# EDGAR Filing Document

**Accession Number:** 0001819438
**File Stem:** 0001819438-25-000079
**Filing Date:** 2025-12
**Character Count:** 13595
**Document Hash:** 37665333d59f55a5a0e4225d7472cffe
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001819438-25-000079.hdr.sgml**: 20251205

**ACCESSION NUMBER**: 0001819438-25-000079

**CONFORMED SUBMISSION TYPE**: 8-K

**PUBLIC DOCUMENT COUNT**: 14

**CONFORMED PERIOD OF REPORT**: 20251204

**ITEM INFORMATION**: Entry into a Material Definitive Agreement

**ITEM INFORMATION**: Financial Statements and Exhibits

**FILED AS OF DATE**: 20251205

**DATE AS OF CHANGE**: 20251205

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** ESS Tech, Inc.
- **CENTRAL INDEX KEY:** 0001819438
- **STANDARD INDUSTRIAL CLASSIFICATION:** MISCELLANEOUS ELECTRICAL MACHINERY, EQUIPMENT & SUPPLIES [3690]
- **ORGANIZATION NAME:** 04 Manufacturing
- **EIN:** 981550150
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 8-K
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-39525
- **FILM NUMBER:** 251553201

**BUSINESS ADDRESS:**
- **STREET 1:** 26440 SW PARKWAY AVE.
- **STREET 2:** BLDG. 83
- **CITY:** WILSONVILLE
- **STATE:** OR
- **ZIP:** 97070
- **BUSINESS PHONE:** (855) 423-9920

**MAIL ADDRESS:**
- **STREET 1:** 26440 SW PARKWAY AVE.
- **STREET 2:** BLDG. 83
- **CITY:** WILSONVILLE
- **STATE:** OR
- **ZIP:** 97070

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** ACON S2 Acquisition Corp.
- **DATE OF NAME CHANGE:** 20200728

?xml version='1.0' encoding='ASCII'? wk-20251204

**UNITED STATES**

**SECURITIES AND EXCHANGE COMMISSION**

**Washington, D.C. 20549**

**FORM 8-K**

**CURRENT REPORT**

**Pursuant to Section 13 or 15(d)**

**of the Securities Exchange Act of 1934**

**Date of report (Date of earliest event reported): December 4, 2025**

**ESS TECH, INC.**

**(Exact Name of Registrant as Specified in Charter)**

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| | | |
|:---|:---|:---|
| **Delaware** | **001-39525** | **98-1550150** |
| **(State or other jurisdiction**<br>**of incorporation)** | **(Commission**<br>**File Number)** | **(I.R.S. Employer**<br>**Identification Number)** |

---

---

| | |
|:---|:---|
| **26440 SW Parkway Ave., Bldg. 83**<br>**Wilsonville, Oregon** | **97070** |
| **(Address of principal executive offices)** | **(Zip code)** |

---

**(855) 423-9920**

**(Registrant's telephone number, including area code)**

**Not Applicable**

**(Former name or former address, if changed since last report)**

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the Registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

**Securities registered pursuant to Section 12(b) of the Act:**

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| | | |
|:---|:---|:---|
| **Title of each class** | **Trading**<br>**Symbol(s)** | **Name of each exchange**<br>**on which registered** |
| **Common Stock, $0.0001 par value per share** | **GWH** | **The New York Stock Exchange** |
| **Warrants, each whole warrant exercisable for one share of common stock at an exercise price of $11.50** | **GWH.W** | **The New York Stock Exchange** |

---

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2).

Emerging growth company ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

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**Item 1.01&nbsp;&nbsp;&nbsp;&nbsp; Entry into a Material Definitive Agreement.** 

On December 4, 2025, ESS Tech, Inc. (the "Company") and YA II PN, LTD., an investment fund managed by Yorkville Advisors Global, L.P. ("Yorkville"), entered into Amendment No. 2 (the "Note Amendment") to the promissory note, originally issued on October 14, 2025, and as amended on October 31, 2025 (the "First Note Amendment"), by and between the Company and Yorkville (the "Note"). Capitalized terms used but not otherwise defined herein shall have the meanings ascribed thereto in the Note. The Note Amendment revised the Second Tranche Date from December 12, 2025 to February 28, 2026, extending the deadline by which Yorkville shall pay the Company the second tranche of $10 million less the applicable discount. In addition, the Note Amendment provides that the principal amount outstanding under Tranche One must be equal to or less than $7,000,000 instead of $20,000,000 for the second tranche to be paid. For more information on the Note and the First Note Amendment, please refer to our Current Report on Form 8-K, filed with the Securities and Exchange Commission (the "SEC") on October 14, 2025, and our Quarterly Report on Form 10-Q, filed with the SEC on November 13, 2025.

The foregoing summary of the terms and conditions of the Note Amendment is qualified in its entirety by reference to the full text of the Note Amendment, a copy of which is filed as Exhibit 10.1 to this Current Report on Form 8-K and is incorporated herein by reference.

**Item 9.01 &nbsp;&nbsp;&nbsp;&nbsp;Financial Statements and Exhibits.** 

*(d)&nbsp;&nbsp;&nbsp;&nbsp;Exhibits.*

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| | |
|:---|:---|
| **Exhibit<br>No.** | |
| 10.1 | [Note Amendment, dated December 4, 2025](exhibit101-noteamendmentda.htm) |
| 104 | Cover Page Interactive Data File (embedded within the Inline XBRL document) |

---

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**SIGNATURE** 

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, hereunto duly authorized.

