OrbiMed funds tied to Xu buy 1,875,000 Q32 Bio shares

Q32 Bio Inc. director and 10% owner Diyong Xu reported indirect purchases totaling 1,875,000 shares of common stock at $8.00 per share.

Rhea-AI Filing Summary

Q32 Bio Inc. director and 10% owner Diyong Xu reported indirect purchases totaling 1,875,000 shares of common stock at $8.00 per share. The shares were acquired by affiliated OrbiMed investment funds in a private placement directly from Q32 Bio, with one fund’s indirect holdings reaching 3,502,987 shares after the transactions.

Insights

Insider transactions analyst

Large affiliated funds bought newly issued Q32 Bio shares in a private deal.

Affiliated OrbiMed funds associated with director and 10% owner Diyong Xu acquired a total of 1,875,000 Q32 Bio common shares at $8.00 per share. The purchases occurred in a private placement directly from the company rather than on the open market.

After one of the purchases, an OrbiMed-related holding reached 3,502,987 shares, indicating a sizable indirect position. The filing notes complex ownership through OrbiMed entities and expressly disclaims beneficial ownership beyond each party’s pecuniary interest, so the economic exposure is shared across these funds and managers.

Insider Trade Summary

Net Buyer: 1,875,000 shares

Net Buy 2 txns

Insider Xu Diyong

Role Director, 10% Owner

Bought 1,875,000 shs ($15.00M)

Type	Security	Shares	Price	Value
Purchase	Common Stock	1,250,000	$8.00	$10.00M
Purchase	Common Stock	625,000	$8.00	$5.00M

Holdings After Transaction: Common Stock — 625,000 shares (Indirect, See footnotes)

Footnotes (4)

1. F1. These shares of the Issuer's common stock were purchased from the Issuer in a private placement.
2. F2. These securities are held of record by OrbiMed Private Investments VII, LP ("OPI VII"). OrbiMed Capital GP VII LLC ("OrbiMed GP") is the general partner of OPI VII and OrbiMed Advisors LLC ("OrbiMed Advisors") is the managing member of OrbiMed GP. By virtue of such relationships, OrbiMed GP and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VII 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 shares held by OPI VII.
3. F3. These securities are held of record by OrbiMed Genesis Master Fund, L.P. ("Genesis"). OrbiMed Genesis GP LLC ("Genesis GP") is the general partner of Genesis and OrbiMed Advisors is the managing member of Genesis GP. By virtue of such relationships, Genesis GP and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by Genesis 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 shares held by Genesis.
4. F4. Each of the Reporting Person, OrbiMed Advisors, OrbiMed GP, and Genesis GP 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 its pecuniary interest therein, if any. This report shall not be deemed an admission that any such person or entity is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

Key Figures

Total shares purchased: 1,875,000 shares First block purchased: 625,000 shares Second block purchased: 1,250,000 shares +3 more

6 metrics

Total shares purchased 1,875,000 shares Aggregate indirect common stock purchases by OrbiMed-linked entities

First block purchased 625,000 shares Indirect common stock purchase on May 28, 2026

Second block purchased 1,250,000 shares Indirect common stock purchase on May 28, 2026

Purchase price $8.00 per share Price for both indirect common stock purchases

Indirect holdings after larger trade 3,502,987 shares Common shares indirectly held following one purchase

Indirect holdings after smaller trade 625,000 shares Common shares indirectly held following the other purchase

Key Terms

private placement, beneficial ownership, voting power and investment power, OrbiMed Advisors LLC, +2 more

6 terms

private placement financial

"These shares of the Issuer's common stock were purchased from the Issuer in a private placement."

A private placement is a sale of securities directly to a selected group of investors, typically institutions or accredited investors, instead of through a public offering. It lets a company raise money faster and with fewer regulatory steps; for existing shareholders it matters because the newly issued shares, often sold at a discount, increase the share count and can dilute their ownership.

beneficial ownership financial

"may be deemed to have beneficial ownership over such securities."

