# EDGAR Filing Document

**Accession Number:** 0001819438
**File Stem:** 0001628280-25-052031
**Filing Date:** 2025-11
**Character Count:** 207313
**Document Hash:** 4759734b25a025efa27d7c4e91d612e5
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001628280-25-052031.hdr.sgml**: 20251113

**ACCESSION NUMBER**: 0001628280-25-052031

**CONFORMED SUBMISSION TYPE**: 424B5

**PUBLIC DOCUMENT COUNT**: 3

**FILED AS OF DATE**: 20251113

**DATE AS OF CHANGE**: 20251113

**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:** 424B5
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 333-268138
- **FILM NUMBER:** 251478588

**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

**Filed Pursuant to Rule 424(b)(5)**

**Registration No. 333-268138**

**PROSPECTUS SUPPLEMENT**

**(To Prospectus dated November 17, 2022)**

**Up to $75,000,000**

![prospectus1a.jpg](prospectus1a.jpg)

**Common Stock**

We have entered into a Sales Agreement, dated November 13, 2025, (the "Sales Agreement"), with Yorkville Securities, LLC ("Yorkville Securities"), BMO Capital Markets Corp. ("BMO"), Canaccord Genuity LLC ("Canaccord"), Needham & Company, LLC ("Needham") and Stifel, Nicolaus & Company, Incorporated ("Stifel") (each of Yorkville Securities, BMO, Canaccord, Needham and Stifel individually an "Agent" and collectively, the "Agents") relating to shares of our common stock, $0.0001 par value per share, offered by this prospectus supplement and the accompanying prospectus. In accordance with the terms of the Sales Agreement, we may offer and sell shares of our common stock under this prospectus supplement having an aggregate gross sales price of up to $75,000,000 shares of the Company's common stock, from time to time through or to the Agents, as sales agents or principals.

Our common stock is listed on the New York Stock Exchange (the "NYSE") under the symbol "GWH." On November 12, 2025, the last quoted sale price for our common stock as reported on the NYSE was $4.40 per share.

Sales of shares of our common stock under this prospectus supplement, if any, may be made by any method deemed to be an "at the market offering" as defined in Rule 415(a)(4) promulgated under the Securities Act of 1933, as amended (the "Securities Act"). The Agents are not required to sell any specific number of shares of our common stock. The Agents have agreed to use their commercially reasonable efforts consistent with its normal trading and sales practices, on mutually agreed terms between the Agents and us. There is no arrangement for funds to be received in any escrow, trust or similar arrangement.

The Agents will be entitled to compensation under the terms of the Sales Agreement at a commission rate equal to 3.0% of the gross proceeds of the sales price of common stock that they sell under the Sales Agreement. The net proceeds from any sales under this prospectus supplement will be used as described under "*Use of Proceeds*." The proceeds we receive from sales of our common stock, if any, will depend on the number of shares actually sold and the offering price of such shares.

In connection with the sale of our shares of common stock on our behalf, the Agents will each be deemed to be an "underwriter" within the meaning of the Securities Act, and their compensation as Agents will be deemed to be underwriting commissions or discounts. We have also agreed to provide indemnification and contribution to the Agents with respect to certain liabilities, including liabilities under the Securities Act. See the section titled "*<u>[Plan of Distribution (Conflict of Interest)](#id801b4f9f77a4843b524d65cbdc4902b_1016)</u>*" beginning on page [S-12](#id801b4f9f77a4843b524d65cbdc4902b_1016) of this prospectus supplement.

**Investing in our securities involves a high degree of risk. See "<u>[Risk Factors](#id801b4f9f77a4843b524d65cbdc4902b_934)</u>" beginning on page [S-4](#id801b4f9f77a4843b524d65cbdc4902b_934) of this prospectus supplement, as well as the documents incorporated by reference in this prospectus supplement, for a discussion of the factors you should carefully consider before deciding to purchase our securities.**

**Neither the Securities and Exchange Commission ("SEC") nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.**

---

| | | | |
|:---|:---|:---|:---|
| **Yorkville Securities** | **Yorkville Securities** | **Yorkville Securities** | **Yorkville Securities** |
| **BMO Capital Markets** | **Canaccord Genuity** | **Needham & Company** | **Stifel** |

---

**The date of this prospectus supplement is November 13, 2025.**

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S

**TABLE OF CONTENTS**

**Prospectus Supplement**

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| | |
|:---|:---|
| | **Page** |
| <u>[About This Prospectus Supplement](#id801b4f9f77a4843b524d65cbdc4902b_909)</u> | <u>[S-1](#id801b4f9f77a4843b524d65cbdc4902b_909)</u> |
| <u>[Prospectus Supplement Summary](#id801b4f9f77a4843b524d65cbdc4902b_751)</u> | <u>[S-2](#id801b4f9f77a4843b524d65cbdc4902b_751)</u> |
| <u>[Risk Factors](#id801b4f9f77a4843b524d65cbdc4902b_934)</u> | <u>[S-4](#id801b4f9f77a4843b524d65cbdc4902b_934)</u> |
| <u>[Special Note Regarding Forward-Looking Statements](#id801b4f9f77a4843b524d65cbdc4902b_964)</u> | <u>[S-7](#id801b4f9f77a4843b524d65cbdc4902b_964)</u> |
| <u>[Use of Proceeds](#id801b4f9f77a4843b524d65cbdc4902b_977)</u> | <u>[S-8](#id801b4f9f77a4843b524d65cbdc4902b_977)</u> |
| <u>[Description of Capital Stock](#id801b4f9f77a4843b524d65cbdc4902b_990)</u> | <u>[S-9](#id801b4f9f77a4843b524d65cbdc4902b_990)</u> |
| <u>[Dilution](#id801b4f9f77a4843b524d65cbdc4902b_1003)</u> | <u>[S-10](#id801b4f9f77a4843b524d65cbdc4902b_1003)</u> |
| <u>[Plan of Distribution (Conflict of Interest)](#id801b4f9f77a4843b524d65cbdc4902b_1016)</u> | <u>[S-12](#id801b4f9f77a4843b524d65cbdc4902b_1016)</u> |
| <u>[Legal Matters](#id801b4f9f77a4843b524d65cbdc4902b_1029)</u> | <u>[S-14](#id801b4f9f77a4843b524d65cbdc4902b_1029)</u> |
| <u>[Experts](#id801b4f9f77a4843b524d65cbdc4902b_1042)</u> | <u>[S-14](#id801b4f9f77a4843b524d65cbdc4902b_1042)</u> |
| <u>[Where You Can Find Additional Information](#id801b4f9f77a4843b524d65cbdc4902b_1055)</u> | <u>[S-14](#id801b4f9f77a4843b524d65cbdc4902b_1055)</u> |
| <u>[Incorporation of Certain Information by Reference](#id801b4f9f77a4843b524d65cbdc4902b_1068)</u> | <u>[S-15](#id801b4f9f77a4843b524d65cbdc4902b_1068)</u> |

---

**Prospectus**

---

| | |
|:---|:---|
| | **Page** |
| <u>[About this Prospectus](#id801b4f9f77a4843b524d65cbdc4902b_52)</u> | <u>[ii](#id801b4f9f77a4843b524d65cbdc4902b_52)</u> |
| <u>[Prospectus Summary](#id801b4f9f77a4843b524d65cbdc4902b_55)</u> | <u>[1](#id801b4f9f77a4843b524d65cbdc4902b_55)</u> |
| <u>[Risk Factors](#id801b4f9f77a4843b524d65cbdc4902b_58)</u> | <u>[4](#id801b4f9f77a4843b524d65cbdc4902b_58)</u> |
| <u>[Cautionary Note Regarding Forward-Looking Statements](#id801b4f9f77a4843b524d65cbdc4902b_61)</u> | <u>[5](#id801b4f9f77a4843b524d65cbdc4902b_61)</u> |
| <u>[Use of Proceeds](#id801b4f9f77a4843b524d65cbdc4902b_64)</u> | <u>[6](#id801b4f9f77a4843b524d65cbdc4902b_64)</u> |
| <u>[Description of Capital Stock](#id801b4f9f77a4843b524d65cbdc4902b_67)</u> | <u>[7](#id801b4f9f77a4843b524d65cbdc4902b_67)</u> |
| <u>[Description of Debt Securities](#id801b4f9f77a4843b524d65cbdc4902b_70)</u> | <u>[18](#id801b4f9f77a4843b524d65cbdc4902b_70)</u> |
| <u>[Description of Depositary Shares](#id801b4f9f77a4843b524d65cbdc4902b_73)</u> | <u>[26](#id801b4f9f77a4843b524d65cbdc4902b_73)</u> |
| <u>[Description of Warrants](#id801b4f9f77a4843b524d65cbdc4902b_76)</u> | <u>[29](#id801b4f9f77a4843b524d65cbdc4902b_76)</u> |
| <u>[Description of Subscription Rights](#id801b4f9f77a4843b524d65cbdc4902b_79)</u> | <u>[30](#id801b4f9f77a4843b524d65cbdc4902b_79)</u> |
| <u>[Description of Purchase Contracts](#id801b4f9f77a4843b524d65cbdc4902b_82)</u> | <u>[31](#id801b4f9f77a4843b524d65cbdc4902b_82)</u> |
| <u>[Description of Units](#id801b4f9f77a4843b524d65cbdc4902b_85)</u> | <u>[32](#id801b4f9f77a4843b524d65cbdc4902b_85)</u> |
| <u>[Plan of Distribution](#id801b4f9f77a4843b524d65cbdc4902b_88)</u> | <u>[33](#id801b4f9f77a4843b524d65cbdc4902b_88)</u> |
| <u>[Legal Matters](#id801b4f9f77a4843b524d65cbdc4902b_91)</u> | <u>[36](#id801b4f9f77a4843b524d65cbdc4902b_91)</u> |
| <u>[Experts](#id801b4f9f77a4843b524d65cbdc4902b_94)</u> | <u>[36](#id801b4f9f77a4843b524d65cbdc4902b_94)</u> |
| <u>[Where You Can Find More Information](#id801b4f9f77a4843b524d65cbdc4902b_97)</u> | <u>[36](#id801b4f9f77a4843b524d65cbdc4902b_97)</u> |
| <u>[Incorporation by Reference](#id801b4f9f77a4843b524d65cbdc4902b_100)</u> | <u>[37](#id801b4f9f77a4843b524d65cbdc4902b_100)</u> |

---

S-i

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**ABOUT THIS PROSPECTUS SUPPLEMENT**

This document is in two parts. The first part is this prospectus supplement, including the documents incorporated by reference, which describes the specific terms of this offering. The second part, the accompanying prospectus, including the documents incorporated by reference, provides more general information. Before you invest in our securities, you should read both this prospectus supplement and the accompanying prospectus together with the additional information described in the sections titled "*Where You Can Find More Information*" and "*Incorporation of Certain Information by Reference*."

Neither we nor any Agent has authorized anyone to provide you with information that is different from that contained, or incorporated by reference, in this prospectus supplement, the accompanying prospectus or in any related free writing prospectus. Neither we nor any Agent takes any responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. This prospectus supplement, the accompanying prospectus or any related free writing prospectus do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the securities described in this prospectus supplement or an offer to sell or the solicitation of an offer to buy such securities in any circumstances in which such offer or solicitation is unlawful. You should assume that the information appearing in this prospectus supplement, the accompanying prospectus, the documents incorporated by reference herein and therein and any related free writing prospectus is accurate only as of their respective dates. Our business, financial condition, results of operations and prospects may have changed materially since those dates.

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**PROSPECTUS SUPPLEMENT SUMMARY**

*This summary highlights selected information about us, this offering and information appearing elsewhere in this prospectus supplement and in the documents we incorporate by reference. This summary is not complete and does not contain all the information you should consider before investing in our common stock pursuant to this prospectus supplement and the accompanying prospectus. Before making an investment decision, to fully understand this offering and its consequences to you, you should carefully read this entire prospectus supplement and the accompanying prospectus, including "<u>[Risk Factors](#id801b4f9f77a4843b524d65cbdc4902b_934)</u>" beginning on page <u>[S-4](#id801b4f9f77a4843b524d65cbdc4902b_934)</u> of this prospectus supplement and the financial statements and related notes and the other information that we incorporated by reference herein, including our most recent Annual Report on Form 10-K and our subsequently filed Quarterly Reports on Form 10-Q, which are incorporated by reference herein. Unless the context otherwise requires, all references in this prospectus supplement to "ESS," "we," "us," "our," the "Company" or similar words refer to ESS Tech, Inc.*

**Company Overview**

ESS is a long-duration energy storage company specializing in iron flow battery technology. We design and produce long-duration batteries predominantly using earth-abundant materials that we believe can be cycled over 20,000 times without capacity fade based on lab-scale results. Because our batteries are designed to operate using an electrolyte of primarily salt, iron and water, they are environmentally sustainable and substantially recyclable or reusable.

Our long-duration iron flow batteries are the product of nearly 50 years of scientific advancement. Our founders began advancing this technology in 2011 and formed legacy ESS. Our team has significantly enhanced the technology, improved round-trip efficiency and developed an innovative solution to the hydroxide build-up problem that plagued previous researchers developing iron flow batteries. Our proprietary solution to eliminate the hydroxide formation is known as the Proton Pump, which works by utilizing hydrogen generated by side reactions on the negative electrode. The Proton Pump converts the hydrogen back into protons in the positive electrolyte. This process eliminates the hydroxide and stabilizes the electrolytes' pH levels.

Our batteries provide flexibility to grid operators and energy assurance for commercial and industrial customers. Our technology addresses energy delivery, duration and cycle-life in a single battery platform that compares favorably to lithium-ion batteries, the most widely deployed alternative technology. Using our iron flow battery technology, we have developed several products, each of which was designed to provide reliable, safe, long-duration energy storage. Our first energy storage product, the Energy Warehouse, was our 'behind-the-meter' solution (referring to solutions that are located on the customer's premises, behind the service demarcation with the utility) that was used for initial testing and technology validation. Our product offering evolved to a larger scale energy storage product with the Energy Center, designed for either 'behind-the-meter' or 'front-of-the-meter' (referring to solutions that are located outside the customer's premises, typically operated by the utility or by third-party providers who sell energy into the grid, often known as independent power producers) deployments specifically for utility and large commercial and industrial consumers, before the launch of our 10+ hour Energy Base product earlier this year. We also offer productized versions of our core technology components for integration into third-party systems.

**Corporate Information**

Our principal executive offices are located at 26440 SW Parkway Ave., Bldg. 83 Wilsonville, Oregon 97070 and our telephone number is (855) 423-9920. Our website is https://essinc.com. We make available free of charge through our website our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q and Current Reports on Form 8-K, and amendments to these reports filed or furnished pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), as soon as reasonably practicable after we electronically file such material with, or furnish such material to, the SEC. These reports and other information are also available, free of charge, at www.sec.gov. Information contained on, or that can be accessed through, the websites referenced in this prospectus supplement are not a part of, and are not incorporated into, this prospectus supplement.

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**The Offering**

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| | |
|:---|:---|
| **Common stock offered by us:**  | Shares of our common stock having an aggregate gross sales price of up to $75,000,000. |
| **Plan of Distribution:**  | "At the market offering" that may be made, from time to time, through or to Yorkville Securities, BMO, Canaccord, Needham, and Stifel, as sales agents or principals. See "*<u>[Plan of Distribution (Conflict of Interest)](#id801b4f9f77a4843b524d65cbdc4902b_1016)</u>*" beginning on page <u>[S-12](#id801b4f9f77a4843b524d65cbdc4902b_1016)</u>. |
| **Use of Proceeds:**  | We intend to use the net proceeds from this offering, if any, in compliance with the terms of that certain Promissory Note, dated October 14, 2025, between us and YA II PN, LTD. ("YA II"), which is an affiliate of Yorkville Securities (the "Promissory Note"), which generally requires that proceeds first be used to satisfy any installment payments under the Promissory Note due within thirty days. After any such payments, 80% of the remaining proceeds from this offering be used to satisfy installment payments under the Promissory Note in direct order of maturity until the Promissory Note is repaid in full. In respect of the remaining 20% of proceeds that we may receive while the Promissory Note is outstanding, and all net proceeds we may receive following the repayment of the Promissory Note, we intend to use such net proceeds for working capital and general corporate purposes. See "*<u>[Use of Proceeds](#id801b4f9f77a4843b524d65cbdc4902b_977)</u>*" on page <u>[S-8](#id801b4f9f77a4843b524d65cbdc4902b_977)</u>. |
| **Risk Factors:**  | This investment involves a high degree of risk. See "*<u>[Risk Factors](#id801b4f9f77a4843b524d65cbdc4902b_934)</u>*" beginning on page <u>[S-4](#id801b4f9f77a4843b524d65cbdc4902b_934)</u> of this prospectus supplement, as well as the other information included in or incorporated by reference in this prospectus supplement and the accompanying prospectus, for a discussion of risks you should carefully consider before investing in our securities. |
| **NYSE Symbol:**  | GWH |
| **Conflict of Interest:**  | Yorkville Securities will act as a sales agent in connection with the offering of the shares of Common Stock. Yorkville Securities is an affiliate of YA II, the holder of the Promissory Note. The Company intends to use a portion of any net proceeds from this offering to satisfy installment payments under the Promissory Note until the Promissory Note is repaid in full. Therefore, Yorkville Securities has a "conflict of interest" in this offering within the meaning of Rule 5121 of the Financial Industry Regulatory Authority ("FINRA"), and this offering will be conducted in accordance with FINRA Rule 5121. Yorkville Securities may not make sales of shares of Common Stock in this offering to any of its discretionary accounts without the prior written approval of the account holder. FINRA Rule 5121 requires that a "qualified independent underwriter" meeting certain standards participate in the preparation of this Prospectus Supplement and exercise the usual standards of due diligence with respect thereto. Canaccord has assumed the responsibilities of acting as a "qualified independent underwriter" within the meaning of Rule 5121 in connection with this offering. We have agreed to indemnify Canaccord for acting as a qualified independent underwriter against certain liabilities, including liabilities under the Securities Act and to contribute to payments that may be required to make for these liabilities. See "*<u>[Plan of Distribution (Conflict of Interest)](#id801b4f9f77a4843b524d65cbdc4902b_1016)</u>*" on page <u>[S-12](#id801b4f9f77a4843b524d65cbdc4902b_1016)</u>. |

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**RISK FACTORS**

*Investing in our securities involves a high degree of risk and uncertainty. In addition to the other information included or incorporated by reference in this prospectus supplement and the accompanying prospectus, you should carefully consider the risks described below before making an investment decision with respect to our common stock. We expect to update the risk factors described or incorporated by reference herein and in the accompanying prospectus from time to time in the periodic and current reports that we file with the SEC after the date of this prospectus supplement. These updated risk factors will be incorporated by reference in this prospectus supplement and the accompanying prospectus. Please refer to these subsequent reports for additional information relating to the risks associated with investing in our common stock. If any of such risks and uncertainties actually occurs, our business, financial condition, and results of operations could be severely harmed. This could cause the trading price of our common stock to decline, and you could lose all or part of your investment.*

**Risks Related to this Offering**

***Sales of substantial amounts of our common stock in the public markets, or the perception that such sales could occur, could cause the market price of our common stock to drop significantly, even if our business is doing well.***

Sales of a substantial number of shares of our common stock in the public market could occur at any time, including as a result of the shares sold in this offering. These sales, or the perception in the market that the holders of a large number of shares intend to sell shares, could reduce the market price of our common stock.

