ESS Tech, Inc.

ESS Tech, Inc. (NYSE: GWH) is a manufacturer of iron flow battery systems for long-duration, grid-scale energy storage that completed its de-SPAC business combination with ACON S2 Acquisition Corp. — sponsored by ACON S2 Acquisition Management, LLC, an affiliate of ACON Investments — in October 2021. The Portland, Oregon-based company operates in the clean energy and industrial technology sector and filed an 8-K current report with the SEC on May 29, 2026. ESS Tech has navigated a challenging post-merger operating environment that has been broadly characteristic of de-SPAC clean energy issuers in the years following the 2021 SPAC wave. Sign up on SpacDesk for full data, filings, and event-driven alerts on GWH and the wider SPAC universe.