X0306 4 2017-12-18 0 0001399529 Dicerna Pharmaceuticals Inc DRNA 0001703031 Bain Capital Life Sciences Investors, LLC 200 CLARENDON STREET BOSTON MA 02116 1 0 1 0 0001703030 Bain Capital Life Sciences Partners, LP 200 CLARENDON STREET BOSTON MA 02116 1 0 1 0 0001687968 Bain Capital Life Sciences Fund, L.P. 200 CLARENDON STREET BOSTON MA 02116 1 0 1 0 0001702921 BCIP Life Sciences Associates, LP 200 CLARENDON STREET BOSTON MA 02116 1 0 1 0 0001702957 Schwartz Jeffrey Lawrence 200 CLARENDON STREET BOSTON MA 02116 1 0 1 0 0001578965 Koppel Adam 200 CLARENDON STREET BOSTON MA 02116 1 0 1 0 Common Stock 2017-12-18 4 P 0 285000 7.00 A 285000 I See footnotes Common Stock 2017-12-18 4 M 0 8454388 A 8739388 I See footnotes Common Stock 2017-12-18 4 A 0 190849 A 8930237 I See footnotes Redeemable Convertible Preferred Stock 2017-12-18 4 M 0 250000 3.19 D Common Stock 8454388 0 I See footnotes On December 18, 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") purchased 257,798 and 27,202 shares of common stock, respectively, in an underwritten public offering. Each share of Redeemable Convertible Preferred Stock had a stated value of $100 (the "Stated Value") and accrued dividends daily at an initial rate of 12% per annum, which was reduced to 8% per annum on October 28, 2017 in accordance with the Certificate of Designations for the Redeemable Convertible Preferred Stock. The Stated Value, as adjusted to give effect to such dividends, was referred to as the "Accrued Value." Each share of Redeemable Convertible Preferred Stock was convertible, at the option of the holder or, upon the occurrence of certain events, at the option of the Issuer, into a number of shares of common stock determined by dividing the Accrued Value by the conversion price. The Redeemable Convertible Preferred Stock was not convertible to the extent that such conversion would have resulted in the beneficial owner of such Redeemable Convertible Preferred Stock and its affiliates owning in excess of 19.99% of the Issuer's voting power. On December 18, 2017, the 226,139 shares of Redeemable Convertible Preferred Stock held by BC LS and the 23,861 shares of Redeemable Convertible Preferred Stock held by BCIP LS were converted, at the option of the Bain Life Sciences Entities, into 7,647,468 and 806,920 shares of common stock, respectively. On December 18, 2017, each of BC LS and BCIP LS received an additional 172,633 and 18,216 shares of common stock, respectively, from the Issuer representing the additional dividend accruals on the Redeemable Convertible Preferred Stock that each of BC LS and BCIP LS would have been entitled to receive up to and including March 31, 2018. 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. Dr. Koppel is a director of the Issuer. BAIN CAPITAL LIFE SCIENCES INVESTORS, LLC, By: /s/ Adam Koppel, 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, 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, Managing Director 2017-12-19 BCIP LIFE SCIENCES ASSOCIATES, LP, By: Boylston Coinvestors, LLC, its general partner, By: /s/ Adam Koppel, Authorized Signatory 2017-12-19 /s/ Jeffrey Schwartz 2017-12-19 /s/ Adam Koppel 2017-12-19