Avalyn Pharma holder converts 1,275,486 shares to common

Wellington Biomedical Innovation Master Investors (Cayman) II L.P., a 10% owner of Avalyn Pharma Inc., reported converting its preferred stock into common shares.

Rhea-AI Filing Summary

Wellington Biomedical Innovation Master Investors (Cayman) II L.P., a 10% owner of Avalyn Pharma Inc., reported converting its preferred stock into common shares. On May 1, 2026, it acquired 1,275,486 shares of Common Stock through the automatic conversion of Series C-1 and Series D Convertible Preferred Stock immediately prior to Avalyn’s initial public offering. Following these transactions, the reporting holder’s remaining position consists of common stock, with the preferred stock fully converted.

Insider Trade Summary

24,542,548 shares exercised/converted

Exercise 3 txns

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

Role 10% Owner

Type	Security	Shares	Price	Value
Conversion	Series C-1 Convertible Preferred Stock	20,482,289	$0.00	$0.00
Conversion	Series D Convertible Preferred Stock	4,060,259	$0.00	$0.00
Conversion	Common Stock	1,275,486	$0.00	$0.00

Holdings After Transaction: Series C-1 Convertible Preferred Stock — 0 contracts (Direct); Series D Convertible Preferred Stock — 0 contracts (Direct); Common Stock — 1,275,486 shares (Direct)

Footnotes (1)

1. 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.

Key Figures

Common shares acquired: 1,275,486 shares Series D preferred converted: 4,060,259 shares Common underlying Series D: 211,013 shares +3 more

6 metrics

Common shares acquired 1,275,486 shares Common Stock held following conversion on May 1, 2026

Series D preferred converted 4,060,259 shares Series D Convertible Preferred Stock converted into common

Common underlying Series D 211,013 shares Common Stock underlying converted Series D preferred

Series C-1 preferred converted 20,482,289 shares Series C-1 Convertible Preferred Stock converted into common

Common underlying Series C-1 1,064,473 shares Common Stock underlying converted Series C-1 preferred

Conversion ratio 19.2417-for-one Preferred Stock automatically converted into Common Stock at IPO

Key Terms

Conversion of derivative security, Series C-1 Convertible Preferred Stock, Series D Convertible Preferred Stock, initial public offering, +1 more

5 terms

Conversion of derivative security financial

"transaction_code_description: "Conversion of derivative security""

Series C-1 Convertible Preferred Stock financial

"security_title: "Series C-1 Convertible Preferred Stock""

Series D Convertible Preferred Stock financial

"security_title: "Series D Convertible Preferred Stock""

Series D convertible preferred stock is a class of shares issued in a later-stage funding round that gives holders priority over common shareholders for payouts and often a fixed dividend, while including an option to convert those shares into common stock. It matters to investors because it affects who gets paid first if a company is sold or liquidates and can change ownership stakes and voting power when converted, similar to holding a safer ticket that can be exchanged for regular tickets later.

initial public offering financial

"Immediately prior to the closing of the Issuer's initial public offering"

An initial public offering (IPO) is when a private company first sells its shares to the public and becomes a stock-listed company. It matters because it allows the company to raise money from a wide range of investors, helping it grow, while giving early shareholders a way to sell some of their ownership.

Preferred Stock financial

"collectively, the "Preferred Stock" automatically converted into shares"

Preferred stock is a type of ownership in a company that typically offers investors higher and more consistent dividend payments than common stock. Unlike regular shares, preferred stock usually doesn’t come with voting rights but provides a priority claim on the company’s assets and profits, making it a more stable and predictable investment option. This makes preferred stock attractive to those seeking steady income with lower risk.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 05/01/2026 - 06:26 PM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
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hours per response:			0.5

X

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

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

(Last) (First) (Middle)

C/O WELLINGTON MANAGEMENT COMPANY LLP

280 CONGRESS STREET

(Street)

BOSTON MASSACHUSETTS 02210

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Avalyn Pharma Inc. [ AVLN ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/01/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	05/01/2026		C		1,275,486	A	(1)	1,275,486	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series C-1 Convertible Preferred Stock	(1)	05/01/2026		C			20,482,289	(1)	(1)	Common Stock	1,064,473	$0	0	D
Series D Convertible Preferred Stock	(1)	05/01/2026		C			4,060,259	(1)	(1)	Common Stock	211,013	$0	0	D

Explanation of Responses:

1. 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.

	Wellington Biomedical Innovation Master Investors (Cayman) II L.P., By: Wellington Management Company LLP, as Investment Adviser, /s/ Jennifer C. Boylan, Authorized Person	05/01/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)