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

CIK: 0001903360

Transaction Breakdown

Open Market Buys (P)0 (0.0%)

High conviction signal

Open Market Sales (S)0 (0.0%)

Position reduction

Option Exercises (M)0 (0.0%)

Derivative conversions

Awards (A)0 (0.0%)

Compensation grants

Other (G, F, J, C, D, …)5 (100.0%)

Gifts, tax withholding, conversions, dispositions to the issuer and other codes

Companies & Roles (4)

AVLN

Avalyn Pharma Inc.

10% Owner

MTSR

Metsera, Inc.

10% Owner

UPB

Upstream Bio, Inc.

10% Owner

MBX

MBX Biosciences, Inc.

10% Owner

Discretionary Trading P&L

Holdings

Transaction History (5 total)

AVLN
Avalyn Pharma Inc.
May 1, 2026
Conversion(C)
Direct
1.3M shares-
MTSR
Metsera, Inc.
Jan 30, 2025
Conversion(C)
Direct
1.9M shares-
UPB
Upstream Bio, Inc.
Oct 15, 2024
Conversion(C)
Direct
894.7K shares-
MBX
MBX Biosciences, Inc.
Sep 16, 2024
Conversion(C)
Direct
1.4M shares-
MBX
MBX Biosciences, Inc.
Sep 16, 2024
Conversion(C)
Direct
403.8K shares-

		Type	Shares	Price		Ownership
May 1, 2026	AVLN Avalyn Pharma Inc.	Conversion(C)	1,275,486	-	$0	Direct
Jan 30, 2025	MTSR Metsera, Inc.	Conversion(C)	1,857,699	-	-	Direct
Oct 15, 2024	UPB Upstream Bio, Inc.	Conversion(C)	894,733	-	$0	Direct
Sep 16, 2024	MBX MBX Biosciences, Inc.	Conversion(C)	1,386,335	-	$0	Direct
Sep 16, 2024	MBX MBX Biosciences, Inc.	Conversion(C)	403,787	-	$0	Direct

1-5 of 5 transactions

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

Wellington Biomedical Innovation Master Investors (Cayman) II L.P. (SEC CIK 0001903360) files insider reports with the SEC as 10% Owner of Avalyn Pharma Inc. (AVLN), 10% Owner of Metsera, Inc. (MTSR) and 10% Owner of Upstream Bio, Inc. (UPB). Signal8 also holds filings tied to 1 other company.

Signal8 holds 8 ownership filings by Wellington Biomedical Innovation Master Investors (Cayman) II L.P. (4 Form 3, 4 Form 4), filed between Sep 12, 2024 and May 1, 2026. Those filings report 5 transactions, from Sep 16, 2024 to May 1, 2026. Signal8's Form 4 history starts in Sep 2024.

The business address on Wellington Biomedical Innovation Master Investors (Cayman) II L.P.'s filings is in BOSTON, MA.

Recent filings by Wellington Biomedical Innovation Master Investors (Cayman) II L.P.

May 1, 2026: Conversion of AVLN shares (Form 4, code C).
Jan 30, 2025: Conversion of MTSR shares (Form 4, code C).
Oct 15, 2024: Conversion of UPB shares (Form 4, code C).
Sep 16, 2024: Conversions of MBX shares (2 lines, Form 4, code C).

Other insiders filing for Avalyn Pharma Inc. (AVLN)

Meyer Robert J., Director
Novo Holdings A/S, 10% Owner
FMR LLC, 10% Owner
Golden Adam H., General Counsel
Carroll Jill, Director
SR ONE CAPITAL MANAGEMENT, LLC, 10% Owner

How to read Form 4 transaction codes