ZENAS BIOPHARMA INC ZBIO
COM · Common Stock · CUSIP 98937L105
- SectorHealth care
- IndustryPharmaceutical Preparations
- HeadquartersWaltham, MA
- FilingsSEC EDGAR
* Summed across managers. Shares that two managers' reports both contain – a subsidiary's holdings that its parent's report includes too, or a sub-adviser's in its client's – are counted once ($43.6k this quarter). Holder counts are more reliable. Shares outstanding: 42.1m as of 2025-07-31, from the company's own SEC filing; the percentage can still exceed 100%: lent-out shares are counted by the lender and the buyer, and some reports overlap without saying so. Implied quarter-end price ≈ $9.69.
Trends to Q2 2025
Institutional holders
Managers reporting a position, each quarter
Numbers
| Quarter | Holders |
|---|---|
| Q3 2024 | 45 |
| Q4 2024 | 66 |
| Q1 2025 | 68 |
| Q2 2025 | 74 |
Buyers vs sellers
Managers adding to or starting a position, vs cutting or selling out
Numbers
| Quarter | Bought or added | Cut or sold out |
|---|---|---|
| Q4 2024 | 43 | 20 |
| Q1 2025 | 25 | 29 |
| Q2 2025 | 44 | 17 |
Biggest buyers
| FEDERATED HERMES, INC. | Added | +703.8k |
| FMR LLC | Added | +471.2k |
| CITADEL ADVISORS LLC | New | +293.8k |
| SECTORAL ASSET MANAGEMENT INC | New | +210.6k |
| NEA Management Company, LLC | Added | +119.8k |
| BlackRock, Inc. | Added | +81.5k |
| MORGAN STANLEY | Added | +46.4k |
| STATE STREET CORP | Added | +44.0k |
| Pivotal bioVenture Partners Investment Advisor LLC | Added | +42.4k |
| NOVO HOLDINGS A/S | Added | +35.0k |
Biggest sellers
| Rock Springs Capital Management LP | Reduced | -238.2k |
| Eversept Partners, LP | Reduced | -120.1k |
| Catalio Capital Management, LP | Reduced | -79.8k |
| Jefferies Financial Group Inc. | Sold out | -44.1k |
| PRICE T ROWE ASSOCIATES INC /MD/ | Reduced | -32.4k |
| GSA CAPITAL PARTNERS LLP | Sold out | -31.8k |
| GOLDMAN SACHS GROUP INC | Sold out | -24.0k |
| BNP PARIBAS FINANCIAL MARKETS | Reduced | -23.9k |
| DEUTSCHE BANK AG\ | Reduced | -22.7k |
| STONERIDGE INVESTMENT PARTNERS LLC | Sold out | -11.0k |
Major shareholders (over 5%)
Anyone who owns more than 5% of a class of the company's shares has to say so: on Schedule 13D if they may try to influence or control the company, on 13G if they're a passive investor, and update it as the stake changes. Each holder's latest filing, from 19 Dec 2024 on; percentages are of the share class, as the holder worked them out.
| Holder | Stake |
|---|---|
| FMR LLC 13G · institution +3.3 pts · filed 2026-02-05 | 14.3% |
| InnoCare Pharma Inc. 13G · passive investor +1.0 pts · filed 2026-09-08 | 10.4% |
| WELLINGTON MANAGEMENT GROUP LLP 13G · institution new · filed 2026-09-08 | 10.1% |
SR ONE CAPITAL MANAGEMENT, LLC
13D · may seek influence
-1.7 pts · filed 2026-08-17
Stated purposeNot applicable. Full filing |
7.7% |
MOULDER LEON O JR
13D · may seek influence
+0.3 pts · filed 2026-05-05
Stated purposeThe information set forth in Item 3 of this Statement is incorporated herein by reference. Mr. Moulder serves as the Chairman of the Issuer's Board of Directors and as its Chief Executive Officer. In such capacity, Mr. Moulder has influence over the corporate activities of the Issuer, including activities that may relate to items described in subparagraphs (a) through (j) of Item 4 of Schedule 13D. Except as described herein, the Reporting Persons have no present plans or proposals that relate to or would result in any of the transactions described in subparagraphs (a) through (j) of Item 4 of Schedule 13D. However, the Reporting Persons reserve the right to formulate in the future plans or proposals which may relate to or result in the transactions described in subparagraphs (a) through … Full filing |
5.1% |
| BlackRock, Inc. 13G · institution new · filed 2026-10-27 | 5.0% |
Fell to 5% or below in the last year: Enavate Sciences GP, LLC (4.9%, 2026-08-19), Novo Holdings A/S (4.7%, 2025-11-14)
Insider purchases and sales in Q2 2025
Shares bought or sold by the company's own officers, directors and 10% owners, in the open market or privately, as they reported to the SEC on Form 4 (due within two business days of the trade). Grants, option exercises, shares withheld for tax and gifts aren't included.
