X0306 4 2022-02-18 0 0001666134 BLACKLINE, INC. BL 0001688365 Tucker Therese 21300 VICTORY BLVD., 12TH FLOOR WOODLAND HILLS CA 91367 1 1 0 0 Executive Chair Common Stock 2022-02-18 4 F 0 7693 72.12 D 143571 D Common Stock 1509881 I Brian & Therese Tucker Living Trust Common Stock 100178 I Brian & Therese Tucker Charitable Remainder Trust Common Stock 100178 I Tucker Family CLAT Common Stock 874128 I Tucker Legacy Trust Common Stock 129897 I Tucker Legacy Trust II Common Stock 577200 I Isaac Tucker 2012 Irrevocable Trust Common Stock 577200 I Roseanna Tucker 2012 Irrevocable Trust Common Stock 250916 I Tucker Seimetz Safety Net Trust Common Stock 54074 I Claire Seimetz 2015 Trust The reported shares were withheld to cover the Reporting Person's tax liability in connection with the vesting of restricted stock units. /s/ Karole Morgan-Prager, Attorney-in-Fact 2022-02-22