We maintain a shelf registration statement on Form S-3, of which this prospectus supplement forms a part, pursuant to which we may, from time to time, sell up to an aggregate of $300 million of our common stock, preferred stock, debt securities, depositary shares, warrants, subscription rights, purchase contracts, or units. We have also filed, and expect to file in the future, registration statements with the SEC to register the resale of shares of our common stock by certain stockholders who have rights, subject to certain conditions, to require us to file registration statements covering their shares or to include their shares in registration statements that we may file for ourselves or other stockholders. We have also filed, and expect to file in the future, registration statements with the SEC to register shares reserved for future issuance under our equity compensation plans. Registration of these shares under the Securities Act results in the shares becoming freely tradable in the public market, subject to the restrictions of Rule 144 in the case of our affiliates.

Any issuance of securities under the shelf registration statement may cause stockholders to experience significant dilution of their ownership interests and any sales of securities by us or our stockholders under the resale registration statements could have a material adverse effect on the market price for our common stock. For example, we sold an aggregate of 6,458,634 shares of common stock at a weighted average sales price of $3.87 per share under the standby equity purchase agreement (the "SEPA") we entered into with YA II, and we issued an additional 157,768 shares of common stock as a commitment fee under the SEPA, each of which were dilutive to our shareholders. Sales of shares of our common stock pursuant to the exercise of registration rights may make it more difficult for us to sell equity securities in the future at a time and at a price that we deem appropriate. These sales also could cause the trading price of our common stock to fall and make it more difficult for you to sell shares of our common stock at a time and price that you deem appropriate.

***We may issue additional shares of common stock or preferred stock. Any such issuances would dilute the interest of our stockholders and likely present other risks.***

We may issue a substantial number of additional shares of common stock or preferred stock. The issuance of additional securities:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• may significantly dilute the equity interests of our investors;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• may subordinate the rights of our stockholders if preferred stock is issued with rights senior to those afforded our common stock;

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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• could cause a change in control if a substantial number of securities are issued, which may affect, among other things, our ability to use our net operating loss carry forwards, if any, and could result in the resignation or removal of our present officers and directors; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• may adversely affect prevailing market prices for our common stock and/or warrants.

***Raising additional capital may cause dilution to our stockholders, including purchasers of our common stock in this offering, restrict our operations or require us to relinquish substantial rights.***

We expect to raise additional capital through the sale of equity or convertible debt securities. As a result of any such issuance, your ownership interest will be diluted, and the terms of these new securities may include liquidation or other preferences that adversely affect your rights as a common stockholder. Debt financing, if available, may involve fixed payment obligations or agreements that include covenants limiting or restricting our ability to take specific actions such as incurring additional debt, making capital expenditures or declaring dividends. If we raise additional funds through partnerships, collaborations, strategic alliances or licensing arrangements with third parties, we may have to relinquish valuable rights to our technologies, products or future revenue streams, or grant licenses on terms that are not favorable to us. We cannot assure you that we will be able to obtain additional funding if and when necessary. If we are unable to obtain adequate financing on a timely basis, we could be required to delay or scale back our development or production efforts or grant rights to develop, produce and market our products that we would otherwise prefer to develop, produce and market ourselves. In addition, we may seek additional capital due to favorable market conditions or strategic considerations even if we believe we have sufficient funds for our current or future operating plans.

***We have discretion in the use of our cash and cash equivalents, including certain net proceeds from this offering.***

We intend to use the net proceeds from this offering in compliance with the terms of the Promissory Note, which generally requires that 80% of the proceeds from this offering be used to satisfy installment payments under the Promissory Note until the promissory note is repaid in full. In respect of the remaining 20% of proceeds that we may receive while the Promissory Note is outstanding, and all net proceeds we may receive following the repayment of the Promissory Note, we intend to use such net proceeds for working capital and general corporate purposes. We have discretion in the use of our cash and cash equivalents, including the portion of any net proceeds from this offering that are not used to repay the Promissory Note. Our management may not use cash and cash equivalents in ways that ultimately increase the value of your investment. Our failure to use our cash and cash equivalents effectively could result in financial losses that could have a material adverse effect on our business, cause the price of our common stock to decline and delay the commercialization of our products. Pending their use, we may invest our cash and cash equivalents in short-term or long-term, investment-grade, interest-bearing securities. These investments may not yield favorable returns. If we do not invest or apply our cash and cash equivalents in ways that enhance shareholder value, we may fail to achieve expected financial results, which could cause the price of our common stock to decline.

***You may experience immediate and substantial dilution in the book value per share of the common stock you purchase.***

Because the prices per share at which shares of our common stock are sold in this offering may be substantially higher than the book value per share of our common stock, you may suffer immediate and substantial dilution in the net tangible book value of the common stock you purchase in this offering. The shares sold in this offering, if any, will be sold from time to time at various prices. After giving effect (i) to the issuance and sale of 4,213,694 shares of common stock for aggregate gross proceeds of approximately $21.4 million under the SEPA since October 1, 2025, and (ii) to the sale of our common stock in the maximum aggregate offering amount of $75,000,000 at an assumed offering price of $4.13 per share, the last reported sale price of our common stock on the NYSE on October 31, 2025 and after deducting estimated offering commissions and expenses payable by us, the as-adjusted net tangible book value of our common stock as of September 30, 2025 would have been approximately $87.2 million, or $2.31 per share of common stock. This represents an immediate increase in the pro forma net tangible book value after giving effect to such SEPA sales of $1.94 per share to our existing stockholders and an immediate and substantial dilution in as-adjusted net tangible book value of approximately $1.82 per share to new investors who

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purchase our common stock in the offering. See "*<u>[Dilution](#id801b4f9f77a4843b524d65cbdc4902b_1003)</u>*" beginning on page <u>[S-10](#id801b4f9f77a4843b524d65cbdc4902b_1003)</u> of this prospectus supplement for a more detailed discussion of the dilution you may incur in connection with this offering.

***We do not expect to declare any dividends in the foreseeable future.***

We do not anticipate declaring any cash dividends to holders of our common stock in the foreseeable future. Consequently, investors may need to rely on sales of their shares after price appreciation, which may never occur, as the only way to realize any future gains on their investment.

***It is not possible to predict the actual number of shares we will sell under the Sales Agreement, or the gross proceeds resulting from those sales.***

Subject to certain limitations in the Sales Agreement and compliance with applicable law, we have the discretion to deliver a placement notice to the Agents at any time throughout the term of the Sales Agreement. The number of shares that are sold through the Agents after delivering a placement notice will fluctuate based on a number of factors, including the market price of the common stock during the sales period, the limits we set with the Agents in any applicable placement notice, and the demand for our common stock during the sales period. Because the price per share of each share sold will fluctuate during the sales period, it is not currently possible to predict the number of shares that will be sold or the gross proceeds to be raised in connection with those sales.

***The common stock offered hereby will be sold in "at the market offerings," and investors who buy shares at different times will likely pay different prices.***

Investors who purchase shares in this offering at different times will likely pay different prices, and so may experience different levels of dilution and different outcomes in their investment results. We will have discretion, subject to market demand, to vary the timing, prices, and numbers of shares sold in this offering. In addition, there is no minimum or maximum sales price for shares to be sold in this offering. Investors may experience a decline in the value of the shares they purchase in this offering as a result of sales made at prices lower than the prices they paid.

***The report of our independent registered public accounting firm includes a "going concern" explanatory paragraph.***

We will require substantial additional funds to continue our operations. Our cash and cash equivalents and short-term investments were $3.5 million at September 30, 2025. Given our recurring history of losses and an insufficient amount of cash available to fund our ongoing operations for the next year, we have concluded that there is a substantial doubt regarding our ability to continue as a going concern for a period of at least 12 months beyond the filing of our Quarterly Report on Form 10-Q for the period ended September 30, 2025. Any such inability to continue as a going concern may result in our stockholders losing their entire investment. There is no guarantee that we will become profitable or secure additional financing on acceptable terms or at all, and we may not be able to raise additional capital either in this offering or otherwise. Further, the inclusion of disclosures expressing substantial doubt about our ability to continue as a going concern could materially adversely affect our stock price and our ability to raise new capital or enter into partnerships or other agreements.

We have prepared our condensed financial statements on a going concern basis, which contemplates the realization of assets and the satisfaction of liabilities and commitments in the normal course of business. Our condensed financial statements included in our Quarterly Report on Form 10-Q for the period ended September 30, 2025 do not include any adjustments to reflect the possible inability to continue as a going concern within at least 12 months after the issuance of such financial statements.

------

**SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS**

This prospectus supplement, the accompanying prospectus and the information incorporated by reference herein and therein contain certain statements that constitute "forward-looking statements" within the meaning of Section 27A of the Securities Act and Section 21E of the Exchange Act. The words "believe," "may," "will," "estimate," "continue," "anticipate," "intend," "expect," "could," "would," "project," "plan," "potentially," "likely," and similar expressions and variations thereof are intended to identify forward-looking statements, but are not the exclusive means of identifying such statements. Those statements appear in this prospectus supplement, the accompanying prospectus and the information incorporated by reference herein and therein by reference, particularly in the sections titled "*Risk Factors*" and "*Management's Discussion and Analysis of Financial Condition and Results of Operations*" and include statements regarding the intent, belief or current expectations of our management that are subject to known and unknown risks, uncertainties and assumptions. You are cautioned that any such forward-looking statements are not guarantees of future performance and involve risks and uncertainties, and that actual results may differ materially from those projected in the forward-looking statements as a result of various factors.

Because forward-looking statements are inherently subject to risks and uncertainties, some of which cannot be predicted or quantified, you should not rely upon forward-looking statements as predictions of future events. The events and circumstances reflected in the forward-looking statements may not be achieved or occur and actual results could differ materially from those projected in the forward-looking statements. Except as required by applicable law, including the securities laws of the United States and the rules and regulations of the SEC, we do not plan to publicly update or revise any forward-looking statements contained herein after we distribute this prospectus supplement, whether as a result of any new information, future events or otherwise.

In addition, statements that "we believe" and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date of this prospectus supplement, and although we believe such information forms a reasonable basis for such statements, such information may be limited or incomplete, and our statements should not be read to indicate that we have conducted a thorough inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain and investors are cautioned not to unduly rely upon these statements.

This prospectus supplement, the accompanying prospectus and the information incorporated by reference herein and therein may contain market data that we obtain from industry sources. These sources do not guarantee the accuracy or completeness of the information. Although we believe that our industry sources are reliable, we do not independently verify the information. The market data may include projections that are based on a number of other projections. While we believe these assumptions to be reasonable as of the date of this prospectus supplement, actual results may differ from the projections.

------

**USE OF PROCEEDS**

The amount of proceeds from this offering, if any, will depend upon the number of shares of our common stock sold and the market price at which they are sold. There can be no assurance that we will be able to sell any shares under or fully utilize the Sales Agreement with the Agents.

We intend to use the net proceeds from this offering in compliance with the terms of the Promissory Note, which generally requires that proceeds first be used to satisfy any installment payments under the Promissory Note due within thirty days. After any such payments, 80% of the remaining proceeds from this offering will be used to satisfy installment payments under the Promissory Note in direct order of maturity until the promissory note is repaid in full. In respect of the remaining 20% of proceeds that we may receive while the Promissory Note is outstanding, and all net proceeds we may receive following the repayment of the Promissory Note, we intend to use such net proceeds for working capital and general corporate purposes.

------

**DESCRIPTION OF CAPITAL STOCK**

The description of our capital stock is incorporated by reference to Exhibit <u>[4.2](https://www.sec.gov/Archives/edgar/data/0001819438/000162828025015649/exhibit42-descriptionofsec.htm)</u> to our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, filed with the SEC on <u>[March 31, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000162828025015649/ghw-20241231.htm)</u>.

------

**DILUTION**

If you invest in our common stock, your interest will be diluted to the extent of the difference between the public offering price per share and the adjusted net tangible book value per share of our common stock after this offering.

The net tangible book value of our common stock as of September 30, 2025 was approximately $(6.2) million, or approximately $(0.40) per share. Net tangible book value per share represents the amount of our total tangible assets, excluding goodwill and intangible assets, less total liabilities, divided by the total number of shares of our common stock outstanding. Dilution per share to new investors represents the difference between the amount per share paid by purchasers for each share of common stock in this offering and the net tangible book value per share of our common stock immediately following the completion of this offering.

After giving effect to the issuance and sale of 4,213,694 shares of common stock under the SEPA in the period following September 30, 2025 for aggregate gross proceeds of approximately $21.4 million, and after deducting the related fees and estimated offering expenses payable by us, the pro forma net tangible book value of our common stock as of September 30, 2025 would have been approximately $15.2 million, or approximately $0.77 per share.

After giving further effect to the sale of shares of our common stock pursuant to the Sales Agreement in the aggregate amount of $75 million at an assumed offering price of $4.13 per share, which was the last reported sale price of our common stock on October 31, 2025 on the NYSE, and after deducting estimated commissions and estimated offering expenses, our as-adjusted net tangible book value as of September 30, 2025 would have been approximately $87.2 million, or approximately $2.31 per share. This represents an immediate increase in pro forma net tangible book value after giving effect to such SEPA sales of approximately $1.94 per share to our existing stockholders and an immediate dilution in as-adjusted net tangible book value of approximately $1.82 per share to purchasers of our common stock in this offering, as illustrated by the following table:

---

| | | |
|:---|:---|:---|
| Assumed offering price per share |  | $4.13 |
| Net tangible book value per share as of September 30, 2025 | $(0.40) |  |
| Pro forma net tangible book value per share as of September 30, 2025 after giving effect to sales under the SEPA | $0.77 |  |
| Increase per share attributable to this offering | $1.94 |  |
| As-adjusted net tangible book value per share as of September 30, 2025, after giving effect to this offering  |  | $2.31 |
| Dilution per share to new investors participating in this offering |  | $1.82 |

---

Unless otherwise noted in the table above, such information is based on 15,390,884 shares of our common stock outstanding as of September 30, 2025 and excludes:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• 93,952 shares of our common stock issuable upon the exercise of outstanding options granted under the ESS Tech, Inc. 2021 Equity Incentive Plan (the "2021 Plan"), with a weighted average exercise price of $13.23 per share;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• 1,216,387 shares of our common stock issuable upon the vesting of outstanding restricted stock units granted under the 2021 Plan;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• 37,372 shares of our common stock reserved for future issuance under the ESS Tech, Inc. 2021 Employee Stock Purchase Plan;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• 33,333 shares of our common stock issuable upon the exercise of a warrant issued to Sacramento Municipal Utility District, with an exercise price of $64.44 per share;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• 708,775 shares of our common stock issuable upon the exercise of a warrant held by Honeywell ACS Ventures LLC ("Honeywell Ventures"), with an exercise price of $43.50 per share;

------

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• 417,997 shares of our common stock issuable upon the exercise of a warrant held by Honeywell Ventures, with an exercise price of $28.35 per share;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• 51,717 shares of our common stock issuable upon the exercise of a warrant held by UOP LLC, with an exercise price of $21.75 per share;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• 764,081 shares of our common stock issuable upon the exercise of our public warrants, with an exercise price of $172.50 per share;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• 129,312 shares of our common stock issuable upon the exercise of warrants held by YA II and certain of our directors and members of our management that were issued in connection with the bridge loan, with an exercise price of $3.48 per share; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• 4,213,694 shares of common stock issued pursuant to the SEPA.

To the extent that any outstanding options or warrants are exercised, outstanding restricted stock units vest, new equity awards are issued under our equity incentive plan, or we otherwise issue additional shares of common stock in the future at prices per share below the price per share for any shares sold in this offering, there will be further dilution to new investors.

------

**PLAN OF DISTRIBUTION (CONFLICT OF INTEREST)**

We have entered into the Sales Agreement with Yorkville Securities, BMO, Canaccord, Needham and Stifel, under which we may issue and sell our common stock from time to time through or to the Sales Agents acting as sales agent or principal. Sales of shares of our common stock, if any, under this prospectus supplement may be made by any method that is deemed an "at the market offering" as defined in Rule 415 promulgated under the Securities Act. We may instruct the Sales Agents not to sell common stock if the sales cannot be effected at or above the price designated by us from time to time. We or the Sales Agents may suspend the offering of common stock upon notice and subject to other conditions.

The Sales Agents will offer our common stock, if any, subject to the terms and conditions of the Sales Agreement as agreed upon by us and the Sales Agents. Each time we wish to issue and sell common stock under the Sales Agreement, we will notify a Sales Agent of the number or dollar value of shares to be issued, the time period during which such sales are requested to be made, any limitation on the number of shares that may be sold in one day, any minimum price below which sales may not be made and other sales parameters as we deem appropriate. Once we have so instructed such Sales Agent, unless such Sales Agent declines to accept the terms of the notice, such Sales Agent has agreed to use its commercially reasonable efforts consistent with its normal trading and sales practices to sell such shares up to the amount specified on such terms. The obligations of the Sales Agents under the Sales Agreement to sell our common stock are subject to a number of conditions that we must meet.

We will pay the Sales Agents commissions for their services in acting as sales agents in the sale of common stock at a commission rate equal to 3.0% of the gross sales price per share sold. Because there is no minimum offering amount required as a condition to close this offering, the actual total public offering amount, commissions and proceeds to us, if any, are not determinable at this time. We have also agreed to reimburse the Sales Agents for certain specified expenses, including the fees and disbursements of their legal counsel in an amount not to exceed (i) $75,000 in connection with the execution of the Sales Agreement, (ii) $10,000 per calendar in connection with ongoing diligence arising from the transactions contemplated by the Sales Agreement and (iii) $40,000 in connection with the filing of a new registration statement, prospectus or prospectus supplement relating to the common stock sold under the Sales Agreement and/or an amendment of the Sales Agreement. We estimate that the total expenses for the offering, excluding commissions and reimbursements payable to the Sales Agents under the terms of the Sales Agreement, will be approximately $475,000.

Settlement for sales of our common stock will occur on the first trading day following the date on which any sales were made in return for payment of the net proceeds to us unless we agree otherwise with the Sales Agents in connection with a particular transaction. There is no arrangement for funds to be received in an escrow, trust or similar arrangement.

