ADDITIONAL INFORMATION

You may request copies of this proxy statement/prospectus/information statement and any other publicly available information concerning STWO, without charge, by written request to ACON S2 Acquisition Corp., 1133 Connecticut Avenue NW, Ste. 700, Washington, DC 20036, or by telephone request at (202) 454-1100; or                 , our proxy solicitor, by calling                 , or banks and brokers can call collect at                 , or by emailing                  or from the SEC through the SEC website at http://www.sec.gov.

In order for STWO’s shareholders to receive timely delivery of the documents in advance of the extraordinary general meeting of STWO to be held on                , 2021, you must request the information no later than five (5) business days prior to the date of the extraordinary general meeting, by                , 2021.

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ABOUT THIS PROXY STATEMENT/PROSPECTUS/INFORMATION STATEMENT

This document, which forms part of a registration statement on Form S-4 filed with the SEC, by STWO (File No. 333-                ) (the “Registration Statement”), constitutes a prospectus of STWO under Section 5 of the Securities Act, with respect to the ordinary shares in the capital of STWO to be issued if the Business Combination described below is consummated. This document also constitutes a notice of meeting and a proxy statement under Section 14(a) of the Exchange Act with respect to the extraordinary general meeting of STWO shareholders at which STWO shareholders will be asked to consider and vote upon a proposal to approve the Business Combination by the approval and adoption of the Merger Agreement, among other matters.

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FREQUENTLY USED TERMS

In this document:

“2014 Equity Incentive Plan” means the ESS 2014 Equity Incentive Plan, as amended, supplemented or modified from time to time.

“2021 Employee Stock Purchase Plan” means the ESS Tech, Inc. 2021 Employee Stock Purchase Plan, as amended, supplemented or modified from time to time.

“2021 Equity Incentive Plan” means the ESS 2021 Equity Incentive Plan, as amended, supplemented or modified from time to time.

“Adjournment Proposal” means a proposal to adjourn the extraordinary general meeting of shareholders of STWO to a later date or dates, if necessary, to permit further solicitation and vote of proxies if, based upon the tabulated vote at the time of the extraordinary general meeting, there are not sufficient votes to approve one or more proposals presented to shareholders for vote at such extraordinary general meeting.

“BEV” means Breakthrough Energy Ventures, LLC.

“broker non-vote” means the failure of an STWO shareholder, who holds his or her shares in “street name” through a broker or other nominee, to give voting instructions to such broker or other nominee.

“Business Combination” means the transactions contemplated by the Merger Agreement.

“Business Combination Proposal” means the proposal to approve the adoption of the Merger Agreement and the Business Combination.

“Charter Proposal” means the proposal to approve the adoption of the Proposed Certificate of Incorporation.

“Closing” means the consummation of the Business Combination.

“Closing Date” means the date on which the Closing occurs.

“Code” means the Internal Revenue Code of 1986, as amended.

“Companies Act” means the Companies Act (2021 Revision) of the Cayman Islands as the same may be amended from time to time.

“Condition Precedent Proposals” means the Domestication Proposal, the Business Combination Proposal, the Charter Proposal, the Election of Directors Proposal, the Equity Incentive Plan Proposal, the Nasdaq Proposal and the Employee Stock Purchase Plan Proposal, collectively.

“DGCL” means the General Corporation Law of the State of Delaware.

“Domestication” means the deregistration by way of continuation of STWO under the Companies Act and domestication of STWO into a Delaware corporation under the DGCL, with the ordinary shares of STWO becoming shares of common stock of the Delaware corporation under the applicable provisions of the Cayman Islands Companies Act and the DGCL; the term includes all matters and necessary or ancillary changes in order to effect such Domestication, including the adoption of the Proposed Certificate of Incorporation consistent with the DGCL and changing the name and registered office of STWO.

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“Domestication Proposal” means the proposal to approve the domestication of STWO as a Delaware corporation.

“Employee Stock Purchase Plan Proposal” means the proposal to approve the adoption of the ESPP.

