S&P MidCap 400 in Focus: OSK MLHR

On the index, shares of Oshkosh Corp., which makes specialty vehicles, declined $7.68, or 22.9 percent, to $25.80, and set a three-year low of $25.23. Oshkosh expects to post a third-quarter loss, missing its prior forecast and Wall Street expectations.

Shares of Chemtura Corp. declined $1.71, or 20.9 percent, to $6.47, after the company ended talks to sell itself.

Shares of auto-parts supplier Lear Corp. declined $3.65, or 20.1 percent, to $14.47, and set an all-time low of $14.25, following an analyst downgrade.

On the rising side, shares of Herman Miller Inc. gained $1.51, or 6.3 percent, to $25.50. Strong sales from overseas markets boosted the furniture maker's fiscal fourth-quarter profit.

An analyst upgrade lifted shares of health care company Lincare Holdings Inc. to $28.26, up $1.33, or 4.9 percent.

Shares of City National Corp. advanced $1.71, or 4.3 percent, to $42.98, also on an analyst upgrade.

The S&P MidCap 400 is an index used to track mid-sized companies which have 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 declined 16.54 points, or 2 percent, to 832.61.