The Agents will use their commercially reasonable efforts, consistent with their normal trading and sales practices, to solicit offers to purchase shares of our common stock under the terms and subject to the conditions set forth in the Sales Agreement. In connection with the sale of the common stock on our behalf, each Sales Agent will be deemed to be an "underwriter" within the meaning of the Securities Act and the compensation of the Sales Agents will be deemed to be underwriting commissions or discounts. We have agreed to provide indemnification and contribution to the Sales Agents against certain civil liabilities, including liabilities under the Securities Act.

This offering of our common stock pursuant to this prospectus supplement will terminate upon the earlier of (i) the sale of all of our common stock subject to this prospectus supplement, or (ii) termination of the Sales Agreement as provided therein.

**Other Relationships**

The Sales Agents and their respective affiliates are full service financial institutions engaged in various activities, which may include securities trading, commercial and investment banking, financial advisory, investment management, investment research, principal investment, hedging, financing and brokerage activities. Certain of the Sales Agents and their respective affiliates have, from time to time, performed, and may in the future perform, various financial advisory and investment banking services for us, for which they received or will receive customary fees and expenses.

------

In July 2025, the Company issued, among others, an unsecured promissory note to YA II (the "July Promissory Note") in the aggregate principal amount of $585,000. The July Promissory Note was repaid in full on or before the maturity date of July 24, 2025, including the payment of an exit fee of 15%. In connection with the July Promissory Notes, the Company issued to YA II warrants exercisable for an aggregate number of up to 84,052 shares of common stock (the "Bridge Financing Warrant") at an exercise price of $3.48 per share, payable in cash or, under certain circumstances, pursuant to net exercise.

Also in July 2025, YA II and the Company entered into the SEPA, pursuant to which and subject to the satisfaction of certain conditions, YA II committed to purchase shares of our common stock in increments up to an aggregate gross sales price of up to $25 million during the 36 months following the date of the SEPA. In connection with the execution of the SEPA, the Company issued 157,768 shares of our common stock as a 1.00% commitment fee on the $25 million commitment amount, in accordance with the terms of the SEPA, and reimbursed YA II's expenses in an amount of $85,000. All $25 million of commitments under the SEPA were satisfied on October 21, 2025 and the SEPA terminated in accordance with its terms.

In connection with that the entrance into the SEPA, we also granted Yorkville Securities certain rights of first refusal to serve as our placement agent or underwriter in connection with certain financing transactions that we may conduct through July 10, 2026, including serving as a Sales Agent under the Sales Agreement.

On October 14, 2025, the Company entered into the Promissory Note with YA II in the aggregate principal amount of up to $40 million, in two tranches consisting of a first tranche of $30 million and a second tranche of $10 million, in each case less an original issue discount of 8% and certain fees and expenses to be paid to YA II.

In connection with the Promissory Note, the Company issued to YA II a warrant exercisable for an aggregate number of up to 1,052,104 shares of the Company's common stock (the "Promissory Note Warrant"). The Promissory Note Warrant has an exercise price of $9.98 per share, payable in cash or, under certain circumstances, pursuant to net exercise. The Promissory Note Warrant is exercisable for five years from the date of issuance.

In addition, in the ordinary course of their various business activities, the Sales Agents and their respective affiliates may make or hold a broad array of investments and actively trade debt and equity securities (or related derivative securities) and financial instruments (including bank loans) for their own account and for the accounts of their customers and may at any time hold long and short positions in such securities and instruments. Such investments and securities activities may involve our securities and instruments (directly, as collateral securing other obligations or otherwise) and/or persons and entities with relationships with us. The Sales Agents and their respective affiliates may also make investment recommendations or publish or express independent research views in respect of such securities or instruments and may at any time hold, or recommend to clients that they acquire, long or short positions in such securities and instruments.

**Conflict of Interest**

Yorkville Securities will act as a sales agent in connection with the offering of the shares of Common Stock. Yorkville Securities is an affiliate of YA II, the holder of the Promissory Note. The Company intends to use a portion of any net proceeds from this offering to satisfy installment payments under the Promissory Note until the Promissory Note is repaid in full. Therefore, Yorkville Securities has a "conflict of interest" in this offering within the meaning of Rule 5121 of the Financial Industry Regulatory Authority ("FINRA"), and this offering will be conducted in accordance with FINRA Rule 5121. Yorkville Securities may not make sales of shares of Common Stock in this offering to any of its discretionary accounts without the prior written approval of the account holder. FINRA Rule 5121 requires that a "qualified independent underwriter" meeting certain standards participate in the preparation of this Prospectus Supplement and exercise the usual standards of due diligence with respect thereto. Canaccord has assumed the responsibilities of acting as a "qualified independent underwriter" within the meaning of Rule 5121 in connection with this offering. We have agreed to indemnify Canaccord for acting as a qualified independent underwriter against certain liabilities, including liabilities under the Securities Act and to contribute to payments that may be required to make for these liabilities.

------

**LEGAL MATTERS**

The validity of the securities offered hereby will be passed upon for us by Wilson Sonsini Goodrich & Rosati, Professional Corporation, Palo Alto, California. The Agents are being represented in connection with this offering by Duane Morris LLP, New York, New York.

**EXPERTS**

The financial statements of ESS Tech, Inc. as of December 31, 2024 and 2023, and for each of the years in the two-year period ended December 31, 2024, have been incorporated by reference herein in reliance upon the report of KPMG LLP, independent registered public accounting firm, incorporated by reference herein, and upon the authority of said firm as experts in accounting and auditing. The audit report covering the December 31, 2024 financial statements contains an explanatory paragraph that states that the Company's recurring net losses from operations and negative cash flows from operating activities raise substantial doubt about the entity's ability to continue as a going concern. The financial statements do not include any adjustments that might result from the outcome of that uncertainty.

**WHERE YOU CAN FIND ADDITIONAL INFORMATION**

We file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to the public over the Internet at the SEC's website at *www.sec.gov*. Copies of certain information filed by us with the SEC are also available on our website at *https://essinc.com*. Information accessible on or through our website is not a part of this prospectus supplement.

This prospectus supplement and the accompanying prospectus are part of a registration statement that we filed with the SEC and does not contain all of the information in the registration statement. You should review the information and exhibits in the registration statement for further information on us and the securities that we are offering. The Sales Agreement and other documents establishing the terms of the offered securities are filed as exhibits to the registration statement of which this prospectus supplement forms a part or under cover of a Current Report on Form 8-K and incorporated in this prospectus supplement by reference. Statements in this prospectus supplement about these documents are summaries and each statement is qualified in all respects by reference to the document to which it refers. You should read the actual documents for a more complete description of the relevant matters.

------

**INCORPORATION OF CERTAIN INFORMATION BY REFERENCE**

The SEC allows us to incorporate by reference much of the information that we file with the SEC, which means that we can disclose important information to you by referring you to those publicly available documents. The information that we incorporate by reference in this prospectus supplement is considered to be part of this prospectus supplement. Because we are incorporating by reference future filings with the SEC, this prospectus supplement is continually updated and those future filings may modify or supersede some of the information included or incorporated by reference in this prospectus supplement. This means that you must look at all of the SEC filings that we incorporate by reference to determine if any of the statements in this prospectus supplement or in any document previously incorporated by reference have been modified or superseded. This prospectus supplement incorporates by reference the documents listed below and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act (in each case, other than those documents or the portions of those documents furnished rather than filed), from and after the date on which the registration statement of which this prospectus supplement and the accompanying prospectus forms a part was initially filed with the SEC and prior to the effectiveness of such registration statement, until the offering of the securities under the registration statement of which this prospectus supplement and the accompanying prospectus forms a part is terminated or completed:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• our Annual Report on Form 10-K for the year ended December 31, 2024, filed with the SEC on <u>[March 31, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000162828025015649/ghw-20241231.htm)</u> (the "Annual Report");

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• our Quarterly Report on Form 10-Q for the quarter ended March 31, 2025, June 30, 2025, and September 30, 2025, filed with the SEC on <u>[May 15, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000162828025026025/ghw-20250331.htm)</u>, <u>[August 14, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000181943825000014/ghw-20250630.htm)</u>, and <u>[November 13, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000181943825000076/ghw-20250930.htm)</u>, respectively;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• our Current Reports on Form 8-K filed with the SEC on <u>[February 14, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000162828025005510/wk-20250213.htm)</u>, <u>[March 28, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000162828025015467/wk-20250324.htm)</u>, <u>[March 31, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000162828025015704/wk-20250331.htm)</u>, <u>[May 28, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000162828025028027/wk-20250527.htm)</u>, <u>[June 4, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000162828025029215/wk-20250603.htm)</u>, <u>[July 11, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000162828025034769/wk-20250709.htm)</u>, <u>[August 7, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000181943825000007/wk-20250801.htm)</u>, <u>[August 18, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000181943825000019/wk-20250812.htm)</u>, <u>[August 29, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000181943825000027/wk-20250829.htm)</u>, <u>[October 14, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000181943825000065/wk-20251014.htm)</u> and <u>[October 14, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000181943825000057/wk-20251013.htm)</u>; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the description of our common stock contained in <u>[Exhibit 4.2](https://www.sec.gov/Archives/edgar/data/1819438/000162828025015649/exhibit42-descriptionofsec.htm)</u> to the Annual Report, including any amendments or reports filed for the purpose of updating such description.

Any documents we file with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this prospectus supplement and prior to the termination of the offering of our common stock to which this prospectus supplement relates will automatically be deemed to be incorporated by reference into this prospectus supplement and to be part hereof from the date of filing those documents. We are not, however, incorporating by reference any documents or portions thereof that are not deemed "filed" with the SEC, including any information furnished pursuant to Item 2.02 or Item 7.01 of Form 8-K or related exhibits furnished pursuant to Item 9.01 of Form 8-K. Any statements in any such future filings will automatically be deemed to modify and supersede any information in any document we previously filed with the SEC that is incorporated or deemed to be incorporated herein by reference to the extent that statements in the later filed document modify or replace such earlier statements.

You may request a copy of these filings, at no cost, by writing or telephoning us at the following address and telephone number:

ESS Tech, Inc.

26440 SW Parkway Ave., Bldg. 83

Wilsonville, Oregon 97070

Attn: Investor Relations

(855) 423-9920

------

**PROSPECTUS**

![esslogoa.jpg](esslogoa.jpg)

**$300,000,000**

**Common Stock**

**Preferred Stock**

**Debt Securities**

**Depositary Shares**

**Warrants**

**Subscription Rights**

**Purchase Contracts**

**Units**

The securities covered by this prospectus may be sold by ESS Tech, Inc. from time to time. This prospectus provides you with a general description of the securities.

We may issue securities from time to time in one or more offerings, in amounts, at prices and on terms determined at the time of offering. This prospectus describes the general terms of these securities and the general manner in which these securities will be offered. We will provide the specific terms of these securities in supplements to this prospectus, which will also describe the specific manner in which these securities will be offered and may also supplement, update or amend information contained in this prospectus. You should read this prospectus and any applicable prospectus supplement before you invest. The aggregate offering price of the securities we sell pursuant to this prospectus will not exceed $300,000,000.

The securities may be sold directly to you, through agents or through underwriters and dealers. If agents, underwriters or dealers are used to sell the securities, we will name them and describe their compensation in a prospectus supplement. The price to the public of those securities and the net proceeds we expect to receive from that sale will also be set forth in a prospectus supplement.

Our common stock is listed on the New York Stock Exchange under the symbol "GWH" and our public warrants are listed on the New York Stock Exchange under the symbol "GWH.W." Each prospectus supplement will indicate whether the securities offered thereby will be listed on any securities exchange.

We are an "emerging growth company" as defined under the federal securities laws, and, as such, may elect to comply with certain reduced public company reporting requirements for this and future filings. We will provide information in any applicable prospectus supplement regarding any listing of securities other than shares of our common stock on any securities exchange.

**INVESTING IN OUR SECURITIES INVOLVES A HIGH DEGREE OF RISK. PLEASE CAREFULLY READ THE INFORMATION UNDER THE HEADINGS "<u>[RISK FACTORS](#id801b4f9f77a4843b524d65cbdc4902b_58)</u>" BEGINNING ON PAGE <u>[4](#id801b4f9f77a4843b524d65cbdc4902b_58)</u> OF THIS PROSPECTUS AND "ITEM 1A – RISK FACTORS" OF OUR MOST RECENT REPORT ON FORM 10-K OR 10-Q THAT IS INCORPORATED BY REFERENCE IN THIS PROSPECTUS BEFORE YOU INVEST IN OUR SECURITIES.**

**Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.**

The date of this prospectus is November 17, 2022.

------

**TABLE OF CONTENTS**

---

| | |
|:---|:---|
| | **Page** |
| <u>[About this Prospectus](#id801b4f9f77a4843b524d65cbdc4902b_52)</u> | <u>[ii](#id801b4f9f77a4843b524d65cbdc4902b_52)</u> |
| <u>[Prospectus Summary](#id801b4f9f77a4843b524d65cbdc4902b_55)</u> | <u>[1](#id801b4f9f77a4843b524d65cbdc4902b_55)</u> |
| <u>[Risk Factors](#id801b4f9f77a4843b524d65cbdc4902b_58)</u> | <u>[4](#id801b4f9f77a4843b524d65cbdc4902b_58)</u> |
| <u>[Cautionary Note Regarding Forward-Looking Statements](#id801b4f9f77a4843b524d65cbdc4902b_61)</u> | <u>[5](#id801b4f9f77a4843b524d65cbdc4902b_61)</u> |
| <u>[Use of Proceeds](#id801b4f9f77a4843b524d65cbdc4902b_64)</u> | <u>[6](#id801b4f9f77a4843b524d65cbdc4902b_64)</u> |
| <u>[Description of Capital Stock](#id801b4f9f77a4843b524d65cbdc4902b_67)</u> | <u>[7](#id801b4f9f77a4843b524d65cbdc4902b_67)</u> |
| <u>[Description of Debt Securities](#id801b4f9f77a4843b524d65cbdc4902b_70)</u> | <u>[18](#id801b4f9f77a4843b524d65cbdc4902b_70)</u> |
| <u>[Description of Depositary Shares](#id801b4f9f77a4843b524d65cbdc4902b_73)</u> | <u>[26](#id801b4f9f77a4843b524d65cbdc4902b_73)</u> |
| <u>[Description of Warrants](#id801b4f9f77a4843b524d65cbdc4902b_76)</u> | <u>[29](#id801b4f9f77a4843b524d65cbdc4902b_76)</u> |
| <u>[Description of Subscription Rights](#id801b4f9f77a4843b524d65cbdc4902b_79)</u> | <u>[30](#id801b4f9f77a4843b524d65cbdc4902b_79)</u> |
| <u>[Description of Purchase Contracts](#id801b4f9f77a4843b524d65cbdc4902b_82)</u> | <u>[31](#id801b4f9f77a4843b524d65cbdc4902b_82)</u> |
| <u>[Description of Units](#id801b4f9f77a4843b524d65cbdc4902b_85)</u> | <u>[32](#id801b4f9f77a4843b524d65cbdc4902b_85)</u> |
| <u>[Plan of Distribution](#id801b4f9f77a4843b524d65cbdc4902b_88)</u> | <u>[33](#id801b4f9f77a4843b524d65cbdc4902b_88)</u> |
| <u>[Legal Matters](#id801b4f9f77a4843b524d65cbdc4902b_91)</u> | <u>[36](#id801b4f9f77a4843b524d65cbdc4902b_91)</u> |
| <u>[Experts](#id801b4f9f77a4843b524d65cbdc4902b_94)</u> | <u>[36](#id801b4f9f77a4843b524d65cbdc4902b_94)</u> |
| <u>[Where You Can Find More Information](#id801b4f9f77a4843b524d65cbdc4902b_97)</u> | <u>[36](#id801b4f9f77a4843b524d65cbdc4902b_97)</u> |
| <u>[Incorporation by Reference](#id801b4f9f77a4843b524d65cbdc4902b_100)</u> | <u>[37](#id801b4f9f77a4843b524d65cbdc4902b_100)</u> |

---

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**ABOUT THIS PROSPECTUS**

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission (the "SEC"), using a "shelf" registration process. Under this shelf registration process, we may from time to time sell any combination of the securities described in this prospectus in one or more offerings for an aggregate offering price of up to $300,000,000.

This prospectus provides you with a general description of the securities that may be offered. Each time we sell securities, we will provide one or more prospectus supplements that will contain specific information about the terms of the offering. The prospectus supplement may also add, update or change information contained in this prospectus. You should read both this prospectus and any applicable prospectus supplement together with the additional information described under the headings "*Where You Can Find More Information*" and "*Incorporation by Reference*."

We have not authorized anyone to provide you with information that is different from that contained, or incorporated by reference, in this prospectus, any applicable prospectus supplement or in any related free writing prospectus. We take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. This prospectus and any applicable prospectus supplement or any related free writing prospectus do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the securities described in the applicable prospectus supplement or an offer to sell or the solicitation of an offer to buy such securities in any circumstances in which such offer or solicitation is unlawful. You should assume that the information appearing in this prospectus, any prospectus supplement, the documents incorporated by reference and any related free writing prospectus is accurate only as of their respective dates. Our business, financial condition, results of operations and prospects may have changed materially since those dates.

The ESS design logo and the ESS mark appearing in this prospectus are the property of ESS Tech, Inc. Trade names, trademarks and service marks of other companies appearing in this prospectus are the property of their respective holders. We have omitted the® and TM designations, as applicable, for the trademarks used in this prospectus.

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**PROSPECTUS SUMMARY**

*This summary highlights selected information that is presented in greater detail elsewhere, or incorporated by reference, in this prospectus. It does not contain all of the information that may be important to you and your investment decision. Before investing in our securities, you should carefully read this entire prospectus, including the matters set forth under the section of this prospectus captioned "Risk Factors" and the financial statements and related notes and other information that we incorporate by reference herein, including our Annual Report on Form 10-K and our Quarterly Reports on Form 10-Q. Unless the context indicates otherwise, references in this prospectus to "ESS," "we," "our," "us," the "registrant" and the "Company" refer, collectively, to ESS Tech, Inc., a Delaware corporation, and its subsidiaries taken as a whole.*

**Company Overview**

ESS is a long-duration energy storage company specializing in iron flow battery technology. We design and produce long-duration batteries predominantly using earth-abundant materials that we expect can be cycled over 20,000 times without capacity fade. Because we designed our batteries to operate using an electrolyte of primarily salt, iron and water, they are non-toxic and substantially recyclable.

