Third Rock Ventures funds (RAPP) report 15.1% combined stake in Rapport Therapeutics

Rhea-AI Filing Summary

Third Rock Ventures funds report significant ownership stakes in Rapport Therapeutics, Inc. common stock. Third Rock Ventures V, L.P. directly holds 6,280,525 shares, representing approximately 13.1% of the outstanding common stock. Third Rock Ventures VI, L.P. directly holds 969,218 shares, representing approximately 2.0% of the class.

These percentages are based on 47,978,286 shares of common stock outstanding as of August 3, 2026. The affiliated general partners (TRV GP V, TRV GP V LLC, TRV GP VI, TRV GP VI LLC) may be deemed to beneficially own the respective shares, with shared voting and dispositive power over these holdings and no sole voting or dispositive power. The reporting entities state they disclaim the existence of a "group" under Rule 13d-5.

Key Figures

TRV V shares owned: 6,280,525 shares TRV VI shares owned: 969,218 shares TRV V percent of class: 13.1% +4 more

7 metrics

TRV V shares owned 6,280,525 shares Common Stock directly owned by Third Rock Ventures V, L.P.

TRV VI shares owned 969,218 shares Common Stock directly owned by Third Rock Ventures VI, L.P.

TRV V percent of class 13.1% Percent of Rapport Therapeutics common stock represented by TRV V shares

TRV VI percent of class 2.0% Percent of Rapport Therapeutics common stock represented by TRV VI shares

Shares outstanding 47,978,286 shares Common stock issued and outstanding as of August 3, 2026

Shared voting power (TRV V complex) 6,280,525 shares Shared voting and dispositive power for TRV V, TRV GP V, TRV GP V LLC

Shared voting power (TRV VI complex) 969,218 shares Shared voting and dispositive power for TRV VI, TRV GP VI, TRV GP VI LLC

Key Terms

beneficially own, shared voting power, shared dispositive power, percent of class, +1 more

5 terms

beneficially own financial

"TRV GP V is the general partner of TRV V and may be deemed to beneficially own the V Shares."

Beneficially own means having the economic rights and risks of a security—such as the right to receive dividends, sell the shares, or profit from price changes—whether or not your name appears on the official share register. Think of it like renting a car: you use it and reap the benefits even if the title lists someone else. Investors care because beneficial ownership determines who truly controls value, must be disclosed under securities rules, and can signal potential influence or trading activity that affects a stock’s price.

shared voting power financial

"Shared power to vote or to direct the vote: TRV V - 6,280,525 ... TRV VI - 969,218"

Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.

shared dispositive power financial

"Shared power to dispose or to direct the disposition of: TRV V - 6,280,525 ... TRV VI - 969,218"

percent of class financial

"Percent of class: The V shares represent approximately 13.1% of the outstanding shares of Common Stock."

Percent of class is the portion of a specific category of securities—such as a company’s common shares, preferred shares, or a bond series—that takes part in or approves a corporate action (vote, consent, tender, etc.). Investors watch this number because it reveals how much support or opposition exists within that particular shareholder group; like counting how many members of a club back a proposal, it can determine whether a plan passes or how influence is distributed.

Rule 13d-5 regulatory

"disclaim the existence of a "group" for purposes of Rule 13d-5 of the Securities Exchange Act of 1934"

FAQ

How many RAPP shares does Third Rock Ventures V, L.P. report owning?

Third Rock Ventures V, L.P. reports directly owning 6,280,525 shares of Rapport Therapeutics, Inc. common stock, representing approximately 13.1% of the outstanding shares based on 47,978,286 shares outstanding as of August 3, 2026.

What is Third Rock Ventures VI, L.P.’s ownership stake in RAPP?

Third Rock Ventures VI, L.P. reports directly owning 969,218 shares of Rapport Therapeutics, Inc. common stock, which represents approximately 2.0% of the outstanding shares, calculated using 47,978,286 shares outstanding as of August 3, 2026.

