.33. The Nasdaq Composite Index decreased 103.96 points, or 0.90 percent, to 11,448.40.

Nine of the 11 primary S&P 500 sectors ended in red, with energy and industrial down 2.17 percent and 2.06 percent, respectively, leading the laggards. The consumer staples and the real estate groups eked out modest gains.

Wall Street weighed how high the Federal Reserve will raise rates when its meets next week and Tuesday's hotter-than-expected U.S. consumer price index report cemented another big rate hike.

"While it's a near certainty they go at least 75 basis points, there's growing speculation they could raise by 100 bps," Kevin Matras, executive vice president at Zacks Investment Research, said Friday in a note, adding investors will also look for clues on how high Fed policymakers intend to raise "for the rest of the year, and next."

As macroeconomic and policy uncertainty remains elevated, further market volatility is expected ahead, according to analysts.

For the week, the Dow declined 4.1 percent, the S&P 500 lost 4.8 percent, and the Nasdaq dropped about 5.5 percent.

  - Xinhua