SCHEDULE 13D/A Filed 2026-07-24 Event 2026-07-22 SEC 0001104659-26-086728 →

Redmile Group, LLC → Atara Biotherapeutics, Inc. ATRA

Stake: 9.90% Shares: 950,994 CUSIP: 046513206 Class: Common Stock, par value $0.0001 per share

Composite Decision Signal · WATCH (DEVELOPING SETUP) Conviction Score: 55/100 · Filer 90d Win Rate: 100% · Hist. 90d Edge: +12.1%

Filer track record (3 filings): 100% 90d win rate, +12.1% 90d edge
High conviction ownership stake (9.9%)
Held by 1 tracked 13F institutional manager
Elevated short days-to-cover (8.1 DTC)

Item 4 — Purpose of Transaction

Not extracted from this filing — typically because it's an amendment (13D/A) and Item 4 is unchanged from the parent filing. Read the raw SEC filing →

Cross-References

Insider Activity (last 365d)

6 transactions

0 buys · 1 sales · 4 awards/exercises

Issuer Cluster

3 13D/G filings on this issuer

2 other filings besides this one

Filer Track Record

24 filings by this filer

23 other filings in the data moat

Short Interest · settle 2026-09-30

DTC 8.11

321,792 shares short · -20.4% vs prior

Institutional Consensus · 2025-12-31

Held by elite portfolio managers

1 holder · $331K

Point72 Asset Mgmt

Form 4 Insider Transactions · last 365d

Date	Insider	Role	Type	Shares	Price	Value
2026-08-17	Nguyen AnhCo	director, officer	Sale	5,062	$8.08	$41K
2026-07-22	Redmile Group, LLC	director	Option exercise	195,211	—	—
2026-07-22	Redmile Group, LLC	director	F	60	—	—
2026-07-22	Redmile Group, LLC	director	Option exercise	101,089	$0.00	$253
2026-07-22	Redmile Group, LLC	director	Option exercise	38,735	$0.00	$97
2026-07-22	Redmile Group, LLC	director	Option exercise	55,387	$0.00	$138

Other 13D/G Filings on Atara Biotherapeutics, Inc.

Filed	Form	Filer	Stake	Shares
2026-05-14	SCHEDULE 13D/A	Redmile Group, LLC	9.90%	950,994	view →
2026-05-11	SCHEDULE 13D/A	Panacea Innovation Ltd	—	1,318,894	view →

Other Filings by Redmile Group, LLC

Filed	Form	Issuer	Stake	Shares
2026-09-28	SCHEDULE 13G	Electra Therapeutics, Inc.	—	—	view →
2026-07-17	SCHEDULE 13D/A	Shattuck Labs, Inc.	9.90%	10,019,421	view →
2026-06-11	SCHEDULE 13D/A	Shattuck Labs, Inc. STTK	9.90%	9,819,084	view →
2026-05-14	SCHEDULE 13D/A	Atara Biotherapeutics, Inc. ATRA	9.90%	950,994	view →
2025-04-29	SCHEDULE	Absci Corp ABSI	6.50%	8,335,116	view →
2024-07-19	SC	Augmedix, Inc.	—	—	view →
2023-12-28	SC	FATE THERAPEUTICS INC FATE	—	—	view →
2023-06-21	SC	MedAvail Holdings, Inc.	—	—	view →
2023-06-13	SC	IGM Biosciences, Inc.	—	—	view →
2023-03-15	SC	MedAvail Holdings, Inc.	—	—	view →
2022-10-05	SC	IGM Biosciences, Inc.	—	—	view →
2022-07-06	SC	MedAvail Holdings, Inc.	—	—	view →
2022-01-14	SC	MedAvail Holdings, Inc.	—	—	view →
2021-11-29	SC	MedAvail Holdings, Inc.	—	—	view →
2021-03-01	SC	Augmedix, Inc.	—	—	view →
2021-01-12	SC	FATE THERAPEUTICS INC FATE	—	—	view →
2020-12-15	SC	IGM Biosciences, Inc.	—	—	view →
2020-09-10	SC	IGM Biosciences, Inc.	—	—	view →
2019-10-24	SC	ALDER BIOPHARMACEUTICALS INC	—	—	view →
2019-09-17	SC	FATE THERAPEUTICS INC FATE	—	—	view →

Showing 20 of 23

Want this depth on every filing the moment it hits SEC EDGAR?

Free $0 (48h-delayed alerts) · Individual $49/mo (real-time) · Team & API $199/mo · Enterprise.

See pricing →