Alexion Pharmaceuticals Inc. (NASDAQ: ALXN) short interest fell just 0.2% between August 15 and August 31 to 5.27 million shares, the smallest number of shares sold short since the mid May reading.
Amgen Inc. (NASDAQ: AMGN) short interest rose 8.8% to 12.89 million shares. The average daily volume was the lowest it has been this year.
Arena Pharmaceuticals Inc. (NASDAQ: ARNA) short interest rose 2.7% to 43.93 million shares. Days to cover has increased to nearly four.
Biogen Idec Inc. (NASDAQ: BIIB) short interest fell 5.6% to 2.12 million shares. The average daily volume was the lowest it has been this year. Short interest was 0.9% of the float.
Celgene Corp. (NASDAQ: CELG) short interest declined 8.4% to 5.86 million shares. That was its lowest level this year.
Dendreon Corp. (NASDAQ: DNDN) short interest fell 2.4% to 42.31 million shares. This decline ended a five-period streak of rising short interest. Days to cover is up to 12 and short interest was 28.1% of the float.
Gilead Sciences Inc. (NASDAQ: GILD) short interest dropped 10.4% to 18.85 million shares. That followed a 16.6% percent rise in the previous period. Average daily volume fell 33.2% between August 15 and August 31.
Illumina Inc. (NASDAQ: ILMN) short interest rose 7.2% to 23.68 million shares. Days to cover slipped to less than 24.
Onyx Pharmaceuticals Inc. (NASDAQ: ONXX) short interest fell 6.7% to 5.35 million shares. That was its lowest level since March. Short interest was 8.4% of the float.
Pharmacyclics Inc. (NASDAQ: PCYC) short interest retreated 2.3% to 5.21 million shares. Average daily volume was the lowest it has been since mid May. Short interest was 9.6% of the float.
Regeneron Pharmaceuticals Inc. (NASDAQ: REGN) short interest fell 3.7% to 4.79 million shares. Short interest was 6.4% of the float.
Vertex Pharmaceuticals Inc. (NASDAQ: VRTX) short interest declined 1.6% to 6.29 million shares. Days to cover is more than four.
VIVUS Inc. (NASDAQ: VVUS) short interest fell 4.2% to 15.73 million shares. Days to cover rose to more than six. Short interest was 15% of the float.
To show how the sector has held up: the iShares Nasdaq Biotechnology (NASDAQ: IBB) ETF closed at $136.38 on the same date. Its current 52-week range is $87.67 to $141.52.
Trey Thoelcke