“Equity Incentive Plan Proposal” means the proposal to approve the adoption of the 2021 Equity Incentive Plan.

“ESPP” means the ESS Tech, Inc. 2021 Employee Stock Purchase Plan, as amended, supplemented or modified from time to time.

“ESS” means ESS Tech, Inc., a Delaware corporation.

“ESS Board” means the board of directors of ESS, prior to the Business Combination.

“ESS Capital Stock” means ESS Common Stock and ESS Preferred Stock.

“ESS Common Stock” means ESS’ common stock, par value $0.0001 per share. “ESS Options” means all options to purchase outstanding shares of ESS Common Stock, whether or not exercisable and whether or not vested, immediately prior to the Closing under ESS option plans or otherwise, other than the ESS Warrants.

“ESS Preferred Stock” means ESS Series A Preferred Stock, ESS Series B Preferred Stock and ESS Series C Preferred Stock.

“ESS Restricted Stock” means all outstanding shares of restricted stock granted under ESS option plans or acquired via the early exercise of ESS Options, immediately prior to the Closing.

“ESS RSUs” means all outstanding restricted stock units granted by ESS, immediately prior to the Closing under ESS option plans or otherwise.

“ESS Series A Preferred Stock” means ESS’ Class A preferred stock, par value $0.0001 per share.

“ESS Series B Preferred Stock” means ESS’ Class B preferred stock, par value $0.0001 per share.

“ESS Series C Preferred Stock” means ESS Series C-1 Preferred Stock and ESS Series C-2 Preferred Stock.

“ESS Series C-1 Preferred Stock” means ESS’ Class C-1 preferred stock, par value $0.0001 per share.

“ESS Series C-2 Preferred Stock” means ESS’ Class C-2 preferred stock, par value $0.0001 per share.

“ESS Stockholders” means certain shareholders of ESS who have entered into the Transaction Support Agreement with STWO.

“ESS Warrants” means all outstanding and unexercised warrants to purchase shares of ESS Capital Stock.

“Exchange Act” means the U.S. Securities Exchange Act of 1934, as amended.

“Existing Governing Documents” means STWO’s current amended and restated memorandum and articles of association.

“GAAP” means United States generally accepted accounting principles.

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“Investment Company Act” means the Investment Company Act of 1940, as amended.

“IPO” means STWO’s initial public offering of units, consummated on September 21, 2020.

“JOBS Act” means the Jumpstart Our Business Startups Act of 2012, as amended.

“Merger” means the merging of Merger Sub with and into ESS with ESS surviving the Merger as a wholly-owned subsidiary of STWO.

“Merger Agreement” means the Agreement and Plan of Merger, dated as of May 6, 2021, as may be amended from time to time, among ESS, STWO and Merger Sub.

“Merger Sub” means SCharge Merger Sub, Inc., a Delaware corporation and wholly-owned direct subsidiary of STWO.

“Merger Sub Common Stock” means Merger Sub’s common stock, par value $0.0001 per share.

“Nasdaq” means the Nasdaq Stock Market LLC.

“New ESS” means STWO Delaware, immediately upon the completion of the Domestication.

“New ESS Board” means the board of directors of New ESS, immediately upon the Closing.

“New ESS Common Stock” means New ESS common stock, par value $0.0001 per share, as in effect immediately upon completion of the Domestication.

“New ESS Preferred Stock” means New ESS preferred stock, par value $0.0001 per share, as in effect immediately upon completion of the Domestication.

“NYSE” means the New York Stock Exchange.

“PIPE Financing” means the sale of PIPE Shares to the PIPE Investors, for a purchase price of $10.00 per share and an aggregate purchase price of $250 million, in a private placement.

“PIPE Investors” means the purchasers of the PIPE Shares.

“PIPE Shares” means an aggregate of 25,000,000 shares of New ESS Common Stock to be issued to PIPE Investors in the PIPE Financing.

“Private Placement Warrants” means the warrants to purchase shares of STWO Class A Ordinary Shares owned by the Sponsor.

