X0607 3 2026-03-24 1 0001666134 BLACKLINE, INC. BL 0002124309 Prichard Megan false 21300 VICTORY BLVD., 12TH FLOOR WOODLAND HILLS CA 91367-7734 1 This Form 3 reports Ms. Prichard's appointment to the Issuer's board of directors on March 11, 2026. The filing was delayed due to a procedural delay in Ms. Prichard receiving the requisite EDGAR access codes from the SEC. This Form 3 was filed promptly upon receipt of the codes. /s/ Karole Morgan-Prager, Attorney-in-Fact 2026-03-26