Officers and directors buying vs selling
Number of people, by quarter (10% owners not included)
Numbers
| Quarter | Buying | Bought | Selling | Sold | Sold under a plan |
|---|---|---|---|---|---|
| Q3 2023 | 0 | — | 0 | — | — |
| Q4 2023 | 0 | — | 0 | — | — |
| Q1 2024 | 0 | — | 0 | — | — |
| Q2 2024 | 0 | — | 0 | — | — |
| Q3 2024 | 5 | $28.9m | 0 | — | — |
| Q4 2024 | 1 | $867.0k | 0 | — | — |
| Q1 2025 | 2 | $244.3k | 0 | — | — |
| Q2 2025 | 0 | — | 0 | — | — |
None reported in Q2 2025.
Holders, Q2 2025
| Manager | Shares | Change |
|---|---|---|
| SR One Capital Management, LP 10.32% of their portfolio | 4.9m $47.6m | Unchanged |
| ENAVATE SCIENCES GP, LLC 20.65% of their portfolio | 3.8m $36.4m | Unchanged |
| FMR LLC 0.00% of their portfolio | 3.3m $32.2m | Added +471.2k |
| NEA Management Company, LLC 1.99% of their portfolio | 2.7m $26.5m | Added +119.8k |
| NOVO HOLDINGS A/S 1.54% of their portfolio | 2.2m $21.8m | Added +35.0k |
| Fairmount Funds Management LLC 2.38% of their portfolio | 1.9m $18.3m | Unchanged |
| FEDERATED HERMES, INC. 0.03% of their portfolio | 1.9m $18.0m | Added +703.8k |
| NVP ASSOCIATES, LLC 9.67% of their portfolio | 1.8m $17.8m | Unchanged |
| DEERFIELD MANAGEMENT COMPANY, L.P. 0.27% of their portfolio | 1.6m $15.1m | Unchanged |
| Vivo Capital, LLC 1.17% of their portfolio | 1.2m $11.5m | Unchanged |
| BlackRock, Inc. 0.00% of their portfolio | 1.1m $10.6m | Added +81.5k |
| ArrowMark Colorado Holdings LLC 0.19% of their portfolio | 1.1m $10.6m | Reduced -3.0k |
| VANGUARD GROUP INC 0.00% of their portfolio | 992.2k $9.6m | Added +16.3k |
| WELLINGTON MANAGEMENT GROUP LLP 0.00% of their portfolio | 878.9k $8.5m | Added +5.3k |
| Pivotal bioVenture Partners Investment Advisor LLC 4.68% of their portfolio | 779.0k $7.5m | Added +42.4k |
| Rock Springs Capital Management LP 0.39% of their portfolio | 640.5k $6.2m | Reduced -238.2k |
| PRICE T ROWE ASSOCIATES INC /MD/ 0.00% of their portfolio | 485.2k $4.7m | Reduced -32.4k |
| GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 373.6k $3.6m | Added +16.5k |
| Eversept Partners, LP 0.32% of their portfolio | 325.5k $3.2m | Reduced -120.1k |
| STATE STREET CORP 0.00% of their portfolio | 310.2k $3.0m | Added +44.0k |
| CITADEL ADVISORS LLC 0.00% of their portfolio | 293.8k $2.8m | New |
| Catalio Capital Management, LP 0.44% of their portfolio | 215.3k $2.1m | Reduced -79.8k |
| SECTORAL ASSET MANAGEMENT INC 1.35% of their portfolio | 210.6k $2.0m | New |
| SCHRODER INVESTMENT MANAGEMENT GROUP 0.00% of their portfolio | 154.9k $1.5m | Reduced -9.1k |
| MORGAN STANLEY 0.00% of their portfolio | 124.3k $1.2m | Added +46.4k |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio | 122.2k $1.2m | Added +6.1k |
| NORTHERN TRUST CORP 0.00% of their portfolio | 119.5k $1.2m | Reduced -723 |
| SUPERSTRING CAPITAL MANAGEMENT LP 1.35% of their portfolio | 111.6k $1.1m | Unchanged |
| Bank of New York Mellon Corp 0.00% of their portfolio | 38.4k $372.4k | Added +3.2k |
| Nuveen, LLC 0.00% of their portfolio | 31.6k $306.5k | Unchanged |
| BARCLAYS PLC 0.00% of their portfolio | 27.8k $269.5k | Added +11.7k |
| AQR CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 24.7k $239.0k | New |
| UBS Group AG 0.00% of their portfolio | 24.3k $235.1k | Added +3.5k |
