RA Capital discloses 9.99% Adicet Bio (ACET) stake with warrant blocker

Rhea-AI Filing Summary

RA Capital Management, L.P., RA Capital Healthcare Fund, L.P., Peter Kolchinsky, and Rajeev Shah report beneficial ownership of 935,486 shares of Adicet Bio, Inc. common stock as of June 30, 2026, subject to a 9.99% beneficial ownership limitation.

The Fund directly holds 932,624 shares and Pre-Funded Warrants exercisable for up to 1,402,833 shares, but a Beneficial Ownership Blocker in the warrants prevents exercises that would raise aggregate ownership above 9.99% of Adicet’s outstanding common stock. Based on 9,361,371 shares outstanding and 2,862 warrant shares counted for this calculation, each Reporting Person’s beneficial ownership is 9.99% of the class, rounded down to 9.9% in the cover pages due to EDGAR field limits.

RA Capital acts as investment adviser to the Fund and has delegated voting and dispositive power over the Fund’s holdings. The Reporting Persons state that they may be deemed beneficial owners for Section 13(d) purposes but expressly disclaim beneficial ownership except to determine their reporting obligations.

Key Figures

Beneficially owned shares: 935,486 shares Ownership percentage: 9.99% Shares outstanding: 9,361,371 shares +5 more

8 metrics

Beneficially owned shares 935,486 shares Aggregate Adicet Bio common stock beneficially owned as of June 30, 2026

Ownership percentage 9.99% Beneficial ownership of Adicet Bio common stock as of June 30, 2026

Shares outstanding 9,361,371 shares Adicet Bio common stock outstanding as of June 30, 2026

Directly held shares 932,624 shares Adicet Bio common stock directly held by RA Capital Healthcare Fund, L.P.

Pre-Funded Warrants capacity 1,402,833 shares Shares of Adicet Bio common stock exercisable under Pre-Funded Warrants held by the Fund

Warrant shares in ownership calc 2,862 shares Shares issuable from Pre-Funded Warrants included in the 9.99% ownership calculation

Rounded percentage on cover pages 9.9% Ownership percentage rounded down in EDGAR row 11 due to field limitations

Notice period to revoke delegation 61 days Minimum notice for the Fund to revoke delegated voting and investment power

Key Terms

Pre-Funded Warrants, Beneficial Ownership Blocker, Section 13(d), beneficial ownership, +1 more

5 terms

Pre-Funded Warrants financial

"The Fund directly holds 932,624 shares of common stock and pre-funded warrants ("Pre-Funded Warrants")"

Pre-funded warrants are financial instruments that give investors the right to purchase a company's stock at a set price, but with most or all of the purchase price paid upfront. They function like a coupon or gift card for stock, allowing investors to buy shares later at a fixed price, which can be beneficial if they want to avoid future price increases. This makes them important for investors seeking flexibility and certainty in their investment plans.

Beneficial Ownership Blocker financial

"The Pre-Funded Warrants contain a provision (the "Beneficial Ownership Blocker"), which precludes the exercise"

A beneficial ownership blocker is a legal or structural device that prevents a shareholder from being treated as the ultimate owner of enough shares to trigger control, reporting, or voting thresholds. Think of it like a speed bump that stops an investor from reaching a stake size that would force corporate disclosure or change control rights. Investors care because it affects who controls the company, how shares vote, regulatory filings, takeover risk and therefore potential value or liquidity of their holdings.

Section 13(d) regulatory

"may be deemed a beneficial owner, for purposes of Section 13(d) of the Act"

beneficial ownership financial

"each Reporting Person's beneficial ownership percentage was 9.99% as of June 30, 2026"

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.

investment adviser financial

"RA Capital serves as investment adviser for the Fund and may be deemed a beneficial owner"

An investment adviser is a person or firm that professionally manages money and gives recommendations about buying, selling, or holding investments. Like a financial coach or guide, they have a legal duty to act in a client's best financial interest, so their advice, fees and potential conflicts can directly affect returns and risk — making their role important for investors who want informed, accountable help with portfolios.

FAQ

What percentage of Adicet Bio (ACET) does RA Capital report owning in this Schedule 13G/A?

RA Capital and related Reporting Persons report beneficial ownership of 9.99% of Adicet Bio’s common stock as of June 30, 2026, based on 9,361,371 shares outstanding and 2,862 warrant shares included in the calculation.

