X0508 4 2024-03-25 0 0001394056 ONE STOP SYSTEMS, INC. OSS 0001729652 Ison James 2235 ENTERPRISE STREET #110 ESCONDIDO CA 92029 0 1 0 0 CPO 0 Common Stock 2024-03-25 4 F 0 9677 3.90 D 87490 D Common Stock 2024-03-25 4 G 0 15656 0.00 D 71834 D Common Stock 2024-03-25 4 G 0 15656 0.00 A 190883 I By Trust The Reporting Person forfeited 9,677 shares of common stock upon conversion of 25,333 vested and outstanding restricted stock units into shares of common stock to cover tax withholdings, using the market price of the Issuer's common stock at the time of forfeiture. These restricted stock units were part of the grant reported in Table I of the Form 4 filed by the Reporting Person with the Securities and Exchange Commission on March 20, 2023. Includes 71,834 unvested restricted stock units held by the Reporting Person, all of which remain subject to certain vesting conditions. On March 25, 2024, the Reporting Person transferred 15,656 shares of common stock to the James J. Ison Jr. & Sha-Marie A Ison TR UA 06 04 2020 James J. Ison Jr. & Sha-Marie A Ison Inter Vivos Revocable Trust (the "Trust"), of which the Reporting Person is trustee. The Reporting Person and members of his immediate family are the sole beneficiaries of the Trust. These shares are owned directly by the Trust, and indirectly by James Ison as trustee of the Trust. /s/ James Ison 2024-03-27