Boundless Bio CMO awarded 230,000 stock options

Boundless Bio, Inc. Chief Medical Officer Robert Doebele reported receiving a stock option award on January 23, 2026.

Rhea-AI Filing Summary

Boundless Bio, Inc. Chief Medical Officer Robert Doebele reported receiving a stock option award on January 23, 2026. The option covers 230,000 shares of Boundless Bio common stock at an exercise price of $1.26 per share, held directly.

The vesting commencement date is January 1, 2026. The option vests in 48 substantially equal monthly installments, so 1/48th of the award vests on February 1, 2026 and then monthly thereafter until fully vested. Following this grant, Doebele beneficially owns 230,000 derivative securities in the form of stock options.

Insider Trade Summary

Grant/Award: 230,000 shares

Grant/Award 1 txn

Insider Doebele Robert

Role Chief Medical Officer

Type	Security	Shares	Price	Value
Grant/Award	Stock Option (right to buy)	230,000	$0.00	$0.00

Holdings After Transaction: Stock Option (right to buy) — 230,000 contracts (Direct)

Footnotes (1)

1. F1. 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.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did Boundless Bio (BOLD) disclose in this Form 4 filing?

The filing reports that Chief Medical Officer Robert Doebele received a stock option award covering 230,000 shares of Boundless Bio common stock.

How many stock options were granted to Robert Doebele and at what exercise price?

Robert Doebele was granted a stock option for 230,000 shares of Boundless Bio common stock with an exercise price of $1.26 per share.

What is the vesting schedule for the Boundless Bio (BOLD) stock options?

The vesting commencement date is January 1, 2026, and the option vests in 48 equal monthly installments. 1/48th vests on February 1, 2026, and the remainder vests monthly thereafter.

How many derivative securities does Robert Doebele own after this transaction?

After this transaction, Robert Doebele beneficially owns 230,000 derivative securities in the form of stock options, held directly.

Does this Boundless Bio Form 4 show any insider stock sales?

No sales are listed. The reported transaction is coded as "A", indicating an acquisition of stock options rather than a sale of shares.

When do the Boundless Bio (BOLD) stock options held by Robert Doebele expire?

The stock options reported in the filing have an expiration date of January 22, 2036.

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

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Accepted by SEC EDGAR 01/26/2026 - 07:00 AM 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^*

Doebele Robert

(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 Medical 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 Robert Doebele	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.