Short Sellers Increase Their Bets Against Biotech Stocks

The March 31 short interest data have been compared with the March 13 figures, and for the majority of the selected stocks, short interest has increased.

Amgen Inc. (NASDAQ: AMGN) saw its short interest rise slightly to 10.32 million shares, with 2.7 days to cover. The previous short interest reading was 10.20 million with 3.6 days to cover. The number of Amgen shares short has remained consistent for these past two settlement dates, recording the lowest levels on the year. Shares closed Friday at $163.38, in a 52-week trading range of $108.20 to $173.14.

Biogen Idec Inc. (NASDAQ: BIIB) saw its short interest fall dramatically to 2.79 million shares, with one day to cover, from the last level of 3.59 million shares with 2.4 days to cover. The company is making its way back to its lowest short interest readings in November and seemingly returning to its recent historic levels. Shares ended last week at $425.65, within a 52-week trading range of $272.02 to $480.18.

Celgene Corp. (NASDAQ: CELG) short interest subtly increase for this settlement date, up to 14.60 million shares, with 2.0 days to cover. The level for the previous settlement date was 14.54 million with 3.4 days to cover. Currently this is the second highest short interest reading in the past year, potentially signaling some optimism from investors. Shares of Celgene closed Friday at $117.07, in a 52-week trading range of $66.85 to $129.06.

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Gilead Sciences Inc. (NASDAQ: GILD) saw its short interest jump to 57.31 million, with 4.6 days to cover, from 55.99 million with 6.3 days to cover two weeks earlier. Shares closed most recently at $101.77, in a 52-week trading range of $63.59 to $116.83.

Mannkind Corp. (NASDAQ: MNKD) saw its short interest rise again to 95.72 million shares, with 28.4 days to cover. The previous reading for short interest was 90.88 million with 13.0 days to cover. Short interest for Mannkind is currently pushing new highs for the year. Shares closed Friday at $5.25, in a 52-week trading range of $4.45 to $11.48.

Alexion Pharmaceuticals Inc. (NASDAQ: ALXN) short interest increased to 3.45 million shares, with 2.3 days to cover, up from the previous level of 3.30 million with 3.1 days to cover. Shares closed Friday at $182.68, in a 52-week trading range of $136.37 to $203.30.