Tang-linked entities report 11.3% stake in Boundless Bio (NASDAQ: BOLD)

Rhea-AI Filing Summary

Boundless Bio disclosed ownership by Tang-linked investors totaling 11.3%. The Schedule 13G states 2,533,845 shares are beneficially owned collectively by Tang Capital Management, Kevin Tang and affiliated entities, based on 22,474,777 shares outstanding as of June 15, 2026.

The filing lists shared voting and dispositive power across Tang Capital Management, Tang Capital Partners, Tang Capital Partners International, Tang Capital Partners III, Tang Capital Partners IV and Kevin Tang; signatures are dated June 29, 2026.

Insights

Equity Ownership Analyst

13G shows a passive >10% position by Tang-linked entities.

The filing reports 2,533,845 shares representing 11.3% of the outstanding common stock as of June 15, 2026. The ownership is reported as shared voting and dispositive power among multiple Tang entities and Kevin Tang.

As a Schedule 13G, this filing characterizes the holding as an investment intent rather than an activist position; subsequent filings could show changes in intent or disposition.

Corporate Governance Specialist

Shared control across affiliated entities requires careful attribution.

The statement attributes shared voting and dispositive power to TCM, TCP, TCPI, TCP III, TCP IV and Kevin Tang, with signatures reflecting multiple capacities. The percentages use an explicit outstanding share count: 22,474,777.

Disclosure clarifies organizational relationships and addresses beneficial ownership reporting; any future voting coordination or change in status would appear in amended filings.

Key Figures

Beneficially owned: 2,533,845 shares Percent of class: 11.3% Shares outstanding: 22,474,777 shares +1 more

4 metrics

Beneficially owned 2,533,845 shares Amount reported as beneficially owned by Tang-linked parties

Percent of class 11.3% Percent of common stock based on outstanding shares as of June 15, 2026

Shares outstanding 22,474,777 shares Outstanding common stock used to calculate percentage (as of June 15, 2026)

CUSIP 10170A100 CUSIP for Boundless Bio common stock listed on the filing

Key Terms

Schedule 13G, Beneficially owned, Shared dispositive power, Outstanding shares as of

4 terms

Schedule 13G regulatory

"This Statement on (this "Statement") is filed by TCM, the general partner"

A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.

Beneficially owned financial

"Item 4. | Ownership (a) | Amount beneficially owned: 2,533,845"

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

Shared dispositive power financial

"Shared Dispositive Power 2,533,845.00"

Outstanding shares as of regulatory

"based on 22,474,777 shares of Common Stock outstanding as of June 15, 2026"

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Available on EDGAR 06/29/2026 - 07:58 PM Accepted by SEC EDGAR 06/29/2026 - 07:58 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

Boundless Bio, Inc.

(Name of Issuer)

Common stock, par value $0.0001 per share

(Title of Class of Securities)

10170A100

(CUSIP Number)

06/23/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 10170A100

1

Names of Reporting Persons

TANG CAPITAL MANAGEMENT, LLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 2,533,845.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,533,845.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,533,845.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

11.3 %

12

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person: Tang Capital Management, LLC ("TCM") shares voting and dispositive power over such shares with Tang Capital Partners, LP ("TCP"), Tang Capital Partners International, LP ("TCPI"), Tang Capital Partners III, Inc. ("TCP III"), Tang Capital Partners IV, Inc. ("TCP IV") and Kevin Tang. The percentages used herein are based on 22,474,777 shares of Common Stock outstanding as of June 15, 2026, as set forth in the Current Report filed on Form 8-K that was filed with the Securities and Exchange Commission on June 23, 2026.

SCHEDULE 13G

CUSIP Number(s): 10170A100

1

Names of Reporting Persons

KEVIN TANG

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 2,533,845.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,533,845.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,533,845.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

11.3 %

12

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person: Kevin Tang shares voting and dispositive power over such shares with TCP, TCPI, TCP III, TCP IV and TCM.

