X0306 4 2021-01-04 false 0001503274 Quanterix Corp QTRX 0001219039 CRANDELL KEITH 8755 WEST HIGGINS ROAD, SUITE 1025 CHICAGO IL 60631 true false true false Common Stock 2021-04-01 4 A false 211.00 61.45 A 14637.00 D Common Stock 1905481.00 I See Footnote Common Stock 1214770.00 I See Footnote Consists of stock granted in lieu of cash fees for service on the Company's Board of Directors and committees thereof for the first quarter of 2021. Closing price of the Company's common stock on the Nasdaq Global Market on April 1, 2021. Includes 2,270 restricted stock units. These shares are directly held by ARCH Venture Fund VI, L.P. ("ARCH VI"). ARCH Venture Partners VI, L.P. ("GPLP"), the sole general partner of ARCH VI, may be deemed to beneficially own the shares held by ARCH VI. ARCH Venture Partners VI, LLC ("GPLLC"), as the sole general partner of GPLP, may be deemed to beneficially own the shares held by ARCH VI. The Reporting Person is a managing director of the GPLLC and shares voting and investment control with respect to these shares. The Reporting Person may be deemed to beneficially own the shares held by ARCH VI. The Reporting Person disclaims beneficial ownership of the securities reported herein, except to the extent of his pecuniary interest therein, if any. These shares are directly held by ARCH Venture Fund VIII Overage, L.P. ("ARCH Overage"). ARCH Venture Partners VIII, LLC ("ARCH VIII LLC") the sole general partner of ARCH Overage, may be deemed to beneficially own the shares held by ARCH Overage. The Reporting Person is a managing director of the ARCH VIII LLC and shares voting and investment control with respect to these shares. The Reporting Person may be deemed to beneficially own the shares held by ARCH Overage. The Reporting Person disclaims beneficial ownership of the securities reported herein, except to the extent of his pecuniary interest therein, if any. /s/ Brian Keane, as Attorney-in-Fact for Keith L. Crandell 2021-04-02