The Standard & Poor's SmallCap 600 Index climbed in midday trading Tuesday after Federal Reserve Chairman Ben Bernanke said in a speech the economy would improve during the second half of the year, though he indicated that interest rates are unlikely to change.
The index _ which tracks stocks with a market capitalization between $300 million and $2 billion _ rose 2.19 points to 391.59.
Small-cap companies comprise 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.
Florida-based bank BankAtlantic Bancorp Inc. took the biggest gain, jumping 19 cents, or 10.8 percent, to $1.95.
Carbo Ceramics Inc., which makes components used in oil and gas wells, surged $5, or 10.4 percent, to $52.93.
W-H Energy Services Inc. advanced $8.32, or 9.7 percent, to $93.86. On Tuesday, oilfield services provider Smith International Inc. said it would buy W-H in a deal valued at about $93.55 per share, a 9.4 percent premium over W-H's Monday closing price.
Among the decliners, Children's Place Retail Stores Inc. tumbled $2.23, or 6.6 percent, to $31.71 after a Buckingham Research Group analyst downgraded the company to "Neutral" from "Strong Buy," saying sales in May were worse than many are expecting.
East West Bancorp Inc. declined 82 cents, or 6.3 percent, to $12.26. The stock hit a multi-year low of $12.21 earlier in the session.
ABM Industries gave up $1.04, or 4.7 percent, to $20.88 after the facilities service provider said its fiscal second-quarter profit tumbled 34 percent due to higher costs and a one-time charge.