TSBX Form 4: Director Rishi Gupta reports sale under XOMA tender offer

Rhea-AI Filing Summary

Turnstone Biologics director Rishi Gupta reported a disposition of common stock on 08/08/2025 pursuant to an Agreement and Plan of Merger dated June 26, 2025, under which XOMA Royalty Corporation completed a cash tender offer. The tender paid $0.34 per share in cash and one non-transferable contingent value right (CVR) per share.

The filing identifies that these securities are held of record by OrbiMed Private Investments VI, LP, with OrbiMed Capital GP VI LLC as general partner and OrbiMed Advisors LLC as managing member; the reporting person is an employee of OrbiMed Advisors. The report shows 3,099,265 shares beneficially owned following the reported transaction and disclaims beneficial ownership except to the extent of any pecuniary interest. The disposition occurred pursuant to the merger terms rather than as an open-market sale.

Positive

• Transaction provided explicit consideration: cash of $0.34 per share plus one non-transferable CVR per share as part of the tender offer.
• Clear ownership disclosure: shares held of record by OrbiMed Private Investments VI, LP with GP and advisor relationships identified.

Negative

• Disposition of shares: the reporting person disposed of common stock pursuant to the merger, reducing direct holdings under the reported transaction.
• Post-transaction holdings: the filing shows 3,099,265 shares beneficially owned following the reported transaction, indicating a reduction relative to prior positions disclosed in this report.

Insights

M&A Specialist

TL;DR: Sale executed under a negotiated tender offer paying $0.34 plus a CVR; ownership moved through OrbiMed vehicle, not open-market trading.

The filing documents a transaction completed under an Agreement and Plan of Merger with XOMA Royalty Corporation that delivered defined consideration of $0.34 per share plus one non-transferable CVR per share. That explicit purchase price and CVR structure are material deal terms investors can use to value the transaction. The report also clarifies the share record ownership structure (OrbiMed Private Investments VI, LP) and the employee relationship of the reporting person, which matters for governance disclosure and tracking of beneficial ownership.

Impact assessment: the disclosure is impactful insofar as it confirms deal consideration and changes in reported holdings, but it does not provide additional operational or financial guidance.

Securities Analyst

TL;DR: Form 4 shows disposition under merger tender offer and a post-transaction beneficial ownership of 3,099,265 shares held via OrbiMed entities.

The Form 4 reports a disposal pursuant to the merger agreement rather than a market sale, including the cash component of $0.34 per share and issuance of CVRs. It also discloses that record ownership is held by an OrbiMed fund and that OrbiMed Advisors and its GP may be deemed to have voting and investment power, while disclaiming beneficial ownership except for any pecuniary interest. For investors tracking insider alignment and ownership concentration, the filing supplies clear ownership mapping and the post-transaction share count.

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
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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^*

Gupta Rishi

(Last) (First) (Middle)

C/O TURNSTONE BIOLOGICS CORP.

1110 NORTH VIRGIL AVENUE PMB 94659

(Street)

LOS ANGELES CA 90029

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Turnstone Biologics Corp. [ TSBX ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
08/08/2025

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

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

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

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	08/08/2025		U(1)		3,099,265	D	(1)	0	I	See Footnotes(2)(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

Explanation of Responses:

1. Disposed of pursuant to the terms of the Agreement and Plan of Merger, dated June 26, 2025, by and among the Issuer, XOMA Royalty Corporation ("Purchaser") and XRA 3 Corp., a wholly-owned subsidiary of Purchaser, pursuant to which Purchaser completed a cash tender offer for all outstanding shares of common stock of the Issuer for (i) $0.34 per share in cash, payable subject to any applicable tax withholding and without interest, plus (ii) one non-transferable contractual contingent value right per share, payable subject to any applicable tax withholding and without interest.

2. These securities are held of record by OrbiMed Private Investments VI, LP ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI, and OrbiMed Advisors LLC ("OrbiMed Advisors") is the managing member of GP VI. The Reporting Person is an employee of OrbiMed Advisors. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and, as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the securities held by OPI VI.

3. Each of the Reporting Person, OrbiMed Advisors and GP VI, disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of his or its pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Person, GP VI or OrbiMed Advisors, is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

	/s/ Rishi Gupta	08/08/2025
	** 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).
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Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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FAQ

What transaction did the Form 4 for Turnstone Biologics (TSBX) report?

The Form 4 reports a disposition of common stock on 08/08/2025 pursuant to an Agreement and Plan of Merger, completed via a cash tender offer by XOMA Royalty Corporation.

What consideration was paid in the tender offer reported on the Form 4?

The tender offer paid $0.34 per share in cash plus one non-transferable contingent value right (CVR) per share, payable subject to applicable tax withholding.

How many shares does the reporting person beneficially own after the transaction?

The filing shows 3,099,265 shares beneficially owned following the reported transaction.

Who holds the shares of record and what relationships are disclosed?

The securities are held of record by OrbiMed Private Investments VI, LP; OrbiMed Capital GP VI LLC is the general partner and OrbiMed Advisors LLC is the managing member; the reporting person is an employee of OrbiMed Advisors.

Was this an open-market sale or a sale under merger terms?

This disposition was made pursuant to the Agreement and Plan of Merger and the related tender offer, not as an open-market transaction.