Boundless Bio (NASDAQ: BOLD) major Tang Capital holder adds 4,863 shares

Rhea-AI Filing Summary

Boundless Bio, Inc. reported that investment entities managed by Tang Capital Management, associated with ten percent owner Kevin Tang, purchased a total of 4,863 shares of common stock in open market or private transactions at $2.44 per share between July 17 and July 21, 2026, through indirect ownership.

Insider Trade Summary

Net Buyer: 4,863 shares

Net Buy 3 txns

Insider TANG KEVIN, TANG CAPITAL MANAGEMENT LLC

Role 10% Owner | 10% Owner

Bought 4,863 shs ($12K)

Type	Security	Shares	Price	Value
Purchase	Common Stock F1, F2	2,975	$2.44	$7K
Purchase	Common Stock F1, F2	1,623	$2.44	$4K
Purchase	Common Stock F1, F2	265	$2.44	$646.60

Holdings After Transaction: Common Stock — 2,858,935 shares (Indirect, See Footnote)

Footnotes (2)

1. F1. The prices reported are weighted-average prices. These shares were all purchased at $2.44. 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 ranges set forth in Footnote 1.
2. F2. Tang Capital Partners, LP ("TCP") beneficially owns 655,170 shares, Tang Capital Partners International, LP ("TCPI") beneficially owns 893,434 shares, Tang Capital Partners III, Inc. ("TCP III") beneficially owns 655,161 shares, and Tang Capital Partners IV, Inc. ("TCP IV") beneficially owns 655,170 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.

Key Figures

Total shares purchased: 4,863 shares Purchase price: $2.44 per share July 21, 2026 purchase: 2,975 shares +5 more

8 metrics

Total shares purchased 4,863 shares Common stock bought between July 17 and July 21, 2026

Purchase price $2.44 per share Weighted-average price for reported purchases

July 21, 2026 purchase 2,975 shares Common stock bought indirectly at $2.44 per share

July 20, 2026 purchase 1,623 shares Common stock bought indirectly at $2.44 per share

July 17, 2026 purchase 265 shares Common stock bought indirectly at $2.44 per share

Tang Capital Partners, LP holdings 655,170 shares Beneficially owned by Tang Capital Partners, LP

Tang Capital Partners International, LP holdings 893,434 shares Beneficially owned by Tang Capital Partners International, LP

Tang Capital Partners III & IV holdings 655,161 and 655,170 shares Beneficially owned by Tang Capital Partners III, Inc. and IV, Inc.

Key Terms

weighted-average prices, beneficially owns, pecuniary interest, indirectly wholly owned

4 terms

weighted-average prices financial

"The prices reported are weighted-average prices."

beneficially owns financial

"Tang Capital Partners, LP ("TCP") beneficially owns 655,170 shares"

Beneficially owns means a person or entity enjoys the economic benefits and control of a security even if the legal title or registration is held in another name. Think of it like having the keys and profits from a car that is registered to a friend: you use it, benefit from it, and make decisions about it even though the official paperwork lists someone else. For investors, this matters because it reveals who truly controls shares, affects voting power, potential conflicts of interest, and regulatory disclosure obligations.

pecuniary interest financial

"Mr. Tang has a pecuniary interest in the shares beneficially held"

indirectly wholly owned financial

"TCP III and TCP IV, which are indirectly wholly owned by TCP"

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 07/21/2026 - 07:39 PM Accepted by SEC EDGAR 07/21/2026 - 07:38 PM Learn about SEC filing dates

FAQ

What insider buying did Tang Capital report in Boundless Bio (BOLD)?

Tang Capital–managed entities reported buying 4,863 shares of Boundless Bio common stock. These indirect purchases occurred over three days in July 2026 and are tied to funds in which ten percent owner Kevin Tang has a pecuniary interest.

At what price were the recent Boundless Bio (BOLD) shares purchased?

All reported shares were purchased at $2.44 per share, disclosed as weighted-average prices. The reporting persons state they can provide detailed breakdowns of the number of shares purchased at each price level within the disclosed ranges upon request.

Who is the beneficial owner of the recently purchased Boundless Bio (BOLD) shares?

The purchased shares are beneficially owned by Tang Capital entities, including Tang Capital Partners, LP and related funds. Kevin Tang, as manager and director of these entities, has a pecuniary interest in the shares they beneficially hold.

Are the Boundless Bio (BOLD) shares held directly or indirectly by Kevin Tang?

The reported Boundless Bio shares are held indirectly through Tang Capital Partners, Tang Capital Partners International, and affiliated corporations. Kevin Tang controls these entities and has a pecuniary interest, rather than holding the shares in his own name.

How many Boundless Bio (BOLD) shares do Tang Capital funds beneficially own?

Disclosed holdings include 655,170 shares by Tang Capital Partners, LP, 893,434 shares by Tang Capital Partners International, LP, 655,161 shares by Tang Capital Partners III, Inc., and 655,170 shares by Tang Capital Partners IV, Inc., all associated with Kevin Tang.

Were the recent Boundless Bio (BOLD) purchases made under a Rule 10b5-1 trading plan?

The transactions are not affirmed as executed under a Rule 10b5-1 trading plan. The Rule 10b5-1 plan affirmation box is not marked, so these purchases are not reported as being made pursuant to such a pre-arranged plan.

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 CALIFORNIA 92121

(City) (State) (Zip)

UNITED STATES

(Country)

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)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
07/17/2026

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

	Form filed by One Reporting Person
X	Form filed by More than One Reporting Person

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

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
Common Stock	07/17/2026		P		265	A	$2.44(1)	2,854,337	I	See Footnote(2)
Common Stock	07/20/2026		P		1,623	A	$2.44(1)	2,855,960	I	See Footnote(2)
Common Stock	07/21/2026		P		2,975	A	$2.44(1)	2,858,935	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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

1. Name and Address of Reporting Person^*

TANG KEVIN

(Last) (First) (Middle)

4747 EXECUTIVE DRIVE

SUITE 210

(Street)

SAN DIEGO CALIFORNIA 92121

(City) (State) (Zip)

UNITED STATES

(Country)

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 CALIFORNIA 92121

(City) (State) (Zip)

UNITED STATES

(Country)

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 all purchased at $2.44. 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 ranges set forth in Footnote 1.

2. Tang Capital Partners, LP ("TCP") beneficially owns 655,170 shares, Tang Capital Partners International, LP ("TCPI") beneficially owns 893,434 shares, Tang Capital Partners III, Inc. ("TCP III") beneficially owns 655,161 shares, and Tang Capital Partners IV, Inc. ("TCP IV") beneficially owns 655,170 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	07/21/2026
	Kevin Tang, Manager	07/21/2026
	** 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: SEC 1474 (03-26)