Atara Biotherapeutics, Inc. - Common Stock, par value $0.0001 per share (ATRA)

Q: What does CUSIP 046513107 represent in this 13F holders report?

CUSIP 046513107 is the security identifier for ATRA - Atara Biotherapeutics, Inc. - Common Stock, par value $0.0001 per share used to aggregate holder disclosures.

Q: How many institutions held ATRA - Atara Biotherapeutics, Inc. - Common Stock, par value $0.0001 per share in Q1 2021?

148 institutional investors reported ATRA - Atara Biotherapeutics, Inc. - Common Stock, par value $0.0001 per share for Q1 2021. Use the holders table for investor-level position and value details.

CUSIP: 046513107

Q1 2021 13F Holders as of 31 Mar 2021

Security type / class: Equity / Common Stock, par value $0.0001 per share
Total 13F shares: 85,650,758
Total 13F value: $1,229,931,921
Share change: +59,612
Put/Call ratio: 30%
SEC-reported price per share: $14.36
Number of holders: 148
Value change: -$3,128,334
Number of buys: 80
Number of sells: 60
Shares outstanding: 9,606,000

Security key

046513107

Report period

Q1 2021

Institutions

148

Top holders

ATRA full security history Ownership snapshot Full 13F holder table Newer quarter: Q3 2025 Atara Biotherapeutics, Inc. SEC filings Atara Biotherapeutics, Inc. company facts

Broader feeds

Latest 13F filings Latest 13D/G filings Investors directory

Reporting periods

Holder history for CUSIP 046513107

Newer quarter: Q3 2025

Recent filing periods:

Q2 2026 Q1 2026 Q4 2025 Q3 2025

Ownership snapshot

Top reported holders of ATRA - Atara Biotherapeutics, Inc. - Common Stock, par value $0.0001 per share (13F + 13D/G + 3/4/5)

Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.

Comparable stake leader

BAUPOST GROUP LLC/MA

Disclosed value leader

BAUPOST GROUP LLC/MA

Comparable rows

0/15

Latest evidence

31 Dec 2020

13F Highest disclosed value: $178,809,000 15 rows are not safely comparable across share classes. Showing 1-6 of 15 holder rows.

Quick read

BAUPOST GROUP LLC/MA has the largest disclosed position value at $178.81M.

0 of 15 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.

Open SEC evidence Opens BAUPOST GROUP LLC/MA's linked filing trail.

Disclosed position value Top 5

BAUPOST GROUP LLC/MA $178.81M

MAVERICK CAPITAL LTD $143.78M

Redmile Group, LLC $134.72M

BlackRock Finance, Inc. $126.7M

JPMORGAN CHASE & CO $121.86M

Value bars compare disclosed positions; verify each figure against the linked filing evidence.

Detailed SEC evidence table Showing 1-6 of 15 holder rows

Holder	Evidence	Ownership %	Position	12M Net Δ	As of
BAUPOST GROUP LLC/MA	13F Company 13F	— denominator unverified	$178,809,000 9,108,988 shares	—	31 Dec 2020
MAVERICK CAPITAL LTD	13F Company 13F	— denominator unverified	$143,781,000 7,324,539 shares	—	31 Dec 2020
Redmile Group, LLC	13F Company 13F	— denominator unverified	$134,722,000 6,863,070 shares	—	31 Dec 2020
BlackRock Finance, Inc.	13F Company 13F	— denominator unverified	$126,700,000 6,454,415 shares	—	31 Dec 2020
JPMORGAN CHASE & CO	13F Company 13F	— denominator unverified	$121,858,000 6,207,767 shares	—	31 Dec 2020
VANGUARD GROUP INC	13F Company 13F	— denominator unverified	$110,680,000 5,638,274 shares	—	31 Dec 2020

How to read this table

Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.

13F holder rows

Institutional holders as of Q1 2021

Investor-level positions for this CUSIP, loaded as an interactive table.

Institutions

148

85,650,758

Rows available

148

Investor	Option	Weight %	Change %	SEC-reported value	* Price	Shares	Share Change	Activity	Report Period

^* SEC-reported price is the security price as of the portfolio date and can indicate the last known price at which the security was still held. The marker flags a reported price that did not pass the local price check.

Compare Q1 2021 vs Q1 2026 Across Filers

Q1 2026 holders

Q1 2021 holders

148

Holder diff

147

Investor	Q1 2026 Shares	Q1 2021 Shares	Share Diff	Share Chg %	Q1 2026 value	Q1 2021 value	Value change	Value Chg %

Trend: ostatnie 8 kwartałów (+ wybrane okresy porównania).

Quarterly Holders Trend

Quarterly Value Trend

Quarterly Shares Trend