ATRA Institutional Ownership & Shareholders
ATARA BIOTHERAPEUTICS INC (ATRA) is currently held by 36 institutional investors tracked by InsiderSet, with a combined reported market value of approximately $50.11M based on the latest available SEC Form 13F filings for the quarter ended June 30, 2026.
Ecor1 Capital, Llc is currently the largest disclosed institutional shareholder of ATRA tracked by InsiderSet, reporting ownership valued at approximately $17.82M in its June 30, 2026 SEC Form 13F filing. Based on current market prices and the latest disclosed share count, the position is now estimated to be worth approximately $12.43M, representing an estimated loss of -30.23% since the filing period.
The top 10 institutional shareholders tracked on this page collectively account for approximately 95% of the total disclosed ATRA value among the investors covered in this analysis. Major shareholders include Ecor1 Capital, Llc, Adage Capital Partners Gp, L.L.C., Point72 Asset Management, L.P., and several other long-term asset managers with concentrated positions in ATARA BIOTHERAPEUTICS INC (ATRA).
This page ranks the largest institutional ATRA shareholders using publicly disclosed SEC Form 13F data, including reported values, estimated current holding values, portfolio allocation percentages, ownership concentration metrics, and historical holding changes across major hedge funds and investment firms.
Institutional Holders
36
Total Reported Value
$50.11M
Largest Holder
Ecor1 Capital, Llc
Largest Position
$17.82M
Insider Transactions (90d)
2
Latest Filing Quarter
Q2 2026
New Institutional Positions
51
Funds Exiting Positions
0
| Name | Investor/Manager | Portfolio % | Quantity | Reported Balance | Current Estimated Value | Gain/loss Since Filing | Estimated Portfolio Performance |
|---|---|---|---|---|---|---|---|
| Ecor1 Capital, Llc | 0.88% | 1,552,000 | $17,816,960 | $12,431,520 | -$5,385,440 | -30.23% | |
| Adage Capital Partners Gp, L.L.C. | 0.01% | 850,000 | $9,758,000 | $6,808,500 | -$2,949,500 | -30.23% | |
| Point72 Asset Management, L.P. | 0.01% | 687,718 | $7,895,003 | $5,508,621 | -$2,386,382 | -30.23% | |
| Redmile Group, Llc | 0.34% | 441,701 | $5,070,727 | $3,538,025 | -$1,532,702 | -30.23% | |
| Vanguard Capital Management Llc | 0.00% | 247,047 | $2,836,100 | $1,978,846 | -$857,254 | -30.23% | |
| Mackenzie Financial Corp | 0.00% | 176,758 | $1,502,443 | $1,415,832 | -$86,611 | -5.76% | |
| Blackrock, Inc. | 0.00% | 84,455 | $969,544 | $676,485 | -$293,059 | -30.23% | |
| Geode Capital Management, Llc | 0.00% | 75,128 | $862,924 | $601,775 | -$261,149 | -30.26% | |
| Staley Capital Advisers Inc | 0.02% | 50,000 | $574,000 | $400,500 | -$173,500 | -30.23% | |
| Vanguard Fiduciary Trust Co | 0.00% | 43,036 | $494,053 | $344,718 | -$149,335 | -30.23% | |
| Acadian Asset Management Llc | 0.00% | 38,845 | $444,000 | $311,148 | -$132,852 | -29.92% | |
| Jane Street Group, Llc | 0.00% | 30,345 | $348,360 | $243,063 | -$105,297 | -30.23% | |
| State Street Corp | 0.00% | 26,453 | $303,680 | $211,889 | -$91,791 | -30.23% | |
| Northern Trust Corp | 0.00% | 16,591 | $190,465 | $132,894 | -$57,571 | -30.23% | |
| Fmr Llc | 0.00% | 16,238 | $186,412 | $130,066 | -$56,346 | -30.23% | |
| Xtx Topco Ltd | 0.00% | 15,303 | $175,678 | $122,577 | -$53,101 | -30.23% | |
| Bridgeway Capital Management, Llc | 0.00% | 14,000 | $160,720 | $112,140 | -$48,580 | -30.23% | |
| Millennium Management Llc | 0.00% | 12,680 | $145,566 | $101,567 | -$43,999 | -30.23% | |
| Citadel Advisors Llc | 0.00% | 10,159 | $116,625 | $81,374 | -$35,251 | -30.23% | |
| Morgan Stanley | 0.00% | 9,178 | $105,368 | $73,516 | -$31,852 | -30.23% | |
