X0508 4 2026-02-13 0001819438 ESS Tech, Inc. GWH 0002083724 Suhadolnik Kate Eileen C/O ESS TECH, INC. 26440 SW PARKWAY AVE., BLDG. 83 WILSONVILLE OR 97070 false true false false Chief Financial Officer 0 Common Stock 2026-02-13 4 A 0 137500 0 A 165155 D Stock Option (right to buy) 1.44 2026-02-13 4 A 0 137500 0 A 2036-02-13 Common Stock 137500 137500 D The reported shares are represented by restricted stock units ("RSUs"), which vest as to 1/16th of the RSUs on May 20, 2026 and 1/16th of the RSUs shall vest quarterly thereafter, subject to the Reporting Person remaining a Service Provider to the Issuer through each such vest date. A portion of these securities are RSUs. Each RSU represents a contingent right to receive one share of the Issuer's Common Stock. 1/16th of the shares subject to the option shall vest on May 20, 2026 and 1/16th of the shares subject to the option shall vest quarterly thereafter, subject to the Reporting Person remaining a Service Provider to the issuer through each such vest date. /s/ Kate Suhadolnik 2026-02-26