“Proposed Bylaws” means the proposed bylaws of New ESS which will be effective upon completion of the Domestication.

“Proposed Certificate of Incorporation” means the proposed certificate of incorporation of New ESS which will be effective upon completion of the Domestication.

“Proposed Governing Documents” means New ESS’ proposed bylaws, certificate of incorporation and amended and restated memorandum and articles of association which will be effective upon completion of the Domestication.

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“Proposed Transactions” means the Business Combination and other proposed transactions contemplated by the Merger Agreement.

“prospectus” means the prospectus included in the Registration Statement on Form S-4 (Registration No. 333-                ) filed with the SEC.

“Public Shares” means shares of STWO Class A Ordinary Shares issued as part of the STWO Units sold in the IPO.

“Public Shareholders” means the holders of shares of STWO Class A Ordinary Shares.

“Public Warrants” means the warrants included in the STWO Units sold in the IPO, each of which is exercisable for one share of STWO Class A Ordinary Shares, in accordance with its terms.

“Recapitalization” means the automatic conversion by operation of law, on a one-to-one basis, of the STWO Class B Ordinary Shares to shares of New ESS Common Stock.

“SBE” means SB Energy Global Holdings One Ltd.

“SEC” means the U.S. Securities and Exchange Commission.

“Securities Act” means the U.S. Securities Act of 1933, as amended.

“Sponsor” means ACON S2 Sponsor, L.L.C., a Delaware limited liability company.

“Sponsor Shares” means the 6,250,000 shares of STWO Class B Ordinary Shares purchased by the Sponsor in a private placement prior to the IPO.

“Stockholder Agreement” means the Stockholder Agreement entered into as of May 6, 2021, by and among ESS, SBE and BEV.

“Transaction Support Agreements” means the Transaction Support Agreement entered into as of May 6, 2021 by and among STWO and each of BEV, Pangaea Ventures Fund III, LP, Cycle Capital Fund III, L.P., BASF Venture Capital GmbH, Presidio-IPM j.s.a., SBE, Michael Niggli, Michael R. Niggli Family Trust, Craig Evans and Evergy Ventures, Inc.

“STWO” means ACON S2 Acquisition Corp., a Cayman Islands exempted company.

“STWO Board” means the board of directors of STWO, prior to the Closing.

“STWO Class A Ordinary Shares” means STWO’s Class A ordinary shares, par value $0.0001 per share, as in effect immediately prior to the Domestication.

“STWO Class B Ordinary Shares” means STWO’s Class B ordinary shares, par value $0.0001 per share, as in effect immediately prior to the Domestication.

“STWO Delaware” means STWO as a Delaware corporation immediately after the Domestication.

“STWO Ordinary Shares” means the STWO Class A Ordinary Shares and STWO Class B Ordinary Shares.

“STWO Initial Shareholders” means the Sponsor, STWO’s officers and STWO’s directors.

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“STWO Unit” means one share of STWO Class A Ordinary Shares and one-third of one STWO Warrant.

“STWO Warrant Agreement” means the Warrant Agreement dated as of September 16, 2020 by and between STWO and Continental Stock Transfer & Trust Company, governing the STWO Warrants.

“STWO Warrants” means the warrants to purchase shares of STWO Class A Ordinary Shares contemplated by the STWO Warrant Agreement, with each warrant exercisable for one share of STWO Class A Ordinary Shares at an exercise price of $11.50.

“trust account” means the trust account that holds a portion of the proceeds of the IPO and the concurrent sale of the Private Placement Warrants.

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QUESTIONS AND ANSWERS ABOUT THE BUSINESS COMBINATION

The questions and answers below highlight only selected information from this document and only briefly address some commonly asked questions about the proposals to be presented at the extraordinary general meeting, including with respect to the proposed Business Combination. The following questions and answers do not include all the information that is important to STWO’s shareholders. We urge shareholders to read this proxy statement/prospectus/information statement, including the Annexes and the other documents referred to herein, carefully and in their entirety to fully understand the proposed Business Combination and the voting procedures for the extraordinary general meeting, which will be held on                      , 2021, at                Eastern Time, via a virtual meeting (albeit the physical location of the meeting will be at the offices of Kirkland & Ellis LLP, located at 609 Main Street, Houston, Texas 77002 for the purposes of the Existing Governing Documents).

