Sec Form 4 Filing - Atlas Venture Associates VI, Inc. @ Carbon Black, Inc. - 2018-05-08

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 Atlas Venture Associates VI, Inc. 2. Issuer Name and Ticker or Trading Symbol Carbon Black, Inc. [ CBLK] 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) C/O ACCOMPLICE, 25 FIRST STREET, SUITE 303 3. Date of Earliest Transaction (MM/DD/YY) 05/08/2018 (Street) CAMBRIDGE, MA02141 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 05/08/2018 C 8,148,778 A 9,365,231 I By Atlas Venture Fund VI, L.P. ( 1 ) Common Stock 05/08/2018 C 249,193 A 286,392 I By Atlas Venture Entrepreneurs' Fund VI, L.P. ( 2 ) Common Stock 05/08/2018 C 149,207 A 171,480 I By Atlas Venture Fund VI GmbH & Co. KG ( 3 )

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 B Convertible Preferred Stock ( 4 ) 05/08/2018 C 7,398,761 ( 4 ) ( 4 ) Common Stock 3,699,380 ( 4 ) 0 I By Atlas Venture Fund VI, L.P. ( 1 ) Series B Convertible Preferred Stock ( 4 ) 05/08/2018 C 226,258 ( 4 ) ( 4 ) Common Stock 113,129 ( 4 ) 0 I By Atlas Venture Entrepreneurs' Fund VI, L.P. ( 2 ) Series B Convertible Preferred Stock ( 4 ) 05/08/2018 C 135,475 ( 4 ) ( 4 ) Common Stock 67,737 ( 4 ) 0 I By Atlas Venture Fund VI GmbH & Co. KG ( 3 ) Series C Convertible Preferred Stock ( 4 ) 05/08/2018 C 4,544,751 ( 4 ) ( 4 ) Common Stock 2,272,375 ( 4 ) 0 I By Atlas Venture Fund VI, L.P. ( 1 ) Series C Convertible Preferred Stock ( 4 ) 05/08/2018 C 138,981 ( 4 ) ( 4 ) Common Stock 69,490 ( 4 ) 0 I By Atlas Venture Entrepreneurs' Fund VI, L.P. ( 2 ) Series C Convertible Preferred Stock ( 4 ) 05/08/2018 C 83,217 ( 4 ) ( 4 ) Common Stock 41,608 ( 4 ) 0 I By Atlas Venture Fund VI GmbH & Co. KG ( 3 ) Series D Convertible Preferred Stock ( 4 ) 05/08/2018 C 1,263,264 ( 4 ) ( 4 ) Common Stock 631,632 ( 4 ) 0 I By Atlas Venture Fund VI, L.P. ( 1 ) Series D Convertible Preferred Stock ( 4 ) 05/08/2018 C 38,631 ( 4 ) ( 4 ) Common Stock 19,315 ( 4 ) 0 I By Atlas Venture Entrepreneurs' Fund VI, L.P. ( 2 ) Series D Convertible Preferred Stock ( 4 ) 05/08/2018 C 23,131 ( 4 ) ( 4 ) Common Stock 11,565 ( 4 ) 0 I By Atlas Venture Fund VI GmbH & Co. KG ( 3 ) Series E Convertible Preferred Stock ( 4 ) 05/08/2018 C 3,090,783 ( 4 ) ( 4 ) Common Stock 1,545,391 ( 4 ) 0 I By Atlas Venture Fund VI, L.P. ( 1 ) Series E Convertible Preferred Stock ( 4 ) 05/08/2018 C 94,518 ( 4 ) ( 4 ) Common Stock 47,259 ( 4 ) 0 I By Atlas Venture Entrepreneurs' Fund VI, L.P. ( 2 ) Series E Convertible Preferred Stock ( 4 ) 05/08/2018 C 56,594 ( 4 ) ( 4 ) Common Stock 28,297 ( 4 ) 0 I By Atlas Venture Fund VI GmbH & Co. KG ( 3 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Atlas Venture Associates VI, Inc. C/O ACCOMPLICE 25 FIRST STREET, SUITE 303 CAMBRIDGE, MA02141 X ATLAS VENTURE ENTREPRENEURS FUND VI LP C/O ACCOMPLICE 25 FIRST STREET, SUITE 303 CAMBRIDGE, MA02141 X Atlas Venture Associates VI, L.P. C/O ACCOMPLICE 25 FIRST STREET, SUITE 303 CAMBRIDGE, MA02141 X ATLAS VENTURE FUND VI LP C/O ACCOMPLICE 25 FIRST STREET, SUITE 303 CAMBRIDGE, MA02141 X Atlas Venture Fund VI GmbH & Co KG C/O ACCOMPLICE 25 FIRST STREET, SUITE 303 CAMBRIDGE, MA02141 X Signatures /s/ Frank Castellucci, Secretary of Atlas Venture Associates VI, Inc. 05/10/2018 Signature of Reporting Person Date /s/ Frank Castellucci, Secretary of Atlas Venture Associates VI, Inc., the general partner of Atlas Venture Associates VI, L.P. 05/10/2018 Signature of Reporting Person Date /s/ Frank Castellucci, Secretary of Atlas Venture Associates VI, Inc., the general partner of Atlas Venture Associates VI, L.P., the general partner of Atlas Venture Entrepreneurs' Fund VI, L.P. 05/10/2018 Signature of Reporting Person Date /s/ Frank Castellucci, Secretary of Atlas Venture Associates VI, Inc., the general partner of Atlas Venture Associates VI, L.P., the managing limited partner of Atlas Venture Fund VI GmbH & Co. KG 05/10/2018 Signature of Reporting Person Date /s/ Frank Castellucci, Secretary of Atlas Venture Associates VI, Inc., the general partner of Atlas Venture Associates VI, L.P., the general partner of Atlas Venture Fund VI, L.P. 05/10/2018 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The shares are held directly by Atlas Venture Fund VI, L.P. ("AVF VI"). Atlas Venture Associates VI, L.P. ("AVA VI LP") is the sole general partner of AVF VI. Atlas Venture Associates VI, Inc. ("AVA VI Inc.") is the sole general partner of AVA VI LP. Each of AVA VI LP and AVA VI Inc. disclaims Section 16 beneficial ownership of all shares except to the extent of its pecuniary interest, if any, therein. This report shall not be deemed to be an admission that the reporting persons are the beneficial owners of such securities for purposes of Section 16 or for any other purpose. ( 2 )The shares are held directly by Atlas Venture Entrepreneurs' Fund VI, L.P. ("AVEF VI"). AVA VI LP is the sole general partner of AVEF VI. AVA VI Inc. is the sole general partner of AVA VI LP. Each of AVA VI LP and AVA VI Inc. disclaims Section 16 beneficial ownership of all shares except to the extent of its pecuniary interest, if any, therein. This report shall not be deemed to be an admission that the reporting persons are the beneficial owners of such securities for purposes of Section 16 or for any other purpose. ( 3 )The shares are held directly by Atlas Venture Fund VI GmbH & Co. KG ("AVFG VI"). AVA VI LP is the managing partner of AVFG VI. AVA VI Inc. is the sole general partner of AVA VI LP. Each of AVA VI LP and AVA VI Inc. disclaims Section 16 beneficial ownership of all shares except to the extent of its pecuniary interest, if any, therein. This report shall not be deemed to be an admission that the reporting persons are the beneficial owners of such securities for purposes of Section 16 or for any other purpose. ( 4 )Each share of preferred stock automatically converted into Common Stock on a 1-for-2 basis upon the closing of the Issuer's initial public offering. The shares have no expiration date.

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).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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