$BIIB is one of biggest losers #stocks today. read more:

Biogen Idec Inc. (symbol: BIIB) was one of the worst losers of the trading
day today (2015-07-24), losing -22.08%. The number of shares that changed
hands was 16,614,646, or about 10 times the average daily volume in the
stock.
The closing price was $300.03, amounting to a market cap of
$70,580,000,000, about -37.52% off the highest price in the last 12 months.
The stock has been trading at a range between $290.85 and $480.18.
BIIB is in the Biotechnology: Biological Products (No Diagnostic
Substances) industry, part of the Health Care sector.
Looking at its valuation, the stock is now trading at 21.67 times earnings.