Stock Trading Canary

United States · SEC Form 4 · Snapshot date: 2026-10-19 · Built: 2026-10-19 · 中文

← United States · Coverage record

US · SEC FORM 4

Atara Biotherapeutics, Inc.

ATRA · Nasdaq · CIK 0001604464 · Healthcare · Biotechnology

INSIDER SIGNAL

57.4 / 100

2 buyers · 2 purchase transaction lines · $5.7M gross purchase

WHY THIS SIGNAL?

Buyer breadthLow
Purchase sizeStrong
RoleModerate
RecencyModerate
ConvictionLow
Score anatomy

Each bar shows the contribution to the current score; the weights and formula stay unchanged.

Cluster+14.0 / 35
Purchase size+20.4 / 25
Role+14.0 / 20
Recency+4.7 / 10
Conviction+4.3 / 10

What is holding the score back?

  • ⚠ Cluster breadth is moderate · 2 insider(s), not 4+
  • ⚠ Role scores low · most senior buyer: TenPercentOwner (CEO, chair and 10% owners score lowest)
  • ⚠ Buying conviction is reduced by concurrent selling

Purchase-size comments are relative to the model scale. Average daily volume is a separate market-context diagnostic.

US-v1.2 ranks qualifying equity purchases under the current 180-day rules. The score is a research priority, not a return forecast or probability. Backtests have not shown that a higher US score is followed by better returns.

Purchase breadth & concentration

QUALIFYING BUYERS2
PURCHASE CONCENTRATION83%Largest buyer: EcoR1 Capital, LLC · $4.7M
CLUSTER BUYING · 15D1 insiderPeak activity: 2026-05-07–2026-05-07

Roles in the peak window: TenPercentOwner. Concentration uses priced qualifying P lines only and does not change the saved score.

Insider activity timeline

Owner lanes show the latest 180 days. Symbol shape identifies the transaction type; sales remain context only.

AprMayJunJulAugSepOct
Cherry Brian NDirector
○●
Nguyen AnhCoPresident and CEO
▼▼
Green Jeremy; Redmile Group, LLCDirector
○○
HEIDEN WILLIAM KDirector
○
Fust Matthew KDirector
○
Ciongoli Gregory AustinDirector,TenPercentOwner,Other
○
● Purchase▼ Sale○ Other

Showing the six most active owners; 3 additional owner(s) remain in Form 4 evidence.

SIGNAL HISTORY

57.4 / 100

Latest recorded score

→ +0.0 ptsversus the previous recorded snapshot
  1. 57.8
  2. 57.8
  3. 57.6
  4. 57.4
  5. 57.4

Only scores saved when a full US scoring run completed are shown; gaps are not reconstructed.

Recent Form 4 activity

2Purchases
18Sales
12Other Form 4 lines
20SEC filings · 365 days
BUYING2 qualifying P line(s) · 180 days
SELLING4 sale line(s) · context only
OTHER6 exercise / withholding / award / gift / other lines
10b5-1 / PLANNEDNot assessed

P is an open-market or private purchase. S is a sale. M, F, A and G usually describe exercises, tax withholding, awards and gifts. These categories remain visually separate.

Market context

Market context provides additional background on recent price performance and risk. It does not affect the Insider Signal.

Price performance

1M
-4.1%
3M
+9.3%
6M
+103.9%
12M
-40.2%

Volatility & liquidity

Volatility
125.3%
Beta
—
Avg daily value
USD 490,800

Valuation

Market cap
USD 95.2M
P/E
2.9×

Fundamentals

Profit margin
27.1%
ROE
—
Industry
Biotechnology

Market data

Price data up to: 2026-10-09 · Price source: OpenBB/yfinance; volume from price cache (yfinance) · From SEC filings: Market cap, P/E, Profit margin · Fiscal year ended: 2025-12-31 · Market cap is the shares outstanding stated on the filing cover multiplied by the latest close. Share count date: 2026-08-10 · Status: PASS

Short interest

Short interest is external context reported to FINRA by broker-dealers. It does not affect the Insider Signal.

Shares short
321,792
Previous report
404,270
Avg daily volume
39,657
Days to cover
8.1

FINRA settlement date: 2026-09-30 · Captured 2026-10-12 · FINRA equity short interest ↗. A share count, published about a week after each of two settlement dates a month; not a percentage of shares outstanding.

Historical equity purchases

Qualifying code P transactions in the local Form 4 history, including purchases outside the current signal window.

Transaction dateReporting ownerTypeSecuritySharesAvg. priceApprox. valueSource
2026-09-04Cherry Brian NPurchase (P)Common Stock104,166USD 9.60USD 999,994SEC filing ↗
2026-05-07EcoR1 Capital, LLCPurchase (P)Common Stock507,407USD 9.35USD 4,744,255SEC filing ↗
2025-08-15Huang James; Panacea Innovation LtdPurchase (P)Common Stock55,000USD 12.19USD 670,450SEC filing ↗
2025-07-17Huang James; Panacea Innovation LtdPurchase (P)Common Stock19,335USD 9.64USD 186,389SEC filing ↗
2023-11-14Gallagher Carol GiltnerPurchase (P)Common Stock90,980USD 0.31USD 28,204SEC filing ↗
2023-11-13Gallagher Carol GiltnerPurchase (P)Common Stock179,020USD 0.22USD 39,384SEC filing ↗
2023-11-10HEIDEN WILLIAM KPurchase (P)Common Stock100,000USD 0.25USD 25,000SEC filing ↗
2023-11-10DOBMEIER ERICPurchase (P)Common Stock446,825USD 0.23USD 102,770SEC filing ↗
2021-06-14Yarema KristinPurchase (P)Common Stock32,333USD 14.57USD 471,065SEC filing ↗
2021-06-11Yarema KristinPurchase (P)Common Stock2,021USD 14.50USD 29,304SEC filing ↗

Form 4 evidence

32 transaction lines in the latest 365-day window; 273 in local history.

