$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 (2016-08-18), losing -15.07%. The number of shares
that changed hands was 10,931,916, or about 15 times the average daily
volume in the stock.
The closing price was $20.12, amounting to a market cap of $1,140,000,000,
about -65.29% 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.