Y-MABS THERAPEUTICS, INC.
Y-MABS THERAPEUTICS, INC. is a registered legal entity registered in United States under 5737747, and its current status with Delaware Division of Corporations is active. The company was incorporated on 4 June 2017 and lists its registered address as United States. 5 shareholders are on record for Y-MABS THERAPEUTICS, INC., and since every one of them is a company rather than an individual, this particular filing does not on its own establish an ultimate beneficial owner (UBO) — identifying one would mean tracing the ownership of each shareholding company in turn. This profile is sourced directly from Delaware Division of Corporations and was last updated on 4 October 2026.
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Shareholders
5
Five shareholders are currently on record for Y-MABS THERAPEUTICS, INC., reflecting the stock ledger maintained under state corporate law (e.g. §219 of the Delaware General Corporation Law) rather than a public filing.
The largest of these is Paradigm Biocapital Advisors LP, holding 16.9% — the largest recorded stake — followed by Acorn Capital Advisors, LLC at 13.7%; the remaining 3 shareholders shown hold smaller stakes.
The register reports 20 shareholders in total, though only the top 5 by holding are shown in this view.
Because every shareholder shown is a company rather than an individual, the ownership chain continues above this level, and no beneficial owner can be established from this filing alone.
| Shareholder | Type | Holding | Source Document |
|---|---|---|---|
| Paradigm Biocapital Advisors LP | 16.9% | Delaware Division of Corporations | |
| Acorn Capital Advisors, LLC | 13.7% | Delaware Division of Corporations | |
| Blackrock Inc. | 11% | Delaware Division of Corporations | |
| Caligan Partners, LP | 9.4% | Delaware Division of Corporations | |
| Sofinnova Investments, Inc. | 8.8% | Delaware Division of Corporations |
Officers
5
The Ceo, President & Director of Y-MABS THERAPEUTICS, INC. currently on record is Michael Rossi; five officers are currently on record for Y-MABS THERAPEUTICS, INC., filed with Delaware Division of Corporations.
The register reports 10 officers in total, including past appointments, though only the 5 most relevant records are shown here.
Management authority at Y-MABS THERAPEUTICS, INC. sits with these individuals, not with shareholders, who are covered separately and hold ownership rather than control.
The source filing doesn't specify representation authority — whether officers can act individually or must sign jointly to bind the company — so that detail isn't available here.
Group Structure
Y-MABS THERAPEUTICS, INC. sits 3 levels below its ultimate parent, SERB HOLDING FRANCE, registered in France. 1 subsidiary is recorded beneath it, across 2 jurisdictions. The full chain up to SERB HOLDING FRANCE is derived by walking shareholder filings across jurisdictions; no link in it is independently corroborated by Y-MABS THERAPEUTICS, INC.'s own shareholder record. Each of these downward relationships is derived rather than filed: resolved by matching entities across the registry network, not stated directly in a single document.
Those 1 subsidiary spans United States, Denmark jurisdictions, though this list should not be read as complete — subsidiaries only become visible here where shareholder data has actually been filed with a register, so holdings in jurisdictions without that filing simply won't appear.
SERB HOLDING FRANCE
France
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Frequently Asked Questions
Who owns Y-MABS THERAPEUTICS, INC.?
Five shareholders are currently on record for Y-MABS THERAPEUTICS, INC., reflecting the stock ledger maintained under state corporate law (e.g. §219 of the Delaware General Corporation Law) rather than a public filing. The largest of these is Paradigm Biocapital Advisors LP, holding 16.9% — the largest recorded stake — followed by Acorn Capital Advisors, LLC at 13.7%; the remaining 3 shareholders shown hold smaller stakes. Because every shareholder shown is a company rather than an individual, the ownership chain continues above this level, and no beneficial owner can be established from this filing alone.
Who is Y-MABS THERAPEUTICS, INC.'s UBO (Ultimate Beneficial Owner)?
Every shareholder recorded for Y-MABS THERAPEUTICS, INC. is itself a company rather than a natural person, so no Ultimate Beneficial Owner (UBO) is identified at this level; establishing one would require tracing the ownership of each shareholding company in turn.
How many shareholders does Y-MABS THERAPEUTICS, INC. have on record?
5 shareholders are shown on record for Y-MABS THERAPEUTICS, INC.. The register reports 20 in total; only the top 5 by holding are shown here.
What is Y-MABS THERAPEUTICS, INC.'s company registration number?
Y-MABS THERAPEUTICS, INC.'s registration number is 5737747, filed with Delaware Division of Corporations in United States. Its current status on the register is active.
Is Y-MABS THERAPEUTICS, INC. still an active company?
Y-MABS THERAPEUTICS, INC.'s status on Delaware Division of Corporations is listed as active.
When was Y-MABS THERAPEUTICS, INC. incorporated?
Y-MABS THERAPEUTICS, INC. was incorporated on 4 June 2017, according to Delaware Division of Corporations.
What is Y-MABS THERAPEUTICS, INC.'s registered address?
The registered address on file for Y-MABS THERAPEUTICS, INC. is United States.
Who are the officers/directors of Y-MABS THERAPEUTICS, INC.?
The Ceo, President & Director of Y-MABS THERAPEUTICS, INC. currently on record is Michael Rossi; five officers are currently on record for Y-MABS THERAPEUTICS, INC., filed with Delaware Division of Corporations. Management authority at Y-MABS THERAPEUTICS, INC. sits with these individuals, not with shareholders, who are covered separately and hold ownership rather than control.
Does Y-MABS THERAPEUTICS, INC. have a parent company or subsidiaries?
Y-MABS THERAPEUTICS, INC. sits 3 levels below its ultimate parent, SERB HOLDING FRANCE, registered in France. 1 subsidiary is recorded beneath it, across 2 jurisdictions. Those 1 subsidiary spans United States, Denmark jurisdictions, though this list should not be read as complete — subsidiaries only become visible here where shareholder data has actually been filed with a register, so holdings in jurisdictions without that filing simply won't appear.
Can Zavia monitor changes to Y-MABS THERAPEUTICS, INC.'s ownership over time?
This profile reflects a point-in-time snapshot from Delaware Division of Corporations. Zavia's monitoring API can track changes to Y-MABS THERAPEUTICS, INC.'s registered shareholders, officers, and group structure going forward, flagging updates as they're filed rather than requiring a manual recheck.
Can I access Y-MABS THERAPEUTICS, INC.'s data through an API?
Yes. Zavia's API connects directly to official government ownership registries across 195 countries and territories, including United States, so records like Y-MABS THERAPEUTICS, INC.'s registration, shareholder, UBO, and group-structure data can be queried programmatically instead of viewed one page at a time.
Where does this company information come from, and how current is it?
This record is sourced directly from Delaware Division of Corporations and was last synced on 4 October 2026.