Sec Form 4 Filing - Rho Ventures III Holdings LLC @ ON24 INC. - 2021-02-05

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Rho Ventures III Holdings LLC 2. Issuer Name and Ticker or Trading Symbol ON24 INC. [ ONTF] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O RHO CAPITAL PARTNERS, 152 WEST 57TH STREET, 23RD FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 02/05/2021 (Street) NEW YORK, NY10019 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 02/05/2021 C 3,932,859 A 3,932,859 I See Footnote ( 2 ) Common Stock 02/05/2021 S 294,965 D $ 50 3,637,894 I See Footnote ( 2 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Class A-1 Convertible Preferred Stock ( 1 ) 02/05/2021 C 567,991 ( 1 ) ( 1 ) Common Stock 567,991 $ 0 0 I See Footnote ( 2 ) Class A-2 Convertible Preferred Stock ( 1 ) 02/05/2021 C 3,364,868 ( 1 ) ( 1 ) Common Stock 3,364,868 $ 0 0 I See Footnote ( 2 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Rho Ventures III Holdings LLC C/O RHO CAPITAL PARTNERS 152 WEST 57TH STREET, 23RD FLOOR NEW YORK, NY10019 X Rho Capital Partners LLC 152 WEST 57TH STREET, 23RD FLOOR NEW YORK, NY10019 X KAIROUZ HABIB 152 WEST 57TH STREET, 23RD FLOOR NEW YORK, NY10019 X LESCHLY MARK 152 WEST 57TH STREET, 23RD FLOOR NEW YORK, NY10019 X RUCH JOSHUA 152 WEST 57TH STREET, 23RD FLOOR NEW YORK, NY10019 X Signatures /S/ Habib Kairouz 02/08/2021 Signature of Reporting Person Date s/ Habib Kairouz 02/08/2021 Signature of Reporting Person Date /s/ Habib Kairouz 02/08/2021 Signature of Reporting Person Date / s/ Mark Leschly 02/08/2021 Signature of Reporting Person Date s/ Joshua Ruch 02/08/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )All of the shares of convertible preferred stock automatically converted into shares of the Issuer's common stock on a 1-for-1 basis upon the closing of the Issuer's initial public offering. The convertible preferred stock had no expiration date. ( 2 )These securities are owned directly by Rho Ventures III Holdings LLC ("RV III"). Rho Capital Partners LLC ("RCP") is the managing member of RV III, and each of Mark Leschly, Habib Kairouz and Joshua Ruch are managing members of RCP and exercise shared voting and investment power with respect to the shares owned by RV III. Each of the reporting persons disclaims beneficial ownership of such securities, except to the extent of his or its respective pecuniary interest therein.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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