S&P MidCap 400 in Focus: AAI CHRS

The Standard & Poor's MidCap 400 index fell in midday trading Tuesday as crude oil prices remained high and Federal Reserve Chairman Ben Bernanke said a substantial economic downturn seems unlikely, fueling speculation interest rates may go up.

The S&P MidCap 400 is an index used to track midsized companies with a market capitalization of $1.5 billion to $5.5 billion. According to S&P, midcap stocks make up roughly 7 percent of the U.S. equities market.

The index lost 6.49 points to 866.35.

Prices for light, sweet crude slipped $1 to $133.35 a barrel during early afternoon trading on the New York Mercantile Exchange. Last week prices touched a record $139.12.

Shares of airline AirTran Holdings Inc. shed 10 cents, or 3.3 percent, to $2.93.

Shares of Steel Dynamics Inc. fell $1.33, or 3.4 percent, to $37.64.

Shares of FMC Technologies Inc. slipped $2.44, or 3.2 percent, to $75.68.

On the gaining side, shares of women's apparel retailer Charming Shoppes Inc. added 9 cents to $5.30.

Shares of First Niagara Financial Group Inc. rose 34 cents, or 2.5 percent, to $14.12.

Shares of Dick's Sporting Goods Inc. increased 38 cents to $22.70.