What total percentage of RAPP does the Third Rock Ventures complex report?

Third Rock Ventures entities report stakes of 13.1% (TRV V) and 2.0% (TRV VI) in RAPP. Each fund and its general partners may be deemed to beneficially own their respective shares but disclaim forming a "group" under Rule 13d-5.

Do the Third Rock Ventures entities have sole or shared voting power over RAPP shares?

The reporting entities indicate 0 shares with sole voting or dispositive power. They report shared voting and dispositive power over 6,280,525 shares for the TRV V structure and 969,218 shares for the TRV VI structure.

On what share count is Third Rock Ventures’ RAPP ownership percentage based?

The ownership percentages are based on 47,978,286 shares of Rapport Therapeutics, Inc. common stock issued and outstanding as of August 3, 2026, as referenced from the company’s Form 10-Q filed on August 5, 2026.

Which entities are included in the Third Rock Ventures Schedule 13G/A for RAPP?

The filing covers TRV V, TRV GP V, TRV GP V LLC, TRV VI, TRV GP VI, and TRV GP VI LLC. The partnerships directly hold the shares, and the general partners may be deemed to beneficially own those shares through their control relationships.

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

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Available on EDGAR 08/14/2026 - 04:21 PM Accepted by SEC EDGAR 08/14/2026 - 04:15 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. 1)

Rapport Therapeutics, Inc.

(Name of Issuer)

Common Stock, $0.001 par value per share

(Title of Class of Securities)

75383L102

(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): 75383L102

1

Names of Reporting Persons

Third Rock Ventures V, 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 6,280,525.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 6,280,525.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

6,280,525.00

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)

13.1 %

12

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person: (1) The percent of class was calculated based on 47,978,286 shares of common stock issued and outstanding as of August 3, 2026, as disclosed in the Issuer's 10-Q filed with the Securities and Exchange Commission on August 5, 2026.

SCHEDULE 13G

CUSIP Number(s): 75383L102

1

Names of Reporting Persons

Third Rock Ventures GP V, 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 6,280,525.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 6,280,525.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

6,280,525.00

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)

13.1 %

12

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13G

CUSIP Number(s): 75383L102

1

Names of Reporting Persons

TRV GP V, LLC

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 6,280,525.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 6,280,525.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

6,280,525.00

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)

13.1 %

12

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13G

CUSIP Number(s): 75383L102

1

Names of Reporting Persons

Third Rock Ventures VI, 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 969,218.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 969,218.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

969,218.00

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)

2.0 %

12

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13G

CUSIP Number(s): 75383L102

1

Names of Reporting Persons

Third Rock Ventures GP VI, 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 969,218.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 969,218.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

969,218.00

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)

2.0 %

12

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13G

CUSIP Number(s): 75383L102

1

Names of Reporting Persons

TRV GP VI, LLC

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 969,218.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 969,218.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

969,218.00

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)