Our long-duration iron flow batteries are the product of nearly 50 years of scientific advancement. Our founders, Craig Evans and Dr. Julia Song, began advancing this technology in 2011 and formed ESS. Our team has significantly enhanced the technology, improved the round-trip efficiency and developed an innovative and patented solution to the hydroxide build-up problem that plagued previous researchers developing iron flow batteries. Our proprietary solution to eliminate the hydroxide formation is known as the Proton Pump, and it works by utilizing hydrogen generated by side reactions on the negative electrode. The Proton Pump converts the hydrogen back into protons in the positive electrolyte. This process eliminates the hydroxide and stabilizes the electrolytes' pH levels. The Proton Pump is designed to allow the electrolyte to be used for over 20,000 cycles without any capacity fade.

Our batteries provide flexibility to grid operators and energy assurance for commercial and industrial customers. Our technology addresses energy delivery, duration and cycle-life in a single battery platform that compares favorably to lithium-ion batteries, the most widely deployed alternative technology. Using our iron flow battery technology, we are developing two products, each of which is able to provide reliable, safe, long-duration energy storage. Our first energy storage product, the Energy Warehouse, is our "behind-the-meter" solution (referring to solutions that are located on the customer's premises, behind the service demarcation with the utility) that offers energy storage ranging from four to 12-hour duration. Our second, larger scale energy storage product, the Energy Center, is designed for "front-of-the-meter" (referring to solutions that are located outside the customer's premises, typically operated by the utility or by third-party providers who sell energy into the grid, often known as independent power producers) deployments specifically for utility and large commercial and industrial consumers.

We began shipping our second-generation Energy Warehouses in the third quarter of 2021 and, during the second quarter of 2022, we received final customer acceptance for the first units shipped. With each battery deployed, we will further our mission to accelerate the transition to a zero-carbon energy future with increased grid reliability.

**Corporate Information**

On October 8, 2021 (the "Closing Date"), ESS, f/k/a ACON S2 Acquisition Corp., a Cayman Islands exempted company ("STWO"), consummated a merger pursuant to that certain Agreement and Plan of Merger, dated May 6, 2021 (the "Merger Agreement"), by and among STWO, SCharge Merger Sub, Inc., a Delaware corporation and wholly owned direct subsidiary of STWO ("Merger Sub"), and ESS Tech Subsidiary, Inc., a Delaware corporation, f/k/a ESS Tech, Inc. ("Legacy ESS") following the approval at a special meeting of the stockholders of STWO held on October 5, 2021.

Pursuant to the terms of the Merger Agreement, STWO deregistered by way of continuation under the Cayman Islands Companies Act (2021 Revision) and registered as a corporation in the State of Delaware under Part XII of the Delaware General Corporation Law, and a business combination between STWO and ESS was effected through the merger of Merger Sub with and into Legacy ESS, with Legacy ESS surviving as a wholly owned subsidiary of

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STWO (together with the other transactions described in the Merger Agreement, the "Merger"). On the Closing Date, the registrant changed its name from "ACON S2 Acquisition Corp" to "ESS Tech, Inc."

On October 11, 2021, our common stock and public warrants to purchase shares of common stock, exercisable for one share of common stock at a price of $11.50 per share, subject to adjustments, formerly those of STWO, began trading on the New York Stock Exchange under the ticker symbols "GWH" and "GWH.W," respectively.

Our principal executive offices are located at 26440 SW Parkway Ave., Bldg. 83, Wilsonville, Oregon 97070, and our telephone number is (855) 423-9920.

Our website address is https://essinc.com. The information on, or that can be accessed through, our website is not part of this prospectus and should not be considered to be part of this prospectus unless expressly noted.

**The Securities That May Be Offered**

We may offer or sell common stock, preferred stock, depositary shares, debt securities, warrants, subscription rights, purchase contracts and units in one or more offerings and in any combination. The aggregate offering price of the securities we sell pursuant to this prospectus will not exceed $300,000,000. Each time securities are offered with this prospectus, we will provide a prospectus supplement that will describe the specific amounts, prices and terms of the securities being offered and the net proceeds we expect to receive from that sale.

The securities may be sold to or through underwriters, dealers or agents or directly to purchasers or as otherwise set forth in the section of this prospectus under the heading "*Plan of Distribution*." Each prospectus supplement will set forth the names of any underwriters, dealers, agents or other entities involved in the sale of securities described in that prospectus supplement and any applicable fee, commission or discount arrangements with them.

***Common Stock***

We may offer shares of our common stock, par value $0.0001 per share, either alone or underlying other registered securities convertible into our common stock. Holders of our common stock are entitled to receive dividends declared by our board of directors out of funds legally available for the payment of dividends, subject to rights, if any, of preferred stockholders. We have not paid dividends in the past and have no current plans to pay dividends. Each holder of common stock is entitled to one vote per share. The holders of common stock have no preemptive rights.

***Preferred Stock***

Our board of directors has the authority, subject to limitations prescribed by Delaware law, to issue preferred stock in one or more series, to establish from time to time the number of shares to be included in each series, and to fix the designation, powers, preferences and rights of the shares of each series and any of its qualifications, limitations or restrictions, in each case without further vote or action by our stockholders. Each series of preferred stock offered by us will be more fully described in the particular prospectus supplement that will accompany this prospectus, including redemption provisions, rights in the event of our liquidation, dissolution or winding up, voting rights and rights to convert into common stock.

***Depositary Shares***

We may issue fractional shares of preferred stock that will be represented by depositary shares and depositary receipts.

Each series of depositary shares or depositary receipts offered by us will be more fully described in the particular prospectus supplement that will accompany this prospectus, including redemption provisions, rights in the event of our liquidation, dissolution or winding up, voting rights and rights to convert into common stock.

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***Debt Securities***

We may offer secured or unsecured obligations in the form of one or more series of senior or subordinated debt. The senior debt securities and the subordinated debt securities are together referred to in this prospectus as the "debt securities." The subordinated debt securities generally will be entitled to payment only after payment of our senior debt. Senior debt generally includes all debt for money borrowed by us, except debt that is stated in the instrument governing the terms of that debt to be not senior to, or to have the same rank in right of payment as, or to be expressly junior to, the subordinated debt securities. We may issue debt securities that are convertible into or exchangeable for shares of our common stock.

The debt securities will be issued under an indenture between us and a trustee to be identified in an accompanying prospectus supplement. We have summarized the general features of the debt securities to be governed by the indenture in this prospectus and the form of indenture has been filed as an exhibit to the registration statement of which this prospectus forms a part. We encourage you to read the indenture.

***Warrants***

We may offer warrants for the purchase of common stock, preferred stock, debt securities or depositary shares. We may offer warrants independently or together with other securities.

***Subscription Rights***

We may offer subscription rights to purchase our common stock, preferred stock, debt securities, depositary shares, warrants or units consisting of some or all of these securities. These subscription rights may be offered independently or together with any other security offered hereby and may or may not be transferable by the stockholder receiving the subscription rights in such offering.

***Purchase Contracts***

We may offer purchase contracts, including contracts obligating holders or us to purchase from the other a specific or variable number of securities at a future date or dates.

***Units***

We may offer units comprised of one or more of the other classes of securities described in this prospectus in any combination. Each unit will be issued so that the holder of the unit is also the holder of each security included in the unit.

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**RISK FACTORS**

An investment in our securities involves a high degree of risk. The prospectus supplement applicable to each offering of our securities will contain a discussion of the risks applicable to an investment in our securities. Prior to making a decision about investing in our securities, you should carefully consider the specific factors discussed under the section in the applicable prospectus supplement captioned "*Risk Factors*," together with all of the other information contained or incorporated by reference in the prospectus supplement or appearing or incorporated by reference in this prospectus. You should also consider the risks, uncertainties and assumptions discussed under "*Part I—Item 1A—Risk Factors*" of our most recent Annual Report on Form 10-K and in "*Part II—Item 1A—Risk Factors*" in our most recent Quarterly Report on Form 10-Q filed subsequent to such Form 10-K that are incorporated herein by reference, as may be amended, supplemented or superseded from time to time by other reports we file with the SEC in the future. The risks and uncertainties we have described are not the only ones we face. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also affect our operations.

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**CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS**

This prospectus, each prospectus supplement and the information incorporated by reference in this prospectus and each prospectus supplement contain certain statements that constitute "forward-looking statements" within the meaning of Section 27A of the Securities Act of 1933, as amended (the "Securities Act"), and Section 21E of the Securities Exchange Act of 1934, as amended (the "Exchange Act"). The words "believe," "may," "will," "estimate," "continue," "anticipate," "intend," "expect," "could," "would," "project," "plan," "potentially," "likely," and similar expressions and variations thereof are intended to identify forward-looking statements, but are not the exclusive means of identifying such statements. Those statements appear in this prospectus, any accompanying prospectus supplement and the documents incorporated herein and therein by reference, particularly in the sections captioned "*Risk Factors*" and "*Management's Discussion and Analysis of Financial Condition and Results of Operations*" and include statements regarding the intent, belief or current expectations of our management that are subject to known and unknown risks, uncertainties and assumptions. You are cautioned that any such forward-looking statements are not guarantees of future performance and involve risks and uncertainties, and that actual results may differ materially from those projected in the forward-looking statements as a result of various factors.

Because forward-looking statements are inherently subject to risks and uncertainties, some of which cannot be predicted or quantified, you should not rely upon forward-looking statements as predictions of future events. The events and circumstances reflected in the forward-looking statements may not be achieved or occur and actual results could differ materially from those projected in the forward-looking statements. Except as required by applicable law, including the securities laws of the United States and the rules and regulations of the SEC, we do not plan to publicly update or revise any forward-looking statements contained herein after we distribute this prospectus, whether as a result of any new information, future events or otherwise.

In addition, statements that "we believe" and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date of this prospectus, and although we believe such information forms a reasonable basis for such statements, such information may be limited or incomplete, and our statements should not be read to indicate that we have conducted a thorough inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain and investors are cautioned not to unduly rely upon these statements.

This prospectus, any prospectus supplement and the documents incorporated by reference in this prospectus may contain market data that we obtain from industry sources. These sources do not guarantee the accuracy or completeness of the information. Although we believe that our industry sources are reliable, we do not independently verify the information. The market data may include projections that are based on a number of other projections. While we believe these assumptions to be reasonable and sound as of the date of this prospectus, actual results may differ from the projections.

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**USE OF PROCEEDS**

We will retain broad discretion over the use of the net proceeds to us from the sale of our securities under this prospectus. Unless otherwise provided in the applicable prospectus supplement, we currently expect to use the net proceeds that we receive from this offering for working capital and other general corporate purposes. The expected use of net proceeds of this offering represents our current intentions based on our present plans and business conditions. We cannot specify with certainty all of the particular uses for the net proceeds to be received upon the closing of this offering. Pending these uses, we plan to invest the net proceeds of this offering in short- and intermediate-term, interest-bearing obligations, investment-grade instruments, certificates of deposit or direct or guaranteed obligations of the U.S. government.

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**DESCRIPTION OF CAPITAL STOCK**

*The following descriptions of our capital stock and certain provisions of our certificate of incorporation and amended and restated bylaws are summaries and are qualified by reference to the certificate of incorporation and the amended and restated bylaws. Copies of these documents have been filed with the SEC as exhibits to our registration statement, of which this prospectus forms a part.*

Our authorized capital stock consists of 2,200,000,000 shares of capital stock, of which:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• 2,000,000,000 shares are designated as common stock, par value $0.0001 per share; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• 200,000,000 shares are designated as preferred stock, par value $0.0001 per share.

Our board of directors is authorized, without stockholder approval, except as required by the listing standards of the New York Stock Exchange, to issue additional shares of capital stock.

**Common Stock**

The holders of our common stock are entitled to one vote per share on all matters submitted to a vote of the stockholders and do not have cumulative voting rights. Accordingly, subject to the rights of holders of any preferred stock outstanding at the time, where a quorum is present at a meeting of stockholders, directors are elected by plurality vote. Subject to preferences that may be applicable to any preferred stock outstanding at the time, the holders of outstanding shares of our common stock are entitled to receive ratably any dividends declared by the board of directors out of assets legally available. Upon the liquidation, dissolution or winding up, holders of our common stock are entitled to share ratably in all assets remaining after payment of liabilities and the liquidation preference of any then outstanding shares of preferred stock. Holders of our common stock have no preemptive or conversion rights or other subscription rights. There are no redemption or sinking fund provisions applicable to our common stock.

**Preferred Stock**

Our board of directors is authorized, subject to limitations prescribed by the Delaware General Corporation Law ("DGCL"), to issue preferred stock in one or more series, to establish from time to time the number of shares to be included in each series, and to fix the designation, powers, preferences, and rights of the shares of each series and any of its qualifications, limitations, or restrictions, in each case without further vote or action by the stockholders. The board of directors is empowered to increase, but not above the total number of authorized shares of preferred stock, or decrease the number of shares of any series of preferred stock, but not below the number of shares of that series then outstanding, without any further vote or action by the stockholders. Our board of directors is able to authorize the issuance of preferred stock with voting or conversion rights that could adversely affect the voting power or other rights of the holders of our common stock. The issuance of preferred stock, while providing flexibility in connection with possible acquisitions and other corporate purposes, could, among other things, have the effect of delaying, deferring, or preventing a change in control of ESS and might adversely affect the market price of our common stock and the voting and other rights of the holders of our common stock. There are currently no plans to issue any shares of preferred stock.

**Warrants**

***Public Warrants***

Each whole warrant entitles the registered holder to purchase one share of common stock at a price of $11.50 per share, subject to adjustment as discussed below. Pursuant to the Warrant Agreement, dated September 16, 2020, as amended by the Assignment, Assumption and Amendment Agreement, dated October 8, 2021 (together, the "Warrant Agreement"), a warrant holder may exercise its warrants only for a whole number of shares of common stock. This means only a whole warrant may be exercised at a given time by a warrant holder. No fractional warrants will be issued upon separation of the units and only whole warrants trade. The warrants expire on October 8, 2026, at 5:00 p.m., New York City time, or earlier upon redemption or liquidation.

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*Redemption of Warrants when the price per share of our common stock equals or exceeds $18.00*. Once the public warrants become exercisable, we may redeem the outstanding warrants (excluding the private placement warrants):

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• in whole and not in part;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• at a price of $0.01 per public warrant;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• upon a minimum of 30 days' prior written notice of redemption to each warrant holder; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• if, and only if, the closing price of our common stock equals or exceeds $18.00 per share (as adjusted for adjustments to the number of shares issuable upon exercise or the exercise price of a warrant as described under the heading "—*Anti-dilution Adjustments*") for any 20 trading days within a 30-trading day period ending three trading days before we send the notice of redemption to the warrant holders.

We will not redeem the warrants as described above unless a registration statement under the Securities Act covering the issuance of our common stock issuable upon exercise of the warrants is then effective and a current prospectus relating to those shares of our common stock is available throughout the 30-day Redemption Period (as defined below). If and when the warrants become redeemable, we may exercise our redemption right even if we are unable to register or qualify the underlying securities for sale under all applicable state securities laws.

We have established the last of the redemption criteria discussed above to prevent a redemption call unless there is at the time of the call a significant premium to the warrant exercise price. If the foregoing conditions are satisfied and we issue a notice of redemption of the warrants, each warrant holder will be entitled to exercise his, her or its warrant prior to the scheduled redemption date. However, the price of our common stock may fall below the $18.00 redemption trigger price (as adjusted for adjustments to the number of shares issuable upon exercise or the exercise price of a warrant as described under the heading "—*Anti-dilution Adjustments*") as well as the $11.50 (for whole shares) warrant exercise price after the redemption notice is issued.

Redemption of warrants when the price per share of our common stock equals or exceeds $10.00. Once the warrants become exercisable, we may redeem the outstanding warrants:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• in whole and not in part;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• at $0.10 per warrant upon a minimum of 30 days' prior written notice of redemption provided that holders will be able to exercise their warrants on a cashless basis prior to redemption and receive that number of shares determined by reference to the table below, based on the redemption date and the "fair market value" of our common stock (as defined below) except as otherwise described below;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• if, and only if, the closing price of our common stock equals or exceeds $10.00 per public share (as adjusted for adjustments to the number of shares issuable upon exercise or the exercise price of a warrant as described under the heading "—*Anti-Dilution Adjustments*") for any 20 trading days within the 30-trading day period ending three trading days before we send the notice of redemption to the warrant holders; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• if the closing price of our common stock for any 20 trading days within a 30-trading day period ending on the third trading day prior to the date on which we send the notice of redemption to the warrant holders is less than $18.00 per share (as adjusted for adjustments to the number of shares issuable upon exercise or the exercise price of a warrant as described under the heading "—*Anti-dilution Adjustments*"), the preferred stock must also be concurrently called for redemption on the same terms as the outstanding public warrants, as described above.

In accordance with the Warrant Agreement, in the event that we elect to redeem the outstanding warrants as set forth under the headings "—*Redemption of Warrants when the price per share of our common stock equals or exceeds $18.00*" and "—*Redemption of Warrants when the price per share of our common stock equals or exceeds $10.00*," we will fix a date for the redemption. Notice of redemption will be mailed by first class mail, postage prepaid, by us to all shareholders, including beneficial owners, not less than 30 days prior to the redemption date (the "30-day Redemption Period") to the registered holders of the warrants to be redeemed at their last addresses as

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they appear on the registration books. Any notice mailed in the manner provide above will be conclusively presumed to have been duly given whether or not the registered holder of the warrants received such notice. We are not contractually obligated to notify investors when its warrants become eligible for redemption, and does not intend to so notify investors upon eligibility of the warrants for redemption.

Beginning on the date the notice of redemption is given until the warrants are redeemed or exercised, holders may elect to exercise their warrants on a cashless basis. The numbers in the table below represent the number of shares of our common stock that a warrant holder will receive upon such cashless exercise in connection with a redemption by us pursuant to this redemption feature, based on the "fair market value" of our common stock on the corresponding redemption date (assuming holders elect to exercise their warrants and such warrants are not redeemed for $0.10 per warrant), determined for these purposes based on volume weighted average price of our common stock during the 10 trading days immediately following the date on which the notice of redemption is sent to the holders of warrants, and the number of months that the corresponding redemption date precedes the expiration date of the warrants, each as set forth in the table below. We will provide warrant holders with the final fair market value no later than one business day after the 10-trading day period described above ends.

