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

Horizon Pharma plc (symbol: HZNP) was one of the worst losers of the
trading day today (2015-10-20), losing -19.98%. The number of shares that
changed hands was 19,498,154, or about 5 times the average daily volume in
the stock.
The closing price was $15.26, amounting to a market cap of $2,430,000,000,
about -61.36% off the highest price in the last 12 months. The stock has
been trading at a range between $11.67 and $39.49.
HZNP is in the Major Pharmaceuticals industry, part of the Health Care
sector. It first went public in 2011.