2.0 %

12

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Rapport Therapeutics, Inc.
(b)	Address of issuer's principal executive offices: 1325 Boylston Street, Suite 401 Boston, MA 02215
Item 2.
(a)	Name of person filing: (i) Third Rock Ventures V, L.P. ("TRV V"); (ii) Third Rock Ventures GP V, L.P. ("TRV GP V"), which is the sole general partner of TRV V; (iii) TRV GP V, LLC ("TRV GP V LLC"), which is the sole general partner of TRV GP V; (iv) Third Rock Ventures VI, L.P. ("TRV VI"); (v) Third Rock Ventures GP VI, L.P. ("TRV GP VI"), which is the sole general partner of TRV VI; and (vi) TRV GP VI, LLC ("TRV GP VI LLC"), which is the sole general partner of TRV GP VI.
(b)	Address or principal business office or, if none, residence: The address of the principal business office of each of the Reporting Persons is Third Rock Ventures, LLC, 201 Brookline Ave, Suite 1401, Boston, MA 02215.
(c)	Citizenship: Each of TRV V, TRV GP V, TRV VI and TRV GP VI is a Delaware limited partnership. Each of TRV GP V LLC and TRV GP VI LLC is a Delaware limited liability company.
(d)	Title of class of securities: Common Stock, $0.001 par value per share
(e)	CUSIP No.: 75383L102
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: (i) TRV V directly owns 6,280,525 shares of Common Stock (the "V Shares"). (ii) TRV GP V is the general partner of TRV V and may be deemed to beneficially own the V Shares. (iii) TRV GP V LLC is the general partner of TRV GP V and may be deemed to beneficially own the V Shares. (iv) TRV VI directly owns 969,218 shares of Common Stock (the "VI Shares"). (v) TRV GP VI is the general partner of TRV VI and may be deemed to beneficially own the VI Shares. (vi) TRV GP VI LLC is the general partner of TRV GP VI and may be deemed to beneficially own the VI Shares. Each of TRV V, TRV GP V, and TRV GP V LLC, on the one hand, and TRV VI, TRV GP VI and TRV GP VI LLC, on the other hand, disclaim the existence of a "group" for purposes of Rule 13d-5 of the Securities Exchange Act of 1934, as amended, and nothing contained in this report shall be deemed an admission that any such group exists or may exist.
(b)	Percent of class: The V shares represent approximately 13.1% of the outstanding shares of Common Stock. The VI shares represent approximately 2.0% of the outstanding shares of Common Stock. The percent of class was calculated based on 47,978,286 shares of common stock issued and outstanding as of August 3, 2026, as disclosed in the Issuer's 10-Q filed with the Securities and Exchange Commission on August 5, 2026.
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: TRV V - 0 TRV GP V - 0 TRV GP V LLC - 0 TRV VI - 0 TRV GP VI - 0 TRV GP VI LLC - 0
	(ii) Shared power to vote or to direct the vote: TRV V - 6,280,525 TRV GP V - 6,280,525 TRV GP V LLC - 6,280,525 TRV VI - 969,218 TRV GP VI - 969,218 TRV GP VI LLC - 969,218
	(iii) Sole power to dispose or to direct the disposition of: TRV V - 0 TRV GP V - 0 TRV GP V LLC - 0 TRV VI - 0 TRV GP VI - 0 TRV GP VI LLC - 0
	(iv) Shared power to dispose or to direct the disposition of: TRV V - 6,280,525 TRV GP V - 6,280,525 TRV GP V LLC - 6,280,525 TRV VI - 969,218 TRV GP VI - 969,218 TRV GP VI LLC - 969,218
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:
	Not Applicable

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.

Third Rock Ventures V, L.P.

Signature:	By: THIRD ROCK VENTURES GP V, L.P., General Partner, By: TRV GP V, LLC, General Partner, By: /s/ Kevin Gillis
Name/Title:	Kevin Gillis, Chief Operating Officer
Date:	08/14/2026

Third Rock Ventures GP V, L.P.

Signature:	By: TRV GP V, LLC, General Partner, By: /s/ Kevin Gillis
Name/Title:	Kevin Gillis, Chief Operating Officer
Date:	08/14/2026

TRV GP V, LLC

Signature:	By: /s/ Kevin Gillis
Name/Title:	Kevin Gillis, Chief Operating Officer
Date:	08/14/2026

Third Rock Ventures VI, L.P.

Signature:	By: THIRD ROCK VENTURES GP VI, L.P., General Partner, By: TRV GP VI, LLC, General Partner, By: /s/ Kevin Gillis
Name/Title:	Kevin Gillis, Chief Operating Officer
Date:	08/14/2026

Third Rock Ventures GP VI, L.P.

Signature:	By: TRV GP VI, LLC, General Partner, By: /s/ Kevin Gillis
Name/Title:	Kevin Gillis, Chief Operating Officer
Date:	08/14/2026

TRV GP VI, LLC

Signature:	By: /s/ Kevin Gillis
Name/Title:	Kevin Gillis, Chief Operating Officer
Date:	08/14/2026