SCHEDULE 13G/A 0000950170-24-125753 0002027404 XXXXXXXX LIVE 1 Class A common stock, $0.0001 par value per share 03/31/2025 0001889956 ONESTREAM, INC. 68278B107 191 N. Chester Street Birmingham MI 48009 Rule 13d-1(d) Craig Colby b X1 9128763.00 0.00 9128763.00 0.00 9128763.00 10.9 IN ONESTREAM, INC. 191 N. Chester Street, Birmingham, MI, 48009. This statement is filed by Craig Colby, also referred to herein as the "Reporting Person." c/o OneStream, Inc. 191 N. Chester Street Birmingham, Michigan 48009 See response in Row 4 on the cover page. Y See response in Row 9 on the cover page hereto. See response in Row 11 on the cover page hereto. Based on the quotient obtained by dividing (a) the aggregate amount beneficially owned by Mr. Colby as set forth in Row 9 on the cover page hereto by (b) the sum of (i) 75,209,102 shares of Class A common stock, par value $0.0001 per share ("Class A Common Stock"), outstanding as of March 31, 2025; (ii) 6,894,697 shares of Class D common stock, par value $0.0001 per share ("Class D Common Stock"); (iii) 1,675,503 shares of Class D Common Stock beneficially owned by Mr. Colby; and (iv) 383,438 shares of Class A Common Stock subject to options that were vested and exercisable within 60 days of March 31, 2025. The aggregate number of shares of Class D Common Stock beneficially owned by Mr. Colby, as set forth in clauses (ii) and (iii) of this note are treated as converted into Class A Common Stock only for the purpose of computing the percentage ownership of Mr. Colby. See response in Row 5 on the cover page hereto. Such response represents (i) 175,125 shares of Class A Common Stock held by CCICU Corp., of which Mr. Colby is the sole owner and maintains control; (ii) 6,894,697 shares of Class D Common Stock held of record by Mr. Colby; (iii) 1,675,503 shares of Class D Common Stock held by the Trust for Jake A. Colby and Descendants dated December 28, 2019, of which Mr. Colby serves as the investment trustee; and (iv) 383,438 shares of Class A Common Stock subject to options that were vested and exercisable within 60 days of March 31, 2025. Such response assumes conversion of Class D Common Stock beneficially owned by Mr. Colby into Class A Common Stock. Each share of Class D Common Stock is convertible at any time at the option of the holder into one share of Class A Common Stock. In addition, each share of Class D Common Stock will convert automatically into one share of Class A Common Stock upon the earlier of (i) any transfer, whether or not for value, except for certain transfers exempted by the Issuer's amended and restated certificate of incorporation, (ii) death or incapacity (if the holder is a natural person), and (iii) the first trading day following the seventh anniversary of the Issuer's initial public offering. See response in Row 6 on the cover page hereto. See response in Row 7 on the cover page hereto. See response in Row 8 on the cover page hereto. Y Y Y Y Y Y Craig Colby /s/ Craig Colby 05/14/2025