ESS Tech, Inc.

ESS Tech, Inc. (NYSE: GWH) is an Oregon-based manufacturer of iron flow battery systems designed for long-duration, grid-scale energy storage. The company completed its business combination with ACON S2 Acquisition Corp. (STWO) in October 2021, with the SPAC sponsored by ACON Investments LLC. ESS Tech entered the public markets under the clean energy infrastructure sector, targeting utility and commercial customers requiring multi-hour storage solutions that pair with renewable generation assets. The company filed an 8-K with the SEC on August 11, 2026 (accession 0001819438-26-000072), the full details of which are available in SpacDesk's filing tracker. For complete historical SPAC transaction data, sponsor disclosures, and real-time SEC filing alerts on GWH, sign up for full access at SpacDesk.