| Royal Bank Of Canada | 0.00% | 4,743 | $55,000 | $37,991 | -$17,009 | -30.92% | |
| Ubs Group Ag | 0.00% | 3,979 | $45,679 | $31,872 | -$13,807 | -30.23% | |
| Vanguard Global Advisers, Llc | 0.00% | 1,456 | $16,715 | $11,663 | -$5,052 | -30.23% | |
| Sbi Securities Co., Ltd. | 0.00% | 1,404 | $11,934 | $11,246 | -$688 | -5.76% | |
| Jones Financial Companies Lllp | 0.00% | 803 | $8,440 | $6,432 | -$2,008 | -23.79% | |
| Barclays Plc | 0.00% | 304 | $3,490 | $2,435 | -$1,055 | -30.23% | |
| Banque Transatlantique Sa | 0.00% | 176 | $3,096 | $1,410 | -$1,686 | -54.47% | |
| Wells Fargo & Company/Mn | 0.00% | 251 | $2,881 | $2,011 | -$870 | -30.21% | |
| Jpmorgan Chase & Co | 0.00% | 216 | $2,413 | $1,730 | -$683 | -28.30% | |
| Caitong International Asset Management Co., Ltd | 0.00% | 266 | $2,261 | $2,131 | -$130 | -5.76% | |
| Citigroup Inc | 0.00% | 97 | $1,114 | $777 | -$337 | -30.25% | |
| Bnp Paribas Financial Markets | 0.00% | 46 | $528 | $368 | -$160 | -30.22% | |
| Kerr Financial Planning Corp | 0.00% | 24 | $276 | $192 | -$84 | -30.35% | |
| Osaic Holdings, Inc. | 0.00% | 10 | $114 | $80 | -$34 | -29.74% | |
| Rockefeller Capital Management L.P. | 0.00% | 8 | $92 | $64 | -$28 | -30.35% | |
| Ifp Advisors, Inc | 0.00% | 1 | $8 | $8 | +$0 | +0.12% |
Frequently asked questions about ATRA
Who are the largest institutional holders of ATRA?
The largest institutional holders of ATRA reported in the latest SEC Form 13F filings include Ecor1 Capital, Llc, Adage Capital Partners Gp, L.L.C., Point72 Asset Management, L.P., Redmile Group, Llc, and Vanguard Capital Management Llc. InsiderSet ranks institutional holders by their latest reported ATRA position.
What is ATRA institutional ownership?
This page tracks ATRA positions reported by institutional investment managers through SEC Form 13F. ATARA BIOTHERAPEUTICS INC (ATRA) institutional ownership on InsiderSet reflects disclosed 13F holdings among the managers we analyze, not every shareholder of the stock.
How many institutions own ATRA?
InsiderSet currently tracks 36 institutional managers reporting ATRA holdings in the latest available 13F data. This count reflects institutions included in the SEC Form 13F filings analyzed by InsiderSet and should not be interpreted as the total number of ATRA shareholders.
How much ATRA stock do institutions own?
Institutional investment managers disclosed approximately $50.11M in ATRA holdings for Q2 2026. This figure is reported 13F value as of the filing period, not necessarily today's market value.
When was ATRA institutional ownership last updated?
The latest ATRA institutional ownership data on InsiderSet is based on SEC Form 13F filings for the quarter ended June 30, 2026. Form 13F filings are generally reported after the quarter ends, so the holdings shown represent the latest publicly disclosed positions rather than real-time institutional holdings.
Are institutional ATRA holdings real-time?
No. Form 13F data is not real-time. It represents positions reported by institutional investment managers as of the end of the reporting quarter. An institution may have changed its ATRA position after the reporting date.
Are institutions buying or selling ATRA?
Institutional buying and selling can be analyzed by comparing ATRA positions across consecutive 13F reporting periods. InsiderSet's ATRA Ownership Changes page shows institutions that increased, reduced, initiated, or exited positions based on reported 13F holdings. View ATRA ownership changes.
How has ATRA institutional ownership changed over time?
InsiderSet tracks ATRA institutional holdings across multiple 13F reporting periods, allowing investors to compare institutional holder counts, reported value, and reported shares over time.