A copy of the Merger Agreement is attached to this proxy statement/prospectus/information statement as Annex A and you are encouraged to read the Merger Agreement in its entirety.

The approval of each of the Business Combination Proposal, the Governance Proposals, the Equity Incentive Plan Proposal, the Nasdaq Proposal, the Employee Stock Plan Proposal and the Adjournment Proposal requires an ordinary resolution under Cayman Islands law, being the affirmative vote of at least a majority of the votes cast by the holders of the issued ordinary shares present in person or represented by proxy at the extraordinary general meeting and entitled to vote on such matter, and the Domestication Proposal and the Charter Proposals each require a special resolution under Cayman Islands law, being the affirmative vote of the holders of a majority of at least a two-thirds (2/3) of the ordinary shares who, being present in person or represented by proxy at the extraordinary general meeting and entitled to vote on such matter, vote on such matter.

In connection with the Domestication, on the Closing Date prior to the Effective Time, (i) each issued and outstanding Class A ordinary share will convert automatically by operation of law, on a one-for-one basis, into shares of New ESS Common Stock; (ii) each issued and outstanding Class A ordinary share of STWO

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received by the STWO Initial Shareholders in exchange for the same number of Class B ordinary shares pursuant to the Recapitalization will convert automatically by operation of law, on a one-for-one basis, into shares of New ESS Common Stock, (iii) each issued and outstanding warrant to purchase Class A ordinary shares of STWO will automatically represent the right to purchase one share of New ESS Common Stock at an exercise price of $11.50 per share of New ESS Common Stock on the terms and conditions set forth in the warrant agreement, and (iv) each issued and outstanding unit of STWO that has not been previously separated into the underlying Class A ordinary share and underlying warrant upon the request of the holder thereof, will be cancelled and will entitle the holder thereof to one share of New ESS Common Stock and one-third of one warrant of New ESS Common Stock, with such whole warrant representing the right to acquire one share of New ESS Common Stock at an exercise price of $11.50 per share of New ESS Common Stock on the terms and conditions set forth in the STWO Warrant Agreement. See “Proposal No. 1—The Domestication Proposal.”

The provisions of the Proposed Governing Documents (which will, if approved, amend and restate the Existing Governing Documents upon the Merger) will differ in certain material respects from the Existing Governing Documents. Please see “What amendments will be made to the Existing Governing Documents of STWO?” below.

THE VOTE OF SHAREHOLDERS IS IMPORTANT. SHAREHOLDERS ARE ENCOURAGED TO VOTE AS SOON AS POSSIBLE AFTER CAREFULLY REVIEWING THIS PROXY STATEMENT/PROSPECTUS/INFORMATION STATEMENT.

A:    At the extraordinary general meeting, STWO is asking holders of its ordinary shares to consider and vote upon twelve (12) separate proposals:

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For more information, please see “Proposal No. 1—The Domestication Proposal,” “Proposal No. 2—The Business Combination Proposal,” “Proposal No. 3—The Charter Proposal and Governance Proposals,” “Proposal No. 4—The Election of Directors Proposal,” “Proposal No. 5—The Equity Incentive Plan Proposal,” “Proposal No. 6—The Nasdaq Proposal,” “Proposal No. 7—The Employee Stock Purchase Plan Proposal” and “Proposal No. 8—The Adjournment Proposal.”

STWO will hold the extraordinary general meeting to consider and vote upon these proposals. This proxy statement/prospectus/information statement contains important information about the Business Combination and the other matters to be acted upon at the extraordinary general meeting. Shareholders of STWO should read it carefully.

