[Form 4] Boundless Bio, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Boundless Bio director Christine Brennan received a stock option grant on June 23, 2025. Key details of the transaction:

• Granted 16,000 stock options to purchase common stock
• Exercise price set at $1.03 per share
• Options expire on June 22, 2035
• Vesting schedule: Equal monthly installments over 12 months through June 23, 2026
• Accelerated vesting provision if next annual stockholder meeting occurs before June 23, 2026

The grant was executed under direct ownership, and the filing was signed by Jessica Oien as attorney-in-fact for Christine Brennan. This equity compensation aligns with standard director compensation practices and aims to align the director's interests with shareholders.

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

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^*

Brennan Christine

(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)

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

3. Date of Earliest Transaction (Month/Day/Year)
06/23/2025

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

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)	$1.03	06/23/2025		A		16,000		(1)	06/22/2035	Common Stock	16,000	$0	16,000	D

Explanation of Responses:

1. The stock option shall vest in substantially equal monthly installments over the 12 months following June 23, 2025 (or, in the event the next annual meeting of the issuer's stockholders occurs prior to June 23, 2026, any remaining unvested portion of the stock option will vest on the date of such annual meeting), subject to the reporting person's continuing service on the issuer's board of directors through such vesting date.

	/s/ Jessica Oien, Attorney-in-Fact for Christine Brennan	06/23/2025
	** 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).
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 stock options did BOLD's director Christine Brennan receive on June 23, 2025?

Christine Brennan received 16,000 stock options with an exercise price of $1.03 per share. These options expire on June 22, 2035 and were granted as part of her compensation as a director of Boundless Bio.

What is the vesting schedule for BOLD director Christine Brennan's stock options granted in June 2025?

The stock options vest in equal monthly installments over 12 months following June 23, 2025. However, if the next annual stockholder meeting occurs before June 23, 2026, any remaining unvested portion will vest on that meeting date, subject to Brennan's continued service on the board.

How long can Christine Brennan exercise her BOLD stock options granted in June 2025?

The stock options have a 10-year term and can be exercised until June 22, 2035, provided the vesting conditions are met and Brennan maintains her position on BOLD's board of directors.

What is the exercise price of BOLD director Christine Brennan's June 2025 stock options?

The exercise price of the stock options granted to Christine Brennan is $1.03 per share.