Ten percent owner of Boundless Bio (NASDAQ: BOLD) adds shares

Rhea-AI Filing Summary

Boundless Bio, Inc. reported that entities associated with Tang Capital Partners made open-market purchases of a total of 57,210 shares of common stock over three days. The buys on July 6–8, 2026 were executed at weighted-average prices between $2.46 and $2.49 per share.

Following these transactions, the indirect holdings reported as "By LP" increased to 2,698,518 shares of Boundless Bio common stock. Footnotes state that various Tang Capital funds collectively beneficially own these shares and that Kevin Tang has a pecuniary interest in the positions.

Insider Trade Summary

Net Buyer: 57,210 shares ($141,865)

Net Buy 3 txns

Insider TANG KEVIN, TANG CAPITAL MANAGEMENT LLC

Role null | null

Bought 57,210 shs ($142K)

Type	Security	Shares	Price	Value
Purchase	Common Stock	14,338	$2.46	$35K
Purchase	Common Stock	15,810	$2.48	$39K
Purchase	Common Stock	27,062	$2.49	$67K

Holdings After Transaction: Common Stock — 2,698,518 shares (Indirect, By LP)

Footnotes (1)

1. The prices reported are weighted-average prices. These shares were purchased in multiple transactions at prices ranging from $2.46 to $2.50. 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 Footnotes 1 and 3 through 4. Tang Capital Partners, LP ("TCP") beneficially owns 618,407 shares, Tang Capital Partners International, LP ("TCPI") beneficially owns 843,301 shares, Tang Capital Partners III, Inc. ("TCP III") beneficially owns 618,403 shares, and Tang Capital Partners IV, Inc. ("TCP IV") beneficially owns 618,407 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. These shares were purchased in multiple transactions at prices ranging from $2.44 to $2.50. These shares were purchased in multiple transactions at prices ranging from $2.42 to $2.48.

Key Figures

Total shares bought: 57,210 shares Weighted-average price July 8: $2.46 per share Weighted-average price July 7: $2.48 per share +5 more

8 metrics

Total shares bought 57,210 shares Open-market purchases on July 6–8, 2026

Weighted-average price July 8 $2.46 per share Common stock open-market purchase

Weighted-average price July 7 $2.48 per share Common stock open-market purchase

Weighted-average price July 6 $2.49 per share Common stock open-market purchase

Indirect holdings after July 8 2,698,518 shares Total Boundless Bio common stock indirectly owned

TCP beneficial ownership 618,407 shares Tang Capital Partners, LP beneficially owns these shares

TCPI beneficial ownership 843,301 shares Tang Capital Partners International, LP beneficially owns these shares

TCP III/IV holdings 618,403 & 618,407 shares Tang Capital Partners III, Inc. and IV, Inc. beneficially own these shares

Key Terms

open-market purchase, weighted-average prices, beneficially owns, pecuniary interest, +1 more

5 terms

open-market purchase financial

"transaction_action: open-market purchase"

An open-market purchase is when an investor or a company buys shares on a public stock exchange at the going market price, rather than through a private deal. It matters to investors because these purchases change how many shares are available, can push the stock price up or signal confidence from large buyers, and often affect per-share metrics like earnings—think of it like someone buying lots of apples off a grocery shelf, reducing supply and potentially raising the price.

weighted-average prices financial

"The prices reported are weighted-average prices. These shares were purchased"

beneficially owns financial

"Tang Capital Partners, LP ("TCP") beneficially owns 618,407 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"

indirect ownership financial

"total_shares_following_transaction ... ownership_type: indirect"

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 07/08/2026 - 08:06 PM Accepted by SEC EDGAR 07/08/2026 - 08:06 PM Learn about SEC filing dates

FAQ

What insider activity did Boundless Bio (BOLD) report in this Form 4?

Boundless Bio reported that entities associated with Tang Capital Partners bought 57,210 shares of common stock in open-market transactions. These purchases occurred over three days, increasing their reported indirect position in the company to 2,698,518 shares held through limited partnership structures.

Who is the reporting person in the Boundless Bio (BOLD) Form 4 filing?

The Form 4 lists Kevin Tang and Tang Capital Management LLC as reporting persons, each identified as a ten percent owner. Footnotes explain that several Tang Capital funds beneficially own the shares and that Kevin Tang has a pecuniary interest through his roles with these investment entities.

How many Boundless Bio (BOLD) shares were bought and at what prices?

The filing shows 57,210 Boundless Bio common shares purchased in total. Weighted-average prices were $2.49, $2.48, and $2.46 per share across July 6–8, 2026, with individual trades executed within stated price ranges around those averages.

What is the total Boundless Bio (BOLD) stake after these insider purchases?

After these transactions, the reporting parties show indirect ownership of 2,698,518 Boundless Bio common shares. The ownership is held through Tang Capital limited partnerships and related entities, with Kevin Tang having a pecuniary interest as manager or director of those investment vehicles.

How are the Boundless Bio (BOLD) insider purchases held, direct or indirect?

The Form 4 classifies all reported transactions as indirect ownership, noted as "By LP." Footnotes detail that Tang Capital Partners, related international and corporate entities hold the shares, and Kevin Tang’s interest arises through his roles with these funds rather than direct personal share ownership.

Over what dates did the Boundless Bio (BOLD) insider purchases occur?

The open-market purchases took place on July 6, July 7, and July 8, 2026. Each day’s transaction is reported separately with its own share count, weighted-average purchase price, and updated total number of Boundless Bio shares indirectly owned following that day’s activity.

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)
07/06/2026

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	07/06/2026		P		27,062	A	$2.49(1)	2,668,370	I	By LP(2)
Common Stock	07/07/2026		P		15,810	A	$2.48(3)	2,684,180	I	By LP(2)
Common Stock	07/08/2026		P		14,338	A	$2.46(4)	2,698,518	I	By LP(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 purchased in multiple transactions at prices ranging from $2.46 to $2.50. 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 Footnotes 1 and 3 through 4.

2. Tang Capital Partners, LP ("TCP") beneficially owns 618,407 shares, Tang Capital Partners International, LP ("TCPI") beneficially owns 843,301 shares, Tang Capital Partners III, Inc. ("TCP III") beneficially owns 618,403 shares, and Tang Capital Partners IV, Inc. ("TCP IV") beneficially owns 618,407 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.

3. These shares were purchased in multiple transactions at prices ranging from $2.44 to $2.50.

4. These shares were purchased in multiple transactions at prices ranging from $2.42 to $2.48.

	Kevin Tang	07/08/2026
	Kevin Tang, Manager	07/08/2026
	** 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)