Who owns Zenas BioPharma (ZBIO)
Which tracked institutional funds hold ZBIO, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See ZBIO company fundamentals →
Ownership as of the 2026-Q1 13F filings (latest filed 2026-05-18). 13F is disclosed up to 45 days after quarter-end, so the most recent quarter fills in over the following weeks.
How the tape is positioned
41 tracked funds added or opened ZBIO while 41 trimmed or exited it between 2025-Q4 and 2026-Q1 — the tape is split. When large holders disagree on a name, the funds moving first are sometimes ahead of the story.
A prompt to read the filings, not a verdict. 13F is a quarter-end snapshot disclosed up to 45 days late; a fund adds or exits for mandate, benchmark, and timing reasons that have nothing to do with a view on the stock. This is a starting question, not a signal to trade.
Conviction spread
ZBIO’s largest tracked holder by dollar value, FMR LLC, sizes it at 0.0% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 0.0pp conviction gap — its largest holder concentrates the name more heavily than the typical one.
Book-share is each fund’s reported value in ZBIO divided by its whole reported 13F book, so it is comparable across funds of different sizes and is unaffected by stock splits. A higher share means a fund has committed more of its book to the name — a starting question about conviction, not a verdict or a signal to trade.
Institutional & insider positioning
Between 2025-Q4 and 2026-Q1, across 139 tracked filers holding ZBIO, 108 increased or opened the position and 47 reduced or closed it; over the same quarter, open-market insider Form 4s were net purchases.
This fuses two public signals for the same quarter — how tracked institutions changed their positions and whether insiders bought or sold in the open market. It describes what was filed; it is a starting question, not a verdict or a signal to trade.
New buyers & exits
Funds opening or closing a position in ZBIO between the 2025-Q4 and 2026-Q1 13F filings, and the largest changes among funds holding it in both. New buyers and exits are counted on fund presence (split-invariant); adds and trims are measured on reported value.
New buyers 28
- Capital International Investors$48M
- VANGUARD CAPITAL MANAGEMENT LLC$24M
- SILVERARC CAPITAL MANAGEMENT, LLC$22M
- Woodline Partners LP$12M
- GREAT POINT PARTNERS LLC$10M
- Sio Capital Management, LLC$6M
Full exits 8
- VANGUARD GROUP INC$53M
- NOVO HOLDINGS A/S$53M
- Vivo Capital, LLC$31M
- Point72 Asset Management, L.P.$9M
- Skandinaviska Enskilda Banken AB (publ)$6M
- Eversept Partners, LP$4M
Largest adds
- ALLIANCEBERNSTEIN L.P.$32M
- STATE STREET CORP$13M
- Polar Capital Holdings Plc$11M
- MARSHALL WACE, LLP$10M
- MILLENNIUM MANAGEMENT LLC$8M
- BALYASNY ASSET MANAGEMENT L.P.$6M
Largest trims
- FMR LLC$102M
- SR One Capital Management, LP$84M
- ENAVATE SCIENCES GP, LLC$66M
- NEA Management Company, LLC$49M
- FEDERATED HERMES, INC.$37M
- Fairmount Funds Management LLC$34M
Institutional holders
One row per tracked fund, largest reported value first. “% of value” is the fund’s share of this security’s tracked institutional value — not of shares outstanding. Rows marked stale are from an earlier filing than the security’s latest quarter — that fund is absent from the newest snapshot (position exited, or reported under a different name).
