Wellington Biomedical Innovation Master Investors (Cayman) II L.P. — SEC Form 4 filings
SEC reporting owner CIK 1903360. 4 Form 4 filings on record with FilingPulse; latest filed 2026-05-01.
Transaction summary — filings shown
Covers all 4 filings on record, filed 2024-09-17 to 2026-05-01. Counts and totals are arithmetic on values as filed — descriptive data, not a recommendation.
- Open-market purchases (code P, non-derivative): none reported.
- Open-market sales (code S, non-derivative): none reported.
- Other reported legs (grants, option exercises, tax withholding, gifts, derivative-security transactions, …): 11.
By issuer — same filings
Open-market purchase/sale legs on non-derivative securities, grouped by issuer. Role is as filed on the newest filing for that issuer. Dollar totals cover priced legs only (shares × price as filed). Ordered by priced transaction value, largest first.
| Issuer | Role (as filed) | Filings | Purchases (P) | Sales (S) | Other legs |
|---|---|---|---|---|---|
| MBX Biosciences, Inc. (MBX) | 10% owner | 1 | — | — | 4 |
| Avalyn Pharma Inc. (AVLN) | 10% owner | 1 | — | — | 3 |
| Metsera, Inc. (MTSR) | 10% owner | 1 | — | — | 2 |
| Upstream Bio, Inc. (UPB) | 10% owner | 1 | — | — | 2 |
Form 4 filings — Wellington Biomedical Innovation Master Investors (Cayman) II L.P.
| Filed | Form | Issuer | Reported transactions | Source |
|---|---|---|---|---|
| 2026-05-01 | 4 | Avalyn Pharma Inc. (AVLN) | Conversion (C): 1,275,486 · Conversion (C): 20,482,289 (derivative) @ $0 · Conversion (C): 4,060,259 (derivative) @ $0 | EDGAR |
| 2025-02-03 | 4 | Metsera, Inc. (MTSR) | Conversion (C): 1,857,699 · Conversion (C): 4,365,079 (derivative) @ $0 | EDGAR |
| 2024-10-15 | 4 | Upstream Bio, Inc. (UPB) | Conversion (C): 894,733 · Conversion (C): 852,940 (derivative) @ $0 | EDGAR |
| 2024-09-17 | 4 | MBX Biosciences, Inc. (MBX) | Conversion (C): 1,386,335 · Conversion (C): 403,787 · Conversion (C): 16,666,666 (derivative) @ $0 · Conversion (C): 4,854,368 (derivative) @ $0 | EDGAR |
FilingPulse's Form 4 archive currently extends back to 2024-01-11 and is expanding backward through EDGAR history — earlier filings by this insider may not be indexed yet. Names and roles are shown as filed.
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