Small stocks were mixed Wednesday and largely kept pace with the confused broader market, staying flat to negative for much of the day before climbing into positive territory.

Seattle-based biotech Dendreon ( DNDN) was the day's biggest loser overall, and one of the most furiously traded, after the Food and Drug Administration asked for additional clinical data on its prostate-cancer vaccine Provenge before granting approval. Shares plummeted 62% to $6.78.

The Russell 2000, of which Dendreon is a component, was nevertheless higher by 0.4% at 834.41. The S&P SmallCap 600 rose 0.5% to 433.32.

Another small biotech, Curis ( CRIS), got a black eye after Proctor & Gamble ( PG) decided to end its collaboration with the Cambridge, Mass., company, citing an unacceptable safety profile for the hair-growth compounds thus far developed under the agreement. Curis shares plunged 20.5% to $1.47; P&G lately added 0.7% to $62.19.

Oil-and-gas driller Toreador Resources ( TRGL) lost 15.1% to $13.13 after swinging to a steep first-quarter loss, largely blamed on a dry exploration well, against Wall Street's upside expectations from Thomson Financial. The Dallas-based company also filed for a $49.2 million shelf offering after the close Tuesday.

Also reporting lower-than-expected first-quarter bottom lines were Illinois-based TreeHouse Foods ( THS), recently sliding 9% to $29.07, and Hawaii's Hoku Scientific ( HOKU), a clean-energy-technologies developer, giving up 12.2% to $4.43.

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