Sec Form 4 Filing - ARCH Venture Fund VIII, L.P. @ Scholar Rock Holding Corp - 2018-05-29

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person ARCH Venture Fund VIII, L.P. 2. Issuer Name and Ticker or Trading Symbol Scholar Rock Holding Corp [ SRRK] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 8755 WEST HIGGINS ROAD, SUITE 1025 3. Date of Earliest Transaction (MM/DD/YY) 05/29/2018 (Street) CHICAGO, IL60631 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 05/29/2018 C 437,859 A 437,859 I By ARCH Venture Fund VIII, L.P. ( 2 ) Common Stock 05/29/2018 C 634,579 A 1,072,438 I By ARCH Venture Fund VIII, L.P. ( 2 ) Common Stock 05/29/2018 C 551,807 A 1,624,245 I By ARCH Venture Fund VIII, L.P. ( 2 ) Common Stock 05/29/2018 C 719,559 A 2,343,804 I By ARCH Venture Fund VIII, L.P. ( 2 ) Common Stock 05/29/2018 C 293,813 A 2,637,617 I By ARCH Venture Fund VIII, L.P. ( 2 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Series A-2 Preferred ( 1 ) 05/29/2018 C 1,249,999 ( 1 ) ( 1 ) Common Stock 437,859 ( 1 ) 0 I By ARCH Venture Fund VIII, L.P. ( 2 ) Series A-3 Preferred ( 1 ) 05/29/2018 C 1,811,595 ( 1 ) ( 1 ) Common Stock 634,579 ( 1 ) 0 I By ARCH Venture Fund VIII, L.P. ( 2 ) Series A-4 Preferred ( 1 ) 05/29/2018 C 1,575,299 ( 1 ) ( 1 ) Common Stock 551,807 ( 1 ) 0 I By ARCH Venture Fund VIII, L.P. ( 2 ) Series B Preferred ( 1 ) 05/29/2018 C 2,054,197 ( 1 ) ( 1 ) Common Stock 719,559 ( 1 ) 0 I By ARCH Venture Fund VIII, L.P. ( 2 ) Series C Preferred ( 1 ) 05/29/2018 C 838,780 ( 1 ) ( 1 ) Common Stock 293,813 ( 1 ) 0 I By ARCH Venture Fund VIII, L.P. ( 2 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other ARCH Venture Fund VIII, L.P. 8755 WEST HIGGINS ROAD, SUITE 1025 CHICAGO, IL60631 X ARCH Venture Partners VIII, LLC 8755 WEST HIGGINS ROAD, SUITE 1025 CHICAGO, IL60631 X CRANDELL KEITH 8755 WEST HIGGINS ROAD, SUITE 1025 CHICAGO, IL60631 X BYBEE CLINTON 8755 WEST HIGGINS ROAD, SUITE 1025 CHICAGO, IL60631 X NELSEN ROBERT 8755 WEST HIGGINS ROAD, SUITE 1025 CHICAGO, IL60631 X ARCH Venture Partners VIII, L.P. 8755 WEST HIGGINS ROAD, SUITE 1025 CHICAGO, IL60631 X Signatures 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 05/31/2018 Signature of Reporting Person Date 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 05/31/2018 Signature of Reporting Person Date ARCH Venture Partners VIII, LLC By: /s/ Mark McDonnell, as Attorney-in-Fact for Keith Crandell, Managing Director 05/31/2018 Signature of Reporting Person Date Keith Crandell, Managing Director By: /s/ Mark McDonnell, as Attorney-in-Fact 05/31/2018 Signature of Reporting Person Date Clinton Bybee, Managing Director By: /s/ Mark McDonnell, as Attorney-in-Fact 05/31/2018 Signature of Reporting Person Date Robert Nelsen, Managing Director By: /s/ Mark McDonnell, as Attorney-in-Fact 05/31/2018 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis at the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date. ( 2 )The reportable securities are owned directly by ARCH Venture Fund VIII, L.P. ("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.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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