| ALPS ADVISORS INC 0.00% of their portfolio | 22.6k $218.5k | Reduced -5.6k |
| RHUMBLINE ADVISERS 0.00% of their portfolio | 19.7k $191.1k | Added +8.2k |
| TWO SIGMA INVESTMENTS, LP 0.00% of their portfolio | 19.6k $190.1k | New |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP 0.00% of their portfolio | 19.5k $189.4k | Added +904 |
| Birchview Capital, LP 0.16% of their portfolio | 16.5k $159.9k | Unchanged |
| ALLIANCEBERNSTEIN L.P. 0.00% of their portfolio | 16.4k $158.5k | New |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC 0.00% of their portfolio | 14.9k $144.4k | New |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 14.0k $135.6k | Added +3.4k |
| INTECH INVESTMENT MANAGEMENT LLC 0.00% of their portfolio | 13.2k $128.0k | Added +1.6k |
| Alpine Global Management, LLC 0.03% of their portfolio | 12.9k $125.1k | New |
| SEI INVESTMENTS CO 0.00% of their portfolio | 12.1k $117.6k | Added +186 |
| WELLS FARGO & COMPANY/MN 0.00% of their portfolio | 10.4k $101.0k | Added +2.3k |
| MetLife Investment Management, LLC 0.00% of their portfolio | 10.1k $97.9k | Added +13 |
| PNC Financial Services Group, Inc. 0.00% of their portfolio | 9.2k $88.9k | Added +2.7k |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. 0.00% of their portfolio | 8.9k $86.1k | Reduced -100 |
| JPMORGAN CHASE & CO 0.00% of their portfolio | 7.7k $74.4k | Added +409 |
| NEW YORK STATE COMMON RETIREMENT FUND 0.00% of their portfolio | 6.2k $60.1k | Unchanged |
| CITIGROUP INC 0.00% of their portfolio | 5.5k $52.8k | Reduced -5.4k |
| Police & Firemen's Retirement System of New Jersey 0.00% of their portfolio | 4.5k $43.6k | Unchanged |
| STRS OHIO 0.00% of their portfolio | 2.8k $27.1k | Unchanged |
| ROYAL BANK OF CANADA 0.00% of their portfolio | 2.7k $26.0k | Added +2.2k |
| Tower Research Capital LLC (TRC) 0.00% of their portfolio | 2.5k $24.7k | Added +1.1k |
| Ameritas Investment Partners, Inc. 0.00% of their portfolio | 1.6k $15.6k | Unchanged |
| Legal & General Group Plc 0.00% of their portfolio | 1.5k $15.0k | Added +29 |
| CWM, LLC 0.00% of their portfolio | 1.5k $14.0k | Added +989 |
| BNP PARIBAS FINANCIAL MARKETS 0.00% of their portfolio | 1.4k $13.9k | Reduced -23.9k |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM 0.00% of their portfolio | 1.1k $11.1k | Unchanged |
| US BANCORP \DE\ 0.00% of their portfolio | 1.1k $10.3k | Added +788 |
| Quarry LP 0.00% of their portfolio | 843 $8.2k | New |
| AMALGAMATED BANK 0.00% of their portfolio | 524 $5.0k | Unchanged |
| Sterling Capital Management LLC 0.00% of their portfolio | 439 $4.3k | Added +308 |
| SIGNATUREFD, LLC 0.00% of their portfolio | 295 $2.9k | Added +167 |
| DEUTSCHE BANK AG\ 0.00% of their portfolio | 280 $2.7k | Reduced -22.7k |
| NISA INVESTMENT ADVISORS, LLC 0.00% of their portfolio | 115 $1.1k | Added +87 |
| GAMMA Investing LLC 0.00% of their portfolio | 79 $766 | Added +38 |
| Physician Wealth Advisors, Inc. 0.00% of their portfolio | 67 $650 | New |
| EverSource Wealth Advisors, LLC 0.00% of their portfolio | 58 $562 | Added +56 |
| Clearstead Advisors, LLC 0.00% of their portfolio | 23 $223 | New |
| True Wealth Design, LLC 0.00% of their portfolio | 3 $30 | Unchanged |
| Essential Partners LLC 0.00% of their portfolio | 2 $19 | First filing |
| CONCOURSE FINANCIAL GROUP SECURITIES, INC. — of their portfolio | 0 $0 | Unchanged |