Ranked by reported Q1 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 | ADAGE CAPITAL PARTNERS GP, L.L.C. | 700K | $3.3M | β | 7.769% | 0.01% |
| 2 | Redmile Group, LLC | 442K | $2.1M | 0.0% | 4.902% | 0.14% |
| 3 | MACKENZIE FINANCIAL CORP | 314K | $1.5M | +434.6% | 3.481% | 0.00% |
| 4 | VANGUARD CAPITAL MANAGEMENT LLC | 218K | $1.0M | β | 2.418% | 0.00% |
| 5 | Point72 Asset Management, L.P. | 194K | $919K | +961.8% | 2.156% | 0.00% |
| 6 | EcoR1 Capital, LLC | 100K | $471K | -82.6% | 1.105% | 0.02% |
| 7 | BlackRock, Inc. | 79K | $374K | +17.8% | 0.877% | 0.00% |
| 8 | GEODE CAPITAL MANAGEMENT, LLC | 66K | $313K | +6.0% | 0.734% | 0.00% |
| 9 | UBS Group AG | 50K | $237K | +3484.1% | 0.556% | 0.00% |
| 10 | STALEY CAPITAL ADVISERS INC | 50K | $237K | 0.0% | 0.555% | 0.01% |
| 11 | MILLENNIUM MANAGEMENT LLC | 48K | $226K | β | 0.529% | 0.00% |
| 12 | JANE STREET GROUP, LLC | 34K | $160K | +142.1% | 0.376% | 0.00% |
| 13 | VANGUARD FIDUCIARY TRUST CO | 34K | $159K | β | 0.373% | 0.00% |
| 14 | BRIDGEWAY CAPITAL MANAGEMENT, LLC | 33K | $155K | 0.0% | 0.363% | 0.00% |
| 15 | STATE STREET CORP | 26K | $125K | 0.0% | 0.294% | 0.00% |
| 16 | FMR LLC | 16K | $77K | -5.3% | 0.180% | 0.00% |
| 17 | NORTHERN TRUST CORP | 12K | $58K | 0.0% | 0.137% | 0.00% |
| 18 | MORGAN STANLEY | 9K | $43K | -42.7% | 0.102% | 0.00% |
| 19 | ROYAL BANK OF CANADA | 4K | $20K | +408.1% | 0.048% | 0.00% |
| 20 | SBI Securities Co., Ltd. | 2K | $7K | +12.1% | 0.017% | 0.00% |
| 21 | Vanguard Global Advisers, LLC | 1K | $7K | β | 0.016% | 0.00% |
| 22 | JONES FINANCIAL COMPANIES LLLP | 703 | $3K | 0.0% | 0.008% | 0.00% |
| 23 | WELLS FARGO & COMPANY/MN | 251 | $1K | 0.0% | 0.003% | 0.00% |
| 24 | Banque Transatlantique SA | 176 | $906 | 0.0% | 0.002% | 0.00% |
| 25 | RHUMBLINE ADVISERS | 175 | $827 | 0.0% | 0.002% | 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 Q1 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 |
|---|---|---|---|---|---|---|
| Q1 2026 | 33 | 20% | 12.27% | 25.76 pp | $12M | 68% |
| Q4 2025 | 41 | +11% | 38.03% | +10.78 pp | $36M | +40% |
| Q3 2025 | 37 | +12% | 27.25% | +13.09 pp | $26M | +92% |
| Q2 2025 | 33 | 13% | 14.16% | +1.80 pp | $13M | +15% |
| Q1 2025 | 38 | 14% | 12.36% | 19.47 pp | $12M | 61% |
| Q4 2024 | 44 | +22% | 31.83% | +11.98 pp | $30M | +60% |
| Q3 2024 | 36 | 25% | 19.85% | 2.63 pp | $19M | 12% |
| Q2 2024 | 48 | β | 22.48% | β | $21M | 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 the highest-conviction signal 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 Q1 2026 13F filings, institutional ownership of Atara Biotherapeutics, Inc. stands at 12.3%, held across 33 reporting institutions.
ADAGE CAPITAL PARTNERS GP, L.L.C. is the largest reported institutional holder of ATRA, with approximately 700,000 shares worth $0.00B as of Q1 2026.
Yes β 3 widely-followed marquee investors appear among the top 25 institutional holders of ATRA, including Point72 Asset Management, L.P., MILLENNIUM MANAGEMENT LLC, JANE STREET GROUP, LLC.
Our composite Smart Money Score for ATRA is 42 out of 100 (Neutral). It combines net institutional buying activity, ownership shift, marquee investor presence, and holder-count growth.
8 institutions opened new positions in ATRA during Q1 2026, while 16 fully exited. 5 added to existing positions and 20 trimmed.
ATRA institutional ownership fell by 25.76 percentage points quarter-over-quarter, with a net change of -8 holders.
The top 10 institutions account for 90.9% 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