Company: BL
Filing Date: 2025-03-27
Form Type: DEFA14A
Source: 0001666134-25-000013
Chunk: 0

Company: BLACKLINE, INC.
Filing Date: 2025-03-27
Form: DEFA14A
Chunk 0
---
### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549

#### SCHEDULE 14A

#### PROXY STATEMENT PURSUANT TO SECTION 14(a) OF THE

#### SECURITIES EXCHANGE ACT OF 1934
| Filed by the Registrant☒                    |     |                                                                                 |
| Filed by a Party other than the Registrant☐ |     |                                                                                 |
| Check the appropriate box:                  |     |                                                                                 |
| ☐                                           |     | Preliminary Proxy Statement                                                     |
| ☐                                           |     | Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) |
| ☐                                           |     | Definitive Proxy Statement                                                      |
| ☒                                           |     | Definitive Additional Materials                                                 |
| ☐                                           |     | Soliciting Material Under §240.14a-12                                           |

| BLACKLINE, INC.                                                          |
| (Name of Registrant as Specified In Its Charter)                         |
| (Name of Person(s) Filing Proxy Statement, if other than the Registrant) |

| Payment of Filing Fee (Check all boxes that apply): |     |                                                                                                     |
| ☒                                                   |     | No fee required                                                                                     |
| ☐                                                   |     | Fee paid previously with preliminary materials                                                      |
| ☐                                                   |     | Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11 |

Your Vote Counts! *Please check the meeting materials for any special requirements for meeting attendance. Smartphone users Point your camera here and vote without entering a control number For complete information and to vote, visit www.ProxyVote.com Control 

# V66469-P26887 BLACKLINE, INC. 21300 VICTORY BLVD, 12TH FLOOR WOODLAND HILLS, CA 91367 BLACKLINE, INC. 2025 Annual Meeting Vote by May 7, 2025 11:59 p.m. ET You invested in BLACKLINE, INC. and it’s time to vote! You have the right to vote on proposals being presented at the Annual Meeting. This is an important notice regarding the availability of proxy materials for the shareholder meeting to be held on May 8, 2025. Vote Virtually at the Meeting* May 8, 2025 9:00 a.m. PT Virtually