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Pro Analysis

Breakingviews: Alnylam loses half its market value

John Maraganore, CEO of Alnylam Pharmaceutical
Source: Alnylam Pharmaceutical
John Maraganore, CEO of Alnylam Pharmaceutical

Half Alnylam Pharmaceuticals' $6 billion market value evaporated on Thursday after patient deaths ended a drug trial. The promise of novel treatments based on RNA interference had pushed the biotech's market value as high as about $12 billion last summer. That's now down to $3 billion, suggesting investors fear trouble with one drug may prove contagious for all of them.