The share prices set forth in the column headings of the table below will be adjusted as of any date on which the number of shares issuable upon exercise of a warrant or the exercise price of a warrant is adjusted as set forth under the heading "—*Anti-dilution Adjustments*" below. If the number of shares issuable upon exercise of a warrant is adjusted, the adjusted share prices in the column headings will equal the share prices immediately prior to such adjustment, multiplied by a fraction, the numerator of which is the number of shares deliverable upon exercise of a warrant immediately prior to such adjustment and the denominator of which is the number of shares deliverable upon exercise of a warrant as so adjusted. The number of shares in the table below shall be adjusted in the same manner and at the same time as the number of shares issuable upon exercise of a warrant. If the exercise price of a warrant is adjusted, (a) in the case of an adjustment pursuant to the fifth paragraph under the heading "—*Anti-dilution Adjustments*" below, the adjusted share prices in the column headings will equal the unadjusted share price multiplied by a fraction, the numerator of which is the higher of the Market Value and the Newly Issued Price as set forth under the heading "—*Anti-dilution Adjustments*" and the denominator of which is $10.00 and (b) in the case of an adjustment pursuant to the second paragraph under the heading "—*Anti-dilution Adjustments*" below, the

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adjusted share prices in the column headings will equal the unadjusted share price less the decrease in the exercise price of a warrant pursuant to such exercise price adjustment.

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| | | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|:---|
| **Redemption Date<br>(period to expiration of warrants)** | **Fair Market Value of Common Stock** | **Fair Market Value of Common Stock** | **Fair Market Value of Common Stock** | **Fair Market Value of Common Stock** | **Fair Market Value of Common Stock** | **Fair Market Value of Common Stock** | **Fair Market Value of Common Stock** | **Fair Market Value of Common Stock** | **Fair Market Value of Common Stock** |
| **Redemption Date<br>(period to expiration of warrants)** | **$10.00** | **$11.00** | **$12.00** | **$13.00** | **$14.00** | **$15.00** | **$16.00** | **$17.00** | **$18.00** |
| 60 months | 0.261 | 0.281 | 0.297 | 0.311 | 0.324 | 0.337 | 0.348 | 0.358 | 0.361 |
| 57 months | 0.257 | 0.277 | 0.294 | 0.310 | 0.324 | 0.337 | 0.348 | 0.358 | 0.361 |
| 54 months | 0.252 | 0.272 | 0.291 | 0.307 | 0.322 | 0.335 | 0.347 | 0.357 | 0.361 |
| 51 months | 0.246 | 0.268 | 0.287 | 0.304 | 0.320 | 0.333 | 0.346 | 0.357 | 0.361 |
| 48 months | 0.241 | 0.263 | 0.283 | 0.301 | 0.317 | 0.332 | 0.344 | 0.356 | 0.361 |
| 45 months | 0.235 | 0.258 | 0.279 | 0.298 | 0.315 | 0.330 | 0.343 | 0.356 | 0.361 |
| 42 months | 0.228 | 0.252 | 0.274 | 0.294 | 0.312 | 0.328 | 0.342 | 0.355 | 0.361 |
| 39 months | 0.221 | 0.246 | 0.269 | 0.290 | 0.309 | 0.325 | 0.340 | 0.354 | 0.361 |
| 36 months | 0.213 | 0.239 | 0.263 | 0.285 | 0.305 | 0.323 | 0.339 | 0.353 | 0.361 |
| 33 months | 0.205 | 0.232 | 0.257 | 0.280 | 0.301 | 0.320 | 0.337 | 0.352 | 0.361 |
| 30 months | 0.196 | 0.224 | 0.250 | 0.274 | 0.297 | 0.316 | 0.335 | 0.351 | 0.361 |
| 27 months | 0.185 | 0.214 | 0.242 | 0.268 | 0.291 | 0.313 | 0.332 | 0.350 | 0.361 |
| 24 months | 0.173 | 0.204 | 0.233 | 0.260 | 0.285 | 0.308 | 0.329 | 0.348 | 0.361 |
| 21 months | 0.161 | 0.193 | 0.223 | 0.252 | 0.279 | 0.304 | 0.326 | 0.347 | 0.361 |
| 18 months | 0.146 | 0.179 | 0.211 | 0.242 | 0.271 | 0.298 | 0.322 | 0.345 | 0.361 |
| 15 months | 0.130 | 0.164 | 0.197 | 0.230 | 0.262 | 0.291 | 0.317 | 0.342 | 0.361 |
| 12 months | 0.111 | 0.146 | 0.181 | 0.216 | 0.250 | 0.282 | 0.312 | 0.339 | 0.361 |
| 9 months | 0.090 | 0.125 | 0.162 | 0.199 | 0.237 | 0.272 | 0.305 | 0.336 | 0.361 |
| 6 months | 0.065 | 0.099 | 0.137 | 0.178 | 0.219 | 0.259 | 0.296 | 0.331 | 0.361 |
| 3 months | 0.034 | 0.065 | 0.104 | 0.150 | 0.197 | 0.243 | 0.286 | 0.326 | 0.361 |
| 0 months |  |  | 0.042 | 0.115 | 0.179 | 0.233 | 0.281 | 0.323 | 0.361 |

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The exact fair market value and redemption date may not be set forth in the table above, in which case, if the fair market value is between two values in the table or the redemption date is between two redemption dates in the table, the number of shares of common stock to be issued for each warrant exercised will be determined by a straight-line interpolation between the number of shares set forth for the higher and lower fair market values and the earlier and later redemption dates, as applicable, based on a 365 or 366-day year, as applicable. For example, if the volume weighted average price of our common stock during the 10 trading days immediately following the date on which the notice of redemption is sent to the holders of the warrants is $11.00 per share, and at such time there are 57 months until the expiration of the warrants, holders may choose to, in connection with this redemption feature, exercise their warrants for 0.277 shares of common stock for each whole warrant. For an example where the exact fair market value and redemption date are not as set forth in the table above, if the volume weighted average price of our common stock during the 10 trading days immediately following the date on which the notice of redemption is sent to the holders of the warrants is $13.50 per share, and at such time there are 38 months until the expiration of the warrants, holders may choose to, in connection with this redemption feature, exercise their warrants for 0.298 shares of common stock for each whole warrant. In no event will the warrants be exercisable on a cashless basis in connection with this redemption feature for more than 0.361 shares of common stock per warrant (subject to adjustment). Finally, as reflected in the table above, if the warrants are out of the money and about to expire, they cannot be exercised on a cashless basis in connection with a redemption by us pursuant to this redemption feature, since they will not be exercisable for any shares of common stock.

This redemption feature differs from the typical warrant redemption features used in some other blank check offerings, which only provide for a redemption of warrants for cash (other than the private placement warrants) when the trading price of our common stock exceeds $18.00 per share for a specified period of time. This redemption feature is structured to allow for all of the outstanding warrants to be redeemed when our common stock

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is trading at or above $10.00 per public share, which may be at a time when the trading price of our common stock is below the exercise price of the warrants. We have established this redemption feature to provide it with the flexibility to redeem the warrants without the warrants having to reach the $18.00 per share threshold set forth above under "—*Redemption of warrants when the price per share of our common stock equals or exceeds $18.00*." Holders choosing to exercise their warrants in connection with a redemption pursuant to this feature will, in effect, receive a number of shares for their warrants based on an option pricing model with a fixed volatility input as of the date of this prospectus. This redemption right provides us with an additional mechanism by which to redeem all of the outstanding warrants, and therefore have certainty as to its capital structure as the warrants would no longer be outstanding and would have been exercised or redeemed. We will be required to pay the applicable redemption price to warrant holders if we choose to exercise this redemption right and it will allow us to quickly proceed with a redemption of the warrants if we determine it is in its best interest to do so. As such, we would redeem the warrants in this manner when we believe it is in its best interest to update its capital structure to remove the warrants and pay the redemption price to the warrant holders.

As stated above, we can redeem the warrants when our common stock is trading at a price starting at $10.00, which is below the exercise price of $11.50, because it will provide certainty with respect to our capital structure and cash position while providing warrant holders with the opportunity to exercise their warrants on a cashless basis for the applicable number of shares. If we choose to redeem the warrants when our common stock is trading at a price below the exercise price of the warrants, this could result in the warrant holders receiving fewer shares of Common Stock than they would have received if they had chosen to wait to exercise their warrants for our common stock if and when such shares were trading at a price higher than the exercise price of $11.50.

No fractional shares of common stock will be issued upon exercise. If, upon exercise, a holder would be entitled to receive a fractional interest in a share, we will round down to the nearest whole number of the number of shares of common stock to be issued to the holder.

*Redemption procedures*. A holder of a warrant may notify us in writing in the event it elects to be subject to a requirement that such holder will not have the right to exercise such warrant, to the extent that after giving effect to such exercise, such person (together with such person's affiliates), to the warrant agent's actual knowledge, would beneficially own in excess of 9.8% (or such other amount as a holder may specify) of our common stock issued and outstanding immediately after giving effect to such exercise.

*Anti-dilution Adjustments*. If the number of outstanding shares of common stock is increased by a capitalization or share dividend payable in shares of common stock, or by a split-up of ordinary shares or other similar event, then, on the effective date of such capitalization or share dividend, split-up or similar event, the number of shares of common stock issuable on exercise of each warrant will be increased in proportion to such increase in the outstanding ordinary shares. A rights offering made to all or substantially all holders of ordinary shares entitling holders to purchase shares of common stock at a price less than the "historical fair market value" (as defined below) will be deemed a share dividend of a number of shares of common stock equal to the product of (i) the number of shares of common stock actually sold in such rights offering (or issuable under any other equity securities sold in such rights offering that are convertible into or exercisable for shares of common stock) and (ii) one minus the quotient of (x) the price per share of common stock paid in such rights offering and (y) the historical fair market value. For these purposes, (i) if the rights offering is for securities convertible into or exercisable for shares of common stock, in determining the price payable for shares of common stock there will be taken into account any consideration received for such rights, as well as any additional amount payable upon exercise or conversion and (ii) "historical fair market value" means the volume weighted average price of our common stock as reported during the 10 trading day period ending on the trading day prior to the first date on which the shares of common stock trade on the applicable exchange or in the applicable market, regular way, without the right to receive such rights.

In addition, if we, at any time while the warrants are outstanding and unexpired, pays a dividend or make a distribution in cash, securities or other assets to all or substantially all of the holders of shares of common stock on account of such shares (or other securities into which the warrants are convertible), other than (a) as described above, or (b) any cash dividends or cash distributions which, when combined on a per share basis with all other cash dividends and cash distributions paid on the shares of common stock during the 365-day period ending on the date of declaration of such dividend or distribution does not exceed $0.50 (as adjusted to appropriately reflect any other

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adjustments and excluding cash dividends or cash distributions that resulted in an adjustment to the exercise price or to the number of the shares of common stock issuable on exercise of each warrant) but only with respect to the amount of the aggregate cash dividends or cash distributions equal to or less than $0.50 per share.

If the number of outstanding shares of common stock is decreased by a consolidation, combination, reverse share split or reclassification of shares of common stock or other similar event, then, on the effective date of such consolidation, combination, reverse share split, reclassification or similar event, the number of shares of common stock issuable on exercise of each warrant will be decreased in proportion to such decrease in outstanding shares of common stock.

Whenever the number of shares of common stock purchasable upon the exercise of the warrants is adjusted, as described above, the warrant exercise price will be adjusted by multiplying the warrant exercise price immediately prior to such adjustment by a fraction (x) the numerator of which will be the number of shares of common stock purchasable upon the exercise of the warrants immediately prior to such adjustment and (y) the denominator of which will be the number of shares of common stock so purchasable immediately thereafter.

In case of any reclassification or reorganization of the outstanding shares of common stock (other than those described above or that solely affects the par value of such shares of common stock), or in the case of any merger or consolidation of us with or into another corporation (other than a consolidation or merger in which we are the continuing corporation and that does not result in any reclassification or reorganization of outstanding shares of common stock), or in the case of any sale or conveyance to another corporation or entity of our assets or other property as an entirety or substantially as an entirety in connection with which we are dissolved, the holders of the warrants will thereafter have the right to purchase and receive, upon the basis and upon the terms and conditions specified in the warrants and in lieu of the shares of common stock immediately theretofore purchasable and receivable upon the exercise of the rights represented thereby, the kind and amount of shares of common stock or other securities or property (including cash) receivable upon such reclassification, reorganization, merger or consolidation, or upon a dissolution following any such sale or transfer, that the holder of the warrants would have received if such holder had exercised their warrants immediately prior to such event. However, if such holders were entitled to exercise a right of election as to the kind or amount of securities, cash or other assets receivable upon such consolidation or merger, then the kind and amount of securities, cash or other assets for which each warrant will become exercisable will be deemed to be the weighted average of the kind and amount received per share by such holders in such consolidation or merger that affirmatively make such election, and if a tender, exchange or redemption offer has been made to and accepted by such holders under circumstances in which, upon completion of such tender or exchange offer, the maker thereof, together with members of any group (within the meaning of Rule 13d-5(b)(1) under the Exchange Act) of which such maker is a part, and together with any affiliate or associate of such maker (within the meaning of Rule 12b-2 under the Exchange Act) and any members of any such group of which any such affiliate or associate is a part, own beneficially (within the meaning of Rule 13d-3 under the Exchange Act) more than 50% of the issued and outstanding shares of common stock, the holder of a warrant will be entitled to receive the highest amount of cash, securities or other property to which such holder would actually have been entitled as a shareholder if such warrant holder had exercised the warrant prior to the expiration of such tender or exchange offer, accepted such offer and all of the shares of common stock held by such holder had been purchased pursuant to such tender or exchange offer, subject to adjustment (from and after the consummation of such tender or exchange offer) as nearly equivalent as possible to the adjustments provided for in the warrant agreement. If less than 70% of the consideration receivable by the holders of shares of common stock in such a transaction is payable in the form of shares in the successor entity that is listed for trading on a national securities exchange or is quoted in an established over-the-counter market, or is to be so listed for trading or quoted immediately following such event, and if the registered holder of the warrant properly exercises the warrant within thirty days following public disclosure of such transaction, the warrant exercise price will be reduced as specified in the warrant agreement based on the Black-Scholes value (as defined in the warrant agreement) of the warrant. The purpose of such exercise price reduction is to provide additional value to holders of the warrants when an extraordinary transaction occurs during the exercise period of the warrants pursuant to which the holders of the warrants otherwise do not receive the full potential value of the warrants. The purpose of such exercise price reduction is to provide additional value to holders of the warrants when an extraordinary transaction occurs during

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the exercise period of the warrants pursuant to which the holders of the warrants otherwise do not receive the full potential value of the warrants.

The warrant holders do not have the rights or privileges of holders of ordinary shares and any voting rights until they exercise their warrants and receive shares of common stock. After the issuance of shares of common stock upon exercise of the warrants, each holder will be entitled to one vote for each share held of record on all matters to be voted on by shareholders.

No fractional warrants will be issued upon separation of the units and only whole warrants will trade. If, upon exercise of the warrants, a holder would be entitled to receive a fractional interest in a share, we will, upon exercise, round down to the nearest whole number the number of shares of common stock to be issued to the warrant holder.

We have agreed that, subject to applicable law, any action, proceeding or claim against it arising out of or relating in any way to the Warrant Agreement will be brought and enforced in the courts of the State of New York or the United States District Court for the Southern District of New York, and we irrevocably submits to such jurisdiction, which jurisdiction will be the exclusive forum for any such action, proceeding or claim. This provision applies to claims under the Securities Act but does not apply to claims under the Exchange Act or any claim for which the federal district courts of the United States of America are the sole and exclusive forum.

***Private Placement Warrants***

Except as described below, the private placement warrants have terms and provisions that are identical to those of the public warrants. 3,500,000 of the private placement warrants vested on October 8, 2021 pursuant to the terms of the Sponsor Letter Agreement (the "Sponsor Letter Agreement"), dated as of May 6, 2021, by and among ACON S2 Sponsor, L.L.C., a Delaware limited liability company (the "Sponsor"), ESS, Legacy ESS, and, solely for purposes of certain sections, the Insiders (as defined in the Sponsor Letter Agreement). The remaining 583,334 of the private placement warrants vested on November 9, 2021, upon the occurrence of the earnout milestone events pursuant to the Sponsor Letter Agreement. The private placement warrants will not be redeemable by us (except as described under "—*Public Warrants—Redemption of warrants when the price per share of our common stock equals or exceeds $10.00*") so long as they are held by the Sponsor or its permitted transferees (except as otherwise set forth herein). The Sponsor, or its permitted transferees, has the option to exercise the private placement warrants on a cashless basis. If the private placement warrants are held by holders other than the Sponsor or its permitted transferees, the private placement warrants will be redeemable by us in all redemption scenarios and exercisable by the holders on the same basis as the public warrants. Any amendment to the terms of the private placement warrants or any provision of the Warrant Agreement with respect to the private placement warrants will require a vote of holders of at least 50% of the number of the then outstanding private placement warrants.

Except as described above under "—*Public Warrants—Redemption of warrants when the price per share of our common stock equals or exceeds $10.00*," if holders of the private placement warrants elect to exercise them on a cashless basis, they would pay the exercise price by surrendering his, her or its warrants for that number of shares of common stock equal to the quotient obtained by dividing (x) the product of the number of shares of common stock underlying the warrants, multiplied by the excess of the "Sponsor fair market value" (as defined below) over the exercise price of the warrants by (y) the Sponsor fair market value. For these purposes, the "Sponsor fair market value" shall mean the average reported closing price of the shares of common stock for the 10 trading days ending on the third trading day prior to the date on which the notice of warrant exercise is sent to the warrant agent.

**Registration Rights**

Under the Registration Rights Agreement (the "Registration Rights Agreement"), dated October 8, 2021, by and among ESS, the Sponsor and other holders of common stock, the holders of 73,022,199 shares of common stock or their permitted transferees have the right to require us to register the offer and sale of their shares, or to include their shares in any registration statement we file, in each case as described below.

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***Resale Registration Statement***

We filed a registration statement on Form S-1 on November 2, 2021 (File No. 333-260693) (the "Initial Resale Registration Statement"), Post-Effective Amendment No. 1 to the Initial Resale Registration Statement on December 9, 2021, and a registration statement on Form S-1 and Post-Effective Amendment No. 2 to the Initial Resale Registration Statement on March 4, 2022 (File No. 333-263316) (the "Additional Resale Registration Statement" and together with the Initial Resale Registration Statement, the "Resale Registration Statements") for an offering of our common stock to be made on a delayed or continuous basis. Pursuant to the Registration Rights Agreement, the holders of at least $30.0 million of shares having registration rights then outstanding can request that we effect an underwritten public offering pursuant to such Resale Registration Statements. We are only obligated to effect no more than four such registrations within any 12-month period. These registration rights are subject to specified conditions and limitations, including the right of the underwriters to limit the number of shares included in any such registration under certain circumstances.

The Additional Resale Registration Statement was declared effective by the SEC on March 16, 2022.

On November 3, 2022, we filed a post-effective amendment to the Resale Registration Statements to convert the Resale Registration Statements on Form S-1 into a registration statement on Form S-3.