After careful consideration, the STWO Board has determined that the Domestication Proposal, Business Combination Proposal, the Governing Documents Proposals, the Election of Directors Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal and the Adjournment Proposal are in the best interests of STWO and its shareholders and unanimously recommends that you vote or give instruction to vote “FOR” each of those proposals.

The existence of financial and personal interests of one or more of STWO’s directors may result in a conflict of interest on the part of such director(s) between what he, she or they may believe is in the best interests of STWO and its shareholders and what he, she or they may believe is best for himself, herself or themselves in determining to recommend that shareholders vote for the proposals. In addition, STWO’s officers have interests in the Business Combination that may conflict with your interests as a shareholder. See the section entitled “Proposal No. 2—The Business Combination Proposal—Interests of STWO’s Directors and Officers in the Business Combination” for a further discussion of these considerations.

Based on its due diligence investigations of ESS and the industry in which it operates, including the financial and other information provided by ESS in the course of negotiations, the STWO Board believes that ESS meets the general criteria and guidelines listed in its registration statement on Form S-1. However, there is no assurance of this. See “Proposal No. 2—The Business Combination Proposal—STWO Board of Directors’ Reasons for the Approval of the Business Combination.”

Although the STWO Board believes that the Business Combination with ESS presents a unique business combination opportunity and is in the best interests of STWO and its shareholders, the board of directors did consider certain potentially material negative factors in arriving at that conclusion. These factors are discussed in greater detail in the sections entitled “Proposal No. 2—The Business Combination Proposal—STWO Board of Directors’ Reasons for the Approval of the Business Combination” and “Risk Factors—Risks Related to the Business Following the Business Combination.”

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The following table illustrates varying ownership levels in New ESS Common Stock immediately following the consummation of the Business Combination based on the varying levels of redemptions by the public shareholders and the following additional assumptions: (i) 96,154,158 shares of New ESS Common Stock are issued to ESS stockholders at Closing in both a no redemption scenario and a maximum redemption scenario; (ii) 25,000,000 shares of New ESS Common Stock are issued to the PIPE Investors; (iii) all outstanding vested and unvested ESS Options are converted into New ESS Options exercisable for shares of New ESS Common Stock; (iv) the Earnout Milestone Events (as defined in the Merger Agreement) have not been satisified; and (v) no STWO Warrants to purchase New ESS Common Stock that will be outstanding immediately following Closing have been exercised. See “Unaudited Pro Forma Condensed Combined Financial Information” for more details. If the actual facts differ from these assumptions, the ownership percentages in STWO will be different and totals may not add up to 100% due to rounding.

For further details, see “Proposal No. 2—The Business Combination Proposal—Consideration to ESS Stockholders in the Business Combination.”

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To effect the Domestication, we will file an application for deregistration by way of continuation with the Cayman Islands Registrar of Companies, together with the necessary accompanying documents, and file a certificate of corporate domestication and a certificate of incorporation with the Secretary of State of the State of Delaware, under which we will be domesticated and continue as a Delaware corporation.

The approval of the Domestication Proposal is a condition to closing the Business Combination under the Merger Agreement. The approval of the Domestication Proposal requires a special resolution under the Existing Governing Documents, being the affirmative vote of the holders of a majority of at least two-thirds (2/3) of the ordinary shares who, being present in person or represented by proxy at the extraordinary general meeting and entitled to vote on such matter, vote on such matter. Abstentions and broker non-votes, while considered present for the purposes of establishing a quorum, will not count as votes cast at the extraordinary general meeting, and otherwise will have no effect on a particular proposal.

