Buy4

Boundless Bio, Inc.

BOLD

Total Value

$25.7K

Net $25.7K bought

Filing Date

Oct 29, 2026

1 transaction

Purchases

$25.7K

1 transaction

Trade Summary

On Oct 27, 2026, TANG KEVIN, Insider, purchased $25.7K of Boundless Bio, Inc. (BOLD) across 1 transaction. The filing covers Common Stock and reflects net buying of $25.7K. Reported prices ranged from $2.40. Insider transactions are sourced from SEC Form 4 disclosures and should be reviewed alongside company fundamentals and the insider's broader trading history.

Price at the Time of the Trade

BOLD daily price with the insider's purchase marked at $2.40.

Bought in the upper half of the 6-month range · the stock trades 2% higher today.

Price data is delayed and provided for context only — not investment advice.

Insider Information

Name: TANG KEVIN
Role: Insider
Location: SAN DIEGO, CA

Filing Details

Filing Date: Oct 29, 2026
Transaction Date: Oct 27, 2026
Accession Number: 0001178579-26-000022
Form Type: 4
Net Trading Amount: $25.7K

Non-Derivative Transactions

Date	Security	Shares	Price	Type	Value
Oct 27, 2026	Common Stock	10,707	$2.40	Purchase	$25.7K

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Footnotes

(F1)The prices reported are weighted-average prices. These shares were purchased in multiple transactions at prices ranging from $2.38 to $2.40. The Reporting Persons undertake to provide the Issuer, any security holder of the Issuer or the SEC staff, upon request, all information regarding the number of shares purchased at each price within the range set forth in Footnote 1.
(F2)Tang Capital Partners, LP ("TCP") beneficially owns 691,177 shares, Tang Capital Partners International, LP ("TCPI") beneficially owns 961,511 shares, Tang Capital Partners III, Inc. ("TCP III") beneficially owns 691,170 shares, and Tang Capital Partners IV, Inc. ("TCP IV") beneficially owns 678,598 shares. Kevin Tang is the sole manager of Tang Capital Management, LLC, which is the general partner of TCP and TCPI. Kevin Tang is the sole director and Chief Executive Officer of TCP III and TCP IV, which are indirectly wholly owned by TCP. Mr. Tang has a pecuniary interest in the shares beneficially held by TCP, TCPI, TCP III and TCP IV.

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^*

TANG KEVIN

(Last)

(First)

(Middle)

4747 EXECUTIVE DRIVE

SUITE 210

(Street)

SAN DIEGO

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

3. Date of Earliest Transaction (Month/Day/Year)
10/27/2026

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

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

	Form filed by One Reporting Person
X	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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	10/27/2026		P		10,707	A	$2.4⁽¹⁾	3,022,456	I	See Footnote⁽²⁾

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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)

1. Name and Address of Reporting Person^*

TANG KEVIN

(Last)

(First)

(Middle)

4747 EXECUTIVE DRIVE

SUITE 210

(Street)

SAN DIEGO

92121

(City)

(State)

(Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

TANG CAPITAL MANAGEMENT LLC

(Last)

(First)

(Middle)

4747 EXECUTIVE DRIVE

SUITE 210

(Street)

SAN DIEGO

92121

(City)

(State)

(Zip)

Relationship of Reporting Person(s) to Issuer

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

Explanation of Responses:

1. The prices reported are weighted-average prices. These shares were purchased in multiple transactions at prices ranging from $2.38 to $2.40. The Reporting Persons undertake to provide the Issuer, any security holder of the Issuer or the SEC staff, upon request, all information regarding the number of shares purchased at each price within the range set forth in Footnote 1.

2. Tang Capital Partners, LP ("TCP") beneficially owns 691,177 shares, Tang Capital Partners International, LP ("TCPI") beneficially owns 961,511 shares, Tang Capital Partners III, Inc. ("TCP III") beneficially owns 691,170 shares, and Tang Capital Partners IV, Inc. ("TCP IV") beneficially owns 678,598 shares. Kevin Tang is the sole manager of Tang Capital Management, LLC, which is the general partner of TCP and TCPI. Kevin Tang is the sole director and Chief Executive Officer of TCP III and TCP IV, which are indirectly wholly owned by TCP. Mr. Tang has a pecuniary interest in the shares beneficially held by TCP, TCPI, TCP III and TCP IV.

	Kevin Tang	10/29/2026
	Kevin Tang, Manager	10/29/2026
	** 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.

Form 4 as rendered by the SEC from accession 0001178579-26-000022.

Boundless Bio, Inc.

Trade Summary

Price at the Time of the Trade

Company Information

Insider Information

Filing Details

Non-Derivative Transactions

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Footnotes

SEC Form 4

SEC Filing

Price at the Time of the Trade

SEC Form 4