DateOwnerTypeSecuritySharesAvg. priceApprox. valueSource
2026-09-04Cherry Brian NPurchase (P)Common Stock104,166USD 9.60USD 999,994SEC filing ↗
2026-08-17Nguyen AnhCoSale (S)Common Stock5,062USD 8.08USD 40,901SEC filing ↗
2026-07-22Green Jeremy; Redmile Group, LLCOption exercise / conversion (M)Common Stock195,211USD —USD —SEC filing ↗
Show recent Form 4 evidence (23 grouped rows)
DateOwnerTypeSecuritySharesAvg. priceApprox. valueSource
2026-09-04Cherry Brian NPurchase (P)Common Stock104,166USD 9.60USD 999,994SEC filing ↗
2026-08-17Nguyen AnhCoSale (S)Common Stock5,062USD 8.08USD 40,901SEC filing ↗
2026-07-22Green Jeremy; Redmile Group, LLCOption exercise / conversion (M)Common Stock195,211USD —USD —SEC filing ↗
2026-07-22Green Jeremy; Redmile Group, LLCTax withholding (F)Common Stock60USD —USD —SEC filing ↗
2026-06-11Cherry Brian NAward / grant (A)Common Stock24,000USD 0.00USD 0SEC filing ↗
2026-06-09HEIDEN WILLIAM KAward / grant (A)Common Stock12,000USD 0.00USD 0SEC filing ↗
2026-06-09Fust Matthew KAward / grant (A)Common Stock12,000USD 0.00USD 0SEC filing ↗
2026-06-09Ciongoli Gregory AustinAward / grant (A)Common Stock12,000USD 0.00USD 0SEC filing ↗
2026-05-18Nguyen AnhCoSale (S)Common Stock5,241USD 9.13USD 47,850SEC filing ↗
2026-05-18Grant-Huerta YaninaSale (S)Common Stock2,414USD 9.13USD 22,040SEC filing ↗
2026-05-07Huang James; Panacea Innovation LtdSale (S)Common Stock313,446USD 10.10USD 3,165,805SEC filing ↗
2026-05-07EcoR1 Capital, LLCPurchase (P)Common Stock507,407USD 9.35USD 4,744,255SEC filing ↗
2026-03-17Huang James; Panacea Innovation LtdOption exercise / conversion (M)Common Stock259,163USD 0.00USD 0SEC filing ↗
2026-03-17Huang James; Panacea Innovation LtdTax withholding (F)Common Stock5USD 5.23USD 26SEC filing ↗
2026-03-09Nguyen AnhCoAward / grant (A)Common Stock81,100USD 0.00USD 0SEC filing ↗
2026-03-09Grant-Huerta YaninaAward / grant (A)Common Stock20,300USD 0.00USD 0SEC filing ↗
2026-03-02Nguyen AnhCoSale (S)Common Stock2,996USD 5.09USD 15,247SEC filing ↗
2026-03-02Grant-Huerta YaninaSale (S)Common Stock2,104USD 5.08USD 10,688SEC filing ↗
2026-01-12Huang James; Panacea Innovation LtdSale (S)Common Stock80,554USD 6.07USD 488,963SEC filing ↗
2025-11-28Huang James; Panacea Innovation LtdOption exercise / conversion (M)Common Stock48,737USD 0.00USD 0SEC filing ↗
2025-11-28Huang James; Panacea Innovation LtdTax withholding (F)Common Stock1USD 14.03USD 14SEC filing ↗
2025-11-17Nguyen AnhCoSale (S)Common Stock2,915USD 13.19USD 38,449SEC filing ↗
2025-11-17Grant-Huerta YaninaSale (S)Common Stock1,804USD 13.19USD 23,795SEC filing ↗

Multiple price lines in one filing are grouped and share-weighted. Price and value are blank when a grouped filing line lacks price evidence.

Snapshot & identity

Snapshot date2026-10-19
Ranking versionUS-v1.2
Data qualityPASS ELIGIBLE · —
TickerATRA
CIK0001604464
SectorHealthcare
IndustryBiotechnology Yahoo Finance
SEC SIC2836 Biological Products, (No Diagnostic Substances)
ExchangeNasdaq

Data coverage

Local Form 4 history273 transaction lines from 2020-01-24 to 2026-09-04
11 P purchase lines · 169 S sale lines · 93 other lines
SEC company submissionsOpen SEC filings ↗

Local ledger as of 2026-10-19. Mapping status is an audit field and does not erase SEC filing evidence.