| Fund | Shares | Reported value | % of value | Quarter |
|---|---|---|---|---|
| FMR LLC added | 9,506,701 | $241M | 16.2% | 2026-Q2 |
| SR One Capital Management, LP | 5,037,854 | $98M | 6.6% | 2026-Q1 |
| NEA Management Company, LLC added | 4,023,219 | $79M | 5.3% | 2026-Q1 |
| ENAVATE SCIENCES GP, LLC | 3,919,159 | $77M | 5.2% | 2026-Q1 |
| BlackRock, Inc. added | 2,686,225 | $68M | 4.6% | 2026-Q2 |
| Capital International Investors added | 2,502,912 | $64M | 4.3% | 2026-Q2 |
| FEDERATED HERMES, INC. added | 3,127,031 | $61M | 4.1% | 2026-Q1 |
| STATE STREET CORP added | 2,055,100 | $52M | 3.5% | 2026-Q2 |
| Polar Capital Holdings Plc added | 2,548,444 | $50M | 3.3% | 2026-Q1 |
| Fairmount Funds Management LLC added | 2,359,025 | $46M | 3.1% | 2026-Q1 |
| WELLINGTON MANAGEMENT GROUP LLP added | 1,593,819 | $40M | 2.7% | 2026-Q2 |
| NVP ASSOCIATES, LLC | 1,838,482 | $36M | 2.4% | 2026-Q1 |
| ALLIANCEBERNSTEIN L.P. added | 897,321 | $33M | 2.2% | 2026-Q1 |
| PRICE T ROWE ASSOCIATES INC /MD/ added | 1,226,928 | $31M | 2.1% | 2026-Q2 |
| VANGUARD CAPITAL MANAGEMENT LLC new | 1,245,391 | $24M | 1.6% | 2026-Q1 |
| SILVERARC CAPITAL MANAGEMENT, LLC new | 1,135,935 | $22M | 1.5% | 2026-Q1 |
| TWO SIGMA INVESTMENTS, LP added | 815,150 | $21M | 1.4% | 2026-Q2 |
| MILLENNIUM MANAGEMENT LLC added | 660,470 | $17M | 1.1% | 2026-Q2 |
| EcoR1 Capital, LLC | 789,500 | $15M | 1.0% | 2026-Q1 |
| BALYASNY ASSET MANAGEMENT L.P. trimmed | 576,717 | $15M | 1.0% | 2026-Q2 |
| ArrowMark Colorado Holdings LLC trimmed | 658,909 | $13M | 0.9% | 2026-Q1 |
| GEODE CAPITAL MANAGEMENT, LLC added | 655,785 | $13M | 0.9% | 2026-Q1 |
| Pivotal bioVenture Partners Investment Advisor LLC | 591,991 | $12M | 0.8% | 2026-Q1 |
| Woodline Partners LP new | 590,525 | $12M | 0.8% | 2026-Q1 |
| GREAT POINT PARTNERS LLC new | 524,066 | $10M | 0.7% | 2026-Q1 |
| Rock Springs Capital Management LP | 502,077 | $10M | 0.7% | 2026-Q1 |
| NEXTBio Capital Management LP added | 426,736 | $8M | 0.6% | 2026-Q1 |
| MARSHALL WACE, LLP trimmed | 323,442 | $8M | 0.6% | 2026-Q2 |
| BANK OF AMERICA CORP /DE/ added | 388,347 | $8M | 0.5% | 2026-Q1 |
| GOLDMAN SACHS GROUP INC added | 381,461 | $7M | 0.5% | 2026-Q1 |
| UBS Group AG added | 367,405 | $7M | 0.5% | 2026-Q1 |
| Sio Capital Management, LLC new | 331,730 | $6M | 0.4% | 2026-Q1 |
| CITADEL ADVISORS LLC added | 195,780 | $5M | 0.3% | 2026-Q2 |
| VANGUARD PORTFOLIO MANAGEMENT LLC new | 251,410 | $5M | 0.3% | 2026-Q1 |
| JENNISON ASSOCIATES LLC new | 250,000 | $5M | 0.3% | 2026-Q1 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC added | 224,402 | $4M | 0.3% | 2026-Q1 |
| Jefferies Financial Group Inc. added | 219,947 | $4M | 0.3% | 2026-Q1 |
| iA Global Asset Management Inc. new | 215,830 | $4M | 0.3% | 2026-Q1 |
