X0306 4 2017-12-15 1 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 2017-12-15 4 S 0 719665 8.0179 D 4530335 I See footnotes Common Stock 2017-12-15 4 S 0 102882 8.636 D 4427453 I See footnotes Common Stock 2017-12-18 4 S 0 300000 7.5048 D 4127453 I See footnotes Common Stock 2017-12-19 4 S 0 94771 7.6209 D 4032682 I See footnotes Common Stock 2017-12-19 4 S 0 55229 7.1055 D 3977453 I See footnotes On December 15, 2017, Bain Capital Life Sciences Fund, L.P. ("BC LS") and BCIP Life Sciences Associates, LP ("BCIP LS" and, together with BC LS, the "Bain Life Sciences Entities") sold 652,840 and 66,825 shares of common stock, respectively, at a weighted average price of $8.0179. The shares were sold in multiple transactions at prices ranging from $7.89 to $8.495. Following such sales, BC LS and BCIP LS held 4,109,671 and 420,664 shares of common stock, respectively. On December 15, 2017, BC LS and BCIP LS sold 93,329 and 9,553 shares of common stock, respectively, at a weighted average price of $8.636. The shares were sold in multiple transactions at prices ranging from $8.50 to $9.045. Following such sales, BC LS and BCIP LS held 4,016,342 and 411,111 shares of common stock, respectively. On December 18, 2017, BC LS and BCIP LS sold 272,143 and 27,857 shares of common stock, respectively, at a weighted average price of $7.5048. The shares were sold in multiple transactions at prices ranging from $7.05 to $7.905. Following such sales, BC LS and BCIP LS held 3,744,199 and 383,254 shares of common stock, respectively. On December 19, 2017, BC LS and BCIP LS sold 85,971 and 8,800 shares of common stock, respectively, at a weighted average price of $7.6209. The shares were sold in multiple transactions at prices ranging from $7.50 to $8.02. Following such sales, BC LS and BCIP LS held 3,658,228 and 374,454 shares of common stock, respectively. On December 19, 2017, BC LS and BCIP LS sold 50,101 and 5,128 shares of common stock, respectively, at a weighted average price of $7.1055. The shares were sold in multiple transactions at prices ranging from $6.86 to $7.498. Following such sales, BC LS and BCIP LS held 3,608,127 and 369,326 shares of common stock, respectively. Each of the Bain Life Sciences Entities 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 ranges set forth in footnotes (1) through (5) to this Form 4. 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 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. 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 2017-12-19 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 2017-12-19 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 2017-12-19 BCIP LIFE SCIENCES ASSOCIATES, LP, By: Boylston Coinvestors, LLC, its general partner, By: /s/ Adam Koppel, Name: Adam Koppel, Title: Authorized Signatory 2017-12-19 /s/ Jeffrey Schwartz 2017-12-19 /s/ Adam Koppel 2017-12-19