OrbiMed funds trim Adicet Bio (ACET) stake with 104,658-share sale

Rhea-AI Filing Summary

Adicet Bio shareholder update: Investment entities affiliated with OrbiMed reported open-market sales of a total of 104,658 shares of Adicet Bio common stock on April 7–8, 2026, at prices between about $6.29 and $6.53 per share. The Form 4 shows these OrbiMed-related funds continuing to hold sizable indirect positions, including 564,147 shares, 280,640 shares, and 78,499 shares of Adicet Bio common stock through various limited partnerships.

Insider Trade Summary

Net Seller: 104,658 shares ($674,847)

Net Sell 7 txns

Insider ORBIMED ADVISORS LLC, OrbiMed Capital GP V LLC, OrbiMed Capital GP VI LLC, OrbiMed Genesis GP LLC, OrbiMed Advisors Israel II Ltd, OrbiMed Israel GP II, L.P., OrbiMed Israel GP Ltd., OrbiMed Israel BioFund GP Limited Partnership

Role 10% Owner | 10% Owner | 10% Owner | 10% Owner | 10% Owner | 10% Owner | 10% Owner | 10% Owner

Sold 104,658 shs ($675K)

Type	Security	Shares	Price	Value
Sale	Common Stock	32,523	$6.29	$205K
Sale	Common Stock	40,416	$6.52	$264K
Sale	Common Stock	29,319	$6.53	$191K
Sale	Common Stock	2,400	$6.38	$15K
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 0 shares (Indirect, See footnotes)

Footnotes (1)

1. These securities are held of record by OrbiMed Israel Partners Limited Partnership ("OIP"). OrbiMed Israel BioFund GP Limited Partnership ("OrbiMed BioFund") is the general partner of OIP, and OrbiMed Israel GP Ltd. ("OrbiMed Israel GP") is the general partner of OrbiMed BioFund. By virtue of such relationships, OrbiMed BioFund and OrbiMed Israel GP may be deemed to have voting and investment power over the shares of common stock held by OIP and, as a result, may be deemed to have beneficial ownership over such shares of common stock. OrbiMed Israel GP exercises this investment and voting power through an investment committee comprised of Carl L. Gordon and Erez Chimovits, each of whom disclaims beneficial ownership over the shares of common stock held by OIP. These securities are held of record by OrbiMed Israel Partners II, L.P. ("OIP II"). OrbiMed Israel GP II, L.P. ("OrbiMed Israel GP II") is the general partner of OIP II, and OrbiMed Advisors Israel II Limited ("OrbiMed Israel II") is the general partner of OrbiMed Israel GP II. By virtue of such relationships, OrbiMed Israel GP II and OrbiMed Israel II may be deemed to have voting and investment power over the shares of common stock held by OIP II and, as a result, may be deemed to have beneficial ownership over such shares of common stock. OrbiMed Israel II exercises this investment and voting power through an investment committee comprised of Carl L. Gordon, David Bonita, and Erez Chimovits, each of whom disclaims beneficial ownership over the shares of common stock held by OIP II. 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 LLC ("OrbiMed Advisors"), a registered investment adviser under the Investment Advisors Act of 1940, as amended, is the managing member of Genesis. By virtue of such relationships, Genesis GP and OrbiMed Advisors may be deemed to have voting and investment power over the shares of common stock held by Genesis and, as a result, may be deemed to have beneficial ownership over such shares of common stock. OrbiMed Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership over the shares of common stock held by Genesis. These securities are held of record by OrbiMed Private Investments V, LP ("OPI V"). OrbiMed Capital GP V LLC ("GP V") is the general partner of OPI V, and OrbiMed Advisors is the managing member of GP V. By virtue of such relationships, GP V and OrbiMed Advisors may be deemed to have voting and investment power over the shares of common stock held by OPI V and, as a result, may be deemed to have beneficial ownership over such shares of common stock. OrbiMed Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership over the shares of common stock held by OPI V. 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 is the managing member of GP VI. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting and investment power over the shares of common stock held by OPI VI and, as a result, may be deemed to have beneficial ownership over such shares of common stock. OrbiMed Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership over the shares of common stock held by OPI VI. Each of OrbiMed Advisors, OrbiMed BioFund, OrbiMed Israel GP, OrbiMed Israel GP II, OrbiMed Israel II, Genesis GP, GP V, 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 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 sold: 104,658 shares Sale block: 32,523 shares at $6.29/share Sale block: 40,416 shares at $6.52/share +3 more

6 metrics

Total shares sold 104,658 shares Net open-market sales on April 7–8, 2026

Sale block 32,523 shares at $6.29/share Open-market sale of Adicet Bio common stock

Sale block 40,416 shares at $6.52/share Open-market sale of Adicet Bio common stock

Indirect holding 564,147 shares Common stock held indirectly as of April 7, 2026

Indirect holding 280,640 shares Common stock held indirectly as of April 7, 2026

Indirect holding 78,499 shares Common stock held indirectly as of April 7, 2026

Key Terms

beneficial ownership, pecuniary interest, general partner, registered investment adviser, +2 more

