US SMALL/MIDCAPS-Energy shares drag as oil prices fall

NEW YORK Oct 3 (Reuters) - Small- and mid-capitalization stocks were flat to slightly lower on Wednesday as shares of oil companies sank in line with a sharp fall in oil prices.

The S&P MidCap 400 energy index ended down 3.1 percent, matching the slide in Brent crude oil prices, which settled at $108.17 a barrel.

Shares of Superior Energy Services were down 6 percent at $19.14. The company late on Tuesday estimated a weak third-quarter profit as operations in the U.S. Gulf of Mexico were hit by Hurricane Isaac.

Also in the energy sector, shares of Oil States International were down 5 percent at $75.10 and Swift Energy declined 8.4 percent to $19.23.

The S&P MidCap 400 index closed up 0.02 percent while the S&P SmallCap 600 index was down 0.3 percent. In comparison, the benchmark S&P 500 endeds up 0.4 percent.