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

voting power and investment power financial

"may be deemed to have voting power and investment power over the securities held"

OrbiMed Advisors LLC financial

"OrbiMed Advisors LLC ("OrbiMed Advisors") is the managing member of OrbiMed GP."

Rule 16a-1(a) regulatory

"disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934"

Section 16 of the Exchange Act regulatory

"not be deemed an admission that any such person or entity is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act"

FAQ

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

What insider transaction did Q32 Bio Inc. (QTTB) report for Diyong Xu?

Q32 Bio reported that entities associated with director and 10% owner Diyong Xu bought 1,875,000 common shares. The purchases were indirect and occurred through OrbiMed-managed investment funds in a private placement directly from the company at $8.00 per share.

At what price were the new Q32 Bio (QTTB) shares purchased by OrbiMed-related entities?

The OrbiMed-related entities purchased Q32 Bio common stock at $8.00 per share. All reported transactions took place on May 28, 2026, as part of a private placement directly from Q32 Bio rather than regular open-market trading.

How many Q32 Bio (QTTB) shares did OrbiMed-affiliated funds acquire in total?

OrbiMed-affiliated funds acquired a total of 1,875,000 Q32 Bio common shares. The Form 4 shows two indirect purchase entries of 625,000 and 1,250,000 shares, both priced at $8.00 per share in a private placement from the issuer.

What are the indirect holdings in Q32 Bio (QTTB) after the reported Form 4 transactions?

Following one of the reported purchases, an OrbiMed-affiliated entity held 3,502,987 Q32 Bio common shares indirectly. Another transaction line shows 625,000 shares held after that purchase, reflecting separate indirect positions through different OrbiMed-related investment vehicles.

Who actually holds the Q32 Bio (QTTB) shares reported in Diyong Xu’s Form 4?

The shares are held of record by OrbiMed Private Investments VII, LP and OrbiMed Genesis Master Fund, L.P. Control is exercised through OrbiMed Capital GP VII LLC, OrbiMed Genesis GP LLC, and OrbiMed Advisors LLC, which collectively manage voting and investment power for these Q32 Bio positions.

Does Diyong Xu fully own the Q32 Bio (QTTB) shares reported on the Form 4?

The filing states that Diyong Xu and the OrbiMed entities disclaim beneficial ownership beyond their pecuniary interest. The securities are attributed to OrbiMed investment funds, and the report should not be viewed as an admission of full beneficial ownership under Section 16 of the Exchange Act.

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

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Accepted by SEC EDGAR 06/01/2026 - 09:15 PM EDT 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^*

Xu Diyong

(Last) (First) (Middle)

C/O Q32 BIO INC.

830 WINTER STREET

(Street)

WALTHAM MASSACHUSETTS 02451

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Q32 Bio Inc. [ QTTB ]

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

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/28/2026

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

X	Form filed by One Reporting Person
	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	05/28/2026		P		1,250,000(1)	A	$8	3,502,987	I	See footnotes(2)(4)
Common Stock	05/28/2026		P		625,000(1)	A	$8	625,000	I	See footnotes(3)(4)

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. These shares of the Issuer's common stock were purchased from the Issuer in a private placement.

2. These securities are held of record by OrbiMed Private Investments VII, LP ("OPI VII"). OrbiMed Capital GP VII LLC ("OrbiMed GP") is the general partner of OPI VII and OrbiMed Advisors LLC ("OrbiMed Advisors") is the managing member of OrbiMed GP. By virtue of such relationships, OrbiMed GP and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VII 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 shares held by OPI VII.

3. These securities are held of record by OrbiMed Genesis Master Fund, L.P. ("Genesis"). OrbiMed Genesis GP LLC ("Genesis GP") is the general partner of Genesis and OrbiMed Advisors is the managing member of Genesis GP. By virtue of such relationships, Genesis GP and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by Genesis 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 shares held by Genesis.

4. Each of the Reporting Person, OrbiMed Advisors, OrbiMed GP, and Genesis GP 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 its pecuniary interest therein, if any. This report shall not be deemed an admission that any such person or entity is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

	/s/Diyong Xu	06/01/2026
	** 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)