X0508 4 2025-12-16 0001889956 OneStream, Inc. OS 0002031265 Hohenstein Ken C/O ONESTREAM, INC. 191 N. CHESTER STREET BIRMINGHAM MI 48009 false true false false Chief Revenue Officer 1 Class A Common Stock 2025-12-16 4 M 0 40000 10.65 A 1030961 D Class A Common Stock 2025-12-16 4 S 0 40000 17.21 D 990961 D Class A Common Stock 790279 I See Footnote Stock Option (right to buy) 10.65 2025-12-16 4 M 0 10000 0 D 2033-03-05 Class A Common Stock 10000 178508 D Stock Option (right to buy) 10.65 2025-12-16 4 M 0 30000 0 D 2031-12-04 Class A Common Stock 30000 69210 D The shares reported include unvested restricted stock units. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 13, 2024. Represents the weighted average share price of an aggregate total of 40,000 shares sold in the price range of $16.91 to $17.65, inclusive, by the Reporting Person. The Reporting Person undertakes to provide upon request by the staff of the Securities and Exchange Commission, the issuer or any security holder of the issuer, full information regarding the number of shares sold at each separate price within the range set forth in this footnote in this Form 4. Shares held by the Hohenstein Purple Elephant 2019 Irrevocable Grantor Trust (the "Hohenstein Purple Elephant Trust"). The Reporting Person may be deemed to have voting and dispositive power over the shares held by the Hohenstein Purple Elephant Trust. One-fourth of the shares subject to the option vested on February 15, 2024, and 1/48th of the shares subject to the option shall vest each month thereafter, subject to the Reporting Person continuing to be a service provider through the applicable vesting date. One-fourth of the shares subject to the option vested on February 15, 2023, and 1/48th of the shares subject to the option shall vest each month thereafter, subject to the Reporting Person continuing to be a service provider through the applicable vesting date. /s/ Holly Koczot, attorney-in-fact 2025-12-18