How many Adicet Bio (ACET) shares does RA Capital’s fund directly hold?

RA Capital Healthcare Fund, L.P. directly holds 932,624 shares of Adicet Bio common stock. It also holds Pre-Funded Warrants exercisable for up to 1,402,833 additional shares, subject to a Beneficial Ownership Blocker limiting how many can be exercised at any time.

What is the Beneficial Ownership Blocker affecting RA Capital’s Adicet Bio (ACET) warrants?

The Pre-Funded Warrants include a Beneficial Ownership Blocker that prevents exercises if, after exercise, the Fund and its affiliates would own more than 9.99% of Adicet Bio’s outstanding common stock, limiting current exercisability of certain warrant shares.

What share count did RA Capital use to calculate its Adicet Bio (ACET) ownership percentage?

The ownership percentage is based on 9,361,371 shares of Adicet Bio common stock outstanding as of June 30, 2026 plus 2,862 shares issuable upon exercise of the Pre-Funded Warrants, yielding a reported 9.99% beneficial ownership of the class.

Why do RA Capital and its principals disclaim beneficial ownership of Adicet Bio (ACET) shares?

RA Capital, the Fund, Peter Kolchinsky, and Rajeev Shah state they may be deemed beneficial owners under Section 13(d) but disclaim beneficial ownership of the reported securities except for determining their reporting obligations, citing delegated voting and investment authority structures.

Who has voting and dispositive power over RA Capital’s Adicet Bio (ACET) holdings?

RA Capital, as investment adviser to the Fund, has been delegated the sole power to vote and dispose of the securities in the Fund’s portfolio, including Adicet Bio shares, while the Fund has divested such voting and investment power and cannot revoke the delegation on less than 61 days’ notice.

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

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Available on EDGAR 08/14/2026 - 04:40 PM Accepted by SEC EDGAR 08/14/2026 - 04:36 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 4)

Adicet Bio, Inc.

(Name of Issuer)

Common Stock, par value $0.0001 per share

(Title of Class of Securities)

007002207

(CUSIP Number)

06/30/2026

(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): 007002207

1

Names of Reporting Persons

RA Capital Management, L.P.

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 935,486.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 935,486.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

935,486.00

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)

9.9 %

12

Type of Reporting Person (See Instructions)

IA, PN

SCHEDULE 13G

CUSIP Number(s): 007002207

1

Names of Reporting Persons

Peter Kolchinsky

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 935,486.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 935,486.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

935,486.00

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)

9.9 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

CUSIP Number(s): 007002207

1

Names of Reporting Persons

Rajeev Shah

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 935,486.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 935,486.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

935,486.00

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)

9.9 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

CUSIP Number(s): 007002207

1

Names of Reporting Persons

RA Capital Healthcare Fund, L.P.

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 935,486.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 935,486.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

935,486.00

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)