| SPHERA FUNDS MANAGEMENT LTD. new | 214,334 | $4M | 0.3% | 2026-Q1 |
| Vestal Point Capital, LP new | 200,000 | $4M | 0.3% | 2026-Q1 |
| NORTHERN TRUST CORP added | 194,640 | $4M | 0.3% | 2026-Q1 |
| VANGUARD FIDUCIARY TRUST CO new | 179,388 | $4M | 0.2% | 2026-Q1 |
| SEB Asset Management AB new | 163,860 | $3M | 0.2% | 2026-Q1 |
| Monashee Investment Management LLC | 150,000 | $3M | 0.2% | 2026-Q1 |
| Maven Securities LTD added | 150,000 | $3M | 0.2% | 2026-Q1 |
| Walleye Capital LLC new | 125,232 | $2M | 0.2% | 2026-Q1 |
| Atom Investors LP new | 107,016 | $2M | 0.1% | 2026-Q1 |
| SEVEN GRAND MANAGERS, LLC new | 100,000 | $2M | 0.1% | 2026-Q1 |
| Verition Fund Management LLC new | 72,988 | $2M | 0.1% | 2026-Q2 |
| MORGAN STANLEY trimmed | 93,396 | $2M | 0.1% | 2026-Q1 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP added | 85,005 | $2M | 0.1% | 2026-Q1 |
| Exome Asset Management LLC new | 80,730 | $2M | 0.1% | 2026-Q1 |
| VOLORIDGE INVESTMENT MANAGEMENT, LLC trimmed | 77,493 | $2M | 0.1% | 2026-Q1 |
| Birchview Capital, LP added | 70,000 | $1M | 0.1% | 2026-Q1 |
| Nuveen, LLC added | 67,770 | $1M | 0.1% | 2026-Q1 |
| Bank of New York Mellon Corp added | 60,864 | $1M | 0.1% | 2026-Q1 |
| Jump Financial, LLC new | 60,001 | $1M | 0.1% | 2026-Q1 |
| Rafferty Asset Management, LLC new | 48,169 | $942K | 0.1% | 2026-Q1 |
| ALPS ADVISORS INC trimmed | 43,694 | $854K | 0.1% | 2026-Q1 |
| Squarepoint Ops LLC added | 42,874 | $838K | 0.1% | 2026-Q1 |
| DAFNA Capital Management LLC new | 42,500 | $831K | 0.1% | 2026-Q1 |
| AQR CAPITAL MANAGEMENT LLC trimmed | 31,100 | $789K | 0.1% | 2026-Q2 |
| Burkehill Global Management, LP new | 40,000 | $782K | 0.1% | 2026-Q1 |
| J. Goldman & Co LP new | 36,797 | $719K | 0.0% | 2026-Q1 |
| Swiss National Bank | 31,600 | $618K | 0.0% | 2026-Q1 |
| SCHRODER INVESTMENT MANAGEMENT GROUP trimmed | 33,697 | $614K | 0.0% | 2026-Q1 |
| Voleon Capital Management LP added | 29,612 | $579K | 0.0% | 2026-Q1 |
| BARCLAYS PLC trimmed | 29,610 | $579K | 0.0% | 2026-Q1 |
| JACOBS LEVY EQUITY MANAGEMENT, INC new | 27,532 | $538K | 0.0% | 2026-Q1 |
| RHUMBLINE ADVISERS added | 26,813 | $524K | 0.0% | 2026-Q1 |
| HRT FINANCIAL LP added | 25,749 | $503K | 0.0% | 2026-Q1 |
| Invesco Ltd. trimmed | 18,954 | $481K | 0.0% | 2026-Q2 |
| JPMORGAN CHASE & CO added | 25,109 | $458K | 0.0% | 2026-Q1 |
| PROFUND ADVISORS LLC new | 21,416 | $419K | 0.0% | 2026-Q1 |
| Quantinno Capital Management LP new | 21,126 | $413K | 0.0% | 2026-Q1 |
| Point72 Asset Management, L.P. trimmed | 16,136 | $410K | 0.0% | 2026-Q2 |
| Vanguard Global Advisers, LLC new | 20,840 | $407K | 0.0% | 2026-Q1 |
| STATE OF WISCONSIN INVESTMENT BOARD added | 20,814 | $407K | 0.0% | 2026-Q1 |
| XTX Topco Ltd added | 19,311 | $378K | 0.0% | 2026-Q1 |
| DEUTSCHE BANK AG\ added | 19,266 | $377K | 0.0% | 2026-Q1 |
