Boundless Bio (BOLD) awards 230,000 stock options to CSO

Rhea-AI Filing Summary

Boundless Bio, Inc. granted Chief Scientific Officer Christian Hassig a stock option covering 230,000 shares of common stock on January 23, 2026. The option has an exercise price of $1.26 per share and was received at no cost on the grant date. It is held directly by the reporting person.

The vesting start date is January 1, 2026. The option vests in 48 substantially equal monthly installments, with 1/48 of the award vesting on February 1, 2026 and additional 1/48 portions vesting each month thereafter until fully vested.

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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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^*

Hassig Christian

(Last) (First) (Middle)

C/O BOUNDLESS BIO, INC.

10955 ALEXANDRIA WAY, SUITE 100

(Street)

SAN DIEGO CA 92121

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Boundless Bio, Inc. [ BOLD ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
01/23/2026

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

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)	$1.26	01/23/2026		A		230,000		(1)	01/22/2036	Common Stock	230,000	$0	230,000	D

Explanation of Responses:

1. The vesting commencement date is January 1, 2026. The stock option vests in 48 substantially equal monthly installments. Accordingly, 1/48th of this stock option vests on February 1, 2026, and monthly thereafter.

	/s/ Jessica Oien, Attorney-in- Fact for Christian Hassig, Ph.D.	01/23/2026
	** 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.

FAQ

What insider transaction did Boundless Bio (BOLD) report for Christian Hassig?

Boundless Bio reported that Chief Scientific Officer Christian Hassig received a grant of 230,000 stock options on January 23, 2026. These are options to purchase Boundless Bio common stock.

What is the exercise price of the new Boundless Bio (BOLD) stock options?

The stock option granted to Christian Hassig has an exercise price of $1.26 per share for Boundless Bio common stock.

How many Boundless Bio (BOLD) options does the insider hold after this grant?

Following this grant, Christian Hassig beneficially owns 230,000 stock options, all reported as held directly.

How do the Boundless Bio (BOLD) options granted to Christian Hassig vest?

The options have a vesting commencement date of January 1, 2026 and vest in 48 substantially equal monthly installments. 1/48 vests on February 1, 2026, with additional installments vesting monthly thereafter.

What type of security is involved in this Boundless Bio (BOLD) Form 4?

The filing reports a derivative security: a stock option (right to buy) Boundless Bio common stock, with 230,000 underlying shares.

Was this Boundless Bio (BOLD) insider transaction an acquisition or a disposition?

The reported transaction is coded A, indicating an acquisition of derivative securities (stock options) by the insider.