X0609 4 2026-08-07 0001394056 ONE STOP SYSTEMS, INC. OSS 0001755059 KNOWLES MICHAEL false 2235 ENTERPRISE STREET, SUITE 110 ESCONDIDO CA 92029 true true false false Chief Executive Officer false Common Stock 2026-08-07 4 F false 8621 13.32 D 598762 D Common Stock 2026-08-15 4 F false 8621 13.61 D 590141 D The Reporting Person forfeited 8,621 shares of common stock upon conversion of an aggregate 21,908 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 February 7, 2025. Includes 311,403 unvested restricted stock units held by the Reporting Person, all of which remain subject to certain vesting conditions. The Reporting Person forfeited 8,621 shares of common stock upon conversion of an aggregate 21,908 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 July 1, 2024. Includes 289,495 unvested restricted stock units held by the Reporting Person, all of which remain subject to certain vesting conditions. /s/ Michael Knowles 2026-09-04