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

Atara Biotherapeutics, Inc. (symbol: ATRA) was one of the biggest winners
of the trading day today (2015-12-29), gaining 8.65%. The number of shares
that changed hands was 327,418, or about 0.8 times the average daily volume
in the stock.
The closing price was $24.74, amounting to a market cap of $708,330,000,
about -62.26% off the highest price in the last 12 months. The stock has
been trading at a range between $17.2 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.