US STOCKS-Wall St ends down in volatile day; materials a drag
* Materials drag, led by Freeport McMoran
* KB Home forecasts drop in gross margins
* Oil settles lower; copper sinks
* Indexes down: Dow 0.2 pct, S&P 0.3 pct, Nasdaq 0.1 pct (Updates close with latest volume, adds details on reversal)
By Caroline Valetkevitch
NEW YORK, Jan 13 (Reuters) - U.S. stocks ended down slightly in a volatile session on Tuesday, led by a drop in materials and energy shares following further weakness in commodity prices.
The S&P 500 slipped under its 50-day moving average of 2,046 around midday, triggering weakness, while volume also picked up. All three indexes fell from session highs of more than 1 percent, with the S&P 500 moving more than 48 points from its high for the day to its low, its widest range since Oct. 15.
Shares of homebuilders fell 1.5 percent after KB Home forecast a drop in gross margins for the first quarter. Homebuilder stocks had been up earlier in the session, but KB Home dropped 16.3 percent to $13.87, its biggest percentage fall since 1992.
Shares of Freeport McMoran Copper & Gold slid 7.5 percent to $21.04, and were the S&P 500's biggest percentage decliner. The S&P materials index fell 1.2 percent and was the S&P 500's worst-performing sector. Continuación...