NEW YORK, Sept 17 (Reuters) - U.S. stocks turned flat in choppy trade on Thursday as investors paused following a 3-day run-up.
* Initially the market was boosted by data that showed factory activity in the U.S. Mid-Atlantic region rose in September to the highest level since June 2007.
* The Dow Jones industrial average was up 5.59 points, or 0.06 percent, at 9,797.30. The Standard & Poor's 500 Index was down 0.14 points, or 0.01 percent, at 1,068.62. The Nasdaq Composite Index was down 1.71 points, or 0.08 percent, at 2,131.44.