Tang Capital adds 63,969 Boundless Bio shares

Tang Capital Management LLC and Kevin Tang, both reported as 10% owners of Boundless Bio, Inc., disclosed open‑market purchases of 63,969 shares of common stock on July 14–16, 2026 at weighted‑average prices between $2.41 and $2.44 per share.

Rhea-AI Filing Summary

Tang Capital Management LLC and Kevin Tang, both reported as 10% owners of Boundless Bio, Inc., disclosed open‑market purchases of 63,969 shares of common stock on July 14–16, 2026 at weighted‑average prices between $2.41 and $2.44 per share.

After these transactions, Tang‑affiliated entities TCP, TCPI, TCP III and TCP IV beneficially own a combined 2,854,072 shares, including 654,055, 891,914, 654,048 and 654,055 shares respectively, in which Kevin Tang has a pecuniary interest through his roles with these entities.

Insider Trade Summary

Net Buyer: 63,969 shares

Net Buy 3 txns

Insider TANG KEVIN, TANG CAPITAL MANAGEMENT LLC

Role 10% Owner | 10% Owner

Bought 63,969 shs ($156K)

Type	Security	Shares	Price	Value
Purchase	Common Stock F4, F2	18,491	$2.44	$45K
Purchase	Common Stock F3, F2	1,600	$2.44	$4K
Purchase	Common Stock F1, F2	43,878	$2.43	$107K

Holdings After Transaction: Common Stock — 2,854,072 shares (Indirect, See Footnote)

Footnotes (4)

1. F1. The prices reported are weighted-average prices. These shares were purchased in multiple transactions at prices ranging from $2.41 to $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 Footnotes 1 and 3 through 4.
2. F2. Tang Capital Partners, LP ("TCP") beneficially owns 654,055 shares, Tang Capital Partners International, LP ("TCPI") beneficially owns 891,914 shares, Tang Capital Partners III, Inc. ("TCP III") beneficially owns 654,048 shares, and Tang Capital Partners IV, Inc. ("TCP IV") beneficially owns 654,055 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. F3. These shares were all purchased at $2.44.
4. F4. These shares were purchased in multiple transactions at prices ranging from $2.43 to $2.44.

Key Figures

Total shares purchased: 63,969 shares Post-transaction holdings: 2,854,072 shares Price range for purchases: $2.41–$2.44 per share +5 more

8 metrics

Total shares purchased 63,969 shares Open-market common stock purchases on July 14–16, 2026

Post-transaction holdings 2,854,072 shares Indirectly beneficially owned across Tang-affiliated entities after July 16, 2026 trades

Price range for purchases $2.41–$2.44 per share Weighted-average price range across reported July 2026 transactions

TCP holdings 654,055 shares Shares of Boundless Bio beneficially owned by Tang Capital Partners, LP (TCP)

TCPI holdings 891,914 shares Shares of Boundless Bio beneficially owned by Tang Capital Partners International, LP (TCPI)

TCP III holdings 654,048 shares Shares of Boundless Bio beneficially owned by Tang Capital Partners III, Inc. (TCP III)

TCP IV holdings 654,055 shares Shares of Boundless Bio beneficially owned by Tang Capital Partners IV, Inc. (TCP IV)

Single-day purchase July 15, 2026 1,600 shares at $2.44 Open-market buy of Boundless Bio common stock, all at $2.44 per share

Key Terms

beneficially owns, pecuniary interest, weighted-average prices, ten percent owner, +1 more

5 terms

beneficially owns financial

"Tang Capital Partners, LP ("TCP") beneficially owns 654,055 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"

weighted-average prices financial

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

ten percent owner financial

"Reporting persons are indicated as is_ten_percent_owner in the filing data"

indirect ownership financial

"Ownership type is reported as indirect with nature of ownership footnoted"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

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

Tang Capital Management LLC and Kevin Tang reported open‑market purchases of 63,969 Boundless Bio common shares on July 14–16, 2026. The trades were executed at weighted‑average prices between $2.41 and $2.44 per share, increasing their indirect beneficial ownership.

How many Boundless Bio (BOLD) shares do Tang-affiliated entities now hold?

Following the reported trades, Tang‑affiliated entities beneficially own a total of 2,854,072 Boundless Bio shares. This includes TCP 654,055, TCPI 891,914, TCP III 654,048, and TCP IV 654,055 shares, all reported as indirect holdings.

On what dates were the Boundless Bio (BOLD) insider purchases made?

The insider purchases of Boundless Bio common stock were made on July 14, 15 and 16, 2026. Across these three days, Tang‑affiliated entities accumulated 63,969 shares through open‑market transactions reported at weighted‑average prices around the mid‑$2 range.

At what prices were the Boundless Bio (BOLD) shares purchased by Tang entities?

The reported Boundless Bio share purchases occurred at weighted‑average prices between $2.41 and $2.44 per share. Individual trades fell within this range, including a block of 1,600 shares bought at $2.44, according to the transaction details and related footnotes.

What is Kevin Tang’s relationship to the Tang Capital entities holding Boundless Bio (BOLD) shares?

Kevin Tang is the sole manager of Tang Capital Management LLC, general partner of TCP and TCPI, and sole director and CEO of TCP III and TCP IV. He has a pecuniary interest in Boundless Bio shares beneficially held by these entities.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 07/16/2026 - 08:10 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)
07/14/2026

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	07/14/2026		P		43,878	A	$2.43(1)	2,833,981	I	See Footnote(2)
Common Stock	07/15/2026		P		1,600	A	$2.44(3)	2,835,581	I	See Footnote(2)
Common Stock	07/16/2026		P		18,491	A	$2.44(4)	2,854,072	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 purchased in multiple transactions at prices ranging from $2.41 to $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 Footnotes 1 and 3 through 4.

2. Tang Capital Partners, LP ("TCP") beneficially owns 654,055 shares, Tang Capital Partners International, LP ("TCPI") beneficially owns 891,914 shares, Tang Capital Partners III, Inc. ("TCP III") beneficially owns 654,048 shares, and Tang Capital Partners IV, Inc. ("TCP IV") beneficially owns 654,055 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 all purchased at $2.44.

4. These shares were purchased in multiple transactions at prices ranging from $2.43 to $2.44.

	Kevin Tang	07/16/2026
	Kevin Tang, Manager	07/16/2026
	** 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)