X0306 4 2020-05-18 0 0001649904 RHYTHM PHARMACEUTICALS, INC. RYTM 0001473930 Foley Todd C/O MPM ASSET MANAGEMENT 450 KENDALL STREET CAMBRIDGE MA 02142 1 0 0 0 Common Stock 2020-05-18 4 S 0 21349 20.00 D 2210528 I See Footnote Common Stock 2020-05-19 4 S 0 2633 20.00 D 2207895 I See Footnote Common Stock 2020-05-20 4 S 0 10527 20.01 D 2197368 I See Footnote The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person. The shares were sold as follows: 20,551 by MPM BioVentures V, L.P. ("BV V") and 798 by MPM Asset Management Investors BV5 LLC ("AM BV5"). MPM BioVentures V GP LLC and MPM BioVentures V LLC ("BV LLC") are the direct and indirect general partners of BV V and BV LLC is the manager of AM BV5. Ansbert Gadicke, Luke Evnin and Todd Foley are the members of BV LLC. The Reporting Person disclaims beneficial ownership of the securities except to the extent of his pecuniary interest therein. The price in Column 4 is a weighted average sale price. The prices actually received ranged from $20.00 to $20.04. The Reporting Person will provide to the issuer, any security holder of the issuer, or the SEC staff, upon request, information regarding the number of shares sold at each price within the range. Shares are held as follows: 2,127,864 by BV V and 82,664 by AM BV5. The Reporting Person disclaims beneficial ownership of the securities except to the extent of his pecuniary interest therein. Shares were sold as follows: 2,535 by BV V and 98 by AM BV5. The price in Column 4 is a weighted average sale price. The prices actually received ranged from $20.00 to $20.02. The Reporting Person will provide to the issuer, any security holder of the issuer, or the SEC staff, upon request, information regarding the number of shares sold at each price within the range. Shares are held as follows: 2,125,329 by BV V and 82,566 by AM BV5. The Reporting Person disclaims beneficial ownership of the securities except to the extent of his pecuniary interest therein. Shares were sold as follows: 10,133 by BV V and 394 by AM BV5. The price in Column 4 is a weighted average sale price. The prices actually received ranged from $20.00 to $20.05. The Reporting Person will provide to the issuer, any security holder of the issuer, or the SEC staff, upon request, information regarding the number of shares sold at each price within the range. Shares are held as follows: 2,115,196 by BV V and 82,172 by AM BV5. The Reporting Person disclaims beneficial ownership of the securities except to the extent of his pecuniary interest therein. /s/ Todd Foley 2020-05-20