6 terms

beneficial ownership financial

"may be deemed to have beneficial ownership over such shares of common stock"

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.

pecuniary interest financial

"except to the extent of his or its pecuniary interest therein, if any"

general partner financial

"OrbiMed Israel BioFund GP Limited Partnership ("OrbiMed BioFund") is the general partner of OIP"

A general partner is the person or firm that runs an investment partnership and legally represents it — they make the day-to-day decisions, choose which assets to buy or sell, and are responsible for the partnership’s obligations. Investors care because the general partner’s judgment, risk-taking and fee and profit-sharing arrangements determine both the potential returns and the level of exposure to losses; think of the GP as the ship’s captain whose skill and honesty shape the voyage’s outcome.

registered investment adviser financial

"OrbiMed Advisors LLC ("OrbiMed Advisors"), a registered investment adviser under the Investment Advisors Act"

A registered investment adviser (RIA) is a firm or individual legally registered with regulators to give personalized investment advice and manage clients' money, with a duty to put clients’ interests ahead of their own. Think of an RIA as a licensed financial guide who must disclose fees, conflicts and how they are paid; that transparency and legal duty matter to investors because it reduces the risk of hidden costs or biased recommendations.

management committee financial

"OrbiMed Advisors exercises this investment and voting power through a management committee"

Section 16 financial

"beneficial owner of such securities for the purpose of Section 16 of the Exchange Act"

Section 16 is a U.S. securities law rule that governs the trading and disclosure obligations of company insiders — typically officers, directors and large shareholders — to promote transparency and deter unfair profit-taking. It requires insiders to publicly report their stock trades and allows companies or the issuer to reclaim quick, short-term profits from certain insider trades, like a scoreboard and a refund policy that help investors see and limit possible insider advantage.

Form 4 Insider Transactions: What Each Field Means →

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

X

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^*

ORBIMED ADVISORS LLC

(Last) (First) (Middle)

601 LEXINGTON AVENUE

54TH FLOOR

(Street)

NEW YORK NEW YORK 10022

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Adicet Bio, Inc. [ ACET ]

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)
04/07/2026

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	04/07/2026		S		29,319	D	$6.53	34,923	I	See footnotes(1)(6)
Common Stock	04/07/2026		S		2,400	D	$6.38	32,523	I	See footnotes(1)(6)
Common Stock	04/08/2026		S		32,523	D	$6.29	0	I	See footnotes(1)(6)
Common Stock	04/08/2026		S		40,416	D	$6.52	0	I	See footnotes(2)(6)
Common Stock								78,499	I	See footnotes(3)(6)
Common Stock								564,147	I	See footnotes(4)(6)
Common Stock								280,640	I	See footnotes(5)(6)

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^*

ORBIMED ADVISORS LLC

(Last) (First) (Middle)

601 LEXINGTON AVENUE

54TH FLOOR

(Street)

NEW YORK NEW YORK 10022

(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^*

OrbiMed Capital GP V LLC

(Last) (First) (Middle)

601 LEXINGTON AVENUE

54TH FLOOR

(Street)

NEW YORK NEW YORK 10022

(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^*

OrbiMed Capital GP VI LLC

(Last) (First) (Middle)

601 LEXINGTON AVENUE, 54TH FLOOR

(Street)

NEW YORK NEW YORK 10022

(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^*

OrbiMed Genesis GP LLC

(Last) (First) (Middle)

601 LEXINGTON AVENUE, 54TH FLOOR

(Street)

NEW YORK NEW YORK 10022

(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^*

OrbiMed Advisors Israel II Ltd

(Last) (First) (Middle)

5 HAHOSHLIM STREET, BUILDING B

1ST FLOOR

(Street)

HERZLIYA PITUACH

(City) (State) (Zip)

ISRAEL

(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^*

OrbiMed Israel GP II, L.P.

(Last) (First) (Middle)

5 HAHOSHLIM STREET, BUILDING B

1ST FLOOR

(Street)

HERZLIYA PITUACH

(City) (State) (Zip)

ISRAEL

(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^*

OrbiMed Israel GP Ltd.

(Last) (First) (Middle)

5 HAHOSHLIM STREET, BUILDING B

1ST FLOOR

(Street)

HERZLIYA PITUACH

(City) (State) (Zip)

ISRAEL

(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^*

OrbiMed Israel BioFund GP Limited Partnership

(Last) (First) (Middle)

5 HAHOSHLIM STREET, BUILDING B

1ST FLOOR

(Street)

HERZLIYA PITUACH

(City) (State) (Zip)

ISRAEL

(Country)

Relationship of Reporting Person(s) to Issuer

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

Explanation of Responses:

1. These securities are held of record by OrbiMed Israel Partners Limited Partnership ("OIP"). OrbiMed Israel BioFund GP Limited Partnership ("OrbiMed BioFund") is the general partner of OIP, and OrbiMed Israel GP Ltd. ("OrbiMed Israel GP") is the general partner of OrbiMed BioFund. By virtue of such relationships, OrbiMed BioFund and OrbiMed Israel GP may be deemed to have voting and investment power over the shares of common stock held by OIP and, as a result, may be deemed to have beneficial ownership over such shares of common stock. OrbiMed Israel GP exercises this investment and voting power through an investment committee comprised of Carl L. Gordon and Erez Chimovits, each of whom disclaims beneficial ownership over the shares of common stock held by OIP.

