RHYTHM PHARMACEUTICALS, INC. — Director's Dealing 2017

Oct 4, 2017

SEC Form 3 — Initial Statement of Beneficial Ownership

Issuer: RHYTHM PHARMACEUTICALS, INC. (RYTM)
CIK: 0001649904
Period of Report: 2017-10-04

Reporting Person: BAKER BROS. ADVISORS LP (10% Owner)
Reporting Person: Baker Bros. Advisors (GP) LLC (10% Owner)
Reporting Person: BAKER FELIX (10% Owner)
Reporting Person: BAKER JULIAN (10% Owner)

Holdings (Derivative)

Security	Exercise Price	Expiration	Underlying	Shares	Ownership
Series A Convertible Preferred	$		Common Stock (82969)		Indirect
Series A Convertible Preferred	$		Common Stock (1081051)		Indirect

Footnotes

F1: These securities consist of Series A Convertible Preferred Stock ("Series A Preferred") of Rhythm Pharmaceuticals, Inc. (the "Issuer") which are convertible into the Issuer's common stock on a 9.17 for 1 basis (the "Conversion Ratio") at any time at the election of the holder and will automatically convert into common stock of the Issuer at the Conversion Ratio into the number of shares of the Issuer's common stock shown in column 3 without payment or further consideration upon closing of the initial public offering of the Issuer. The Series A Preferred have no expiration date.

F2: As a result of Felix J. Baker's and Julian C. Baker's ownership interest in Baker Biotech Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in 760,829 shares of Series A Preferred held directly by 667, L.P. ("667"), a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

F3: As a result of Felix J. Baker's and Julian C. Baker's ownership interest in Baker Brothers Life Sciences Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in 9,913,242 shares of Series A Preferred held directly by Baker Brothers Life Sciences, L.P. ("Life Sciences" and together with "667", the "Funds") a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation
of a portion of the profits from Life Sciences.

F4: Baker Bros. Advisors LP (the "Adviser") serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F5: The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.