Atara Biotherapeutics, Inc. (ATRA) Insider Trading
Over the last 3 months, ATRA insiders made 1 open-market buy and 3 sales, a net purchase of $1.5M (SEC Form 4). Over the last 6 months, 23 institutions increased and 14 reduced their position (13F).
Insider Activity
Sentiment
59/100
Buys (3m)
1
Sells (3m)
3
Net (3m)
$1.5M
Insiders buyingFirst buy in 3 quarters
Insider trades by month Buys Sells
Jul
Aug
Nov
Jan
Mar
May
Context3-month price +158.6%Institutions mixed (13F)
| Date | Insider | Type | Shares | Price |
|---|---|---|---|---|
| Jun 15, 2026 | Cherry Brian Ndirector | Grant | 24,000 | — |
| Jun 11, 2026 | HEIDEN WILLIAM Kdirector | Grant | 12,000 | — |
| Jun 11, 2026 | Ciongoli Gregory Austindirector, 10 percent owner, other: See Remarks | Grant | 12,000 | — |
| Jun 11, 2026 | Fust Matthew Kdirector | Grant | 12,000 | — |
| May 20, 2026 | Grant-Huerta Yaninaofficer: Chief Accounting Officer | Sell | 2,414 | $9.13 |
| May 20, 2026 | Nguyen AnhCodirector, officer: President and CEO | Sell | 5,241 | $9.13 |
| May 11, 2026 | EcoR1 Capital, LLC10 percent owner | Buy | 507,407 | $9.35 |
| May 11, 2026 | Panacea Innovation Ltd10 percent owner | Sell | 313,446 | $10.10 |
| Mar 19, 2026 | Panacea Innovation Ltd10 percent owner | Tax | 5 | $5.23 |
| Mar 19, 2026 | Panacea Innovation Ltd10 percent owner | Option | 259,163 | $0.00 |
| Mar 11, 2026 | Grant-Huerta Yaninaofficer: Chief Accounting Officer | Grant | 20,300 | — |
| Mar 11, 2026 | Nguyen AnhCodirector, officer: President and CEO | Grant | 81,100 | — |
| Mar 4, 2026 | Grant-Huerta Yaninaofficer: Chief Accounting Officer | Sell | 100 | $5.08 |
| Mar 4, 2026 | Nguyen AnhCodirector, officer: President and CEO | Sell | 1,298 | $5.09 |
| Mar 4, 2026 | Nguyen AnhCodirector, officer: President and CEO | Sell | 58 | $5.08 |
| Mar 4, 2026 | Grant-Huerta Yaninaofficer: Chief Accounting Officer | Sell | 377 | $5.08 |
| Mar 4, 2026 | Nguyen AnhCodirector, officer: President and CEO | Sell | 198 | $5.08 |
| Mar 4, 2026 | Nguyen AnhCodirector, officer: President and CEO | Sell | 1,442 | $5.09 |
| Mar 4, 2026 | Grant-Huerta Yaninaofficer: Chief Accounting Officer | Sell | 24 | $5.08 |
| Mar 4, 2026 | Grant-Huerta Yaninaofficer: Chief Accounting Officer | Sell | 1,603 | $5.08 |
| Jan 14, 2026 | Panacea Innovation Ltd10 percent owner | Sell | 80,554 | $6.07 |
| Dec 1, 2025 | Panacea Innovation Ltd10 percent owner | Tax | 1 | $14.03 |
| Dec 1, 2025 | Panacea Innovation Ltd10 percent owner | Option | 48,737 | $0.00 |
| Nov 19, 2025 | Grant-Huerta Yaninaofficer: Chief Accounting Officer | Sell | 85 | $13.19 |
| Nov 19, 2025 | Grant-Huerta Yaninaofficer: Chief Accounting Officer | Sell | 1,645 | $13.19 |
| Nov 19, 2025 | Nguyen AnhCodirector, officer: President and CEO | Sell | 2,859 | $13.19 |
| Nov 19, 2025 | Grant-Huerta Yaninaofficer: Chief Accounting Officer | Sell | 74 | $13.19 |
| Nov 19, 2025 | Nguyen AnhCodirector, officer: President and CEO | Sell | 56 | $13.19 |
| Aug 20, 2025 | Grant-Huerta Yaninaofficer: Chief Accounting Officer | Sell | 1,668 | $11.61 |
| Aug 20, 2025 | Grant-Huerta Yaninaofficer: Chief Accounting Officer | Sell | 55 | $11.61 |
Source: ATRA SEC Form 4 filings, latest Jun 15, 2026. For informational purposes only — not investment advice.
Institutional activity (13F)
How institutions changed their ATRA positions over the last 6 months (SEC Form 13F).
Increased
23
New positions
13
Reduced
14
Sold out
16
Largest moves
| Institution | Action | Shares | Filed |
|---|---|---|---|
| ADAGE CAPITAL PARTNERS GP, L.L.C. | New Position | 700K | May 15, 2026 |
| ECOR1 CAPITAL, LLC | Unchanged | 573K | Feb 17, 2026 |
| REDMILE GROUP, LLC | Unchanged | 442K | May 15, 2026 |
| REDMILE GROUP, LLC | Unchanged | 442K | Feb 17, 2026 |
| VANGUARD CAPITAL MANAGEMENT LLC | New Position | 436K | May 15, 2026 |
| MACKENZIE FINANCIAL CORP | Increased | 314K | May 13, 2026 |
| VANGUARD GROUP INC | Increased | 226K | Jan 29, 2026 |
| POINT72 ASSET MANAGEMENT, L.P. | Increased | 194K | May 15, 2026 |
| MARSHALL WACE, LLP | Increased | 149K | Feb 13, 2026 |
| ACADIAN ASSET MANAGEMENT LLC | Increased | 131K | May 13, 2026 |
| ECOR1 CAPITAL, LLC | Reduced | 100K | May 15, 2026 |
| BLACKROCK, INC. | Increased | 79K | May 13, 2026 |
| GLOBEFLEX CAPITAL L P | Increased | 77K | Feb 11, 2026 |
| BLACKROCK, INC. | Reduced | 67K | Feb 12, 2026 |
| GEODE CAPITAL MANAGEMENT, LLC | Increased | 66K | May 15, 2026 |
Source: SEC Form 13F filings. For informational purposes only — not investment advice.