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

Atara Biotherapeutics, Inc. (symbol: ATRA) was one of the worst losers of
the trading day today (2016-04-07), losing -10.33%. The number of shares
that changed hands was 371,987, or about 1 times the average daily volume
in the stock.
The closing price was $20.48, amounting to a market cap of $586,360,000,
about -68.76% off the highest price in the last 12 months. The stock has
been trading at a range between $13.31 and $65.56.
ATRA is in the Biotechnology: Biological Products (No Diagnostic
Substances) industry, part of the Health Care sector. It first went public
in 2014.