X0206 3 2017-09-19 0 0001267813 MARINUS PHARMACEUTICALS INC MRNS 0001703031 Bain Capital Life Sciences Investors, LLC 200 CLARENDON STREET BOSTON MA 02116 0 0 1 0 0001703030 Bain Capital Life Sciences Partners, LP 200 CLARENDON STREET BOSTON MA 02116 0 0 1 0 0001687968 Bain Capital Life Sciences Fund, L.P. 200 CLARENDON STREET BOSTON MA 02116 0 0 1 0 0001702921 BCIP Life Sciences Associates, LP 200 CLARENDON STREET BOSTON MA 02116 0 0 1 0 0001702957 Schwartz Jeffrey Lawrence 200 CLARENDON STREET BOSTON MA 02116 0 0 1 0 0001578965 Koppel Adam 200 CLARENDON STREET BOSTON MA 02116 0 0 1 0 Common Stock 5250000 I See Footnotes Bain Capital Life Sciences Investors, LLC ("BCI LS") is the general partner of Bain Capital Life Sciences Partners, LP ("BC LS P"), which is the general partner of Bain Capital Life Sciences Fund, L.P. ("BC LS"). As a result, BC LS P may be deemed to share voting and dispositive power with respect to the securities held by BC LS. BC LS holds 4,762,511 shares of Common Stock. BCIP Life Sciences Associates, LP (together with BC LS, the "Bain Life Sciences Entities"), whose general partner is Boylston Coinvestors, LLC, holds 487,489 shares of Common Stock. The governance, investment strategy and decision-making process with respect to the investments held by the Bain Life Sciences Entities is directed by BCI LS, whose managers are Jeffrey Schwartz and Adam Koppel. As a result, BCI LS, Mr. Schwartz and Dr. Koppel may each be deemed to share voting and dispositive power with respect to the securities held by the Bain Life Sciences Entities. BCI LS, Mr. Schwartz and Dr. Koppel each disclaim beneficial ownership of such securities except to the extent of their pecuniary interest therein. BAIN CAPITAL LIFE SCIENCES INVESTORS, LLC, By: /s/ Adam Koppel, Name: Adam Koppel, Title: Managing Director 2017-09-28 BAIN CAPITAL LIFE SCIENCES PARTNERS, LP, By: Bain Capital Life Sciences Investors, LLC, its general partner, By: /s/ Adam Koppel, Name: Adam Koppel, Title: Managing Director 2017-09-28 BAIN CAPITAL LIFE SCIENCES FUND, L.P., By: Bain Capital Life Sciences Partners, LP, its general partner, By: Bain Capital Life Sciences Investors, LLC, its general partner, By: /s/ Adam Koppel, Name: Adam Koppel, Title: Managing Director 2017-09-28 BCIP LIFE SCIENCES ASSOCIATES, LP, By: Boylston Coinvestors, LLC, its general partner, By: /s/ Adam Koppel, Name: Adam Koppel, Title: Authorized Signatory 2017-09-28 /s/ Jeffrey Schwartz 2017-09-28 /s/ Adam Koppel 2017-09-28