X0306 4 2022-09-30 0 0000944480 GSE SYSTEMS INC GVP 0001850386 Horn Donald 6940 COLUMBIA GATEWAY DRIVE SUITE 470 COLUMBIA MD 21046 0 1 0 0 President, Engineering Svcs Common Stock 2022-09-30 4 F 0 1710 0.90 D 67358 D Shares withheld by the Issuer for payment of applicable taxes owed due to the vesting of 5,914 restricted share units pursuant to two restricted share unit agreements between the Reporting Person and the Issuer. /s/ Donald Horn 2022-10-04