The S&P 500 was 12 points, or 0.6%, lower at 1,852.41. The DJIA shed 22.22 points, or 0.1%, to 16,338.16, after being up as much as 127 points at session highs. The Nasdaq Composite was the worst-performing index, falling 58 points, or 1.4%, to 4,018.07, as biotech and Internet stocks led the losses.