$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 (2016-08-17), losing -10.97%. The number of shares
that changed hands was 3,746,766, or about 5 times the average daily volume
in the stock.
The closing price was $23.69, amounting to a market cap of $1,340,000,000,
about -59.13% off the highest price in the last 12 months. The stock has
been trading at a range between $18.2 and $57.96.
PTLA is in the Major Pharmaceuticals industry, part of the Health Care
sector. It first went public in 2013.