X0202 SCHEDULE 13D/A 0000921895-22-003251 0001524362 XXXXXXXX LIVE 6 Common Stock, par value $0.0001 per share 04/01/2026 true 0001110611 68339B104 ON24 INC.

301 HOWARD STREET, SUITE 1100 SAN FRANCISCO CA 94105

Melody Lang 415-680-1030 Indaba Capital Management, L.P. One Letterman Drive, BLDG D, Suite DM700 San Francisco CA 94129 Ryan Nebel 212-451-2300 Olshan Frome Wolosky LLP 1325 Avenue of the Americas New York NY 10019 Dorothy Sluszka 212-451-2300 Olshan Frome Wolosky LLP 1325 Avenue of the Americas New York NY 10019 0001524362 N Indaba Capital Management, L.P. b N DE 0.00 0.00 0.00 0.00 0.00 N 0 IA PN 0001596505 N IC GP, LLC b N DE 0.00 0.00 0.00 0.00 0.00 N 0 HC OO 0001250078 N SCHRIER DEREK C b N X1 0.00 0.00 0.00 0.00 0.00 N 0 IN HC Common Stock, par value $0.0001 per share ON24 INC. 301 HOWARD STREET, SUITE 1100 SAN FRANCISCO CA 94105 The following constitutes Amendment No. 6 ("Amendment No. 6") to the Schedule 13D filed with the SEC by Indaba Capital Management, L.P. (the "Investment Manager"), IC GP, LLC ("IC GP") and Derek C. Schrier (collectively, "Indaba" or the "Reporting Persons") on December 20, 2022, as amended by Amendment No. 1 filed on March 13, 2023, Amendment No. 2 filed on January 18, 2024, Amendment No. 3 filed on February 26, 2024, Amendment No. 4 filed on March 19, 2025 and Amendment No. 5 filed on December 31, 2025. This Amendment No. 6 amends and restates the Schedule 13D as specifically set forth herein. All capitalized terms contained herein but not otherwise defined shall have the meanings ascribed to such terms in the Schedule 13D, as amended. Information given in response to each item shall be deemed incorporated by reference in all other items, as applicable. Item 3 of the Schedule 13D is hereby supplemented and restated as follows: The Reporting Persons no longer beneficially own any shares of common stock of the Issuer. Item 4 of the Schedule 13D is hereby supplemented as follows: Pursuant to the Agreement and Plan of Merger, dated as of December 29, 2025 (the "Merger Agreement"), among the Issuer, Cvent Atlanta, LLC ("Parent") and Summit Sub Corp. ("Merger Sub"), on April 1, 2026, Merger Sub merged with and into the Issuer, with the Issuer continuing as the surviving company and a wholly-owned subsidiary of Parent (the "Merger"). At the effective time of the Merger, each outstanding share of the Issuer's common stock, including each share beneficially owned by the Reporting Persons, was automatically canceled and converted into the right to receive cash in an amount equal to $8.10 per share, without interest. Item 5(a) of the Schedule 13D is hereby supplemented and restated as follows: As of the date hereof, the Reporting Persons no longer beneficially own any shares of common stock of the Issuer. Item 5(c) of the Schedule 13D is hereby supplemented and restated as follows: Except as otherwise reported herein, there have been no transactions in securities of the Issuer by the Reporting Persons during the past 60 days. At the effective time of the Merger, each outstanding share of the Issuer's common stock, including each share beneficially owned by the Reporting Persons, was automatically canceled and converted into the right to receive cash in an amount equal to $8.10 per share, without interest. Item 5(e) of the Schedule 13D is hereby supplemented and restated as follows: As of April 1, 2026, the Reporting Persons ceased to collectively beneficially own more than 5% of the shares of common stock of the Issuer. Indaba Capital Management, L.P. /s/ Derek C. Schrier 04/03/2026 IC GP, LLC /s/ Derek C. Schrier 04/03/2026 SCHRIER DEREK C /s/ Derek C. Schrier 04/03/2026