Third Rock fund sells Rapport Therapeutics shares

Rapport Therapeutics, Inc. insider entities affiliated with Third Rock Ventures reported an open‑market sale of 426,005 shares of common stock at a weighted average price of $40.317 per share.

Rhea-AI Filing Summary

Rapport Therapeutics, Inc. insider entities affiliated with Third Rock Ventures reported an open‑market sale of 426,005 shares of common stock at a weighted average price of $40.317 per share. After the sale, one reporting holder retained 6,709,228 shares directly, while another related fund held 969,218 shares indirectly. The sale was carried out under a pre‑arranged Rule 10b5‑1 trading plan dated November 21, 2025.

Insider Trade Summary 10b5-1

Net Seller: 426,005 shares

Net Sell 2 txns

Insider Third Rock Ventures V, L.P., Third Rock Ventures GP V, LP, TRV GP V, LLC, Third Rock Ventures VI, L.P., Third Rock Ventures GP VI, L.P., TRV GP VI, LLC

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

Sold 426,005 shs ($17.18M)

Type	Security	Shares	Price	Value
Sale	Common Stock	426,005	$40.317	$17.18M
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 6,709,228 shares (Direct); Common Stock — 969,218 shares (Indirect, By Third Rock Ventures VI, L.P.)

Footnotes (4)

1. F1. The reported transactions were effected pursuant to a Rule 10b5-1 trading plan dated November 21, 2025, previously adopted by the Reporting Person.
2. F2. The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $40.00 to $40.79, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (2).
3. F3. These shares are directly held by Third Rock Ventures V, L.P. ("TRV V"). The general partner of TRV V is Third Rock Ventures GP V, L.P. ("TRV GP V"). The general partner of TRV GP V is TRV GP V, LLC ("TRV GP V LLC"). Each of TRV GP V and TRV GP V LLC disclaims beneficial ownership of the shares except to the extent of its pecuniary interest therein, if any, and this report shall not be deemed an admission that it is the beneficial owner of such shares.
4. F4. The shares are held directly by Third Rock Ventures VI, L.P. ("TRV VI"). The general partner of TRV VI is Third Rock Ventures GP VI, L.P. ("TRV GP VI"). The general partner of TRV GP VI is TRV GP VI, LLC ("TRV GP VI LLC"). Each of TRV GP VI, and TRV GP VI LLC, disclaims beneficial ownership of these shares except to the extent of its pecuniary interest therein, if any, and this report shall not be deemed an admission that it is the beneficial owner of such shares. Each of Reporting Persons disclaims the existence of a Section 13(d) "group" as between any TRV V related parties and any TRV VI related parties and this report shall not be deemed an admission that any of such parties is or may be part of such a group with any of the other parties.

Key Figures

Shares sold: 426,005 shares Weighted average sale price: $40.317/share Post-sale direct holdings: 6,709,228 shares +2 more

5 metrics

Shares sold 426,005 shares Open-market sale of common stock

Weighted average sale price $40.317/share Price for 426,005 sold shares

Post-sale direct holdings 6,709,228 shares Common stock held directly by a reporting holder

Indirect holdings 969,218 shares Common stock held indirectly by Third Rock Ventures VI, L.P.

Sale price range $40.00–$40.79/share Range of individual trade prices for sold shares

Key Terms

Rule 10b5-1 trading plan, weighted average price, pecuniary interest, Section 13(d) "group", +1 more

5 terms

Rule 10b5-1 trading plan financial

"The reported transactions were effected pursuant to a Rule 10b5-1 trading plan dated November 21, 2025"

A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.

weighted average price financial

"The price reported is a weighted average price. These shares were sold in multiple transactions"

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

pecuniary interest financial

"disclaims beneficial ownership of the shares except to the extent of its pecuniary interest therein"

Section 13(d) "group" regulatory

"disclaims the existence of a Section 13(d) "group" as between any TRV V related parties"

indirect ownership financial

"The shares are held directly by Third Rock Ventures VI, L.P. ("TRV VI")"

FAQ

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

What insider transaction did Rapport Therapeutics (RAPP) disclose in this Form 4?

Rapport Therapeutics disclosed that entities affiliated with Third Rock Ventures sold 426,005 shares of common stock in an open-market transaction. The sale was reported as a routine Section 16 filing detailing insider activity and resulting share ownership levels after the transaction.

How many Rapport Therapeutics (RAPP) shares were sold and at what price?

The filing shows a sale of 426,005 Rapport Therapeutics common shares at a weighted average price of $40.317 per share. Footnotes state the trades occurred in multiple transactions between $40.00 and $40.79, with full pricing details available on request from the reporting person.

Who executed the share sale reported for Rapport Therapeutics (RAPP)?

The sale was executed by investment entities affiliated with Third Rock Ventures, including Third Rock Ventures V, L.P. The filing notes related general partners and LLCs, which disclaim beneficial ownership beyond any pecuniary interest they may have in the reported Rapport Therapeutics shares.

