---
schema_version: "secwatch.filing_event.v1"
accession: "0001628280-26-003973"
form_type: "8-K"
ticker: "GWH"
cik: "0001819438"
company_name: "ESS Tech, Inc."
filed_at: "2026-01-29T23:59:59+00:00"
generated_at: "2026-05-16T06:31:30.976889+00:00"
event_type: "earnings"
sentiment: "negative"
materiality_score: 0.6
calibrated_materiality_score: 0.6
confidence: "high"
source: SEC EDGAR
---

# ESS Tech prelim FY2025 rev $1.6M, op loss $55M; CEO Buckley added to board

## Summary
- Cash, equivalents, and short-term investments ~$22M at Dec 31, 2025, up $18.5M from Sep 30, 2025.
- Revenue ~$1.6M, down $4.7M YoY due to wind-down of legacy contracts amid shift to Energy Base.
- Operating loss ~$55M, improvement of $34.8M YoY reflecting ongoing cost discipline.
- Repaid $24.4M (81%) of $30M promissory note; $5.6M outstanding; second tranche of $10M available until Feb 28, 2026.
- CEO Drew Buckley elected to board (Class I), effective Jan 23, 2026; board size increased to eight.

## SEC filing metadata
- accession: 0001628280-26-003973
- form_type: 8-K
- ticker: GWH
- cik: 0001819438
- company_name: ESS Tech, Inc.
- filed_at: 2026-01-29T23:59:59+00:00
- event_type: earnings
- sentiment: negative
- materiality_score: 0.6
- calibrated_materiality_score: 0.6
- confidence: high
- sec_items: 2.02, 5.02, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1819438/000162828026003973/0001628280-26-003973-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1819438/000162828026003973/gwh-20260123.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001628280-26-003973
- JSON: https://secwatch.observer/filing/0001628280-26-003973.json
- Plain text: https://secwatch.observer/filing/0001628280-26-003973.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.