Dated: December 5, 2025

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| | |
|:---|:---|
| **ESS TECH, INC.** | **ESS TECH, INC.** |
| By: | /s/ Kate Suhadolnik |
| Name: | Kate Suhadolnik |
| Title: | Interim Chief Financial Officer |

---

## Exhibit 10.1

**ESS TECH, INC.**

**AMENDMENT NO. 2 TO PROMISSORY NOTE** 

This Amendment No. 2 to that certain Promissory Note (this "**Amendment**") is effective as of December 4, 2025 by and between ESS Tech, Inc., a Delaware corporation (the "**Company**") and YA II PN, LTD., a Cayman Islands exempt limited company, or its registered assigns (the "**Holder**"). Each such person is referred to herein as a "**Party**" and, collectively, such persons are referred to herein as the "**Parties**."

**RECITALS**

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;A.Reference is made to that certain Promissory Note, dated as of October 14, 2025, by and between the Parties (as amended by Amendment No. 1 to Promissory Note, effective as of October 31, 2025, the "**Note**"). Capitalized terms used but not otherwise defined herein shall have the meanings ascribed thereto in the Note.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;B.In accordance with Section 11 of the Note, the Parties desire to enter into this Amendment for purposes of amending the Note as set forth herein.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;C.This Amendment shall be effective upon the mutual execution by the Parties.

Now, therefore, in consideration of the premises and the mutual premises set forth in this Amendment, and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the Parties hereby agree as follows.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;1.Amendment of the Note.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;a.Section 1(a)(ii) of the Note is hereby amended and restated to read as follows:

"Subject to the satisfaction (or waiver) of the conditions set forth in Section (4)(b) below, on the date in which all the conditions in Section (4)(b) below are satisfied (or waived) (such date being the "Second Tranche Date"), the Holder shall pay to the Company an amount equal to $10,000,000, less a discount equal to the Original Issue Discount, in immediately available funds to an account designated by the Company in writing as set forth on a closing statement to be signed on the date of the Second Tranche Date. The Company acknowledges and agrees that the Original Issue Discount (i) shall not be funded but shall be deemed to be fully earned upon the Second Tranche Date, and (ii) shall not reduce the principal amount of the Note. The Second Tranche Date shall not be later than February 28, 2026."

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;b.Section 4(b)(ix) of the Note is hereby amended and restated to read as follows:

"(A) the principal amount outstanding under Tranche One is equal to or less than $7,000,000, and (B) the Company (i) has entered into a customary sales agreement with Yorkville Securities, LLC ("Yorkville Securities"), for the potential issuance and sale of shares of common stock in an "at the market offering" as defined in Rule 415 of the Securities Act, with Yorkville serving as sole executing agent and receiving no less than

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60% of the total commissions to be paid by the Company on sales of the Company's common stock under the ATM Offering, and (ii) has filed a prospectus supplement pursuant thereto."

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;2.<u>Limited Effect</u>. Except as expressly provided hereby, all of the terms and provisions of the Note are and shall remain in full force and effect and are hereby ratified and confirmed by the Company. The amendment contained herein shall not be construed as a waiver or amendment of any other provision of the Note or for any purpose except as expressly set forth herein, or a consent to any further or future action on the part of the Company that would require the waiver or consent of the Holder.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3.<u>Representations and Warranties</u>. The Company hereby represents and warrants to the Holder (before and after giving effect to this Amendment) that:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(a)This Amendment has been duly executed and delivered on behalf of the Company. This Amendment together with the Note constitutes the legal, valid and binding obligations of the Company and are enforceable against the Company in accordance with their terms except as enforceability may be limited by applicable bankruptcy, insolvency, reorganization, moratorium or similar laws affecting the enforcement of creditors' rights generally and by general equitable principles (whether enforcement is sought by proceedings in equity or at law);

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(b)Each of the representations and warranties made by the Company herein and the Note is true and correct in all material respects on and as of the date hereof, as if made on and as of the date hereof (except that any representation or warranty which by its terms is made as of an earlier date shall be true and correct in all material respects as of such earlier date); and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(c)No Event of Default has occurred and is continuing, or will result from this Amendment.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.<u>Successors and Assigns</u>. This Amendment shall inure to the benefit of and be binding upon the Company, the Holder, and each of their respective permitted successors and assigns.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5.<u>Governing Law</u>. This Amendment shall be governed by, and construed in accordance with, the laws of the State of New York.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.<u>Counterparts</u>. This Amendment may be executed in any number of counterparts, all of which shall constitute one and the same agreement, and any party hereto may execute this Amendment by signing and delivering one or more counterparts. Delivery of an executed counterpart of this Amendment electronically or by facsimile shall be effective as delivery of an original executed counterpart of this Amendment.

(*Remainder of page left intentionally blank*)

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This Amendment is hereby acknowledged and agreed on behalf of the undersigned:

**COMPANY:**

**ESS TECH, INC.** 

By: *<u>/s/ Kelly F. Goodman</u>*_______

Name: Kelly F. Goodman

Title: Interim Chief Executive Officer

[Signature Page to Amendment No. 1 to Promissory Note]

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This Amendment is hereby acknowledged and agreed on behalf of the undersigned:

**HOLDER:**

**YA II PN, LTD**

By: Yorkville Advisors Global, LP

Its: Investment Manager

&nbsp;&nbsp;&nbsp;&nbsp;

&nbsp;&nbsp;&nbsp;&nbsp;By: Yorkville Advisors Global II, LLC

&nbsp;&nbsp;&nbsp;&nbsp;Its: General Partner

By: <u>/s/ Matt Beckman</u>__________________

Name: Matt Beckman

Title: Member

Date: December 4, 2025

[Signature Page to Amendment No. 1 to Promissory Note]

<br>