Michael R. Niggli - Oct 13, 2025 Form 4 Insider Report for ESS Tech, Inc. (GWH)

Role: Director
Signature: /s/ Kate Suhadolnik, by power of attorney
Stock symbol: GWH
Transactions as of: Oct 13, 2025
Transactions value $: $0
Form type: 4
Date filed: 10/15/2025, 04:51 PM
Previous filing: Sep 3, 2024
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
NIGGLI MICHAEL R	Director	C/O ESS TECH, INC., 26440 SW PARKWAY AVE., BLDG. 83, WILSONVILLE	/s/ Kate Suhadolnik, by power of attorney	2025-10-15	0001377160

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	GWH	Common Stock	Award	$0	+13.5K	+17.48%	$0.00	90.8K	Oct 13, 2025	Direct	F1

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	The reported shares are represented by restricted stock units ("RSUs") which vest on the earlier of (i) May 17, 2025 or (ii) the day prior to the next annual meeting of stockholders. The Reporting Person has elected to defer the settlement of these RSUs to a date within 30 days of the earlier of (i) his or her separation of service from the Issuer within the meaning of Section 409A of the Internal Revenue Code (Section 409A) or (ii) the date on which a change of control (as defined in the Issuer's plan) occurs, provided that such transaction qualifies as a change of control within the meaning of Section 409A.

Content

The reported shares are represented by restricted stock units ("RSUs") which vest on the earlier of (i) May 17, 2025 or (ii) the day prior to the next annual meeting of stockholders. The Reporting Person has elected to defer the settlement of these RSUs to a date within 30 days of the earlier of (i) his or her separation of service from the Issuer within the meaning of Section 409A of the Internal Revenue Code (Section 409A) or (ii) the date on which a change of control (as defined in the Issuer's plan) occurs, provided that such transaction qualifies as a change of control within the meaning of Section 409A.