SEC FORM 3

SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

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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1. Name and Address of Reporting Person^*

Hornby Zachary

(Last)

(First)

(Middle)

C/O BOUNDLESS BIO, INC.

9880 CAMPUS POINT DRIVE, SUITE 120

(Street)

SAN DIEGO

92121

(City)

(State)

(Zip)

2. Date of Event Requiring Statement (Month/Day/Year)
03/27/2024

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

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

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

5. 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 Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	256,410	D

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
1. Title of Derivative Security (Instr. 4)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
Stock Option	⁽¹⁾	06/09/2030	Common Stock	128,205	$3.12	D
Stock Option	⁽²⁾	06/06/2031	Common Stock	256,410	$4.1	D
Stock Option	⁽³⁾	06/12/2033	Common Stock	471,282	$4.1	D
Stock Option	⁽⁴⁾	02/14/2034	Common Stock	257,207	$8.19	D

Explanation of Responses:

1. The stock option vests in 48 substantially equal monthly installments beginning on July 10, 2020.

2. The stock option vests in 48 substantially equal monthly installments beginning on July 7, 2021.

3. The stock option vests in 48 substantially equal monthly installments beginning on July 13, 2023.

4. The stock option vests in 48 substantially equal monthly installments beginning on March 15, 2024.

Remarks:

Exhibit 24 - Power of Attorney.

	/s/ Jessica Oien, Attorney-in-Fact for Zachary Hornby	03/27/2024
	** 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 5 (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.