X0306 4 2017-12-11 1 0001503274 Quanterix Corp QTRX 0001299790 Flagship Ventures Fund 2004 L P 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 0001400249 Flagship Ventures General Partner LLC 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 0001222012 AFEYAN NOUBAR 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 0001255927 KANIA EDWIN M JR 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 Common Stock 2017-12-11 4 C 0 398257 A 398257 D Common Stock 2017-12-11 4 C 0 1045426 A 1443683 D Common Stock 2017-12-11 4 C 0 477042 A 1920725 D Common Stock 2017-12-11 4 C 0 109770 A 2030495 D Series A-1 Preferred Stock 2017-12-11 4 C 0 1280000 D Common Stock 398257 0 D Series A-2 Preferred Stock 2017-12-11 4 C 0 3360000 D Common Stock 1045426 0 D Series B Preferred Stock 2017-12-11 4 C 0 1533214 D Common Stock 477042 0 D Series C Preferred Stock 2017-12-11 4 C 0 352800 D Common Stock 109770 0 D The shares of preferred stock automatically converted into common stock immediately prior to the closing of the Issuer's initial public offering using a calculation defined in the Issuer's Restated Certificate of Incorporation, as amended, based on the initial purchase price and the conversion rate in effect at the time of conversion. The shares of preferred stock automatically converted on a 1-for-3.214 basis and such conversion rate is reflected in the amount of common stock underlying the security. Held by Flagship Ventures Fund 2004, L.P. Flagship Ventures General Partner LLC (the "GP") is the General Partner of Flagship Ventures Fund 2004, L.P. Noubar B. Afeyan, Ph.D. and Edwin M. Kania, Jr. are the Managers of the GP. The GP, Dr. Afeyan and Mr. Kania may be deemed to possess voting and investment control over all shares held by Flagship Ventures Fund 2004, L.P. Each of the reporting persons disclaims beneficial ownership of the shares except to the extent of his or its pecuniary interest therein. These shares were convertible into the Issuer's common stock in accordance with the Issuer's Restated Certificate of Incorporation, as amended, at any time after the issuance of such shares, at the holder's election. Not applicable. FLAGSHIP VENTURES FUND 2004, L.P. By: Flagship Ventures General Partner LLC By: /s/ Noubar B. Afeyan, Ph.D., Manager 2017-12-11 FLAGSHIP VENTURES GENERAL PARTNER LLC By: /s/ Noubar B. Afeyan, Ph.D., Manager 2017-12-11 /s/ Noubar B. Afeyan, Ph.D. 2017-12-11 /s/ Edwin M. Kania, Jr. 2017-12-11