How many Rapport Therapeutics (RAPP) shares do the reporting entities hold after the sale?

After the reported sale, one Third Rock-affiliated holder directly owned 6,709,228 Rapport Therapeutics common shares. A related fund, Third Rock Ventures VI, L.P., held an additional 969,218 shares indirectly, according to the ownership table and accompanying explanatory footnotes.

Was the Rapport Therapeutics (RAPP) insider sale made under a trading plan?

Yes. The filing states the reported transactions were effected under a Rule 10b5-1 trading plan dated November 21, 2025. Such plans are pre-arranged instructions for trading, designed to systematize insider sales irrespective of short-term market developments.

What price range did Rapport Therapeutics (RAPP) shares trade at in this insider sale?

Footnotes explain that the 426,005 sold shares were executed in multiple trades between $40.00 and $40.79 per share. The weighted average sale price reported in the main table was $40.317, aggregating the individual executions within that disclosed price range.

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

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Accepted by SEC EDGAR 04/21/2026 - 07:36 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).

X

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^*

Third Rock Ventures V, L.P.

(Last) (First) (Middle)

C/O THIRD ROCK VENTURES, LLC

201 BROOKLINE AVE, SUITE 1401

(Street)

BOSTON MASSACHUSETTS 02215

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Rapport Therapeutics, Inc. [ RAPP ]

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)
04/17/2026

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	04/17/2026		S(1)		426,005	D	$40.317(2)	6,709,228	D(3)
Common Stock								969,218	I	By Third Rock Ventures VI, L.P.(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

1. Name and Address of Reporting Person^*

Third Rock Ventures V, L.P.

(Last) (First) (Middle)

C/O THIRD ROCK VENTURES, LLC

201 BROOKLINE AVE, SUITE 1401

(Street)

BOSTON MASSACHUSETTS 02215

(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^*

Third Rock Ventures GP V, LP

(Last) (First) (Middle)

201 BROOKLINE AVE, SUITE 1401

(Street)

BOSTON MASSACHUSETTS 02215

(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^*

TRV GP V, LLC

(Last) (First) (Middle)

201 BROOKLINE AVE, SUITE 1401

(Street)

BOSTON MASSACHUSETTS 02215

(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^*

Third Rock Ventures VI, L.P.

(Last) (First) (Middle)

C/O THIRD ROCK VENTURES, LLC

201 BROOKLINE AVE, SUITE 1401

(Street)

BOSTON MASSACHUSETTS 02215

(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^*

Third Rock Ventures GP VI, L.P.

(Last) (First) (Middle)

201 BROOKLINE AVE, SUITE 1401

(Street)

BOSTON MASSACHUSETTS 02215

(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^*

TRV GP VI, LLC

(Last) (First) (Middle)

201 BROOKLINE AVE, SUITE 1401

(Street)

BOSTON MASSACHUSETTS 02215

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

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

Explanation of Responses:

1. The reported transactions were effected pursuant to a Rule 10b5-1 trading plan dated November 21, 2025, previously adopted by the Reporting Person.

2. The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $40.00 to $40.79, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (2).

3. These shares are directly held by Third Rock Ventures V, L.P. ("TRV V"). The general partner of TRV V is Third Rock Ventures GP V, L.P. ("TRV GP V"). The general partner of TRV GP V is TRV GP V, LLC ("TRV GP V LLC"). Each of TRV GP V and TRV GP V LLC disclaims beneficial ownership of the shares except to the extent of its pecuniary interest therein, if any, and this report shall not be deemed an admission that it is the beneficial owner of such shares.

4. The shares are held directly by Third Rock Ventures VI, L.P. ("TRV VI"). The general partner of TRV VI is Third Rock Ventures GP VI, L.P. ("TRV GP VI"). The general partner of TRV GP VI is TRV GP VI, LLC ("TRV GP VI LLC"). Each of TRV GP VI, and TRV GP VI LLC, disclaims beneficial ownership of these shares except to the extent of its pecuniary interest therein, if any, and this report shall not be deemed an admission that it is the beneficial owner of such shares. Each of Reporting Persons disclaims the existence of a Section 13(d) "group" as between any TRV V related parties and any TRV VI related parties and this report shall not be deemed an admission that any of such parties is or may be part of such a group with any of the other parties.

	/s/ Kevin Gillis, Chief Operating Officer of TRV GP V, LLC, general partner of Third Rock Ventures GP V, L.P., general partner of Third Rock Ventures V, L.P.	04/21/2026
	/s/ Kevin Gillis, Chief Operating Officer of TRV GP V, LLC, general partner of Third Rock Ventures GP V, L.P.	04/21/2026
	/s/ Kevin Gillis, Chief Operating Officer of TRV GP V, LLC	04/21/2026
	** 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)