S&P SmallCap 600 in Focus: BKUNA SFY

The S&P 600--which tracks stocks with a market capitalization between $300 million and $2 billion--lost 2.27 points to 382.18.

Smallcap companies make up about 3 percent of the total U.S. securities market, but are often cited as good investments due to their low valuations and potential to grow into big-cap stocks.

BankUnited plunged 37 cents, or 22 percent, to $1.31 after hitting an all-time low of $1.24 earlier in the session. Shares of the regional bank have lost more than half their value in the last week.

Other financial stocks traded lower. Downey Financial Corp. shed 58 cents, or 14 percent, to $3.57.

Flagstar Bancorp Inc. lost 40 cents, or 12.5 percent, to $2.81, after touching an eight-year low of $2.75.

Energy stocks were among the top gainers. Independent oil and gas company Swift Energy Co. rose $4.04, or 6.7 percent, to $64.83, after hitting a fresh all-time high of $65.

Light, sweet crude rose $2.45 to $137.81 a barrel on the New York Mercantile Exchange.

LoJack Corp., which makes security products for automobiles and construction equipment, rose 60 cents, or 6.4 percent, to $9.93.

Petroleum Development Corp. rose $4.14, or 6.1 percent, to $71.89.