Wellington Biomedical Innovation Master Investors (Cayman) II L.P. - 01 May 2026 Form 4 Insider Report for Avalyn Pharma Inc. (AVLN)

Reporting relationship: 10%+ Owner
Issuer ticker: AVLN
Reported as of: 01 May 2026
Net transaction value: $0
SEC form: 4
Accepted by SEC: 01 May 2026, 18:26:58 UTC
Prior SEC filing: 29 Apr 2026
Source filing: View source filing
Reporting owner signature: Wellington Biomedical Innovation Master Investors (Cayman) II L.P., By: Wellington Management Company LLP, as Investment Adviser, /s/ Jennifer C. Boylan, Authorized Person

Key filing fact

Wellington Biomedical Innovation Master Investors (Cayman) II L.P. filed Form 4 for Avalyn Pharma Inc. (AVLN) on 01 May 2026.

Key facts

This page summarizes Wellington Biomedical Innovation Master Investors (Cayman) II L.P.'s Form 4 filing for Avalyn Pharma Inc. (AVLN).
3 reported transactions and 2 derivative rows are listed below.
Accepted by SEC: 01 May 2026, 18:26.

Change

Previous filing in this sequence was filed on 29 Apr 2026.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001903360 Primary reporting owner

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

Relationship: 10%+ Owner
Address: C/O WELLINGTON MANAGEMENT COMPANY LLP, 280 CONGRESS STREET, BOSTON
Signature: Wellington Biomedical Innovation Master Investors (Cayman) II L.P., By: Wellington Management Company LLP, as Investment Adviser, /s/ Jennifer C. Boylan, Authorized Person
Signature date: 01 May 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

AVLN transaction

Common Stock

Conversion of derivative security

Transaction value
Shares: +1,275,486
Change %
Price
Shares after: 1,275,486
Date: 01 May 2026
Ownership: Direct
Footnotes: F1

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

AVLN transaction Derivative

Series C-1 Convertible Preferred Stock

Conversion of derivative security

Transaction value
Shares: -20,482,289
Change %: -100%
Price: $0.000000^*
Shares after: 0
Date: 01 May 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 1,064,473
Exercise price
Footnotes: F1

AVLN transaction Derivative

Series D Convertible Preferred Stock

Conversion of derivative security

Transaction value
Shares: -4,060,259
Change %: -100%
Price: $0.000000^*
Shares after: 0
Date: 01 May 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 211,013
Exercise price
Footnotes: F1

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Section 16 status

Wellington Biomedical Innovation Master Investors (Cayman) II L.P. is no longer subject to Section 16 filing requirements. Form 4 or Form 5 obligations may still apply in specific circumstances.

Explanation of responses 1 footnote

Footnote F1

Immediately prior to the closing of the Issuer's initial public offering, each share of Series C-1 Convertible Preferred Stock and Series D Convertible Preferred Stock (collectively, the "Preferred Stock") automatically converted into shares of the Issuer's Common Stock on a 19.2417-for-one basis. The Preferred Stock had no expiration date.