Yann Mazabraud - 12 Aug 2026 Form 4 Insider Report for RHYTHM PHARMACEUTICALS, INC. (RYTM)

Reporting relationship: EVP, Head of International
Issuer ticker: RYTM
Reported as of: 12 Aug 2026
Net transaction value: -$6,620,575
SEC form: 4
Accepted by SEC: 14 Aug 2026, 19:01:59 UTC
Prior SEC filing: 03 Apr 2026
Source filing: View source filing
Reporting owner signature: /s/ Stephen Vander Stoep, attorney-in-fact for Yann Mazabraud

Key filing fact

Yann Mazabraud filed Form 4 for RHYTHM PHARMACEUTICALS, INC. (RYTM) on 14 Aug 2026.

Key facts

This page summarizes Yann Mazabraud's Form 4 filing for RHYTHM PHARMACEUTICALS, INC. (RYTM).
8 reported transactions and 1 derivative row are listed below.
Accepted by SEC: 14 Aug 2026, 19:01.

Change

Previous filing in this sequence was filed on 03 Apr 2026.
Current net transaction value: -$6,620,575.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001774702 Primary reporting owner

Mazabraud Yann

Relationship: EVP, Head of International
Address: C/O RHYTHM PHARMACEUTICALS, INC., 222 BERKELEY STREET, 12TH FLOOR, BOSTON
Signature: /s/ Stephen Vander Stoep, attorney-in-fact for Yann Mazabraud
Signature date: 14 Aug 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

RYTM transaction

Common Stock

Options Exercise

Transaction value
Shares: +46,625
Change %: +71%
Price: $6.80^*
Shares after: 112,655
Date: 12 Aug 2026
Ownership: Direct
Footnotes: F1

RYTM transaction

Common Stock

Sale

Transaction value: $257,138
Shares: -2,300
Change %: -2%
Price: $111.80
Shares after: 110,355
Date: 12 Aug 2026
Ownership: Direct
Footnotes: F1, F2

RYTM transaction

Common Stock

Sale

Transaction value: $112,856
Shares: -1,000
Change %: -0.91%
Price: $112.86
Shares after: 109,355
Date: 12 Aug 2026
Ownership: Direct
Footnotes: F1, F3

RYTM transaction

Common Stock

Sale

Transaction value: $413,477
Shares: -3,605
Change %: -3.3%
Price: $114.70
Shares after: 105,750
Date: 12 Aug 2026
Ownership: Direct
Footnotes: F1, F4

RYTM transaction

Common Stock

Sale

Transaction value: $1,681,541
Shares: -14,568
Change %: -14%
Price: $115.43
Shares after: 91,182
Date: 12 Aug 2026
Ownership: Direct
Footnotes: F1, F5

RYTM transaction

Common Stock

Sale

Transaction value: $2,121,125
Shares: -18,208
Change %: -20%
Price: $116.49
Shares after: 72,974
Date: 12 Aug 2026
Ownership: Direct
Footnotes: F1, F6

RYTM transaction

Common Stock

Sale

Transaction value: $2,034,439
Shares: -17,319
Change %: -24%
Price: $117.47
Shares after: 55,655
Date: 12 Aug 2026
Ownership: Direct
Footnotes: F1, F7

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

RYTM transaction Derivative

Stock Options (Right to Buy)

Options Exercise

Transaction value
Shares: -46,625
Change %: -57%
Price: $0.000000^*
Shares after: 35,875
Date: 12 Aug 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 46,625
Exercise price: $6.80
Footnotes: F1, F8

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Rule 10b5-1 trading plan

These transactions were reported as open-market trades under a Rule 10b5-1 plan. The plan lets an insider set trading instructions in advance, which can reduce the risk of trading while in possession of material nonpublic information.

Original filing language: transaction made pursuant to a contract, instruction, or written plan intended to satisfy Rule 10b5-1(c).

Explanation of responses 8 footnotes

Footnote F1

The exercise and sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 13, 2026.

Footnote F2

The price reported in Column 4 is a weighted average price. The securities were sold in multiple transactions at prices ranging from $111.58 to $112.30 per common stock. 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 range set forth in this footnote.

Footnote F3

The price reported in Column 4 is a weighted average price. The securities were sold in multiple transactions at prices ranging from $112.84 to $112.92 per common stock. 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 range set forth in this footnote.

Footnote F4

The price reported in Column 4 is a weighted average price. The securities were sold in multiple transactions at prices ranging from $114.01 to $115.00 per common stock. 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 range set forth in this footnote.

Footnote F5

The price reported in Column 4 is a weighted average price. The securities were sold in multiple transactions at prices ranging from $115.01 to $116.00 per common stock. 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 range set forth in this footnote.

Footnote F6

The price reported in Column 4 is a weighted average price. The securities were sold in multiple transactions at prices ranging from $116.01 to $117.00 per common stock. 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 range set forth in this footnote.

Footnote F7

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $117.01 to $117.60 per share. 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 range set forth in this footnote.

Footnote F8

The stock options were granted on February 9, 2022. The options vest and become exercisable in 16 substantially equal installments upon the Reporting Person's completion of each three full months of successive service to the Issuer following the grant date.