SELLAS Life Sciences (SLS) CFO reports RSU tax share withholding

Rhea-AI Filing Summary

SELLAS Life Sciences Group, Inc. reported an insider ownership change by its Chief Financial Officer, John Thomas Burns. On 12/03/2025, the company withheld 58,592 shares of common stock at $1.5 per share to cover the CFO’s tax withholding obligations related to vesting Restricted Stock Units. This reduced his holdings but did not involve an open-market sale. Following the transaction, Burns beneficially owns 254,327 shares of SELLAS common stock directly.

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

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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^*

Burns John Thomas

(Last) (First) (Middle)

C/O SELLAS LIFE SCIENCES GROUP, INC.,

7 TIMES SQUARE, SUITE 2503

(Street)

NEW YORK NY 10036

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
SELLAS Life Sciences Group, Inc. [ SLS ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
12/03/2025

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

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

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

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	12/03/2025		J(1)		58,592(2)	D	$1.5	254,327	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

Explanation of Responses:

1. Transaction relates to shares of common stock withheld by the SELLAS Life Sciences Group, Inc. (the "Issuer") to cover tax withholding obligations of the Reporting Person in connection with the vesting of Restricted Stock Units ("RSUs").

2. Represents the number shares of common stock withheld by the Issuer to cover tax withholding obligations of the Reporting Person in connection with the vesting of RSUs.

	/s/ Kostantinos Skordalos, Power of Attorney For: John Thomas Burns	12/05/2025
	** 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).
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FAQ

What insider transaction did the SELLAS Life Sciences (SLS) CFO report?

The CFO, John Thomas Burns, reported that SELLAS withheld shares of common stock from him to satisfy tax withholding obligations arising from the vesting of his Restricted Stock Units (RSUs).

How many SLS shares were withheld for the CFOs taxes?

The filing states that 58,592 shares of SELLAS common stock were withheld by the company to cover the CFOs tax withholding obligations tied to RSU vesting.

At what price were the withheld SELLAS (SLS) shares valued?

The withheld 58,592 shares of SELLAS common stock were reported at a price of $1.5 per share in the transaction table.

How many SELLAS (SLS) shares does the CFO own after this transaction?

After the reported withholding transaction, the CFO beneficially owns 254,327 shares of SELLAS common stock, held in direct ownership.

Was this CFO transaction an open-market sale of SELLAS (SLS) stock?

No. The explanation states the transaction relates to shares withheld by SELLAS to cover the CFOs tax obligations in connection with RSU vesting, rather than an open-market sale.

Why did SELLAS withhold shares from the CFO in this Form 4 filing?

The filing explains that the shares were withheld by SELLAS Life Sciences Group, Inc. to satisfy the CFOs tax withholding obligations when his Restricted Stock Units vested.