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

Prothena Corporation plc (symbol: PRTA) was one of the worst losers of the
trading day today (2016-06-17), losing -8.85%. The number of shares that
changed hands was 1,197,766, or about 3 times the average daily volume in
the stock.
The closing price was $39.86, amounting to a market cap of $1,370,000,000,
about -47.84% off the highest price in the last 12 months. The stock has
been trading at a range between $28.2 and $76.42.
PRTA is in the Major Pharmaceuticals industry, part of the Health Care
sector.