Sec Form 4 Filing - ICONIQ Strategic Partners, L.P. @ BLACKLINE, INC. - 2017-12-07

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 ICONIQ Strategic Partners, L.P. 2. Issuer Name and Ticker or Trading Symbol BLACKLINE, INC. [ BL] 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 ICONIQ STRATEGIC PARTNERS, 394 PACIFIC AVENUE, 2ND FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 12/07/2017 (Street) SAN FRANCISCO, CA94111 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 12/07/2017 S 878,973 ( 1 ) D $ 34.07 ( 2 ) 4,161,131 D ( 3 ) ( 7 ) ( 8 ) Common Stock 12/07/2017 S 220,605 ( 1 ) D $ 34.07 ( 2 ) 1,044,360 D ( 4 ) ( 7 ) ( 8 ) Common Stock 12/07/2017 S 276,103 ( 1 ) D $ 34.07 ( 2 ) 1,307,091 D ( 5 ) ( 7 ) ( 8 ) Common Stock 12/07/2017 S 39,838 ( 1 ) D $ 34.07 ( 2 ) 188,594 D ( 6 ) ( 7 ) ( 8 ) Common Stock 6,701,176 I ( 9 ) See Footnote ( 9 ) Common Stock 17,087 D ( 10 )

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

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other ICONIQ Strategic Partners, L.P. C/O ICONIQ STRATEGIC PARTNERS 394 PACIFIC AVENUE, 2ND FLOOR SAN FRANCISCO, CA94111 X ICONIQ Strategic Partners-B, L.P. C/O ICONIQ STRATEGIC PARTNERS 394 PACIFIC AVENUE, 2ND FLOOR SAN FRANCISCO, CA94111 X ICONIQ Strategic Partners Co-Invest, L.P., BL Series C/O ICONIQ STRATEGIC PARTNERS 394 PACIFIC AVENUE, 2ND FLOOR SAN FRANCISCO, CA94111 X ICONIQ Strategic Partners Co-Invest, L.P., Series BL2 C/O ICONIQ STRATEGIC PARTNERS 394 PACIFIC AVENUE, 2ND FLOOR SAN FRANCISCO, CA94111 X ICONIQ Strategic Partners GP, L.P. C/O ICONIQ STRATEGIC PARTNERS 394 PACIFIC AVENUE, 2ND FLOOR SAN FRANCISCO, CA94111 X ICONIQ Strategic Partners TT GP, Ltd. C/O ICONIQ STRATEGIC PARTNERS 394 PACIFIC AVENUE, 2ND FLOOR SAN FRANCISCO, CA94111 X Makan Divesh C/O ICONIQ STRATEGIC PARTNERS 394 PACIFIC AVENUE, 2ND FLOOR SAN FRANCISCO, CA94111 X Signatures ICONIQ Strategic Partners, L.P., by ICONIQ Strategic Partners GP, L.P., its general partner, by ICONIQ Strategic Partners TT GP, Ltd., its general partner, by Kevin Foster, its Senior Vice President, /s/ Kevin Foster 12/08/2017 Signature of Reporting Person Date ICONIQ Strategic Partners-B, L.P., by ICONIQ Strategic Partners GP, L.P., its general partner, by ICONIQ Strategic Partners TT GP, Ltd., its general partner, by Kevin Foster, its Senior Vice President, /s/ Kevin Foster 12/08/2017 Signature of Reporting Person Date ICONIQ Strategic Partners Co-Invest, L.P., BL Series, by ICONIQ Strategic Partners GP, L.P., its general partner, by ICONIQ Strategic Partners TT GP, Ltd., its general partner, by Kevin Foster, its Senior Vice President, /s/ Kevin Foster 12/08/2017 Signature of Reporting Person Date ICONIQ Strategic Partners Co-Invest, L.P., BL2 Series, by ICONIQ Strategic Partners GP, L.P., its general partner, by ICONIQ Strategic Partners TT GP, Ltd., its general partner, by Kevin Foster, its Senior Vice President, /s/ Kevin Foster 12/08/2017 Signature of Reporting Person Date ICONIQ Strategic Partners GP, L.P., by ICONIQ Strategic Partners TT GP, Ltd., its general partner, by Kevin Foster, its Senior Vice President, /s/ Kevin Foster 12/08/2017 Signature of Reporting Person Date ICONIQ Strategic Partners TT GP, Ltd., by Kevin Foster, its Senior Vice President, /s/ Kevin Foster 12/08/2017 Signature of Reporting Person Date Divesh Makan, /s/ Divesh Makan 12/08/2017 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents shares of BlackLine, Inc.'s (the "Issuer") Common Stock sold in an underwritten secondary offering. ( 2 )Represents the sale price to the underwriters in the secondary offering of $34.07 per share. ( 3 )ICONIQ Strategic Partners, L.P. ("ICONIQ") is the direct owner of these securities. ( 4 )ICONIQ Strategic Partners-B, L.P. ("ICONIQ B") is the direct owner of these securities. ( 5 )ICONIQ Strategic Partners Co-Invest, L.P., BL Series ("ICONIQ BL") is the direct owner of these securities. ( 6 )ICONIQ Strategic Partners Co-Invest, L.P., BL2 Series ("ICONIQ BL2") is the direct owner of these securities. ( 7 )Iconiq Strategic Partners GP, L.P. ("ICONIQ GP") is the sole general partner of each of ICONIQ, ICONIQ B, ICONIQ BL and ICONIQ BL2 (collectively, the "Funds"). ICONIQ Strategic Partners TT GP, Ltd. (the "ICONIQ Parent GP") is the sole general partner of ICONIQ GP. Divesh Makan ("Makan") is an equity holder and director of ICONIQ Parent GP. ( 8 )Each of ICONIQ GP, ICONIQ Parent GP and Makan disclaims beneficial ownership of the securities reported herein for purposes of Section 16 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its or his pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Persons is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose. ( 9 )This number represents shares held by ICONIQ (4,161,131), ICONIQ B (1,044,360), ICONIQ BL (1,307,091), and ICONIQ BL2 (188,594) respectively. Each of ICONIQ GP, ICONIQ Parent GP and Makan disclaims beneficial ownership of the securities reported herein for purposes of Section 16 of the Exchange Act, except to the extent of its or his pecuniary interest therein, if any . This report shall not be deemed an admission that any of the Reporting Persons is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose. ( 10 )These shares are directly held by Makan through a family trust that he controls.

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

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