***Piggyback Registration Rights***

If we propose to register the offer and sale of our common stock under the Securities Act, all holders of these shares then outstanding can request that we include their shares in such registration, subject to certain marketing and other limitations, including the right of the underwriters to limit the number of shares included in any such registration statement under certain circumstances. As a result, whenever we propose to file a registration statement under the Securities Act, other than with respect to a registration (i) relating to any employee stock option or other benefit plan, (ii) on Form S-4 (or similar form that relates to a transaction subject to Rule 145 under the Securities Act or any successor rule thereto), (iii) relating to an offering of debt that is convertible into equity securities of ESS, or (iv) for a dividend reinvestment plan.

***Termination***

The registration rights terminate upon the date as of which all of the registrable securities have been sold pursuant to a registration statement or are permitted to be sold under Rule 144 or any similar provision under the Securities Act.

**Registration Rights for PIPE Shares**

On May 6, 2021, STWO entered into subscription agreements with certain investors, pursuant to which STWO agreed to issue and sell to the investors 25,000,000 shares of common stock ("PIPE Shares") at a purchase price of $10.00 per share for an aggregate commitment of $250,000,000 (the "PIPE Financing"). The PIPE Financing was consummated on October 8, 2021. The Resale Registration Statements also registered the PIPE Shares for resale.

**Form S-8 Registration Statement**

We filed a registration statement on Form S-8 under the Securities Act to register the shares of Common Stock issued or issuable under our 2021 Employee Stock Purchase Plan, 2021 Equity Incentive Plan and 2014 Equity Incentive Plan. The Form S-8 registration statement became effective automatically upon filing, and shares covered by the registration statement became eligible for sale in the public market, subject to Rule 144 limitations applicable to affiliates and vesting restrictions.

**Limitation of Liability and Indemnification**

Our certificate of incorporation contains provisions that limit the liability of our directors for monetary damages to the fullest extent permitted by the DGCL. In addition, if the DGCL is amended to authorize corporate action further eliminating or limiting the personal liability of directors of corporations, then the personal liability of our directors will be eliminated or limited to the greatest extent permitted by the DGCL.

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In addition, our bylaws, which became effective upon consummation of the Merger, provides that we will indemnify our directors and officers to the fullest extent permitted by the DGCL and we may indemnify our employees, agents and any other persons to the extent not prohibited by the DGCL or other applicable law. Our amended and restated bylaws will also provide that we must advance expenses incurred by or on behalf of a director or officer in advance of the final disposition of any action or proceeding, subject to limited exceptions.

Further, we have entered into indemnification agreements with our directors and executive officers that are broader than the specific indemnification provisions contained in the DGCL and may continue to do so in the future. These indemnification agreements require us to indemnify our directors and executive officers against liabilities that may arise by reason of their status or service. These indemnification agreements also require us to advance all expenses reasonably and actually incurred by our directors and executive officers in investigating or defending any such action, suit or proceeding. We believe that these agreements are necessary to attract and retain qualified individuals to serve as directors and executive officers.

We also maintain insurance policies under which our directors and officers are insured, within the limits and subject to the limitations of those policies, against certain expenses in connection with the defense of, and certain liabilities which might be imposed as a result of, actions, suits, or proceedings to which they are parties by reason of being or having served as a director or officer of ESS. At present, we are not aware of any pending litigation or proceeding involving any person who is one of our directors or officers or is or was one of our directors or officers, or is or was one of our directors or officers serving at our request as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, for which indemnification is sought, and we are not aware of any threatened litigation that may result in claims for indemnification.

**Description of Certain Terms in the Charter Documents and Delaware Law**

The certificate of incorporation and amended and restated bylaws contain provisions that could have the effect of delaying, deferring or discouraging another party from acquiring control of ESS. These provisions and certain provisions of Delaware law, which are summarized below, could discourage takeovers, coercive or otherwise. These provisions are also designed, in part, to encourage persons seeking to acquire control of ESS to negotiate first with our board of directors. ESS believes that the benefits of increased protection of the potential ability to negotiate with an unfriendly or unsolicited acquirer outweigh the disadvantages of discouraging a proposal to acquire the Company.

*Issuance of Undesignated Preferred Stock*. As discussed above under "—*Preferred Stock*," our board of directors has the ability to designate and issue preferred stock with voting or other rights or preferences that could deter hostile takeovers or delay changes in control or management.

*Limits on Ability of Stockholders to Act by Written Consent or Call a Special Meeting*. The certificate of incorporation provides that the stockholders may not act by written consent. This limit on the ability of stockholders to act by written consent may lengthen the amount of time required to take stockholder actions. As a result, the holders of a majority of our capital stock may not be able to amend the amended and restated bylaws or remove directors without holding a meeting of stockholders called in accordance with the amended and restated bylaws.

In addition, the amended and restated bylaws provide that special meetings of the stockholders may be called only by the chairperson of the board of directors, the chief executive officer, the president, or a majority of our board of directors (measured based on the total authorized directorships, including any vacancies or unfilled seats). A stockholder may not call a special meeting, which may delay the ability of the stockholders to force consideration of a proposal or for holders controlling a majority of our capital stock to take any action, including the removal of directors.

*Requirements for Advance Notification of Stockholder Nominations and Proposals*. The amended and restated bylaws establish advance notice procedures with respect to stockholder proposals and the nomination of candidates for election as directors, other than nominations made by or at the direction of our board of directors or a committee of our board of directors. These advance notice procedures may have the effect of precluding the conduct of certain business at a meeting if the proper procedures are not followed and may also discourage or deter a potential acquirer

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from conducting a solicitation of proxies to elect its own slate of directors or otherwise attempt to obtain control of ESS.

*Board Classification*. The certificate of incorporation provides that our board of directors is divided into three classes, one class of which is elected each year by the stockholders. The directors in each class will serve for a three-year term. The classified board of directors may tend to discourage a third party from making a tender offer or otherwise attempting to obtain control of ESS because it generally makes it more difficult for stockholders to replace a majority of the directors.

*Election and Removal of Directors*. The certificate of incorporation contains provisions that establish specific procedures for appointing and removing members of our board of directors. Under the certificate of incorporation and amended and restated bylaws, vacancies and newly created directorships on our board of directors may be filled only by a majority of the directors then serving on our board of directors. Under the certificate of incorporation, directors may be removed only for cause by the affirmative vote of the holders of at least a majority of the voting power of the issued and outstanding capital stock of the Company entitled to vote in the election of directors.

*No Cumulative Voting*. The DGCL provides that stockholders are not entitled to the right to cumulate votes in the election of directors unless a corporation's certificate of incorporation provides otherwise. The certificate of incorporation and amended and restated bylaws do not expressly provide for cumulative voting. Without cumulative voting, a minority stockholder may not be able to gain as many seats on the board of directors as the stockholder would be able to gain if cumulative voting were permitted. The absence of cumulative voting makes it more difficult for a minority stockholder to gain a seat on the board of directors to, among other things, influence the board of directors' decision regarding a takeover.

*Amendment of Charter Provision*. Any amendment of the above provisions in the certificate of incorporation or amended and restated bylaws would require approval by holders of at least 662/3% of the then outstanding capital stock entitled to vote, voting together as a single class.

*Delaware Anti-Takeover Statute*. ESS is subject to the provisions of Section 203 of the DGCL regulating corporate takeovers. In general, Section 203 prohibits a publicly held Delaware corporation from engaging, under certain circumstances, in a business combination with an interested stockholder for a period of three years following the date the person became an interested stockholder unless:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• prior to the date of the transaction, the board of directors approved either the business combination or the transaction that resulted in the stockholder becoming an interested stockholder;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• upon completion of the transaction that resulted in the stockholder becoming an interested stockholder, the interested stockholder owned at least 85% of the voting stock of the corporation outstanding at the time the transaction commenced, excluding for purposes of determining the voting stock outstanding, but not the outstanding voting stock owned by the interested stockholder, (1) shares owned by persons who are directors and also officers and (2) shares owned by employee stock plans in which employee participants do not have the right to determine confidentially whether shares held subject to the plan will be tendered in a tender or exchange offer; or

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• at or subsequent to the date of the transaction, the business combination is approved by the board of directors and authorized at an annual or special meeting of stockholders, and not by written consent, by the affirmative vote of at least 66 2/3% of the outstanding voting stock that is not owned by the interested stockholder.

Generally, a business combination includes a merger, asset or stock sale or other transaction resulting in a financial benefit to the interested stockholder. An interested stockholder is generally defined under Section 203 to be a person who, together with affiliates and associates, owns or, within three years prior to the determination of interested stockholder status, did own 15% or more of a corporation's outstanding voting stock. ESS expects the existence of this provision to have an anti-takeover effect with respect to transactions our board of directors does not approve in advance. We also anticipate that Section 203 may discourage attempts that might result in a premium over the market price for the shares of common stock held by stockholders.

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The provisions of Delaware law and the provisions of the certificate of incorporation and amended and restated bylaws could have the effect of discouraging others from attempting hostile takeovers and as a consequence, they might also inhibit temporary fluctuations in the market price of our common stock that often result from actual or rumored hostile takeover attempts. These provisions might also have the effect of preventing changes in management. It is also possible that these provisions could make it more difficult to accomplish transactions that stockholders might otherwise deem to be in their best interests.

*Choice of Forum*. The amended and restated bylaws provides that the Court of Chancery of the State of Delaware will be the exclusive forum for: (i) any derivative action or proceeding brought on ESS' behalf; (ii) actions asserting a breach of fiduciary duty; (iii) any action arising under the DGCL, the certificate of incorporation or amended and restated bylaws; and (iv) any action asserting a claim against ESS that is governed by the internal-affairs doctrine. The amended and restated bylaws further provide that the federal district courts of the United States will be the exclusive forum for resolving any complaint asserting a cause of action arising under the Securities Act.

**Transfer Agent and Warrant Agent**

The transfer agent and warrant agent for the common stock and warrants is Computershare Inc. The transfer agent's address is 150 Royall Street, Canton, MA 02021 and its telephone number is (206) 406-5789.

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**DESCRIPTION OF DEBT SECURITIES**

The following description, together with the additional information we include in any applicable prospectus supplement, summarizes certain general terms and provisions of the debt securities that we may offer under this prospectus. When we offer to sell a particular series of debt securities, we will describe the specific terms of the series in a supplement to this prospectus. We will also indicate in the supplement to what extent the general terms and provisions described in this prospectus apply to a particular series of debt securities.

We may issue debt securities either separately, or together with, or upon the conversion or exercise of or in exchange for, other securities described in this prospectus. Debt securities may be our senior, senior subordinated or subordinated obligations and, unless otherwise specified in a supplement to this prospectus, the debt securities will be our direct, unsecured obligations and may be issued in one or more series.

The debt securities will be issued under an indenture between us and a trustee to be identified in an accompanying prospectus supplement. We have summarized select portions of the indenture below. The summary is not complete. The form of the indenture has been filed as an exhibit to the registration statement of which this prospectus forms a part and you should read the indenture for provisions that may be important to you. In the summary below, we have included references to the section numbers of the indenture so that you can easily locate these provisions. Capitalized terms used in the summary and not defined herein have the meanings specified in the indenture.

**General**

The terms of each series of debt securities will be established by or pursuant to a resolution of our board of directors and set forth or determined in the manner provided in a resolution of our board of directors, in an officer's certificate or by a supplemental indenture. The particular terms of each series of debt securities will be described in a prospectus supplement relating to such series (including any pricing supplement or term sheet).

We can issue an unlimited amount of debt securities under the indenture that may be in one or more series with the same or various maturities, at par, at a premium, or at a discount. We will set forth in a prospectus supplement (including any pricing supplement or term sheet) relating to any series of debt securities being offered the aggregate principal amount and the following terms of the debt securities, if applicable:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the title and ranking of the debt securities (including the terms of any subordination provisions);

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the price or prices (expressed as a percentage of the principal amount) at which we will sell the debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any limit upon the aggregate principal amount of the debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the date or dates on which the principal of the securities of the series is payable;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the rate or rates (which may be fixed or variable) per annum or the method used to determine the rate or rates (including any commodity, commodity index, stock exchange index or financial index) at which the debt securities will bear interest, the date or dates from which interest will accrue, the date or dates on which interest will commence and be payable and any regular record date for the interest payable on any interest payment date;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the place or places where principal of, and interest, if any, on the debt securities will be payable (and the method of such payment), where the securities of such series may be surrendered for registration of transfer or exchange, and where notices and demands to us in respect of the debt securities may be delivered;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the period or periods within which, the price or prices at which and the terms and conditions upon which we may redeem the debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any obligation we have to redeem or purchase the debt securities pursuant to any sinking fund or analogous provisions or at the option of a holder of debt securities and the period or periods within which, the price or

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prices at which and the terms and conditions upon which securities of the series shall be redeemed or purchased, in whole or in part, pursuant to such obligation;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the dates on which and the price or prices at which we will repurchase debt securities at the option of the holders of debt securities and other detailed terms and provisions of these repurchase obligations;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the denominations in which the debt securities will be issued, if other than denominations of $1,000 and any integral multiple thereof;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• whether the debt securities will be issued in the form of certificated debt securities or global debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the portion of principal amount of the debt securities payable upon declaration of acceleration of the maturity date, if other than the principal amount;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the currency of denomination of the debt securities, which may be United States dollars or any foreign currency, and if such currency of denomination is a composite currency, the agency or organization, if any, responsible for overseeing such composite currency;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the designation of the currency, currencies or currency units in which payment of principal of, premium and interest on the debt securities will be made;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• if payments of principal of, premium or interest on the debt securities will be made in one or more currencies or currency units other than that or those in which the debt securities are denominated, the manner in which the exchange rate with respect to these payments will be determined;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the manner in which the amounts of payment of principal of, premium, if any, or interest on the debt securities will be determined, if these amounts may be determined by reference to an index based on a currency or currencies or by reference to a commodity, commodity index, stock exchange index or financial index;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any provisions relating to any security provided for the debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any addition to, deletion of or change in the Events of Default described in this prospectus or in the indenture with respect to the debt securities and any change in the acceleration provisions described in this prospectus or in the indenture with respect to the debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any addition to, deletion of or change in the covenants described in this prospectus or in the indenture with respect to the debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any depositaries, interest rate calculation agents, exchange rate calculation agents or other agents with respect to the debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any other terms of the debt securities, which may supplement, modify or delete any provision of the indenture as it applies to that series, including any terms that may be required under applicable law or regulations or advisable in connection with the marketing of the securities; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• whether any of our direct or indirect subsidiaries will guarantee the debt securities of that series, including the terms of subordination, if any, of such guarantees.

We may issue debt securities that provide for an amount less than their stated principal amount to be due and payable upon declaration of acceleration of their maturity pursuant to the terms of the indenture. We will provide you with information on the federal income tax considerations and other special considerations applicable to any of these debt securities in the applicable prospectus supplement.

If we denominate the purchase price of any of the debt securities in a foreign currency or currencies or a foreign currency unit or units, or if the principal of and any premium and interest on any series of debt securities is payable in a foreign currency or currencies or a foreign currency unit or units, we will provide you with information on the restrictions, elections, general tax considerations, specific terms and other information with respect to that issue of

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debt securities and such foreign currency or currencies or foreign currency unit or units in the applicable prospectus supplement.

**Transfer and Exchange**

Each debt security will be represented by either one or more global securities registered in the name of a clearing agency registered under the Exchange Act, which we refer to as the depositary, or a nominee of the depositary (we will refer to any debt security represented by a global debt security as a "book-entry debt security"), or a certificate issued in definitive registered form (we will refer to any debt security represented by a certificated security as a "certificated debt security") as set forth in the applicable prospectus supplement. Except as set forth under the heading "—*Global Debt Securities and Book-Entry System*" below, book-entry debt securities will not be issuable in certificated form.

***Certificated Debt Securities***

You may transfer or exchange certificated debt securities at any office we maintain for this purpose in accordance with the terms of the indenture. No service charge will be made for any transfer or exchange of certificated debt securities, but we may require payment of a sum sufficient to cover any tax or other governmental charge payable in connection with a transfer or exchange.

You may effect the transfer of certificated debt securities and the right to receive the principal of, premium and interest on certificated debt securities only by surrendering the certificate representing those certificated debt securities and either reissuance by us or the trustee of the certificate to the new holder or the issuance by us or the trustee of a new certificate to the new holder.

***Global Debt Securities and Book-Entry System***

Each global debt security representing book-entry debt securities will be deposited with, or on behalf of, the depositary, and registered in the name of the depositary or a nominee of the depositary.

**Covenants**

We will set forth in the applicable prospectus supplement any restrictive covenants applicable to any issue of debt securities.

**No Protection in the Event of a Change of Control**

Unless we state otherwise in the applicable prospectus supplement, the debt securities will not contain any provisions which may afford holders of the debt securities protection in the event we have a change in control or in the event of a highly leveraged transaction (whether or not such transaction results in a change in control) which could adversely affect holders of debt securities.

**Conversion or Exchange Rights**

For any series of debt securities that are convertible into or exchangeable for shares of our common stock, we will set forth in the applicable prospectus supplement the terms on which such series of debt securities may be convertible into or exchangeable for our common stock. We will include provisions as to settlement upon conversion or exchange and whether conversion or exchange is mandatory, at the option of the holder or at our option. We may include provisions pursuant to which the number of shares of our common stock that the holders of the series of debt securities receive would be subject to adjustment.

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**Consolidation, Merger and Sale of Assets**

We may not consolidate with or merge with or into, or convey, transfer or lease all or substantially all of our properties and assets to any person, which we refer to as a successor person, unless:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• we are the surviving corporation or the successor person (if other than us) is a corporation organized and validly existing under the laws of any U.S. domestic jurisdiction and expressly assumes our obligations on the debt securities and under the indenture; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• immediately after giving effect to the transaction, no Default or Event of Default, shall have occurred and be continuing.

Notwithstanding the above, any of our subsidiaries may consolidate with, merge into or transfer all or part of its properties to us.

**Events of Default**

"Event of Default" means with respect to any series of debt securities, any of the following:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• default in the payment of any interest upon any debt security of that series when it becomes due and payable, and continuance of such default for a period of 30 days (unless the entire amount of the payment is deposited by us with the trustee or with a paying agent prior to the expiration of the 30-day period);

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• default in the payment of principal of any security of that series at its maturity;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• default in the performance or breach of any other covenant or warranty by us in the indenture (other than a covenant or warranty that has been included in the indenture solely for the benefit of a series of debt securities other than that series), which default continues uncured for a period of 60 days after we receive written notice from the trustee, or we and the trustee receive written notice from the holders of not less than 25% in principal amount of the outstanding debt securities of that series as provided in the indenture;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• certain voluntary or involuntary events of bankruptcy, insolvency or reorganization of us; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any other Event of Default provided with respect to debt securities of that series that is described in the applicable prospectus supplement.

No Event of Default with respect to a particular series of debt securities (except as to certain events of bankruptcy, insolvency or reorganization) necessarily constitutes an Event of Default with respect to any other series of debt securities. The occurrence of certain Events of Default or an acceleration under the indenture may constitute an event of default under certain indebtedness of ours or our subsidiaries outstanding from time to time.