2. These securities are held of record by OrbiMed Israel Partners II, L.P. ("OIP II"). OrbiMed Israel GP II, L.P. ("OrbiMed Israel GP II") is the general partner of OIP II, and OrbiMed Advisors Israel II Limited ("OrbiMed Israel II") is the general partner of OrbiMed Israel GP II. By virtue of such relationships, OrbiMed Israel GP II and OrbiMed Israel II may be deemed to have voting and investment power over the shares of common stock held by OIP II and, as a result, may be deemed to have beneficial ownership over such shares of common stock. OrbiMed Israel II exercises this investment and voting power through an investment committee comprised of Carl L. Gordon, David Bonita, and Erez Chimovits, each of whom disclaims beneficial ownership over the shares of common stock held by OIP II.

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 LLC ("OrbiMed Advisors"), a registered investment adviser under the Investment Advisors Act of 1940, as amended, is the managing member of Genesis. By virtue of such relationships, Genesis GP and OrbiMed Advisors may be deemed to have voting and investment power over the shares of common stock held by Genesis and, as a result, may be deemed to have beneficial ownership over such shares of common stock. OrbiMed Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership over the shares of common stock held by Genesis.

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

5. 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 is the managing member of GP VI. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting and investment power over the shares of common stock held by OPI VI and, as a result, may be deemed to have beneficial ownership over such shares of common stock. OrbiMed Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership over the shares of common stock held by OPI VI.

6. Each of OrbiMed Advisors, OrbiMed BioFund, OrbiMed Israel GP, OrbiMed Israel GP II, OrbiMed Israel II, Genesis GP, GP V, 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 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/ Carl L. Gordon, Member of OrbiMed Advisors LLC	04/09/2026
	/s/ Carl L. Gordon, Member of OrbiMed Capital GP V LLC	04/09/2026
	/s/ Carl L. Gordon, Member of OrbiMed Capital GP VI LLC	04/09/2026
	/s/ Carl L. Gordon, Member of OrbiMed Genesis GP LLC	04/09/2026
	/s/ Carl L. Gordon, Director of OrbiMed Israel GP Ltd.	04/09/2026
	/s/ Carl L. Gordon, Director of OrbiMed Advisors Israel II Ltd.	04/09/2026
	/s/ Carl L. Gordon, Director of OrbiMed Israel GP II, L.P.	04/09/2026
	/s/ Carl L. Gordon, Director of OrbiMed Israel BioFund GP Limited Partnership	04/09/2026
	** 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)

FAQ

What insider activity did OrbiMed-related entities report in Adicet Bio (ACET)?

OrbiMed-affiliated investment entities reported net open-market sales of 104,658 Adicet Bio common shares on April 7–8, 2026. These transactions were indirect holdings through several limited partnerships and funds managed within the OrbiMed group structure, rather than direct insider accounts.

At what prices were the Adicet Bio (ACET) shares sold by OrbiMed-related funds?

Reported sales of Adicet Bio common stock occurred at per-share prices such as $6.29, $6.38, $6.52, and $6.53. These prices reflect multiple open-market sale entries over two days, rather than a single block trade at one uniform price level.

How many Adicet Bio (ACET) shares did OrbiMed-related entities retain after these transactions?

After the reported sales, OrbiMed-affiliated entities continued to hold several indirect positions, including 564,147 shares, 280,640 shares, and 78,499 shares of Adicet Bio common stock. These balances are shown as holdings of different limited partnerships and funds within the OrbiMed structure.

Who legally holds the Adicet Bio (ACET) shares sold and owned in this Form 4?

The shares are held of record by OrbiMed-sponsored funds such as OrbiMed Israel Partners, OrbiMed Israel Partners II, OrbiMed Genesis Master Fund, and OrbiMed Private Investments V and VI. Related OrbiMed general partners may be deemed beneficial owners through voting and investment authority relationships.

Do OrbiMed principals personally claim beneficial ownership of these Adicet Bio (ACET) shares?

Footnotes state that OrbiMed entities and committee members, including named individuals, disclaim beneficial ownership of the reported securities except to the extent of any pecuniary interest. The filing clarifies this is not an admission of beneficial ownership for Section 16 purposes.

What is the nature of OrbiMed Advisors LLC’s role regarding Adicet Bio (ACET) holdings?

OrbiMed Advisors LLC is described as a registered investment adviser and managing member or general partner of several OrbiMed funds. Through these roles, it may be deemed to share voting and investment power over Adicet Bio shares held by the funds, subject to beneficial ownership disclaimers.