X0206 3 2018-05-23 0 0001727196 Scholar Rock Holding Corp SRRK 0001605598 ARCH Venture Fund VIII, L.P. 8755 WEST HIGGINS ROAD, SUITE 1025 CHICAGO IL 60631 0 0 1 0 0001616165 ARCH Venture Partners VIII, LLC 8755 WEST HIGGINS ROAD, SUITE 1025 CHICAGO IL 60631 0 0 1 0 0001219039 CRANDELL KEITH 8755 WEST HIGGINS ROAD, SUITE 1025 CHICAGO IL 60631 0 0 1 0 0001219043 BYBEE CLINTON 8755 WEST HIGGINS ROAD, SUITE 1025 CHICAGO IL 60631 0 0 1 0 0001219042 NELSEN ROBERT 8755 WEST HIGGINS ROAD, SUITE 1025 CHICAGO IL 60631 0 0 1 0 0001616176 ARCH Venture Partners VIII, L.P. 8755 WEST HIGGINS ROAD, SUITE 1025 CHICAGO IL 60631 0 0 1 0 Series A-2 Preferred Common Stock 437859 I By ARCH Venture Fund VIII, L.P. Series A-3 Preferred Common Stock 634579 I By ARCH Venture Fund VIII, L.P. Series A-4 Preferred Common Stock 551807 I By ARCH Venture Fund VIII, L.P. Series B Preferred Common Stock 719559 I By ARCH Venture Fund VIII, L.P. Series C Preferred Common Stock 293813 I By ARCH Venture Fund VIII, L.P. Each share of Preferred Stock is convertible on a 2.8548-for-1 basis into Common Stock at any time at the election of ARCH Venture Fund VIII, L.P. ("ARCH Fund VIII") and will automatically convert upon the closing of the Issuer's initial public offering into the number of shares of the Issuer's Common Stock shown in column 3 without payment or further consideration. The reportable securities are owned directly by ARCH Fund VIII. The sole general partner of ARCH Fund VIII is ARCH Venture Partners VIII, L.P. or ARCH Partners VIII, which may be deemed to beneficially own the shares held by ARCH Fund VIII. The sole general partner of ARCH Partners VIII is ARCH Venture Partners VIII, LLC or ARCH VIII LLC, which may be deemed to beneficially own the shares held by ARCH Fund VIII. ARCH Partners VIII and ARCH VIII LLC disclaim beneficial ownership of such shares, except to the extent of any pecuniary interest therein. The managing directors of ARCH VIII LLC are Keith L. Crandell, Clinton Bybee and Robert Nelsen, and they may be deemed to beneficially own the shares held by ARCH Fund VIII. Messrs. Crandell, Bybee and Nelsen disclaim beneficial ownership of such shares, except to the extent of any pecuniary interest therein. ARCH Venture Fund VIII, L.P. By: ARCH Venture Partners VIII, L.P., its General Partner By: ARCH Venture Partners VIII, LLC, its General Partner By: /s/ Mark McDonnell, as Attorney-in-Fact for Keith Crandell, Managing Director 2018-05-23 ARCH Venture Partners VIII, L.P. By: ARCH Venture Partners VIII, LLC, its General Partner By: /s/ Mark McDonnell, as Attorney-in-Fact for Keith Crandell, Managing Director 2018-05-23 ARCH Venture Partners VIII, LLC By: /s/ Mark McDonnell, as Attorney-in-Fact for Keith Crandell, Managing Director 2018-05-23 Keith Crandell, Managing Director By: /s/ Mark McDonnell, as Attorney-in-Fact 2018-05-23 Clinton Bybee, Managing Director By: /s/ Mark McDonnell, as Attorney-in-Fact 2018-05-23 Robert Nelsen, Managing Director By: /s/ Mark McDonnell, as Attorney-in-Fact 2018-05-23