Scott Leshinski - 01 Jan 2026 Form 3 Insider Report for OneStream, Inc. (OS)

Role: President
Signature: /s/ Holly Koczot, attorney-in-fact
Issuer symbol: OS
Transactions as of: 01 Jan 2026
Net transactions value: $0
Form type: 3
Filing time: 05 Jan 2026, 16:12:06 UTC
Next filing: 12 Mar 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Leshinski Scott	President	C/O ONESTREAM, INC., 191 N. CHESTER STREET, BIRMINGHAM	/s/ Holly Koczot, attorney-in-fact	05 Jan 2026	0002098850

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
holding	OS	Class A Common Stock						142,779	01 Jan 2026	Direct	F1

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
holding	OS	Stock Option (right to buy)							01 Jan 2026	Class A Common Stock	68,871	$10.65	Direct	F2
holding	OS	Stock Option (right to buy)							01 Jan 2026	Class A Common Stock	85,000	$10.65	Direct	F3
holding	OS	Stock Option (right to buy)							01 Jan 2026	Class A Common Stock	20,000	$12.71	Direct	F4
holding	OS	Stock Option (right to buy)							01 Jan 2026	Class A Common Stock	150,000	$14.51	Direct	F5
holding	OS	Stock Option (right to buy)							01 Jan 2026	Class A Common Stock	50,000	$16.40	Direct	F6

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	The shares reported include unvested restricted stock units.
F2	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.
F3	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.
F4	One-fourth of the shares subject to the option vested on October 1, 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.
F5	One-fourth of the shares subject to the option vested on February 15, 2025, 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.
F6	One-fourth of the shares subject to the option vested on May 1, 2025, 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.