EcoR1 Capital ZBIO Position
Active4-Fund ConvergenceEcoR1 Capital initiated a new position in Zenas BioPharma, Inc. (ZBIO) in Q4 2025, holding $28.7M worth of shares across 789,500 shares.
ZBIO is a convergence signal: 4 specialist biotech funds hold this stock, suggesting high institutional conviction.
There is an upcoming Phase 3 readout for Obexelimab in 75 days (Jun 30, 2026), making the timing of EcoR1's position particularly relevant.
Short interest stands at 21.1% of float with 13.0 days to cover, indicating significant bearish positioning against EcoR1's long thesis.
4 insider purchases totaling $5.5M have been filed in the last 90 days, providing an additional conviction signal.
About Zenas BioPharma, Inc.
Zenas BioPharma, Inc., a clinical-stage biopharmaceutical company, engages in the development and commercialization of transformative immunology-based therapies. Its lead product candidate is obexelimab, a bifunctional monoclonal antibody for various indications, including immunoglobulin G4-related disease, multiple sclerosis, systemic lupus erythematosus, and warm autoimmune hemolytic anemia. The company also develops ZB002, an anti-TNFa monoclonal antibody; ZB004, a cytotoxic T-lymphocyte-associated antigen 4-immunoglobulin fusion; ZB001, an anti-insulin-like growth factor-1 receptor monoclonal antibody; and ZB005, an anti-active complement component 1s monoclonal antibody. Zenas BioPharma, Inc. was formerly known as Zenas BioPharma (Cayman) Limited and changed its name to Zenas BioPharma, Inc. in August 2023. The company was incorporated in 2019 and is based in Waltham, Massachusetts.
Full company profile →Short Interest
21.1%
13.0 days to cover
Insider Buys (90d)
4
$5.5M total
Frequently Asked Questions
Does EcoR1 Capital own ZBIO?
Yes. As of Q4 2025, EcoR1 Capital holds 789,500 shares of Zenas BioPharma, Inc. (ZBIO) valued at $28.7M. This data comes from their SEC 13F filing.
How many hedge funds own ZBIO?
4 specialist biotech hedge funds currently hold ZBIO, including Deerfield Management, Perceptive Advisors, Rock Springs Capital. When 3 or more specialist funds hold the same stock, BiotechEdge flags it as a convergence signal.
When did EcoR1 Capital first buy ZBIO?
EcoR1 Capital's position in ZBIO was first reported in Q4 2025. 13F filings are reported with a 45-day delay, so the actual purchase may have occurred earlier in the quarter.
Is EcoR1 Capital's ZBIO position increasing or decreasing?
EcoR1 Capital initiated a new position in ZBIO in the most recent quarter. This is their first reported holding.
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