ATARA BIOTHERAPEUTICS INC (ATRA) Top Institutional Shareholders
ATARA BIOTHERAPEUTICS INC (ATRA) is currently reported in institutional portfolios tracked by InsiderSet based on the latest available SEC Form 13F filings for the quarter ended March 31, 2026. The institutional investors covered on this page collectively reported approximately $11.51M in ATRA holdings during the latest filing period.
Adage Capital Partners Gp, L.L.C. is currently the largest disclosed institutional shareholder of ATRA tracked by InsiderSet, reporting ownership valued at approximately $3.31M in its March 31, 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 $6.77M, representing an estimated gain of +104.44% since the filing period.
The top 10 institutional shareholders tracked on this page collectively account for approximately 91% of the total disclosed ATRA value among the investors covered in this analysis. Major shareholders include Adage Capital Partners Gp, L.L.C., Redmile Group, Llc, Mackenzie Financial Corp, 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
32
Total Reported Value
$11.51M
Largest Holder
Adage Capital Partners Gp, L.L.C.
Largest Position
$3.31M
Insider Transactions (90d)
0
Latest Filing Quarter
Q1 2026
New Institutional Positions
47
Funds Exiting Positions
0
| Name | Investor/Manager | Portfolio % | Quantity | Reported Balance | Current Estimated Value | Gain/loss Since Filing | Estimated Portfolio Performance |
|---|---|---|---|---|---|---|---|
| Adage Capital Partners Gp, L.L.C. | 0.01% | 700,000 | $3,311,000 | $6,769,000 | +$3,458,000 | +104.44% | |
| Redmile Group, Llc | 0.14% | 441,701 | $2,089,246 | $4,271,249 | +$2,182,003 | +104.44% | |
| Mackenzie Financial Corp | 0.00% | 313,620 | $1,483,423 | $3,032,705 | +$1,549,282 | +104.44% | |
| Vanguard Capital Management Llc | 0.00% | 217,862 | $1,030,487 | $2,106,726 | +$1,076,239 | +104.44% | |
| Point72 Asset Management, L.P. | 0.00% | 194,264 | $918,869 | $1,878,533 | +$959,664 | +104.44% | |
| Ecor1 Capital, Llc | 0.02% | 99,593 | $471,075 | $963,064 | +$491,989 | +104.44% | |
| Blackrock, Inc. | 0.00% | 79,022 | $373,773 | $764,143 | +$390,370 | +104.44% | |
| Geode Capital Management, Llc | 0.00% | 66,146 | $313,045 | $639,632 | +$326,587 | +104.33% | |
| Ubs Group Ag | 0.00% | 50,070 | $236,831 | $484,177 | +$247,346 | +104.44% | |
| Staley Capital Advisers Inc | 0.01% | 50,000 | $236,500 | $483,500 | +$247,000 | +104.44% | |
| Millennium Management Llc | 0.00% | 47,689 | $225,569 | $461,153 | +$235,584 | +104.44% | |
| Jane Street Group, Llc | 0.00% | 33,870 | $160,206 | $327,523 | +$167,317 | +104.44% | |
| Vanguard Fiduciary Trust Co | 0.00% | 33,621 | $159,027 | $325,115 | +$166,088 | +104.44% | |
| Bridgeway Capital Management, Llc | 0.00% | 32,691 | $154,628 | $316,122 | +$161,494 | +104.44% | |
| State Street Corp | 0.00% | 26,453 | $125,123 | $255,801 | +$130,678 | +104.44% | |
| Fmr Llc | 0.00% | 16,238 | $76,806 | $157,021 | +$80,215 | +104.44% | |
| Northern Trust Corp | 0.00% | 12,340 | $58,368 | $119,328 | +$60,960 | +104.44% | |
| Morgan Stanley | 0.00% | 9,168 | $43,365 | $88,655 | +$45,290 | +104.44% | |
| Royal Bank Of Canada | 0.00% | 4,319 | $20,000 | $41,765 | +$21,765 | +108.82% | |
| Sbi Securities Co., Ltd. | 0.00% | 1,574 | $7,445 | $15,221 | +$7,776 | +104.44% | |
| Vanguard Global Advisers, Llc | 0.00% | 1,456 | $6,887 | $14,080 | +$7,193 | +104.44% | |
| Jones Financial Companies Lllp | 0.00% | 703 | $3,227 | $6,798 | +$3,571 | +110.66% | |
| Wells Fargo & Company/Mn | 0.00% | 251 | $1,187 | $2,427 | +$1,240 | +104.48% | |
| Banque Transatlantique Sa | 0.00% | 176 | $906 | $1,702 | +$796 | +87.85% | |
| Rhumbline Advisers | 0.00% | 175 | $827 | $1,692 | +$865 | +104.63% | |
| Acadian Asset Management Llc | 0.00% | 130,910 | $617 | $1,265,900 | +$1,265,283 | +205070.13% | |
| Bnp Paribas Financial Markets | 0.00% | 58 | $274 | $561 | +$287 | +104.69% | |
| Kerr Financial Planning Corp | 0.00% | 24 | $116 | $232 | +$116 | +100.07% | |
| Osaic Holdings, Inc. | 0.00% | 10 | $47 | $97 | +$50 | +105.74% | |
| Rockefeller Capital Management L.P. | 0.00% | 8 | $38 | $77 | +$39 | +103.58% | |
| Citigroup Inc | 0.00% | 1 | $5 | $10 | +$5 | +93.40% | |
| Western Wealth Management, Llc | 0.00% | 1 | $5 | $10 | +$5 | +93.40% |
Frequently asked questions about ATRA
Who owns the most ATRA stock?
The largest holders of ATRA are typically major institutional investors such as asset managers and hedge funds reporting on Form 13F. The table above ranks tracked superinvestors by reported position size using the latest available filings for ATARA BIOTHERAPEUTICS INC (ATRA).
Is ATRA widely held by superinvestors?
Many widely followed stocks like ATRA appear across numerous superinvestor portfolios because of liquidity, index inclusion, and fundamentals. The holder count and table above show how broadly ATRA is represented among the institutional managers we track.
What do “Current Estimated Value”, “Gain/loss Since Filing”, and “Estimated Portfolio Performance” mean?
Current Estimated Value is reported share quantity from the latest 13F times our most recent split-adjusted U.S. session close. Gain/loss Since Filing is that estimate minus the reported 13F dollar value; Estimated Portfolio Performance is that difference as a percent of the reported value. Green means the estimate is above the filing value; red means below (not purchase cost). If many filers share the same implied filing price per share, the performance % may match across rows. These are not official fund marks or live quotes.