Ranked by reported Q2 2026 13F market value
Share of total reported institutional value in ATRA held by the largest 10 / 25 filers.
| # | Institution | Shares Held | Market Value | QoQ Change | Ownership % | % of Fund |
|---|---|---|---|---|---|---|
| 1 | EcoR1 Capital, LLC | 1.6M | $17.8M | +1458.3% | 17.225% | 0.87% |
| 2 | ADAGE CAPITAL PARTNERS GP, L.L.C. | 850K | $9.8M | +21.4% | 9.434% | 0.01% |
| 3 | Point72 Asset Management, L.P. | 688K | $7.9M | +254.0% | 7.633% | 0.01% |
| 4 | Redmile Group, LLC | 442K | $5.1M | 0.0% | 4.902% | 0.34% |
| 5 | VANGUARD CAPITAL MANAGEMENT LLC | 247K | $2.8M | +13.4% | 2.742% | 0.00% |
| 6 | MACKENZIE FINANCIAL CORP | 233K | $2.7M | -25.6% | 2.589% | 0.00% |
| 7 | BlackRock, Inc. | 84K | $970K | +6.9% | 0.937% | 0.00% |
| 8 | GEODE CAPITAL MANAGEMENT, LLC | 75K | $863K | +13.6% | 0.834% | 0.00% |
| 9 | RAFFA WEALTH MANAGEMENT, LLC | 48 | $672K | β | 0.001% | 0.00% |
| 10 | STALEY CAPITAL ADVISERS INC | 50K | $574K | 0.0% | 0.555% | 0.02% |
| 11 | VANGUARD FIDUCIARY TRUST CO | 43K | $494K | +28.0% | 0.478% | 0.00% |
| 12 | JANE STREET GROUP, LLC | 30K | $348K | -10.4% | 0.337% | 0.00% |
| 13 | STATE STREET CORP | 26K | $304K | 0.0% | 0.294% | 0.00% |
| 14 | NORTHERN TRUST CORP | 17K | $190K | +34.4% | 0.184% | 0.00% |
| 15 | FMR LLC | 16K | $186K | 0.0% | 0.180% | 0.00% |
| 16 | XTX Topco Ltd | 15K | $176K | β | 0.170% | 0.00% |
| 17 | BRIDGEWAY CAPITAL MANAGEMENT, LLC | 14K | $161K | -57.2% | 0.155% | 0.00% |
| 18 | MILLENNIUM MANAGEMENT LLC | 13K | $146K | -73.4% | 0.141% | 0.00% |
| 19 | CITADEL ADVISORS LLC | 10K | $117K | β | 0.113% | 0.00% |
| 20 | MORGAN STANLEY | 9K | $105K | +0.1% | 0.102% | 0.00% |
| 21 | ROYAL BANK OF CANADA | 5K | $55K | +9.8% | 0.053% | 0.00% |
| 22 | UBS Group AG | 4K | $46K | -92.0% | 0.044% | 0.00% |
| 23 | Vanguard Global Advisers, LLC | 1K | $17K | 0.0% | 0.016% | 0.00% |
| 24 | SBI Securities Co., Ltd. | 1K | $16K | -10.8% | 0.016% | 0.00% |
| 25 | JONES FINANCIAL COMPANIES LLLP | 803 | $8K | +14.2% | 0.009% | 0.00% |
denotes a marquee investor (Buffett, Burry, ARK, Tiger Global, Pershing Square, Baupost and other widely-followed managers). β% of Fundβ shows how much of that investorβs total 13F portfolio is invested in ATRA β a direct measure of their conviction.
Filings activity in ATRA during Q2 2026, grouped by how each filer changed its position.
8 quarters of 13F filings Β· Ξ columns show change vs prior quarter
| Quarter | Inst. Holders | Ξ Holders | Ownership % | Ξ Ownership | Total 13F Value | Ξ Value |
|---|---|---|---|---|---|---|
| Q2 2026 | 38 | +12% | 49.59% | +18.02 pp | $52M | +348% |
| Q1 2026 | 34 | 19% | 31.57% | +2.24 pp | $12M | 68% |
| Q4 2025 | 42 | +11% | 29.33% | +1.95 pp | $36M | +40% |
| Q3 2025 | 38 | +15% | 27.38% | +0.29 pp | $26M | +93% |
| Q2 2025 | 33 | 13% | 27.09% | 9.82 pp | $13M | +15% |
| Q1 2025 | 38 | 14% | 36.91% | 5.45 pp | $12M | 61% |
| Q4 2024 | 44 | +22% | 42.36% | 2.12 pp | $30M | +60% |
| Q3 2024 | 36 | β | 44.48% | β | $19M | β |
Source: SEC 13F institutional filings. Ownership % requires market cap data and will show once linked. Ξ columns compare to the immediately prior filed quarter.
Latest Form 4 transactions by company officers and directors. Insider buys are widely viewed as a key fundamental indicator because executives are risking personal capital.
| Date | Insider | Action | Shares | Price | Value |
|---|---|---|---|---|---|
| May 7, 2026 | EcoR1 Capital, LLC | Buy | 507K | $9.35 | $4.7M |
Quick answers to the most common questions about buying ATRA stock.
Based on Q2 2026 13F filings, institutional ownership of Atara Biotherapeutics, Inc. stands at 49.6%, held across 38 reporting institutions.
EcoR1 Capital, LLC is the largest reported institutional holder of ATRA, with approximately 1,552,000 shares worth $0.02B as of Q2 2026.
Yes β 4 widely-followed marquee investors appear among the top 25 institutional holders of ATRA, including Point72 Asset Management, L.P., JANE STREET GROUP, LLC, MILLENNIUM MANAGEMENT LLC, CITADEL ADVISORS LLC.
Our composite Smart Money Score for ATRA is 80 out of 100 (Strong Smart Money). It combines net institutional buying activity, ownership shift, marquee investor presence, and holder-count growth.
4 institutions opened new positions in ATRA during Q2 2026, while 1 fully exited. 30 added to existing positions and 3 trimmed.
ATRA institutional ownership rose by 18.02 percentage points quarter-over-quarter, with a net change of +4 holders.
The top 10 institutions account for 95.4% of all reported 13F value in ATRA, and the top 25 account for 100.0%.
All data is sourced from SEC Form 13F filings, which institutional investment managers with at least $100M in assets are required to file each quarter. We process every 13F filing from EDGAR and recompute the aggregates after each cycle. Insider transactions are sourced from Form 4 filings.
Atara Biotherapeutics, Inc. (ATRA) Institutional Ownership