
Dow Jones Industrial Average fell 64.05 points to close at 14,946.46, on track for biggest monthly loss since last May.
S&P 500 index dropped 6.72 points to close at 1,656.78.
Most key S&P sectors ended lower, on telecoms and consumer staples; healthcare stocks gained.
Nasdaq composite fell 0.22 points to 3,657.57.