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In accordance with the terms and subject to the conditions of the Merger Agreement, at the Effective Time, among others, (i) each share of common stock of Merger Sub, par value $0.0001 per share, issued and outstanding as of immediately prior to the Effective Time will be converted and exchanged for one share of New ESS Common Stock, (ii) all shares of ESS Common Stock and ESS Preferred Stock held in the treasury of ESS or owned by STWO or Merger Sub will be canceled without any conversion thereof and no payment or distribution will be made with respect thereto, (iii) each share of ESS Common Stock and ESS Preferred Stock issued and outstanding as of immediately prior to the Effective Time (other than any cancelled shares and dissenting shares) will receive a number of shares of New ESS Common Stock based on an adjusted equity value of ESS with the ESS Preferred Stock receiving the consideration calculated on an as-converted basis as set forth in the allocations schedule, plus earnout stock pursuant to the terms and conditions of the Merger Agreement, (iv) each ESS option outstanding as of immediately prior to the Effective Time will be converted into an option to purchase a number of shares of New ESS Common Stock as calculated in accordance with the Merger Agreement, (v) each warrant of ESS issued and outstanding as of immediately prior to the Effective Time shall have been “net” exercised in exchange for shares of ESS Capital Stock, or otherwise shall be assumed by STWO and will be automatically converted into a warrant to acquire a number of shares of STWO common stock at an adjusted exercise price per share, as determined under the Merger Agreement, and (vi) each restricted stock unit of ESS that is outstanding immediately prior to the Effective Time, will be converted into a restricted stock unit covering a number of shares of New ESS Common Stock equal to the number of shares of restricted stock unit of ESS subject to such restricted stock unit of ESS immediately prior to the Effective Time. For further details, see “Proposal No. 2—The Business Combination Proposal—Consideration to ESS Stockholders in the Business Combination.”

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STWO does not expect to have significant cumulative earnings and profits through the date of the Domestication.

Furthermore, even if the Domestication qualifies as a “reorganization” under Section 368(a)(1)(F) of the Code, a U.S. holder of public shares and public warrants may, in certain circumstances, still recognize gain (but not loss) upon the exchange of its STWO public shares or public warrants for STWO Delaware public shares or public warrants pursuant to the Domestication under the “passive foreign investment company” (“PFIC”) rules of the Code equal to the excess, if any, of the fair market value of the STWO Delaware public shares or public warrants received in the Domestication over the U.S. holder’s adjusted tax basis in the corresponding STWO public shares or public warrants surrendered in exchange therefor. The tax on any such gain so recognized would be imposed at the rate applicable to ordinary income and an interest charge would apply. For a more complete discussion of the potential application of the PFIC rules to U.S. holders as a result of the Domestication, see “Certain U.S. Federal Income Tax Considerations of the Redemption and the Business Combination—U.S. Holders—PFIC Considerations.”

Additionally, the Domestication may cause non-U.S. holders (as defined in “Certain U.S. Federal Income Tax Considerations of the Redemption and the Business Combination—Non-U.S. Holders”) to become subject to U.S. federal income withholding taxes on any dividends paid in respect of such non-U.S. holder’s STWO Delaware public shares after the Domestication.

The tax consequences of the Domestication are complex and will depend on a holder’s particular circumstances. All holders are urged to consult their tax advisor on the tax consequences to them of the Domestication, including the applicability and effect of U.S. federal, state, local and foreign income and other tax laws. For a more complete discussion of the U.S. federal income tax considerations of the Domestication, see “Material U.S. Federal Income Tax Considerations of the Redemption and the Business Combination.”

Notwithstanding the foregoing, a public shareholder, together with any affiliate of such public shareholder or any other person with whom such public shareholder is acting in concert or as a “group” (as defined in Section 13(d)(3) of the Exchange Act), will be restricted from redeeming its public shares with respect to more than an aggregate of 15% of the public shares. Accordingly, if a public shareholder, alone or acting in concert or as a group, seeks to redeem more than 15% of the public shares, then any such shares in excess of that 15% limit would not be redeemed for cash and such shares would be converted into the Merger Consideration in connection with the Business Combination.

The Sponsor has agreed to waive its redemption rights with respect to all of its ordinary shares in connection with the consummation of the Business Combination. Such shares will be excluded from the pro rata calculation used to determine the per-share redemption price.

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Holders must complete the procedures for electing to redeem their public shares in the manner described above prior to                , Eastern Time, on                , 2021 (two business days before the extraordinary general meeting) in order for their shares to be redeemed.

The address of Continental, STWO’s transfer agent, is listed under the question “Who can help answer my questions?” below.

