RA CAPITAL MANAGEMENT, L.P. - 31 Dec 2025 SCHEDULE 13G/A Report for RHYTHM PHARMACEUTICALS, INC. Common Stock, $0.001 par value per share (RYTM)

Filing manager: RA CAPITAL MANAGEMENT, L.P.
Reporting owner: RA Capital Management, L.P.
Security: RHYTHM PHARMACEUTICALS, INC. Common Stock, $0.001 par value per share
Symbol: RYTM
Shares outstanding: 67,341,788 shares
Disclosed shares: 6,666,837 shares
Ownership percentage: 9.9%
Form type: SCHEDULE 13G/A
Filing time: 17 Feb 2026, 16:41:42 UTC
Event date: 31 Dec 2025
Previous filing: 14 Aug 2025
SEC filing: View on sec.gov

Key filing fact

RA CAPITAL MANAGEMENT, L.P. disclosed 9.9% ownership in RHYTHM PHARMACEUTICALS, INC. Common Stock, $0.001 par value per share (RYTM) on 31 Dec 2025.

Key facts

RA CAPITAL MANAGEMENT, L.P. filed SCHEDULE 13G/A for RHYTHM PHARMACEUTICALS, INC. Common Stock, $0.001 par value per share (RYTM).
Disclosed ownership: 9.9%.
Date of event: 31 Dec 2025.

This page explains what this Schedule 13D/13G filing tells you before manager-level rows.
You can verify ownership claims directly against the original SEC filing.

Backed by Schedule 13D/13G

Beneficial ownership values are sourced from the original SEC Schedule 13D/13G filing.

Reporting persons

Names, ownership, voting power, signatures, titles, and CIKs as disclosed in this Schedule 13D/G filing.

Name	Ownership	Shares Owned	shared voting power	Signature	Title
RA Capital Management, L.P.	9.9%	6,666,837	6,666,837	/s/ Peter Kolchinsky	By Peter Kolchinsky, Authorized Signatory
Peter Kolchinsky	9.9%	6,666,837	6,666,837	/s/ Peter Kolchinsky	Peter Kolchinsky
Rajeev Shah	9.9%	6,666,837	6,666,837	/s/ Rajeev Shah	Rajeev Shah
RA Capital Healthcare Fund, L.P.	9.9%	6,666,837	6,666,837	/s/ Peter Kolchinsky	By RA Capital Healthcare Fund GP, LLC, its General Partner, By Peter Kolchinsky, Manager

CIK / CUSIP context first

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