Which hedge funds own ATRA? ATARA BIOTHERAPEUTICS INC, Q2 2026 13F holders
5 of the hedge funds tracked by WhaleCreep disclosed a position in ATRA (ATARA BIOTHERAPEUTICS INC) in their Q2 2026 13F filings, worth $32.9m in total. The largest holder by portfolio weight is EcoR1 Capital, LLC at 0.9% of its book. 1 manager opened a new position this quarter: Citadel Advisors LLC.
Who discovered ATRA first?
Earliest meaningful positions among the 8 tracked managers we observed opening ATRA since Q4 2014.
1 Baupost Group LLC First reported Q4 2014 1.2%initial weight · $59.1m Exitedby Q4 2023 · held 36q -81%stock since Q4 2014
Weight of Baupost Group LLC's 13F book in ATRA, by quarter
- 4.2% peak weight, Q2 2015
- $258.6m peak reported value
- 36 quarters held
- 21q before the median tracked entry
The stock's split-adjusted price moved -81% between Q4 2014 and Q3 2023, the last quarter this manager reported the position.
2 Maverick Capital LTD First reported Q1 2019 · ≥1% from Q3 2019 0.5%initial weight · $34.6m Exitedby Q4 2023 · held 19q -89%stock since Q1 2019
Weight of Maverick Capital LTD's 13F book in ATRA, by quarter
- 2.3% peak weight, Q4 2020
- $143.8m peak reported value
- 19 quarters held
- 4q before the median tracked entry
The stock's split-adjusted price moved -89% between Q1 2019 and Q3 2023, the last quarter this manager reported the position.
5 managers already held ATRA when our coverage of them began
Casdin Capital, LLC (Q4 2015), EcoR1 Capital, LLC (Q1 2026), Redmile Group, LLC (Q1 2026), Adage Capital Partners GP, L.L.C. (Q1 2026), Millennium Management LLC (Q1 2026).
Their first filing on record already includes ATRA, so when they first bought it is unknown. They are not ranked above.
View discovery timeline
- Early holdersQ4 2014 – Q3 20151 new tracked holder · 2.0% of tracked managers holding at the end
- Emerging interestQ4 2015 – Q3 20192 new tracked holders · 3.5% of tracked managers holding at the end
- Established ownershipQ4 2019 – now5 new tracked holders · 0.4% of tracked managers holding now
Dots mark the ranked managers' first reported quarters. Price is the quarter-end price implied by 13F filings, split-adjusted, shown from Q1 2026 where the series is continuous. Coverage widened in Q1 2026 from about a hundred managers to over a thousand, so holders and new holders are shown relative to the managers filing each quarter.
How this is calculated
13F filings are quarterly snapshots of long US-listed equity positions. They do not show exact purchase dates, intra-quarter trading, short positions, most derivatives, or a manager's actual performance. "First reported" is the first quarter-end filing that shows the position.
A manager is ranked only if we observed it filing, without ATRA, within two quarters before its first position. Ranking is by the first quarter the position reached 1% of the manager's 13F book in a run of at least 2 filings, then by peak weight. "High conviction" means a peak weight of at least 5%.
Stock changes are the split-adjusted change in the quarter-end price implied by 13F filings, excluding dividends. They describe the stock over the period, not the return any manager earned. Phases are cut where the share of tracked managers holding ATRA passed one third and two thirds of its peak.
Which hedge funds hold ATRA? Current holders by portfolio weight
| Manager | As of | Weight of book | Value | Shares | Δ shares | Action |
|---|---|---|---|---|---|---|
| EcoR1 Capital, LLC | Q2 2026 | 0.9% | $17.8m | 1,552,000 | 1458% | added |
| Redmile Group, LLC | Q2 2026 | 0.3% | $5.1m | 441,701 | 0% | held |
| Adage Capital Partners GP, L.L.C. | Q2 2026 | 0.0% | $9.8m | 850,000 | 21% | added |
| Millennium Management LLC | Q2 2026 | 0.0% | $145.6k | 12,680 | -73% | reduced |
| Citadel Advisors LLC | Q2 2026 | 0.0% | $116.6k | 10,159 | – | new |
Held in a manager's last filing on record
These managers have not filed for the latest quarter; their last disclosure is dated.
| Manager | Last filing | Weight |
|---|---|---|
| point72 | Q2 2026 | 0.0% |
How has hedge fund ownership of ATRA changed?
| Quarter | Managers holding | Combined value |
|---|---|---|
| Q2 2026 | 6 | $40.8m |
| Q1 2026 | 5 | $7.0m |
| Q4 2025 | 2 | $874.4k |
| Q3 2025 | 1 | $271.4k |
| Q2 2025 | 1 | $130.7k |
| Q1 2025 | 1 | $103.6k |
| Q4 2024 | 1 | $893.6k |
| Q3 2024 | 1 | $550.7k |
| Q2 2024 | 2 | $994.1k |
| Q1 2024 | 2 | $1.9m |
| Q4 2023 | 1 | $319.0k |
| Q3 2023 | 4 | $25.8m |
| Q2 2023 | 5 | $30.3m |
| Q1 2023 | 5 | $49.3m |
| Q4 2022 | 5 | $49.1m |
| Q3 2022 | 6 | $63.4m |
Counts every tracked manager that disclosed ATRA in that quarter's filing, including managers that have since stopped filing.