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

Portola Pharmaceuticals, Inc. (symbol: PTLA) was one of the worst losers of
the trading day today (2016-12-27), losing -9.1%. The number of shares that
changed hands was 4,434,913, or about 5 times the average daily volume in
the stock.
The closing price was $22.78, amounting to a market cap of $1,290,000,000,
about -56.61% off the highest price in the last 12 months. The stock has
been trading at a range between $15.68 and $52.5.
PTLA is in the Major Pharmaceuticals industry, part of the Health Care
sector. It first went public in 2013.