Kevin Tang group trims Boundless Bio (BOLD) stake, returns profit

Rhea-AI Filing Summary

Boundless Bio, Inc. (BOLD) had a significant shareholder group associated with Kevin Tang report the sale of 18,300 shares of Common Stock on 2026-08-26 at a weighted-average price of $2.97 per share, in transactions ranging from $2.90 to $3.03. Following this sale, entities affiliated with Tang Capital Partners beneficially hold 2,840,635 shares of Boundless Bio indirectly through several Tang Capital entities. The reporting persons stated they delivered to Boundless Bio the full disgorgeable profit of $10,046.70 arising from this sale and indicated that the transactions were not effected under a Rule 10b5-1 trading plan.

Insider Trade Summary

Net Seller: 18,300 shares

Net Sell 1 txn

Insider TANG KEVIN, TANG CAPITAL MANAGEMENT LLC

Role 10% Owner | 10% Owner

Sold 18,300 shs ($54K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1, F2, F3	18,300	$2.97	$54K

Holdings After Transaction: Common Stock — 2,840,635 shares (Indirect, See Footnote)

Footnotes (3)

1. F1. The Reporting Persons have delivered to the Issuer the full amount of the disgorgeable profit arising the sale reported herein, in the amount of $10,046.70.
2. F2. The price reported herein is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $2.90 to $3.03. 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 sold at each price within the range set forth in Footnote 2.
3. F3. Tang Capital Partners, LP ("TCP") beneficially owns 655,170 shares, Tang Capital Partners International, LP ("TCPI") beneficially owns 887,715 shares, Tang Capital Partners III, Inc. ("TCP III") beneficially owns 655,161 shares, and Tang Capital Partners IV, Inc. ("TCP IV") beneficially owns 642,589 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

Shares sold: 18,300 shares of Common Stock Weighted-average sale price: $2.97 per share Price range of sales: $2.90 to $3.03 per share +5 more

8 metrics

Shares sold 18,300 shares of Common Stock Sale on 2026-08-26 by Tang Capital–related entities

Weighted-average sale price $2.97 per share 18,300 shares sold in multiple transactions

Price range of sales $2.90 to $3.03 per share Range of prices for the 18,300 shares sold

Shares beneficially owned after transaction 2,840,635 shares Indirect holdings by Tang Capital–related entities after sale

TCP holdings 655,170 shares Shares beneficially owned by Tang Capital Partners, LP (TCP)

TCPI holdings 887,715 shares Shares beneficially owned by Tang Capital Partners International, LP (TCPI)

TCP III holdings 655,161 shares Shares beneficially owned by Tang Capital Partners III, Inc. (TCP III)

Disgorgeable profit remitted $10,046.70 Amount delivered to Boundless Bio arising from the reported sale

Key Terms

weighted-average price, beneficially owns, pecuniary interest, ten percent owner

4 terms

weighted-average price financial

"The price reported herein is a weighted-average price."

Weighted-average price is the average of multiple prices where each price is counted according to its size or importance—larger trades carry more weight than smaller ones, like averaging course grades by credit hours. It matters to investors because it gives a more realistic picture of the true price paid or received, helping assess trade execution, compare performance, calculate cost basis, and value positions more accurately than a simple average.

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"

ten percent owner regulatory

"reporting person is marked as a ten percent owner"

FAQ

What insider transaction did BOLD report for Kevin Tang’s affiliated entities?

Kevin Tang–associated entities reported a sale of 18,300 shares of Boundless Bio common stock on 2026-08-26. The sale was reported at a weighted-average price of $2.97 per share, with individual trades executed between $2.90 and $3.03.

What is the remaining Boundless Bio (BOLD) stake held by Tang Capital–related entities after this sale?

After the 18,300-share sale, Tang Capital–related entities beneficially hold 2,840,635 Boundless Bio shares, consisting of 655,170 by TCP, 887,715 by TCPI, 655,161 by TCP III, and 642,589 by TCP IV.

At what prices were the BOLD shares sold by Tang Capital–related entities?

The reported weighted-average sale price was $2.97 per share. The 18,300 shares of Boundless Bio common stock were sold in multiple transactions at prices ranging from $2.90 to $3.03 per share.

How much disgorgeable profit was remitted to Boundless Bio (BOLD) from this insider sale?

The reporting persons stated they delivered to Boundless Bio the full amount of the disgorgeable profit, $10,046.70, arising from the 18,300-share sale reported in this Form 4.

Was the Tang Capital sale of BOLD shares made under a Rule 10b5-1 trading plan?

No. The reporting persons indicated that the transaction was not effected under a Rule 10b5-1 trading plan, as reflected by the unchecked Rule 10b5-1 checkbox.

How is Kevin Tang related to the entities that hold BOLD shares?

Kevin Tang is the sole manager of Tang Capital Management, LLC, the general partner of TCP and TCPI, and the sole director and CEO of TCP III and TCP IV, which are indirectly wholly owned by TCP. He has a pecuniary interest in their Boundless Bio shares.

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 08/28/2026 - 04:17 PM Accepted by SEC EDGAR 08/28/2026 - 04:16 PM 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^*

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)
08/26/2026

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	08/26/2026		S(1)		18,300	D	$2.97(2)	2,840,635	I	See Footnote(3)

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 Reporting Persons have delivered to the Issuer the full amount of the disgorgeable profit arising the sale reported herein, in the amount of $10,046.70.

2. The price reported herein is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $2.90 to $3.03. 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 sold at each price within the range set forth in Footnote 2.

3. Tang Capital Partners, LP ("TCP") beneficially owns 655,170 shares, Tang Capital Partners International, LP ("TCPI") beneficially owns 887,715 shares, Tang Capital Partners III, Inc. ("TCP III") beneficially owns 655,161 shares, and Tang Capital Partners IV, Inc. ("TCP IV") beneficially owns 642,589 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	08/28/2026
	Kevin Tang, Manager	08/28/2026
	** 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)