Ebb & Flow

Investors scrambled last Tuesday to cover the 20% of Dendreon Corp. shares that they had sold short, after the company unveiled a positive topline survival result from the Phase III IMPACT trial of its prostate cancer immunotherapy, Provenge sipuleucel-T. The stock climbed $9.69 (133%) to $16.99 on 65.2 million shares on the day. The three-month average daily volume is 4.8 million shares.

On the week, Dendreon (NASDAQ:DNDN) rose $11.69 (186%) to $17.99. The stock still hasn't quite made a round trip to its $19.39 high on April 30, 2007, after FDA's Cellular, Tissue and Gene Therapies Advisory Committee voted that the company had provided substantial evidence of the efficacy of Provenge...