We will provide the trustee written notice of any Default or Event of Default within 30 days of becoming aware of the occurrence of such Default or Event of Default, which notice will describe in reasonable detail the status of such Default or Event of Default and what action we are taking or propose to take in respect thereof.

If an Event of Default with respect to debt securities of any series at the time outstanding occurs and is continuing, then the trustee or the holders of not less than 25% in principal amount of the outstanding debt securities of that series may, by a notice in writing to us (and to the trustee if given by the holders), declare to be due and payable immediately the principal of (or, if the debt securities of that series are discount securities, that portion of the principal amount as may be specified in the terms of that series) and accrued and unpaid interest, if any, on all debt securities of that series. In the case of an Event of Default resulting from certain events of bankruptcy, insolvency or reorganization, the principal (or such specified amount) of and accrued and unpaid interest, if any, on all outstanding debt securities will become and be immediately due and payable without any declaration or other act on the part of the trustee or any holder of outstanding debt securities. At any time after a declaration of acceleration with respect to debt securities of any series has been made, but before a judgment or decree for payment of the money due has been obtained by the trustee, the holders of a majority in principal amount of the outstanding debt securities of that series may rescind and annul the acceleration if all Events of Default, other than the non-payment

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of accelerated principal and interest, if any, with respect to debt securities of that series, have been cured or waived as provided in the indenture. We refer you to the prospectus supplement relating to any series of debt securities that are discount securities for the particular provisions relating to acceleration of a portion of the principal amount of such discount securities upon the occurrence of an Event of Default.

The indenture provides that the trustee may refuse to perform any duty or exercise any of its rights or powers under the indenture unless the trustee receives indemnity satisfactory to it against any cost, liability or expense which might be incurred by it in performing such duty or exercising such right or power. Subject to certain rights of the trustee, the holders of a majority in principal amount of the outstanding debt securities of any series will have the right to direct the time, method and place of conducting any proceeding for any remedy available to the trustee or exercising any trust or power conferred on the trustee with respect to the debt securities of that series.

No holder of any debt security of any series will have any right to institute any proceeding, judicial or otherwise, with respect to the indenture or for the appointment of a receiver or trustee, or for any remedy under the indenture, unless:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• that holder has previously given to the trustee written notice of a continuing Event of Default with respect to debt securities of that series; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the holders of not less than 25% in principal amount of the outstanding debt securities of that series have made written request, and offered indemnity or security satisfactory to the trustee, to the trustee to institute the proceeding as trustee, and the trustee has not received from the holders of not less than a majority in principal amount of the outstanding debt securities of that series a direction inconsistent with that request and has failed to institute the proceeding within 60 days.

Notwithstanding any other provision in the indenture, the holder of any debt security will have an absolute and unconditional right to receive payment of the principal of, premium and any interest on that debt security on or after the due dates expressed in that debt security and to institute suit for the enforcement of payment.

The indenture requires us, within 120 days after the end of our fiscal year, to furnish to the trustee a statement as to compliance with the indenture. If a Default or Event of Default occurs and is continuing with respect to the securities of any series and if it is known to a responsible officer of the trustee, the trustee shall send to each securityholder of the securities of that series notice of a Default or Event of Default within 90 days after it occurs or, if later, after a responsible officer of the trustee has knowledge of such Default or Event of Default. The indenture provides that the trustee may withhold notice to the holders of debt securities of any series of any Default or Event of Default (except in payment on any debt securities of that series) with respect to debt securities of that series if the trustee determines in good faith that withholding notice is in the interest of the holders of those debt securities.

**Modification and Waiver**

We and the trustee may modify, amend or supplement the indenture or the debt securities of any series without the consent of any holder of any debt security:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• to cure any ambiguity, defect or inconsistency;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• to comply with covenants in the indenture described above under the heading "—*Consolidation, Merger and Sale of Assets*";

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• to provide for uncertificated securities in addition to or in place of certificated securities;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• to add guarantees with respect to debt securities of any series or secure debt securities of any series;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• to surrender any of our rights or powers under the indenture;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• to add covenants or events of default for the benefit of the holders of debt securities of any series;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• to comply with the applicable procedures of the applicable depositary;

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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• to make any change that does not adversely affect the rights of any holder of debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• to provide for the issuance of and establish the form and terms and conditions of debt securities of any series as permitted by the indenture;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• to effect the appointment of a successor trustee with respect to the debt securities of any series and to add to or change any of the provisions of the indenture to provide for or facilitate administration by more than one trustee; or

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• to comply with requirements of the SEC in order to effect or maintain the qualification of the indenture under the Trust Indenture Act.

We may also modify and amend the indenture with the consent of the holders of at least a majority in principal amount of the outstanding debt securities of each series affected by the modifications or amendments. We may not make any modification or amendment without the consent of the holders of each affected debt security then outstanding if that amendment will:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• reduce the amount of debt securities whose holders must consent to an amendment, supplement or waiver;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• reduce the rate of or extend the time for payment of interest (including default interest) on any debt security;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• reduce the principal of or premium on or change the fixed maturity of any debt security or reduce the amount of, or postpone the date fixed for, the payment of any sinking fund or analogous obligation with respect to any series of debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• reduce the principal amount of discount securities payable upon acceleration of maturity;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• waive a default in the payment of the principal of, premium or interest on any debt security (except a rescission of acceleration of the debt securities of any series by the holders of at least a majority in aggregate principal amount of the then outstanding debt securities of that series and a waiver of the payment default that resulted from such acceleration);

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• make the principal of or premium or interest on any debt security payable in currency other than that stated in the debt security;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• make any change to certain provisions of the indenture relating to, among other things, the right of holders of debt securities to receive payment of the principal of, premium and interest on those debt securities and to institute suit for the enforcement of any such payment and to waivers or amendments; or

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• waive a redemption payment with respect to any debt security.

Except for certain specified provisions, the holders of at least a majority in principal amount of the outstanding debt securities of any series may on behalf of the holders of all debt securities of that series waive our compliance with provisions of the indenture. The holders of a majority in principal amount of the outstanding debt securities of any series may on behalf of the holders of all the debt securities of such series waive any past default under the indenture with respect to that series and its consequences, except a default in the payment of the principal of, premium or any interest on any debt security of that series; provided, however, that the holders of a majority in principal amount of the outstanding debt securities of any series may rescind an acceleration and its consequences, including any related payment default that resulted from the acceleration.

**Defeasance of Debt Securities and Certain Covenants in Certain Circumstances**

*Legal Defeasance*

The indenture provides that, unless otherwise provided by the terms of the applicable series of debt securities, we may be discharged from any and all obligations in respect of the debt securities of any series (subject to certain exceptions). We will be so discharged upon the irrevocable deposit with the trustee, in trust, of money and/or U.S.

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government obligations or, in the case of debt securities denominated in a single currency other than U.S. dollars, government obligations of the government that issued or caused to be issued such currency, that, through the payment of interest and principal in accordance with their terms, will provide money or U.S. government obligations in an amount sufficient in the opinion of a nationally recognized firm of independent public accountants or investment bank to pay and discharge each installment of principal, premium and interest on and any mandatory sinking fund payments in respect of the debt securities of that series on the stated maturity of those payments in accordance with the terms of the indenture and those debt securities.

This discharge may occur only if, among other things, we have delivered to the trustee an opinion of counsel stating that we have received from, or there has been published by, the United States Internal Revenue Service a ruling or, since the date of execution of the indenture, there has been a change in the applicable United States federal income tax law, in either case to the effect that, and based thereon such opinion shall confirm that, the holders of the debt securities of that series will not recognize income, gain or loss for United States federal income tax purposes as a result of the deposit, defeasance and discharge and will be subject to United States federal income tax on the same amounts and in the same manner and at the same times as would have been the case if the deposit, defeasance and discharge had not occurred.

*Defeasance of Certain Covenants*

The indenture provides that, unless otherwise provided by the terms of the applicable series of debt securities, upon compliance with certain conditions:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• we may omit to comply with the covenant described under the heading "—*Consolidation, Merger and Sale of Assets*" and certain other covenants set forth in the indenture, as well as any additional covenants which may be set forth in the applicable prospectus supplement; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any omission to comply with those covenants will not constitute a Default or an Event of Default with respect to the debt securities of that series.

We refer to this as covenant defeasance. The conditions include:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• depositing with the trustee money and/or U.S. government obligations or, in the case of debt securities denominated in a single currency other than U.S. dollars, government obligations of the government that issued or caused to be issued such currency, that, through the payment of interest and principal in accordance with their terms, will provide money in an amount sufficient in the opinion of a nationally recognized firm of independent public accountants or investment bank to pay and discharge each installment of principal of, premium and interest on and any mandatory sinking fund payments in respect of the debt securities of that series on the stated maturity of those payments in accordance with the terms of the indenture and those debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• such deposit will not result in a breach or violation of, or constitute a default under the indenture or any other agreement to which we are a party;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• no Default or Event of Default with respect to the applicable series of debt securities shall have occurred or is continuing on the date of such deposit; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• delivering to the trustee an opinion of counsel to the effect that we have received from, or there has been published by, the United States Internal Revenue Service a ruling or, since the date of execution of the indenture, there has been a change in the applicable United States federal income tax law, in either case to the effect that, and based thereon such opinion shall confirm that, the holders of the debt securities of that series will not recognize income, gain or loss for United States federal income tax purposes as a result of the deposit and related covenant defeasance and will be subject to United States federal income tax on the same amounts and in the same manner and at the same times as would have been the case if the deposit and related covenant defeasance had not occurred.

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**No Personal Liability of Directors, Officers, Employees or Stockholders**

None of our past, present or future directors, officers, employees or stockholders, as such, will have any liability for any of our obligations under the debt securities or the indenture or for any claim based on, or in respect or by reason of, such obligations or their creation. By accepting a debt security, each holder waives and releases all such liability. This waiver and release is part of the consideration for the issue of the debt securities. However, this waiver and release may not be effective to waive liabilities under U.S. federal securities laws, and it is the view of the SEC that such a waiver is against public policy.

**Governing Law**

The indenture and the debt securities, including any claim or controversy arising out of or relating to the indenture or the securities, will be governed by the laws of the State of New York.

The indenture will provide that we, the trustee and the holders of the debt securities (by their acceptance of the debt securities) irrevocably waive, to the fullest extent permitted by applicable law, any and all right to trial by jury in any legal proceeding arising out of or relating to the indenture, the debt securities or the transactions contemplated thereby.

The indenture will provide that any legal suit, action or proceeding arising out of or based upon the indenture or the transactions contemplated thereby may be instituted in the federal courts of the United States of America located in the City of New York or the courts of the State of New York in each case located in the City of New York, and we, the trustee and the holder of the debt securities (by their acceptance of the debt securities) irrevocably submit to the non-exclusive jurisdiction of such courts in any such suit, action or proceeding. The indenture will further provide that service of any process, summons, notice or document by mail (to the extent allowed under any applicable statute or rule of court) to such party's address set forth in the indenture will be effective service of process for any suit, action or other proceeding brought in any such court. The indenture will further provide that we, the trustee and the holders of the debt securities (by their acceptance of the debt securities) irrevocably and unconditionally waive any objection to the laying of venue of any suit, action or other proceeding in the courts specified above and irrevocably and unconditionally waive and agree not to plead or claim any such suit, action or other proceeding has been brought in an inconvenient forum.

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**DESCRIPTION OF DEPOSITARY SHARES**

**General**

We may, at our option, elect to offer fractional shares of preferred stock, or depositary shares, rather than full shares of preferred stock. If we do, we will issue to the public receipts, called depositary receipts, for depositary shares, each of which will represent a fraction, to be described in the applicable prospectus supplement, of a share of a particular series of preferred stock. Unless otherwise provided in the prospectus supplement, each owner of a depositary share will be entitled, in proportion to the applicable fractional interest in a share of preferred stock represented by the depositary share, to all the rights and preferences of the preferred stock represented by the depositary share. Those rights include dividend, voting, redemption, conversion and liquidation rights.

The shares of preferred stock underlying the depositary shares will be deposited with a bank or trust company selected by us to act as depositary under a deposit agreement between us, the depositary and the holders of the depositary receipts. The depositary will be the transfer agent, registrar and dividend disbursing agent for the depositary shares.

The depositary shares will be evidenced by depositary receipts issued pursuant to the depositary agreement. Holders of depositary receipts agree to be bound by the deposit agreement, which requires holders to take certain actions such as filing proof of residence and paying certain charges.

The summary of terms of the depositary shares contained in this prospectus is not complete. You should refer to the form of the deposit agreement, our certificate of incorporation and the certificate of designation for the applicable series of preferred stock that are, or will be, filed with the SEC.

**Dividends and Other Distributions**

The depositary will distribute all cash dividends or other cash distributions, if any, received in respect of the preferred stock underlying the depositary shares to the record holders of depositary shares in proportion to the numbers of depositary shares owned by those holders on the relevant record date. The relevant record date for depositary shares will be the same date as the record date for the underlying preferred stock.

If there is a distribution other than in cash, the depositary will distribute property (including securities) received by it to the record holders of depositary shares, unless the depositary determines that it is not feasible to make the distribution. If this occurs, the depositary may, with our approval, adopt another method for the distribution, including selling the property and distributing the net proceeds from the sale to the holders.

**Liquidation Preference**

If a series of preferred stock underlying the depositary shares has a liquidation preference, in the event of the voluntary or involuntary liquidation, dissolution or winding up of us, holders of depositary shares will be entitled to receive the fraction of the liquidation preference accorded each share of the applicable series of preferred stock, as set forth in the applicable prospectus supplement.

**Withdrawal of Stock**

Unless the related depositary shares have been previously called for redemption, upon surrender of the depositary receipts at the office of the depositary, the holder of the depositary shares will be entitled to delivery, at the office of the depositary to or upon his or her order, of the number of whole shares of the preferred stock and any money or other property represented by the depositary shares. If the depositary receipts delivered by the holder evidence a number of depositary shares in excess of the number of depositary shares representing the number of whole shares of preferred stock to be withdrawn, the depositary will deliver to the holder at the same time a new depositary receipt evidencing the excess number of depositary shares. In no event will the depositary deliver fractional shares of preferred stock upon surrender of depositary receipts. Holders of preferred stock thus withdrawn may not thereafter deposit those shares under the deposit agreement or receive depositary receipts evidencing depositary shares therefor.

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**Redemption of Depositary Shares**

Whenever we redeem shares of preferred stock held by the depositary, the depositary will redeem as of the same redemption date the number of depositary shares representing shares of the preferred stock so redeemed, so long as we have paid in full to the depositary the redemption price of the preferred stock to be redeemed plus an amount equal to any accumulated and unpaid dividends on the preferred stock to the date fixed for redemption. The redemption price per depositary share will be equal to the redemption price and any other amounts per share payable on the preferred stock multiplied by the fraction of a share of preferred stock represented by one depositary share. If less than all the depositary shares are to be redeemed, the depositary shares to be redeemed will be selected by lot or pro rata or by any other equitable method as may be determined by the depositary.

After the date fixed for redemption, depositary shares called for redemption will no longer be deemed to be outstanding and all rights of the holders of depositary shares will cease, except the right to receive the monies payable upon redemption and any money or other property to which the holders of the depositary shares were entitled upon redemption upon surrender to the depositary of the depositary receipts evidencing the depositary shares.

**Voting the Preferred Stock**

Upon receipt of notice of any meeting at which the holders of the preferred stock are entitled to vote, the depositary will mail the information contained in the notice of meeting to the record holders of the depositary receipts relating to that preferred stock. The record date for the depositary receipts relating to the preferred stock will be the same date as the record date for the preferred stock. Each record holder of the depositary shares on the record date will be entitled to instruct the depositary as to the exercise of the voting rights pertaining to the number of shares of preferred stock represented by that holder's depositary shares. The depositary will endeavor, insofar as practicable, to vote the number of shares of preferred stock represented by the depositary shares in accordance with those instructions, and we will agree to take all action that may be deemed necessary by the depositary in order to enable the depositary to do so. The depositary will not vote any shares of preferred stock except to the extent that it receives specific instructions from the holders of depositary shares representing that number of shares of preferred stock.

**Charges of the Depositary**

We will pay all transfer and other taxes and governmental charges arising solely from the existence of the depositary arrangements. We will pay charges of the depositary in connection with the initial deposit of the preferred stock and any redemption of the preferred stock. Holders of depositary receipts will pay transfer, income and other taxes and governmental charges and such other charges (including those in connection with the receipt and distribution of dividends, the sale or exercise of rights, the withdrawal of the preferred stock and the transferring, splitting or grouping of depositary receipts) as are expressly provided in the deposit agreement to be for their accounts. If these charges have not been paid by the holders of depositary receipts, the depositary may refuse to transfer depositary shares, withhold dividends and distributions and sell the depositary shares evidenced by the depositary receipt.

**Amendment and Termination of the Deposit Agreement**

The form of depositary receipt evidencing the depositary shares and any provision of the deposit agreement may be amended by agreement between us and the depositary. However, any amendment that materially and adversely alters the rights of the holders of depositary shares, other than fee changes, will not be effective unless the amendment has been approved by the holders of a majority of the outstanding depositary shares. The deposit agreement may be terminated by the depositary or us only if:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• all outstanding depositary shares have been redeemed; or

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• there has been a final distribution of the preferred stock in connection with our dissolution and such distribution has been made to all the holders of depositary shares.

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**Resignation and Removal of Depositary**

The depositary may resign at any time by delivering to us notice of its election to do so, and we may remove the depositary at any time. Any resignation or removal of the depositary will take effect upon our appointment of a successor depositary and its acceptance of such appointment. The successor depositary must be appointed within 60 days after delivery of the notice of resignation or removal and must be a bank or trust company having its principal office in the United States and having the requisite combined capital and surplus as set forth in the applicable agreement.

**Notices**

The depositary will forward to holders of depositary receipts all notices, reports and other communications, including proxy solicitation materials received from us, that are delivered to the depositary and that we are required to furnish to the holders of the preferred stock. In addition, the depositary will make available for inspection by holders of depositary receipts at the principal office of the depositary, and at such other places as it may from time to time deem advisable, any reports and communications we deliver to the depositary as the holder of preferred stock.

**Limitation of Liability**

Neither we nor the depositary will be liable if either is prevented or delayed by law or any circumstance beyond its control in performing its obligations. Our obligations and those of the depositary will be limited to performance in good faith of our and its duties thereunder. We and the depositary will not be obligated to prosecute or defend any legal proceeding in respect of any depositary shares or preferred stock unless satisfactory indemnity is furnished. We and the depositary may rely upon written advice of counsel or accountants, on information provided by persons presenting preferred stock for deposit, holders of depositary receipts or other persons believed to be competent to give such information and on documents believed to be genuine and to have been signed or presented by the proper party or parties.

