The Standard & Poor's MidCap 400 index dropped in a shortened trading session Thursday, as crude oil prices nearly touched $146 a barrel and investors review data showing a drop in the service sector.
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 fell 8.7 points to 786.80.
Light, sweet crude for August delivery added 80 cents to $144.37 on the New York Mercantile Exchange. Earlier in the day, prices rose as high as $145.85 a barrel, topping a trading record set Wednesday.
Meanwhile, the Institute for Supply Management said Thursday its index of service sector activity fell to 48.2 from 51.7 in May.
Shares of Health Net Inc. fell $3.09, or 12.1 percent, to $22.55. A Goldman Sachs analyst downgraded the company to "Sell" from "Neutral" Thursday.
Flowserve Corp., which makes flow control equipment, saw its stock shed $15.09, or 11.6 percent, to $114.65.
Shares of bookstore chain Borders Group Inc. shed 46 cents, or 8.9 percent, to $4.69.
On the gaining side, shares of Palm Inc. rose 40 cents, or 7.7 percent, to $5.58.
Meanwhile, home builder Ryland Group Inc.'s shares gained $1.54, or 7.1 percent, to $23.30.
Shares of marketing services company Valassis Communications Inc. increased 85 cents, or 6.9 percent, to $13.26.