ATARA BIOTHERAPEUTICS INC

CUSIP: 46513107 Class: COM

GROUP ONE TRADING, L.P.'s Holding History (CIK: 0000932540)

Note: Option positions (PUT/CALL) are excluded.

Q1 2016
Shares 561 Value ($000) $11 Avg Close — Range —
Q4 2015
Shares 561 Value ($000) $15 Avg Close — Range —
Q3 2015
Shares 261 Value ($000) $8 Avg Close — Range —