Here are the 10-K annual reports from ESS Tech, Inc. (GWH) in our archive since June 2025, newest first, and each one links through to the document itself with the summary and the scores our analysis gives it.
A 10-K covers the audited annual report, with the full financial statements, so if you follow GWH and want that one kind of document rather than the whole filing history, this is the page to keep. The company's other filings, of every form, are on the full GWH filings page.
ESS Tech, Inc. is an early-stage long-duration energy storage company focused on iron flow batteries for grid and commercial applications. Its technology uses earth-abundant materials, targets up to 20,000 cycles without capacity fade, and is designed for safe, long-duration use in harsh temperatures.
The company remains deeply unprofitable. Revenue fell to $1.6 million in 2025 from $6.3 million in 2024, while net losses were $63.4 million in 2025 and $86.2 million in 2024, leading to an accumulated deficit of $845.8 million. Cash and cash equivalents plus short-term investments were $22.0 million as of December 31, 2025, and management discloses substantial doubt about ESS’s ability to continue as a going concern.
ESS highlights significant risks: early commercialization, manufacturing scale-up challenges, supply chain disruptions, strong competition from lithium-ion and other storage technologies, dependence on government incentives, and the need to raise additional capital. As of mid-2025, non‑affiliate equity market value was about $13.6 million, with 27,173,757 shares outstanding as of February 27, 2026.