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**DESCRIPTION OF WARRANTS**

We may issue warrants to purchase debt securities, preferred stock, depositary shares or common stock. We may offer warrants separately or together with one or more additional warrants, debt securities, preferred stock, depositary shares or common stock, or any combination of those securities in the form of units, as described in the applicable prospectus supplement. If we issue warrants as part of a unit, the applicable prospectus supplement will specify whether those warrants may be separated from the other securities in the unit prior to the expiration date of the warrants. The applicable prospectus supplement will also describe the following terms of any warrants:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the specific designation and aggregate number of, and the offering price at which we will issue, the warrants;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the currency or currency units in which the offering price, if any, and the exercise price are payable;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the date on which the right to exercise the warrants will begin and the date on which that right will expire or, if you may not continuously exercise the warrants throughout that period, the specific date or dates on which you may exercise the warrants;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• whether the warrants are to be sold separately or with other securities as parts of units;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• whether the warrants will be issued in definitive or global form or in any combination of these forms, although, in any case, the form of a warrant included in a unit will correspond to the form of the unit and of any security included in that unit;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any applicable material U.S. federal income tax consequences;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the identity of the warrant agent for the warrants and of any other depositaries, execution or paying agents, transfer agents, registrars or other agents;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the proposed listing, if any, of the warrants or any securities purchasable upon exercise of the warrants on any securities exchange;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the designation and terms of any equity securities purchasable upon exercise of the warrants;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the designation, aggregate principal amount, currency and terms of any debt securities that may be purchased upon exercise of the warrants;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• if applicable, the designation and terms of the debt securities, preferred stock, depositary shares or common stock with which the warrants are issued and the number of warrants issued with each security;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• if applicable, the date from and after which any warrants issued as part of a unit and the related debt securities, preferred stock, depositary shares or common stock will be separately transferable;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the number of shares of preferred stock, the number of depositary shares or the number of shares of common stock purchasable upon exercise of a warrant and the price at which those shares may be purchased;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• if applicable, the minimum or maximum amount of the warrants that may be exercised at any one time;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• information with respect to book-entry procedures, if any;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the antidilution provisions, and other provisions for changes to or adjustment in the exercise price, of the warrants, if any;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any redemption or call provisions; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any additional terms of the warrants, including terms, procedures and limitations relating to the exchange or exercise of the warrants.

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**DESCRIPTION OF SUBSCRIPTION RIGHTS**

We may issue subscription rights to purchase our common stock, preferred stock, debt securities, depositary shares, warrants or units consisting of some or all of these securities. These subscription rights may be offered independently or together with any other security offered hereby and may or may not be transferable by the stockholder receiving the subscription rights in such offering. In connection with any offering of subscription rights, we may enter into a standby arrangement with one or more underwriters or other purchasers pursuant to which the underwriters or other purchasers may be required to purchase any securities remaining unsubscribed for after such offering.

The prospectus supplement relating to any subscription rights we offer, if any, will, to the extent applicable, include specific terms relating to the offering, including some or all of the following:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the price, if any, for the subscription rights;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the exercise price payable for our common stock, preferred stock, debt securities, depositary shares, warrants or units consisting of some or all of these securities upon the exercise of the subscription rights;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the number of subscription rights to be issued to each stockholder;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the number and terms of our common stock, preferred stock, debt securities, depositary shares, warrants or units consisting of some or all of these securities which may be purchased per each subscription right;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the extent to which the subscription rights are transferable;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any other terms of the subscription rights, including the terms, procedures and limitations relating to the exchange and exercise of the subscription rights;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the date on which the right to exercise the subscription rights shall commence, and the date on which the subscription rights shall expire;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the extent to which the subscription rights may include an over-subscription privilege with respect to unsubscribed securities or an over-allotment privilege to the extent the securities are fully subscribed; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• if applicable, the material terms of any standby underwriting or purchase arrangement which may be entered into by us in connection with the offering of subscription rights.

The descriptions of the subscription rights in this prospectus and in any prospectus supplement are summaries of the material provisions of the applicable subscription right agreements. These descriptions do not restate those subscription right agreements in their entirety and may not contain all the information that you may find useful. We urge you to read the applicable subscription right agreements because they, and not the summaries, define your rights as holders of the subscription rights. For more information, please review the forms of the relevant subscription right agreements, which will be filed with the SEC promptly after the offering of subscription rights and will be available as described in the section of this prospectus under the heading "*Where You Can Find More Information*."

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**DESCRIPTION OF PURCHASE CONTRACTS**

The following description summarizes the general features of the purchase contracts that we may offer under this prospectus. Although the features we have summarized below will generally apply to any future purchase contracts we may offer under this prospectus, we will describe the particular terms of any purchase contracts that we may offer in more detail in the applicable prospectus supplement. The specific terms of any purchase contracts may differ from the description provided below as a result of negotiations with third parties in connection with the issuance of those purchase contracts, as well as for other reasons. Because the terms of any purchase contracts we offer under a prospectus supplement may differ from the terms we describe below, you should rely solely on information in the applicable prospectus supplement if that summary is different from the summary in this prospectus.

We will incorporate by reference into the registration statement of which this prospectus is a part the form of any purchase contract that we may offer under this prospectus before the sale of the related purchase contract. We urge you to read any applicable prospectus supplement related to specific purchase contracts being offered, as well as the complete instruments that contain the terms of the securities that are subject to those purchase contracts. Certain of those instruments, or forms of those instruments, have been filed as exhibits to the registration statement of which this prospectus is a part, and supplements to those instruments or forms may be incorporated by reference into the registration statement of which this prospectus is a part from reports we file with the SEC.

We may issue purchase contracts, including contracts obligating holders to purchase from us, and for us to sell to holders, a specific or variable number of our securities at a future date or dates. Alternatively, the purchase contracts may obligate us to purchase from holders, and obligate holders to sell to us, a specific or varying number of our securities.

If we offer any purchase contracts, certain terms of that series of purchase contracts will be described in the applicable prospectus supplement, including, without limitation, the following:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the price of the securities or other property subject to the purchase contracts (which may be determined by reference to a specific formula described in the purchase contracts);

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• whether the purchase contracts are issued separately, or as a part of units each consisting of a purchase contract and one or more of our other securities, including U.S. Treasury securities, securing the holder's obligations under the purchase contract;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any requirement for us to make periodic payments to holders or vice versa, and whether the payments are unsecured or pre-funded;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any provisions relating to any security provided for the purchase contracts;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• whether the purchase contracts obligate the holder or us to purchase or sell, or both purchase and sell, the securities subject to purchase under the purchase contract, and the nature and amount of each of those securities, or the method of determining those amounts;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• whether the purchase contracts are to be prepaid or not;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• whether the purchase contracts are to be settled by delivery, or by reference or linkage to the value, performance or level of the securities subject to purchase under the purchase contract;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any acceleration, cancellation, termination or other provisions relating to the settlement of the purchase contracts;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• a discussion of certain U.S. federal income tax considerations applicable to the purchase contracts;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• whether the purchase contracts will be issued in fully registered or global form; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any other terms of the purchase contracts and any securities subject to such purchase contracts.

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**DESCRIPTION OF UNITS**

We may issue units comprising two or more securities described in this prospectus in any combination. For example, we might issue units consisting of a combination of debt securities and warrants to purchase common stock. The following description sets forth certain general terms and provisions of the units that we may offer pursuant to this prospectus. The particular terms of the units and the extent, if any, to which the general terms and provisions may apply to the units so offered will be described in the applicable prospectus supplement.

Each unit will be issued so that the holder of the unit also is the holder of each security included in the unit. Thus, the unit will have the rights and obligations of a holder of each included security. Units will be issued pursuant to the terms of a unit agreement, which may provide that the securities included in the unit may not be held or transferred separately at any time or at any time before a specified date. A copy of the forms of the unit agreement and the unit certificate relating to any particular issue of units will be filed with the SEC each time we issue units, and you should read those documents for provisions that may be important to you. For more information on how you can obtain copies of the forms of the unit agreement and the related unit certificate, see the section of this prospectus captioned "Where You Can Find More Information."

The prospectus supplement relating to any particular issuance of units will describe the terms of those units, including, to the extent applicable, the following:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the designation and terms of the units and the securities comprising the units, including whether and under what circumstances those securities may be held or transferred separately;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any provision for the issuance, payment, settlement, transfer or exchange of the units or of the securities comprising the units; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• whether the units will be issued in fully registered or global form.

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**PLAN OF DISTRIBUTION**

We may sell securities:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• through underwriters;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• through dealers;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• through agents;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• directly to purchasers; or

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• through a combination of any of these methods of sale.

In addition, we may issue the securities as a dividend or distribution or in a subscription rights offering to our existing securityholders.

We may directly solicit offers to purchase securities or agents may be designated to solicit such offers. We will, in the prospectus supplement relating to such offering, name any agent that could be viewed as an underwriter under the Securities Act and describe any commissions that we must pay. Any such agent will be acting on a best efforts basis for the period of its appointment or, if indicated in the applicable prospectus supplement, on a firm commitment basis. This prospectus may be used in connection with any offering of our securities through any of these methods or other methods described in the applicable prospectus supplement.

The distribution of the securities may be effected from time to time in one or more transactions:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• at a fixed price or prices that may be changed from time to time;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• at market prices prevailing at the time of sale;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• at prices related to such prevailing market prices; or

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• at negotiated prices.

We may also sell equity securities covered by this registration statement in an "at the market offering" as defined in Rule 415(a)(4) under the Securities Act. Such offering may be made into an existing trading market for such securities in transactions at other than a fixed price, either:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• on or through the facilities of the New York Stock Exchange or any other securities exchange or quotation or trading service on which such securities may be listed, quoted or traded at the time of sale; and/or

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• to or through a market maker otherwise than on the New York Stock Exchange or such other securities exchanges or quotation trading services.

Such at the market offerings, if any, may be conducted by underwriters acting as principal or agent.

Each prospectus supplement will describe the method of distribution of the securities and any applicable restrictions.

The prospectus supplement with respect to the securities of a particular series will describe the terms of the offering of the securities, including the following:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the name of the agent or any underwriters;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the public offering or purchase price;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• if applicable, the names of any selling securityholders;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any discounts and commissions to be allowed or paid to the agent or underwriters;

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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• all other items constituting underwriting compensation;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any discounts and commissions to be allowed or paid to dealers; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• any exchanges on which the securities will be listed.

If any underwriters or agents are utilized in the sale of the securities in respect of which this prospectus is delivered, we will enter into an underwriting agreement or other agreement with them at the time of sale to them, and we will set forth in the prospectus supplement relating to such offering the names of the underwriters or agents and the terms of the related agreement with them.

If a dealer is utilized in the sale of the securities in respect of which the prospectus is delivered, we will sell such securities to the dealer, as principal. The dealer may then resell such securities to the public at varying prices to be determined by such dealer at the time of resale.

If we offer securities in a subscription rights offering to our existing securityholders, we may enter into a standby underwriting agreement with dealers, acting as standby underwriters. We may pay the standby underwriters a commitment fee for the securities they commit to purchase on a standby basis. If we do not enter into a standby underwriting arrangement, we may retain a dealer-manager to manage a subscription rights offering for us.

Agents, underwriters, dealers and other persons may be entitled under agreements that they may enter into with us to indemnification by us against certain civil liabilities, including liabilities under the Securities Act.

If so indicated in the applicable prospectus supplement, we will authorize underwriters or other persons acting as our agents to solicit offers by certain institutions to purchase securities from us pursuant to delayed delivery contracts providing for payment and delivery on the date stated in the prospectus supplement. Each contract will be for an amount not less than, and the aggregate amount of securities sold pursuant to such contracts shall not be less nor more than, the respective amounts stated in the prospectus supplement. Institutions with whom the contracts, when authorized, may be made include commercial and savings banks, insurance companies, pension funds, investment companies, educational and charitable institutions and other institutions, but shall in all cases be subject to our approval. Delayed delivery contracts will not be subject to any conditions except that:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the purchase by an institution of the securities covered under that contract shall not at the time of delivery be prohibited under the laws of the jurisdiction to which that institution is subject; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• if the securities are also being sold to underwriters acting as principals for their own account, the underwriters shall have purchased such securities not sold for delayed delivery.

The underwriters and other persons acting as agents will not have any responsibility in respect of the validity or performance of delayed delivery contracts.

Certain agents, underwriters and dealers, and their associates and affiliates may be customers of, have borrowing relationships with, engage in other transactions with, and/or perform services, including investment banking services, for us or one or more of our respective affiliates in the ordinary course of business.

In order to facilitate the offering of the securities, any underwriters may engage in transactions that stabilize, maintain or otherwise affect the price of the securities or any other securities the prices of which may be used to determine payments on such securities. Specifically, any underwriters may over-allot in connection with the offering, creating a short position for their own accounts. In addition, to cover over-allotments or to stabilize the price of the securities or of any such other securities, the underwriters may bid for, and purchase, the securities or any such other securities in the open market. Finally, in any offering of the securities through a syndicate of underwriters, the underwriting syndicate may reclaim selling concessions allowed to an underwriter or a dealer for distributing the securities in the offering if the syndicate repurchases previously distributed securities in transactions to cover syndicate short positions, in stabilization transactions or otherwise. Any of these activities may stabilize or maintain the market price of the securities above independent market levels. Any such underwriters are not required to engage in these activities and may end any of these activities at any time.

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Under Rule 15c6-1 of the Exchange Act, trades in the secondary market generally are required to settle in two business days, unless the parties to any such trade expressly agree otherwise. The applicable prospectus supplement may provide that the original issue date for your securities may be more than two scheduled business days after the trade date for your securities. Accordingly, in such a case, if you wish to trade securities on any date prior to the third business day before the original issue date for your securities, you will be required, by virtue of the fact that your securities initially are expected to settle in more than three scheduled business days after the trade date for your securities, to make alternative settlement arrangements to prevent a failed settlement.

The securities may be new issues of securities and may have no established trading market. The securities may or may not be listed on a national securities exchange. We can make no assurance as to the liquidity of or the existence of trading markets for any of the securities.

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**LEGAL MATTERS**

The validity of the securities offered hereby will be passed upon for us by Wilson Sonsini Goodrich & Rosati, Professional Corporation, Palo Alto, California. Additional legal matters may be passed on for us, or any underwriters, dealers or agents by counsel we will name in the applicable prospectus supplement.

**EXPERTS**

The consolidated financial statements of ESS Tech, Inc. appearing in ESS Tech, Inc.'s Annual Report (Form 10-K) for the year ended December 31, 2021, have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their report thereon, included therein, and incorporated herein by reference. Such consolidated financial statements are incorporated herein by reference in reliance upon such report given on the authority of such firm as experts in accounting and auditing.

**WHERE YOU CAN FIND MORE INFORMATION**

We file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to the public over the Internet at the SEC's website at www.sec.gov. Copies of certain information filed by us with the SEC are also available on our website at https://essinc.com/. Information accessible on or through our website is not a part of this prospectus.

This prospectus and any prospectus supplement is part of a registration statement that we filed with the SEC and do not contain all of the information in the registration statement. You should review the information and exhibits in the registration statement for further information on us and our consolidated subsidiaries and the securities that we are offering. Forms of any indenture or other documents establishing the terms of the offered securities are filed as exhibits to the registration statement of which this prospectus forms a part or under cover of a Current Report on Form 8-K and incorporated in this prospectus by reference. Statements in this prospectus or any prospectus supplement about these documents are summaries and each statement is qualified in all respects by reference to the document to which it refers. You should read the actual documents for a more complete description of the relevant matters.

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**INCORPORATION BY REFERENCE**

The SEC allows us to incorporate by reference much of the information that we file with the SEC, which means that we can disclose important information to you by referring you to those publicly available documents. The information that we incorporate by reference in this prospectus is considered to be part of this prospectus. Because we are incorporating by reference future filings with the SEC, this prospectus is continually updated and those future filings may modify or supersede some of the information included or incorporated by reference in this prospectus. This means that you must look at all of the SEC filings that we incorporate by reference to determine if any of the statements in this prospectus or in any document previously incorporated by reference have been modified or superseded. This prospectus incorporates by reference the documents listed below and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act (in each case, other than those documents or the portions of those documents furnished pursuant to Items 2.02 or 7.01 of any Current Report on Form 8-K and, except as may be noted in any such Form 8-K, exhibits filed on such form that are related to such information), until the offering of the securities under the registration statement of which this prospectus forms a part is terminated or completed:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• our Annual Report on Form 10-K for the year ended December 31, 2021, filed with the SEC on <u>[March 4, 2022](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000162828022005026/ghw-20211231.htm)</u>;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• our Quarterly Reports on Form 10-Q for the quarters ended March 31, 2022, June 30, 2022 and September 30, 2022, filed with the SEC on <u>[May 13, 2022](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000162828022014149/ghw-20220331.htm)</u>, <u>[August 12, 2022](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000162828022022530/ghw-20220630.htm)</u> and <u>[November 3, 2022](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000162828022028231/ghw-20220930.htm)</u>, respectively;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• the portions of our Definitive Proxy Statement on Schedule 14A (other than information furnished rather than filed) that are incorporated by reference into our Annual Report on Form 10-K, filed with the SEC on <u>[April 22, 2022](https://www.sec.gov/Archives/edgar/data/0001819438/000162828022010023/a2022esstechincproxya.htm)</u>;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• our Current Reports on Form 8-K filed on <u>[February 17, 2022](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000119312522044972/d37298d8k.htm)</u>, <u>[March 30, 2022](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000162828022007891/wk-20220330.htm)</u>, <u>[June 2, 2022](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000162828022015952/wk-20220601.htm)</u>, <u>[August 26, 2022](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000162828022023772/wk-20220826.htm)</u> and <u>[October 24, 2022](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001819438/000162828022026830/wk-20221021.htm)</u>; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• The description of our common stock contained in the Registration Statement on Form 8-A relating thereto, filed on <u>[October 8, 2021](https://www.sec.gov/Archives/edgar/data/1819438/000119312521295421/d157489d8a12b.htm)</u>, including any amendment or report filed for the purpose of updating such description.

You may request a copy of these filings, at no cost, by writing or telephoning us at the following address:

ESS Tech, Inc.

26440 SW Parkway Ave., Bldg. 83

Wilsonville, Oregon 97070

Attn: Investor Relations

(855) 423-9920

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**Up to $75,000,000**

![prospectus1a.jpg](prospectus1a.jpg)

**Common Stock**

**PROSPECTUS SUPPLEMENT**

**Yorkville Securities**

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| | | | |
|:---|:---|:---|:---|
| **BMO Capital Markets** | **Canaccord Genuity** | **Needham & Company** | **Stifel** |

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**November 13, 2025**

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