SCHEDULE 13G

CUSIP Number(s): 10170A100

1

Names of Reporting Persons

TANG CAPITAL PARTNERS, LP

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 580,669.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 580,669.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

580,669.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

2.6 %

12

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person: TCP shares voting and dispositive power over such shares with TCM and Kevin Tang.

SCHEDULE 13G

CUSIP Number(s): 10170A100

1

Names of Reporting Persons

TANG CAPITAL PARTNERS INTERNATIONAL, LP

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 791,839.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 791,839.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

791,839.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

3.5 %

12

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person: TCPI shares voting and dispositive power over such shares with TCM and Kevin Tang.

SCHEDULE 13G

CUSIP Number(s): 10170A100

1

Names of Reporting Persons

TANG CAPITAL PARTNERS III, INC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

NEVADA

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 580,668.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 580,668.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

580,668.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

2.6 %

12

Type of Reporting Person (See Instructions)

CO

Comment for Type of Reporting Person: TCP III shares voting and dispositive power over such shares with TCM and Kevin Tang.

SCHEDULE 13G

CUSIP Number(s): 10170A100

1

Names of Reporting Persons

TANG CAPITAL PARTNERS IV, INC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

NEVADA

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 580,669.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 580,669.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

580,669.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

2.6 %

12

Type of Reporting Person (See Instructions)

CO

Comment for Type of Reporting Person: TCP IV shares voting and dispositive power over such shares with TCM and Kevin Tang.

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Boundless Bio, Inc.
(b)	Address of issuer's principal executive offices: 11099 North Torrey Pines Road, Suite 150, La Jolla, CA, 92037
Item 2.
(a)	Name of person filing: This Statement on Schedule 13G (this "Statement") is filed by TCM, the general partner of TCP and TCPI; Kevin Tang, the manager of TCM and Chief Executive Officer of TCP III and TCP IV; TCP; TCPI; TCP III; and TCP IV.
(b)	Address or principal business office or, if none, residence: The address of TCM, Kevin Tang, TCP and TCPI is 4747 Executive Drive, Suite 210, San Diego, CA 92121. The address of TCP III and TCP IV is 400 S. 4th Street, 3rd Floor, Las Vegas, NV 89101.
(c)	Citizenship: TCM is a Delaware limited liability company. Mr. Tang is a United States citizen. TCP and TCPI are Delaware limited partnerships. TCP III and TCP IV are Nevada corporations that are indirectly wholly owned by TCP.
(d)	Title of class of securities: Common stock, par value $0.0001 per share
(e)	CUSIP Number(s): 10170A100
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 2,533,845
(b)	Percent of class: 11.3 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 0 shares
	(ii) Shared power to vote or to direct the vote: 2,533,845 shares
	(iii) Sole power to dispose or to direct the disposition of: 0 shares
	(iv) Shared power to dispose or to direct the disposition of: 2,533,845 shares
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

TANG CAPITAL MANAGEMENT, LLC

Signature:	/s/ Kevin Tang
Name/Title:	Manager
Date:	06/29/2026

KEVIN TANG

Signature:	/s/ Kevin Tang
Name/Title:	Self
Date:	06/29/2026

TANG CAPITAL PARTNERS, LP

Signature:	/s/ Kevin Tang
Name/Title:	Manager, Tang Capital Management, LLC, General Partner
Date:	06/29/2026

TANG CAPITAL PARTNERS INTERNATIONAL, LP

Signature:	/s/ Kevin Tang
Name/Title:	Manager, Tang Capital Management, LLC, General Partner
Date:	06/29/2026

TANG CAPITAL PARTNERS III, INC

Signature:	/s/ Kevin Tang
Name/Title:	Chief Executive Officer
Date:	06/29/2026

TANG CAPITAL PARTNERS IV, INC

Signature:	/s/ Kevin Tang
Name/Title:	Chief Executive Officer
Date:	06/29/2026