ESS Tech, Inc. (NYSE: GWH) ("ESS" or the "company"), a leading provider of non-lithium energy storage solutions, has been added as a member of the Russell Microcap® Index, which was effective upon U.S. market openings on June 29, as part of the first 2026 Russell indexes reconstitution. Inclusion in the Russell Microcap® Index further validates ESS’ strategic focus on addressing rapidly expanding demand for safe, non-lithium energy storage solutions.