---
title: "Wellington Biomedical Innovation Master Investors (Cayman) II L.P. — Ownership Dossier"
canonical: https://whiteintel.dev/entity/bacf0ebb-906d-54df-8b43-e2e45a68f462
json: https://whiteintel.dev/api/public/dossier/bacf0ebb-906d-54df-8b43-e2e45a68f462
identifier: sec:0001903360
jurisdiction: US
risk: Low
source: WhiteIntel corporate-ownership graph
---

# Wellington Biomedical Innovation Master Investors (Cayman) II L.P.

**Type:** Person  
**Jurisdiction:** [US](https://whiteintel.dev/jurisdictions/us)  
**Identifier:** `sec:0001903360`  
**Risk level:** Low  
**Canonical dossier:** https://whiteintel.dev/entity/bacf0ebb-906d-54df-8b43-e2e45a68f462  
**Structured JSON / MCP:** https://whiteintel.dev/api/public/dossier/bacf0ebb-906d-54df-8b43-e2e45a68f462  

## Ownership & control

### Holdings / subsidiaries

- **Metsera, Inc.** (10% owner) — https://whiteintel.dev/entity/545e3c76-456f-5273-ab91-538a1a34ba68
- **Metsera, Inc.** (10% owner) — https://whiteintel.dev/entity/545e3c76-456f-5273-ab91-538a1a34ba68
- **AVALYN PHARMA INC.** (tenpercentowner) — https://whiteintel.dev/entity/e4b640a2-c70f-5ad1-ab56-bd4cf7413743
- **Metsera, Inc.** (tenpercentowner) — https://whiteintel.dev/entity/545e3c76-456f-5273-ab91-538a1a34ba68
- **Upstream Bio, Inc.** (tenpercentowner) — https://whiteintel.dev/entity/d4a67260-0136-5e37-912a-3a65173d819d
- **MBX Biosciences, Inc.** (tenpercentowner) — https://whiteintel.dev/entity/6af50270-7dd4-5262-8756-e6fc9afb96e3
- **CARGO Therapeutics, Inc.** (tenpercentowner) — https://whiteintel.dev/entity/a783c33b-8f92-53e0-844a-0233eef54b40
- **RAYZEBIO, INC.** (tenpercentowner) — https://whiteintel.dev/entity/84c3a732-6df0-59c0-9df6-adef1b5b6dcf

---

_This is the markdown-for-agents view of the WhiteIntel dossier for **Wellington Biomedical Innovation Master Investors (Cayman) II L.P.**. Human view: https://whiteintel.dev/entity/bacf0ebb-906d-54df-8b43-e2e45a68f462 · Structured JSON: https://whiteintel.dev/api/public/dossier/bacf0ebb-906d-54df-8b43-e2e45a68f462._

_Risk levels are heuristic investigative leads, not legal determinations of beneficial ownership. Every claim carries a source; an absent edge means "not yet observed in current sources", not "does not exist"._