Holders of units must elect to separate the units into the underlying public shares and public warrants prior to exercising redemption rights with respect to the public shares. Public holders that hold their units in an account at a brokerage firm or bank, must notify their broker or bank that they elect to separate the units into the underlying public shares and public warrants, or if a holder holds units registered in its own name, the holder must contact Continental, our transfer agent, directly and instruct them to do so.

Public shareholders will be entitled to request that their public shares be redeemed for a pro rata portion of the amount then on deposit in the trust account as of two business days prior to the consummation of the Business Combination including interest earned on the funds held in the trust account and not previously released to us (net of taxes payable). However, the proceeds deposited in the trust account could become subject to the claims of our creditors, if any, which could have priority over the claims of our public shareholders, regardless of whether such public shareholders vote or, if they do vote, irrespective of if they vote for or against the Business Combination Proposal. Therefore, the per share distribution from the trust account in such a situation may be less than originally expected due to such claims. Whether you vote, and if you do vote irrespective of how you vote, on any proposal, including the Business Combination Proposal, will have no impact on the amount you will receive upon exercise of your redemption rights. It is expected that the funds to be distributed to public shareholders electing to redeem their public shares will be distributed promptly after the consummation of the Business Combination.

Any request for redemption, once made by a holder of public shares, may be withdrawn at any time up to the time the vote is taken with respect to the Business Combination Proposal at the extraordinary general meeting. If you deliver your shares for redemption to Continental, our transfer agent, and later decide prior to the extraordinary general meeting not to elect redemption, you may request that our transfer agent return the shares (physically or electronically) to you. You may make such request by contacting Continental, our transfer agent, at the phone number or address listed at the end of this section.

Any corrected or changed written exercise of redemption rights must be received by Continental, our transfer agent, prior to the vote taken on the Business Combination Proposal at the extraordinary general

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meeting. No request for redemption will be honored unless the holder’s public shares have been delivered (either physically or electronically) to Continental, our transfer agent, at least two business days prior to the vote at the extraordinary general meeting.

If a holder of public shares properly makes a request for redemption and the public shares are delivered as described above, then, if the Business Combination is consummated, we will redeem the public shares for a pro rata portion of funds deposited in the trust account, calculated as of two business days prior to the consummation of the Business Combination.

If you are a holder of public shares and you exercise your redemption rights, such exercise will not result in the loss of any warrants that you may hold.

Additionally, because the Domestication will occur immediately prior to the redemption by any public shareholder, U.S. holders exercising redemption rights will take into account the potential tax consequences of Section 367(b) of the Code as well as potential tax consequences of the U.S. federal income tax rules relating to PFICs. The tax consequences of the exercise of redemption rights, including pursuant to Section 367(b) of the Code and the PFIC rules, are discussed more fully below under “Material U.S. Federal Income Tax Considerations—U.S. Holders.” All holders of our public shares considering exercising their redemption rights are urged to consult their tax advisor on the tax consequences to them of an exercise of redemption rights, including the applicability and effect of U.S. federal, state, local and foreign income and other tax laws.

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If our initial business combination is paid for using equity or debt securities or not all of the funds released from the trust account are used for payment of the consideration in connection with our initial business combination or used for redemptions or purchases of the public shares, we may apply the balance of the cash released to us from the trust account for general corporate purposes, including for maintenance or expansion of operations of New ESS, the payment of principal or interest due on indebtedness incurred in completing our Business Combination, to fund the purchase of other companies or for working capital. See “Summary of the Proxy Statement/Prospectus/Information Statement.”

In no event will STWO redeem public shares in an amount that would cause our net tangible assets (as determined in accordance with Rule 3a51-1(g)(1) of the Exchange Act) to be less than $5,000,001 after giving effect to the transactions contemplated by the Merger Agreement and the PIPE Financing.

Additionally, as a result of redemptions, the trading market for the New ESS Common Stock may be less liquid than the market for the public shares was prior to consummation of the Business Combination and we may not be able to meet the listing standards for Nasdaq or another national securities exchange.

