The short interest data is out for the August 15 settlement date. Short sellers might be inclined to bet against biotech companies because of their volatile behavior on the charts, potentially coming from a failed clinical study or even not getting an FDA approval. In an industry like this, it takes courage to bet on the outcomes. Betting on the shorts in this industry is not for the risk-averse, and rarely does news from clinical trials, projects or the FDA have just a small impact on the share price.

Alexion Pharmaceuticals Inc. (NASDAQ: ALXN) saw increased in its short interest to 4.033 million, with 3.87 days to cover, as of August 15. This was up from the previous period’s 3.955 million shares short. Alexion shares recently have been trading toward the high end of their 52-week range of $100.89 to $185.43.

Amgen Inc. (NASDAQ: AMGN) continues the trend of increasing its short interest, reporting it at 10.8 million shares, with 2.9 days to cover. That was is up from 9.5 million on the July 31 settlement date. Accordingly the increased short interest shows investors betting against Amgen, which has been reaching new 52-week highs throughout August. In the past year shares have traded in a range of $105.76 to $137.99.

Biogen Idec Inc. (NASDAQ: BIIB) also posted an increase in short interest for the August 15 settlement date. The number of shares short was 3.3 million, with 2.8 days to cover. This was up from 2.9 million in the previous period. Biogen shares have trended upward over the past year and are approaching its 52-week high of $358.89.

Celgene Corp. (NASDAQ: CELG) saw its short interest remain basically unchanged around 13.0 million shares, with 3.56 days to cover. The stock hit its all-time high Wednesday, and shares have traded in a range of $66.85 to $96.15 over the past year.

MannKind Corp. (NASDAQ: MNKD) continued the trend of increasing short interest, to 77.3 million shares short, with 4.5 days to cover, up from the previous 72.5 million. This trend has played on the falling share price, which has been declining since July. MannKind closed Tuesday at $7.28, and has a 52-week range of $3.80 to $11.48.

READ ALSO: Stocks With the Largest Short Interest

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