ATRA Atara Biotherapeutics, Inc.
Price Chart
Executive Summary
Atara Biotherapeutics saw a mixed insider cluster: 10% owner EcoR1 Capital bought $4.74M worth of shares, while director/10% owner Panacea Innovation sold $3.17M worth on the same day. The net $1.57M buying is modest relative to ATRA's $71M market cap (~2.2%), but the simultaneous insider buying and selling creates a conflicting signal that warrants caution.
Key Financial Metrics
Actionable Insight
The simultaneous large buy and sell by two major 10% owners creates a split signal. EcoR1's $4.74M purchase is a bullish vote of confidence, but Panacea's $3.17M sale suggests some insiders are taking profits. Given ATRA's small $71M market cap and the historical pattern of poor T+20 performance on prior calls, traders should wait for a clearer directional catalyst (e.g., earnings, pipeline update) before taking a position.
Key Facts
- EcoR1 Capital purchased 507,407 shares at $9.35 for $4.74M on 2026-05-07
- Panacea Innovation sold 313,446 shares at $10.10 for $3.17M on 2026-05-07
- Net insider buying of ~$1.57M, representing ~2.2% of ATRA's $71M market cap
- Both parties are 10% owners; no C-suite insiders traded
- Historical calibration shows past neutral calls on ATRA had a 25% win rate at T+20 with avg alpha of -10.81%
Financial Impact
Net insider buying of ~$1.57M, ~2.2% of market cap
Risk Factors
- Insider selling by a 10% owner may signal lack of confidence in near-term prospects
- ATRA's small market cap makes it highly volatile; past neutral calls have underperformed SPY by -10.81% at T+20
- No C-suite participation reduces the signal strength of insider activity
Market Snapshot
Documents Analyzed
This report is based on 1 SEC document filed with EDGAR.
| Document | Accession Number |
|---|---|
| CLUSTER Data (Synthetic) | cluster-ATRA-1778539528445 |
Filters
| Type | Now | ||||
|---|---|---|---|---|---|
|
May 7, 2026
4w ago
|
8-K
| $9.93 $9.63 | ▼ −3.02% | ▼ −6.16% | $9.58 (−3.52%) |
|
May 7, 2026
4w ago
|
Insider Cluster
| $9.93 $9.63 | ▼ −3.02% | ▼ −6.16% | $9.58 (−3.52%) |
|
Apr 24, 2026
6w ago
|
DEFA14A
| $4.99 $9.61 | ▲ +92.59% | ▲ +87.63% | $9.58 (+91.98%) |
|
Mar 17, 2026
12w ago
|
S-3
| $5.00 $5.24 | ▲ +4.80% | ▼ −1.25% | $9.58 (+91.60%) |
|
Mar 12, 2026
12w ago
|
8-K
| $6.90 $4.65 | ▼ −32.61% | ▼ −34.58% | $9.58 (+38.84%) |
|
Mar 3, 2026
14w ago
|
8-K
| $5.42 $4.73 | ▼ −12.73% | ▼ −8.33% | $9.58 (+76.75%) |
|
Mar 2, 2026
14w ago
|
Insider Cluster
| $4.91 $4.32 | ▼ −12.02% | ▼ −4.08% | $9.58 (+95.11%) |
US Market Status
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