GWH

wk-20260811

0001819438False00018194382026-08-112026-08-11

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): August 11, 2026

ESS TECH, INC.

(Exact Name of Registrant as Specified in Charter)

Delaware001-3952598-1550150

(State or other jurisdiction

of incorporation)

(Commission

File Number)

(I.R.S. Employer

Identification Number)

26440 SW Parkway Ave., Bldg. 83

Wilsonville, Oregon 97070

(Address of principal executive offices)(Zip code)

(855) 423-9920

(Registrant’s telephone number, including area code)

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:

Title of each class Trading

Symbol(s)

Name of each exchange

on which registered

Common Stock, $0.0001 par value per shareGWHThe 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. ☐

Item 2.02    Results of Operations and Financial Condition.

On August 11, 2026, ESS Tech, Inc. (the “Company”) issued a press release announcing financial results for the quarter ended June 30, 2026. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

The information furnished in this Item 2.02 and Exhibit 99.1 of this Current Report on Form 8-K shall not be deemed to be “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference into any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing.

Item 9.01    Financial Statements and Exhibits

(d) Exhibits

Exhibit

No.

99.1 Press release, dated August 11, 2026

104Cover page interactive data file

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: August 11, 2026

ESS TECH, INC.

By:/s/ Kate Suhadolnik

Name:Kate Suhadolnik

Title:Chief Financial Officer

wk-20260806

0001819438False00018194382026-08-062026-08-06

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): August 6, 2026

ESS TECH, INC.

(Exact Name of Registrant as Specified in its Charter)

Delaware001-3952598-1550150

(State or other jurisdiction

of incorporation)

(Commission

File Number)

(I.R.S. Employer

Identification Number)

26440 SW Parkway Ave., Bldg. 83

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:

Title of each class Trading

Symbol(s)

Name of each exchange

on which registered

Common Stock, $0.0001 par value per shareGWHThe 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 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

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. ☐

Item 2.02    Results of Operations and Financial Condition.

The information set forth in Item 8.01 is incorporated into this Item 2.02 by reference.

The information furnished under this Item 2.02 shall not be deemed to be “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Item 8.01     Other Information.

Cash Position

As of July 31, 2026, the Company had approximately $5.6 million in cash, cash equivalents and short-term investments.

The Company’s independent registered public accounting firm has not audited, reviewed or performed any procedures with respect to these balances and, accordingly, does not express an opinion or any other form of assurance about it.

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: August 6, 2026

ESS TECH, INC.

By:/s/ Kate Suhadolnik

Name:Kate Suhadolnik

Title:Chief Financial Officer

wk-20260623

0001819438False00018194382026-06-232026-06-230001819438wk:CommonStock0.0001ParValuePerShareMember2026-06-232026-06-230001819438wk:WarrantsEachWholeWarrantExercisableForOneShareOfCommonStockAtAnExercisePriceOf11.50Member2026-06-232026-06-23

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): June 23, 2026

ESS TECH, INC.

(Exact Name of Registrant as Specified in Charter)

Delaware001-3952598-1550150

(State or other jurisdiction

of incorporation)

(Commission

File Number)

(I.R.S. Employer

Identification Number)

26440 SW Parkway Ave., Bldg. 83

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:

Title of each class Trading

Symbol(s)

Name of each exchange

on which registered

Common Stock, $0.0001 par value per shareGWHThe New York Stock Exchange

Warrants, each whole warrant exercisable for one share of common stock at an exercise price of $172.50GWH.WThe 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 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

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. ☐

Item 2.02    Results of Operations and Financial Conditions.

The information set forth in Item 8.01 under the caption “Cash Position” is incorporated into this Item 2.02 by reference.

The information furnished under this Item 2.02 shall not be deemed to be “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or incorporated by reference in any filing under the Securities Act of 1933, as amended (the “Securities Act”), or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Item 7.01    Regulation FD Disclosure.

On June 23, 2026, the Company issued a press release (the “Press Release”) announcing its decision to accelerate its development of sodium-ion battery energy storage systems (the “Sodium-Ion Strategy”). The Company will continue development of its iron flow battery technology for long-duration applications while streamlining its Wilsonville operations, reducing expenses and cash burn, to reallocate capital toward the sodium-ion and related solutions. A copy of the Press Release is furnished as Exhibit 99.1 to this Current Report on Form 8-K.

The information furnished under this Item 7.01, including Exhibit 99.1, shall not be deemed to be “filed” for purposes of Section 18 of the Exchange Act or incorporated by reference in any filing under the Securities Act or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Item 8.01    Other Information.

Cash Position

As of May 31, 2026, the Company had approximately $13.6 million in cash, cash equivalents and short-term investments.

The Company’s independent registered public accounting firm has not audited, reviewed or performed any procedures with respect to the Company’s cash position and, accordingly, does not express an opinion or any other form of assurance about it.

Updates to Risk Factors

The Company is providing as Exhibit 99.2 to this Current Report (“Exhibit 99.2”), which is incorporated by reference to this Item 8.01, updates to the risk factors described in Part II, Item 1A of the Company’s Quarterly Report for the quarterly period ended March 31, 2026 to reflect the receipt of written notice from the New York Stock Exchange (“NYSE”) indicating that the Company did not satisfy the continued listing standard set forth in Section 802.01C of the NYSE Listed Company Manual relating to the minimum share price requirement, as previously reported by the Company in a Form 8-K filed June 15, 2026, and the recently announced expanded product offe