ATRA insider buying and SEC filings, explained
Atara Biotherapeutics, Inc. · CIK 1604464
Tracked: Forms 3/4/5, 8-K, NT · All filings on sec.gov
Insider activity in the last 12 months
Bought
$5.7M
Insiders who bought
2
Sold (not marked 10b5-1)
$3.9M
Planned sales (10b5-1)
$0
Insider purchases and sales, last 12 months
| Traded | Type | What was filed | Source |
|---|---|---|---|
| Sep 4, 2026 | Purchase (code P) | Brian N Cherry (Director) bought 104,166 shares at $9.60 ($1.0M), reported as a purchase (code P). Holdings up 167% to 166,486 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Sep 4, 2026 |
| Aug 17, 2026 | Sale | AnhCo Nguyen (CEO and Director) sold 5,062 shares at about $8.08 ($41K). Holdings down 4% to 132,775 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Aug 26, 2026 |
| May 18, 2026 | Sale | AnhCo Nguyen (CEO and Director) sold 5,241 shares at about $9.13 ($48K). Holdings down 4% to 137,837 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 20, 2026 |
| May 18, 2026 | Sale | Yanina Grant-Huerta (Chief Accounting Officer) sold 2,414 shares at about $9.13 ($22K). Holdings down 5% to 49,636 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 20, 2026 |
| May 7, 2026 | Sale | James Huang (Director and 10% owner) sold 313,446 shares indirectly at about $10.10 ($3.2M). Indirect holdings down 24% to 1,011,000 shares. Not marked as a 10b5-1 plan trade. Filed jointly with 1 other reporting owner. | SEC filing Filed May 11, 2026 |
| May 7, 2026 | Purchase (code P) | EcoR1 Capital, LLC (10% owner) bought 507,407 shares indirectly at about $9.35 ($4.7M), reported as a purchase (code P). Indirect holdings up 49% to 1,552,000 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 11, 2026 |
| Mar 2, 2026 | Sale | Yanina Grant-Huerta (Chief Accounting Officer) sold 2,104 shares at about $5.08 ($11K). Holdings down 6% to 31,750 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Mar 4, 2026 |
| Mar 2, 2026 | Sale | AnhCo Nguyen (CEO and Director) sold 2,996 shares at about $5.09 ($15K). Holdings down 5% to 61,978 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Mar 4, 2026 |
| Jan 12, 2026 | Sale | James Huang (Director and 10% owner) sold 80,554 shares indirectly at about $6.07 ($489K). Indirect holdings down 6% to 1,324,446 shares. Not marked as a 10b5-1 plan trade. Filed jointly with 1 other reporting owner. | SEC filing Filed Jan 14, 2026 |
| Nov 17, 2025 | Sale | AnhCo Nguyen (CEO and Director) sold 2,915 shares at about $13.19 ($38K). Holdings down 4% to 64,974 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Nov 19, 2025 |
| Nov 17, 2025 | Sale | Yanina Grant-Huerta (Chief Accounting Officer) sold 1,804 shares at about $13.19 ($24K). Holdings down 5% to 33,454 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Nov 19, 2025 |
9 routine transactions (such as grants, option exercises or tax withholding) are not listed.
Cluster buys
No cluster buys in the last 12 months.
Red flags
No red flags in the last 12 months.
Key events
No key events in the last 12 months.
8-K filings, last 12 months
No 8-K filings in the last 12 months.
Red flags are objective triggers only: the item or form filed, never an opinion.
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