| Brevan Howard Capital Management LP added | 14,674 | $372K | 0.0% | 2026-Q2 |
| Aquatic Capital Management LLC new | 18,640 | $364K | 0.0% | 2026-Q1 |
| ALLSTATE CORP new | 18,223 | $356K | 0.0% | 2026-Q1 |
| Schonfeld Strategic Advisors LLC added | 17,638 | $345K | 0.0% | 2026-Q1 |
| Corient Private Wealth LLC new | 16,845 | $329K | 0.0% | 2026-Q1 |
| PRELUDE CAPITAL MANAGEMENT, LLC new | 16,645 | $325K | 0.0% | 2026-Q1 |
| VANGUARD GROUP INC added | 1,453,065 | $53M | 3.5% | 2025-Q4 stale |
| NOVO HOLDINGS A/S trimmed | 1,450,000 | $53M | 3.5% | 2025-Q4 stale |
| DEERFIELD MANAGEMENT COMPANY, L.P. | 1,562,942 | $35M | 2.3% | 2025-Q3 stale |
| Vivo Capital, LLC trimmed | 853,495 | $31M | 2.1% | 2025-Q4 stale |
| Skandinaviska Enskilda Banken AB (publ) new | 163,860 | $6M | 0.4% | 2025-Q4 stale |
| Eversept Partners, LP trimmed | 121,016 | $4M | 0.3% | 2025-Q4 stale |
| SECTORAL ASSET MANAGEMENT INC trimmed | 152,025 | $3M | 0.2% | 2025-Q3 stale |
| SUPERSTRING CAPITAL MANAGEMENT LP trimmed | 83,353 | $3M | 0.2% | 2025-Q4 stale |
| SUMMIT WEALTH GROUP LLC / CO new | 51,356 | $3M | 0.2% | 2025-Q3 stale |
| Catalio Capital Management, LP trimmed | 215,314 | $2M | 0.1% | 2025-Q2 stale |
| NORGES BANK added | 75,000 | $1M | 0.1% | 2025-Q3 stale |
| STEMPOINT CAPITAL LP new | 38,742 | $860K | 0.1% | 2025-Q3 stale |
| VOYA INVESTMENT MANAGEMENT LLC new | 14,725 | $535K | 0.0% | 2025-Q4 stale |
| LOS ANGELES CAPITAL MANAGEMENT LLC new | 14,447 | $432K | 0.0% | 2025-Q4 stale |
Ownership over time
Tracked institutional holder count and total shares held by filing quarter (independent scales). The curated-era tail and any mid-ingest latest quarter are handled honestly — a partial quarter is not drawn as a collapse.
Reading this table
Funds hold the same stock for different reasons — an index fund “holds” almost everything, an active manager sizes a name to a mandate and a benchmark, and each fund entered at its own price and time. Because 13F is filed up to 45 days after quarter-end, every row is a backward-looking snapshot; a manager may have traded since. Share-class siblings (a company’s A and C shares) are rolled up to one line so a dual-class name is never double-counted. Compare like-for-like. A large holder is not an endorsement, and a fund exiting is not a warning — this is a starting question, not a verdict.
About 13F filings
A Form 13F is a quarterly disclosure that institutional investment managers with over $100 million in US-listed equities must file with the SEC. In plain English: it is a snapshot of the long stock positions a fund held at the end of a quarter. It covers long US-listed equities only — not short positions, options, cash, or private holdings — and the funds shown are the large sample we track, not the complete 13F universe.