[Form 4] Atrium Therapeutics, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Atrium Therapeutics’ Chief Medical Officer Steven George Hughes reported new equity compensation consisting of restricted stock units and stock options. He received 30,000 RSUs, each representing one future share of common stock, bringing his directly held common shares to 73,097 after the award.

The RSUs vest over four years, with 25% vesting on March 20, 2027 and the rest in three yearly installments, contingent on continued service. He was also granted options for 60,000 shares of common stock at an exercise price of $14.30 per share, expiring on April 20, 2036.

These options vest with 25% becoming exercisable on March 20, 2027 and the remaining 75% vesting in 36 substantially equal monthly installments thereafter, also subject to continued service.

Insider Trade Summary

Net Buyer: 30,000 shares

Net Buy 2 txns

Insider Hughes Steven George

Role Chief Medical Officer

Type	Security	Shares	Price	Value
Grant/Award	Stock Option (Right to Buy)	60,000	$0.00	$0.00
Grant/Award	Common Stock	30,000	$0.00	$0.00

Holdings After Transaction: Stock Option (Right to Buy) — 60,000 shares (Direct); Common Stock — 73,097 shares (Direct)

Footnotes (2)

1. F1. Represents an award of restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's common stock. Twenty-five percent (25%) of the RSUs shall vest on March 20, 2027, with the remaining RSUs vesting in three (3) substantially equal yearly installments each year thereafter, subject to the Reporting Person's continuous service to the Issuer on each such vesting date.
2. F2. Twenty-five percent (25%) of the shares underlying this option shall vest and become exercisable on March 20, 2027, with the remaining shares vesting in thirty-six (36) substantially equal monthly installments each month thereafter, subject to the Reporting Person's continuous service to the Issuer on each such vesting date.

Key Figures

RSU grant: 30,000 RSUs Common shares after award: 73,097 shares Stock options granted: 60,000 options +3 more

6 metrics

RSU grant 30,000 RSUs Award of restricted stock units to CMO on April 20, 2026

Common shares after award 73,097 shares Direct common stock holdings following RSU grant

Stock options granted 60,000 options New stock option grant to buy common stock

Option exercise price <money>$14.30</money> per share Strike price for 60,000 stock options

Option expiration <date>April 20, 2036</date> Expiration date of stock option grant

Initial vesting date <date>March 20, 2027</date> First vesting for RSUs and options (25%)

Key Terms

restricted stock units ("RSUs"), Stock Option (Right to Buy), vesting, continuous service

4 terms

restricted stock units ("RSUs") financial

"Represents an award of restricted stock units ("RSUs"). Each RSU represents a contingent right..."

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.

Stock Option (Right to Buy) financial

"Stock Option (Right to Buy) with an exercise price of 14.3000 per share..."

vesting financial

"Twenty-five percent (25%) of the RSUs shall vest on March 20, 2027, with the remaining RSUs vesting..."

Vesting is the process by which you earn full ownership of something, like company stock or a retirement benefit, over time. It’s like earning the right to keep a gift piece by piece the longer you stay with a company, making sure employees stay committed before they receive all the benefits.

continuous service financial

"subject to the Reporting Person's continuous service to the Issuer on each such vesting date."

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

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Form 4 Insider Transactions: What Each Field Means →

Accepted by SEC EDGAR 04/22/2026 - 05:54 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^*

Hughes Steven George

(Last) (First) (Middle)

C/O ATRIUM THERAPEUTICS, INC.

10578 SCIENCE CENTER DRIVE, SUITE 125

(Street)

SAN DIEGO CALIFORNIA 92121

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Atrium Therapeutics, Inc. [ RNA ]

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

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
04/20/2026

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	04/20/2026		A		30,000(1)	A	$0	73,097	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
Stock Option (Right to Buy)	$14.3	04/20/2026		A		60,000		(2)	04/20/2036	Common Stock	60,000	$0	60,000	D

Explanation of Responses:

1. Represents an award of restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's common stock. Twenty-five percent (25%) of the RSUs shall vest on March 20, 2027, with the remaining RSUs vesting in three (3) substantially equal yearly installments each year thereafter, subject to the Reporting Person's continuous service to the Issuer on each such vesting date.

2. Twenty-five percent (25%) of the shares underlying this option shall vest and become exercisable on March 20, 2027, with the remaining shares vesting in thirty-six (36) substantially equal monthly installments each month thereafter, subject to the Reporting Person's continuous service to the Issuer on each such vesting date.

	/s/ Brendan Winslow, Attorney-in-Fact	04/22/2026
	** 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)