ESS Tech, Inc.

ESS Tech, Inc. completed its de-SPAC merger with ACON S2 Acquisition Corp, which traded under the ticker STWO and was sponsored by ACON Investments, in 2021. The transaction brought ESS Tech into the public markets as a long-duration energy storage company focused on iron flow battery technology for grid-scale applications, placing it squarely within the clean energy and industrial energy storage sector. The company filed an 8-K current report with the SEC on October 14, 2025, reflecting ongoing public-company disclosure obligations in the post-merger period. Sign up at SpacDesk for full filing history, sponsor data, and deal analytics on ESS Tech and hundreds of other SPAC transactions.