X0306 4 2019-06-03 0 0001666134 BLACKLINE, INC. BL 0001688366 Partin Mark 21300 VICTORY BLVD 12TH FLOOR WOODLAND HILLS CA 91367 0 1 0 0 Chief Financial Officer Common Stock 2019-06-03 4 M 0 9500 14.00 A 64640 D Common Stock 2019-06-03 4 S 0 8200 50.0221 D 56440 D Common Stock 2019-06-03 4 S 0 1300 51.3735 D 55140 D Common Stock 2019-06-04 4 M 0 500 14.00 A 55640 D Common Stock 2019-06-04 4 S 0 500 50.00 D 55140 D Common Stock (right to buy) 14.00 2019-06-03 4 M 0 9500 0.00 D 2025-03-29 Common Stock 9500 420676 D Common Stock (right to buy) 14.00 2019-06-04 4 M 0 500 0.00 D 2025-03-29 Common Stock 500 420176 D The sale transaction reported on this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on March 11, 2019. The sale price represents the weighted-average price of shares sold ranging from $50.00 to $50.105 per share. Upon request by the Commission staff, the Issuer or a security holder of the Issuer, the Reporting Person will provide full information regarding the number of shares sold at each separate price within the range set forth in this Form 4. The sale price represents the weighted-average price of shares sold ranging from $51.25 to $51.54 per share. Upon request by the Commission staff, the Issuer or a security holder of the Issuer, the Reporting Person will provide full information regarding the number of shares sold at each separate price within the range set forth in this Form 4. The shares subject to the option vest in 4 equal, annual installments beginning on the one year anniversary of January 20, 2015. /s/ Karole Morgan-Prager, Attorney-in-Fact 2019-06-05