9.9 %

12

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Adicet Bio, Inc.
(b)	Address of issuer's principal executive offices: 131 Dartmouth Street, Floor 3, Boston, MA, 02116.
Item 2.
(a)	Name of person filing: The names of the persons filing this report (collectively, the "Reporting Persons") are: RA Capital Management, L.P. ("RA Capital") Peter Kolchinsky Rajeev Shah RA Capital Healthcare Fund, L.P. (the "Fund") The Reporting Persons expressly disclaim status as a "group" for purposes of this Schedule 13G/A.
(b)	Address or principal business office or, if none, residence: The address of the principal business office of each of the Reporting Persons is: c/o RA Capital Management, L.P., 200 Berkeley Street, 18th Floor, Boston MA 02116
(c)	Citizenship: RA Capital and the Fund are Delaware limited partnerships. Dr. Kolchinsky and Mr. Shah are United States citizens.
(d)	Title of class of securities: Common Stock, par value $0.0001 per share
(e)	CUSIP No.: 007002207
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: Row 9 of each Reporting Person's cover page to this Schedule 13G/A sets forth the aggregate number of shares of common stock of the Issuer beneficially owned by such Reporting Person as of June 30, 2026 and is incorporated by reference. The Fund directly holds 932,624 shares of common stock and pre-funded warrants ("Pre-Funded Warrants") exercisable for up to 1,402,833 shares of common stock. The Pre-Funded Warrants contain a provision (the "Beneficial Ownership Blocker"), which precludes the exercise of the Pre-Funded Warrants to the extent that, following exercise, the Fund, together with its affiliates and other attribution parties, would own more than 9.99% of the common stock outstanding. The Fund is currently prohibited from exercising a portion of the Pre-Funded Warrants to the extent that such exercise would result in beneficial ownership of more than 935,486 shares of common stock. RA Capital Healthcare Fund GP, LLC is the general partner of the Fund. The general partner of RA Capital is RA Capital Management GP, LLC, of which Dr. Kolchinsky and Mr. Shah are the controlling persons. RA Capital serves as investment adviser for the Fund and may be deemed a beneficial owner, for purposes of Section 13(d) of the Act, of any securities of the Issuer held by the Fund. The Fund has delegated to RA Capital the sole power to vote and the sole power to dispose of all securities held in the Fund's portfolio, including the shares of the Issuer's common stock reported herein. Because the Fund has divested voting and investment power over the reported securities it holds and may not revoke that delegation on less than 61 days' notice, the Fund disclaims beneficial ownership of the securities it holds for purposes of Section 13(d) of the Act. As managers of RA Capital, Dr. Kolchinsky and Mr. Shah may be deemed beneficial owners, for purposes of Section 13(d) of the Act, of any securities of the Issuer beneficially owned by RA Capital. RA Capital, Dr. Kolchinsky, and Mr. Shah disclaim beneficial ownership of the securities reported in this Schedule 13G/A other than for the purpose of determining their obligations under Section 13(d) of the Act, and the filing of this Schedule 13G/A shall not be deemed an admission that either RA Capital, Dr. Kolchinsky, or Mr. Shah is the beneficial owner of such securities for any other purpose.
(b)	Percent of class: Due to the Beneficial Ownership Blocker listed in the Pre-Funded Warrants, each Reporting Person's beneficial ownership percentage was 9.99% as of June 30, 2026. Such percentage is based upon the sum of (i) 9,361,371 shares of the Issuer's common stock outstanding as of June 30, 2026, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission (the "SEC") on August 5, 2026, and (ii) 2,862 shares of common stock issuable upon the exercise of the Pre-Funded Warrants. Due to field limitations of the EDGAR filing system, the percentages listed in row 11 of the Reporting Persons' cover pages have been rounded down to 9.9%.
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: Row 5 of each Reporting Person's cover page to this Schedule 13G/A sets forth the sole power to vote or to direct the vote of securities of the Issuer beneficially owned by such Reporting Person as of June 30, 2026 and is incorporated by reference.
	(ii) Shared power to vote or to direct the vote: Row 6 of each Reporting Person's cover page to this Schedule 13G/A sets forth the shared power to vote or to direct the vote of securities of the Issuer beneficially owned by such Reporting Person as of June 30, 2026 and is incorporated by reference.
	(iii) Sole power to dispose or to direct the disposition of: Row 7 of each Reporting Person's cover page to this Schedule 13G/A sets forth the sole power to dispose or to direct the disposition of securities of the Issuer beneficially owned by such Reporting Person as of June 30, 2026 and is incorporated by reference.
	(iv) Shared power to dispose or to direct the disposition of: Row 8 of each Reporting Person's cover page to this Schedule 13G/A sets forth the shared power to dispose or to direct the disposition of securities of the Issuer beneficially owned by such Reporting Person as of June 30, 2026 and is incorporated by reference.
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.

RA Capital Management, L.P.

Signature:	/s/ Peter Kolchinsky
Name/Title:	By Peter Kolchinsky, Authorized Signatory
Date:	08/14/2026

Peter Kolchinsky

Signature:	/s/ Peter Kolchinsky
Name/Title:	Peter Kolchinsky
Date:	08/14/2026

Rajeev Shah

Signature:	/s/ Rajeev Shah
Name/Title:	Rajeev Shah
Date:	08/14/2026

RA Capital Healthcare Fund, L.P.

Signature:	/s/ Peter Kolchinsky
Name/Title:	By RA Capital Healthcare Fund GP, LLC, its General Partner, By Peter Kolchinsky, Manager
Date:	08/14/2026

Exhibit Information

Exhibit 99.1 Joint Filing Agreement (incorporated by reference to Exhibit 1 to Schedule 13G/A filed on November 14, 2024)