Atossa Therapeutics director receives 10,000 RSUs

Chen Shu-Chih reported acquisition or exercise transactions in this Form 4 filing.

Rhea-AI Filing Summary

Chen Shu-Chih reported acquisition or exercise transactions in this Form 4 filing.

ATOSSA THERAPEUTICS, INC. director Shu-Chih Chen reported an equity award and updated holdings. Chen received a grant of 10,000 restricted stock units (RSUs), each representing the right to receive one share of common stock, at a price of $0.0000 per share. The RSUs vest on the first anniversary of May 12, 2026. Following this grant, Chen holds 10,000 common shares directly and 1,483 common shares indirectly through Ensisheim Partners, LLC, where voting and investment power is shared with Dr. Steven C. Quay, and beneficial ownership is disclaimed except to the extent of Chen’s pecuniary interest.

Insider Trade Summary

Grant/Award: 10,000 shares

Grant/Award 2 txns

Insider Chen Shu-Chih

Role Director

Type	Security	Shares	Price	Value
Grant/Award	Common Stock	10,000	$0.00	$0.00
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 10,000 shares (Direct); Common Stock — 1,483 shares (Indirect, By Ensisheim Partners, LLC)

Footnotes (2)

1. F1. Represents a grant of restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Common Stock. The RSUs shall vest on the first anniversary of May 12, 2026.
2. F2. Ensisheim Partners, LLC ("Ensisheim") is wholly owned by the Reporting Person and Dr. Steven C. Quay. The Reporting Person and Dr. Quay share voting and investment power over the securities held by Ensisheim. The Reporting Person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein.

Key Figures

RSU grant size: 10,000 shares Grant price per RSU: $0.0000 per share Direct holdings after grant: 10,000 shares +1 more

4 metrics

RSU grant size 10,000 shares Restricted stock units representing common stock

Grant price per RSU $0.0000 per share Equity award to Shu-Chih Chen

Direct holdings after grant 10,000 shares Common stock held directly by Shu-Chih Chen

Indirect holdings via Ensisheim 1,483 shares Common stock held through Ensisheim Partners, LLC

Key Terms

restricted stock units ("RSUs"), contingent right, beneficial ownership, pecuniary interest

4 terms

restricted stock units ("RSUs") financial

"Represents a grant of restricted stock units ("RSUs"). Each RSU represents"

Restricted stock units (RSUs) are a company promise to give an employee shares of stock (or cash equivalent) in the future, but only after certain conditions—usually staying with the company for a set time or hitting performance goals—are met. Investors watch RSUs because when they vest they increase the number of shares outstanding and can lead insiders to sell shares, affecting share price, company dilution and the true cost of employee pay.

contingent right financial

"Each RSU represents a contingent right to receive one share"

beneficial ownership financial

"The Reporting Person disclaims beneficial ownership of these securities"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

pecuniary interest financial

"disclaims beneficial ownership of these securities except to the extent of his pecuniary interest"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did Shu-Chih Chen report for ATOS?

Shu-Chih Chen reported receiving 10,000 restricted stock units in ATOS common stock as an equity award. Each RSU represents a right to one share, granted at $0.0000 per share, with vesting scheduled on the first anniversary of May 12, 2026.

How many ATOS shares does Shu-Chih Chen hold after this Form 4?

After the reported transactions, Shu-Chih Chen holds 10,000 ATOS common shares directly. In addition, 1,483 common shares are held indirectly through Ensisheim Partners, LLC, where Chen shares voting and investment power and disclaims full beneficial ownership except for pecuniary interest.

What are the terms of the 10,000 RSUs granted to Shu-Chih Chen at ATOS?

The 10,000 RSUs granted to Shu-Chih Chen each represent a contingent right to receive one ATOS common share. They were granted at $0.0000 per share and will vest in full on the first anniversary of May 12, 2026, subject to continued conditions.

How are ATOS shares held through Ensisheim Partners, LLC treated for Shu-Chih Chen?

1,483 ATOS common shares are held indirectly through Ensisheim Partners, LLC, which is wholly owned by Shu-Chih Chen and Dr. Steven C. Quay. They share voting and investment power, and Chen disclaims beneficial ownership except to the extent of his pecuniary interest.

Is the 10,000-share RSU grant to Shu-Chih Chen a market purchase of ATOS stock?

The 10,000-share RSU grant is not a market purchase; it is an equity award reported with code A. The RSUs were granted at $0.0000 per share as compensation and will vest on the first anniversary of May 12, 2026, rather than being bought in the open market.

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

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Accepted by SEC EDGAR 05/14/2026 - 04:27 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
Estimated average burden
hours per response:			0.5

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^*

Chen Shu-Chih

(Last) (First) (Middle)

C/O ATOSSA THERAPEUTICS, INC.

1448 NW MARKET STREET SUITE 500

(Street)

SEATTLE WASHINGTON 98107

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
ATOSSA THERAPEUTICS, INC. [ ATOS ]

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

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/12/2026

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	05/12/2026		A		10,000(1)	A	$0	10,000	D
Common Stock								1,483	I	By Ensisheim Partners, LLC(2)

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

Explanation of Responses:

1. Represents a grant of restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Common Stock. The RSUs shall vest on the first anniversary of May 12, 2026.

2. Ensisheim Partners, LLC ("Ensisheim") is wholly owned by the Reporting Person and Dr. Steven C. Quay. The Reporting Person and Dr. Quay share voting and investment power over the securities held by Ensisheim. The Reporting Person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein.

	Shu-Chih Chen	05/14/2026
	** 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)