Small-cap stocks fared far better than the broader market Wednesday, generally staying positive as the major indices slumped into negative territory. The Russell 2000 was up 0.5% at 739.25, and the S&P SmallCap 600 was likewise up 0.5% at 391.00.

Shares of U.S. Geothermal ( HTM), a Boise, Idaho, company that develops geothermal properties, soared 13% to $2.69. RBC Capital Markets initiated coverage of the stock with an outperform rating. U.S. Geothermal also announced a joint venture with Gerlach Green Energy to explore the Gerlach geothermal system located in northwestern Nevada.

Oil and gas company Endeavour ( END) jumped 12.6% to $1.79. The Houston-based company announced a natural gas discovery in the Norwegian North Sea. It said it will participate in the drilling of eight wells overall in 2008.

Willow Financial Bancorp ( WFBC) added 22% to $9.42. The Wayne, Pa., provider of commercial banking services announced Harleysville National ( HNBC) would buy it in an all-stock deal. Each share of Willow Financial stock will be exchanged for 0.73 shares of Harleysville stock. Harleysville National shares shed 4% to $13.54 on the news.

Also on the losing side, Westborough, Mass., information technology services company Virtusa ( VRTU) stumbled 9% to $10.86 after offering weak guidance. The firm predicted earnings between 70 cents and 79 cents a share for the fiscal year ending in March 2009. Analysts polled by Thomson Reuters are expecting EPS of 90 cents.

Finally, Guaranty Financial ( GFG), an Austin, Texas commercial and retail banking services provider, slipped 11% to $5.34. The company announced a stock offering of up to $350 million.