For more information about conditions to the consummation of the Business Combination, see “Proposal No. 2—The Business Combination Proposal.”

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You can pre-register to attend the virtual extraordinary general meeting virtually three (3) days prior to the meeting date starting           , 2021 at            Eastern Time. Enter the URL address into your browser         , enter your control number, name and email address. Once you pre-register you can vote or enter questions in the chat box. At the start of the meeting you will need to re-log in using your control number and will also be prompted to enter your control number if you vote during the meeting. STWO recommends that you log in at least 15 minutes before the meeting to ensure you are logged in when the extraordinary general meeting starts.

Beneficial investors, who own their investments through a bank or broker, will need to contact CST to receive a control number. If you plan to vote at the extraordinary general meeting you will need to have a legal proxy from your bank or broker or if you would like to join and not vote CST will issue you a guest control number with proof of ownership. Either way you must contact CST for specific instructions on how to receive the control number. We can be contacted at the number or email address above.

Please allow up to 72 hours prior to the meeting for processing your control number.

If you do not have internet capabilities, you can listen only to the meeting by dialing              when prompted enter the pin number             . This is listen-only, you will not be able to vote or enter questions during the meeting.

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As of the record date, STWO had 31,250,000 ordinary shares issued and outstanding consisting of 25,000,000 shares of STWO Class A Ordinary Shares and 6,250,000 shares of STWO Class B Ordinary Shares. On a poll, STWO shareholders are entitled to one vote at the extraordinary general meeting for each ordinary share held of record as of the record date. 6,250,000 ordinary shares are subject to the Sponsor Letter Agreement, pursuant to which the STWO Initial Shareholders have agreed to vote all of their shares (subject to certain exceptions) in favor of the Business Combination. 25,000,000 ordinary shares are not subject to the Sponsor Letter Agreement. For additional information regarding the Sponsor Letter Agreement, see “Certain Agreements Related to the Business Combination Proposal—Sponsor Letter Agreement.”

Assuming all holders that are entitled to vote on such matters vote all of their ordinary shares in person or by proxy, 15,625,001 shares, of which 9,375,001 shares are not subject to the Sponsor Letter Agreement, will need to be voted in favor of each of the Business Combination Proposal, the Governance Proposals, the Election of Directors Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal, and the Adjournment Proposal in order to approve each of the Business Combination Proposal, the Election of Directors Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal and the Adjournment Proposal.

Assuming all holders that are entitled to vote on such matter vote all of their ordinary shares in person or by proxy, 20,833,334 shares, of which 14,583,334 shares are not subject to the Sponsor Letter Agreement, will need to be voted in favor of the Domestication Proposal and the Charter Proposals in order to approve such proposals.

The existence of financial and personal interests of one or more of STWO’s directors may result in a conflict of interest on the part of such director(s) between what he, she or they may believe is in the best interests of STWO and its shareholders and what he, she or they may believe is best for himself, herself or themselves in determining to recommend that shareholders vote for the proposals. In addition, STWO’s officers have interests in the Business Combination that may conflict with your interests as a shareholder. See the section entitled “Proposal No. 2—The Business Combination Proposal—Interests of STWO’s Directors and Executive Officers in the Business Combination” for a further discussion of these considerations.

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At any time at or prior to the Business Combination, during a period when they are not then aware of any material nonpublic information regarding us or our securities, the STWO Initial Shareholders, ESS and/or their respective directors, officers, advisors or respective affiliates may purchase public shares from institutional and other investors who vote, or indicate an intention to vote, against any of the Condition Precedent Proposals, or execute agreements to purchase such shares from such investors in the future, or they may enter into transactions with such investors and others to provide them with incentives to acquire public shares or vote their public shares in favor of the Condition Precedent Proposals. Such a purchase may include a contractual acknowledgement that such shareholder, although still the record or beneficial holder of our shares, is no longer the beneficial owner thereof and therefore agrees not to exercise its redemption rights. In the event that the STWO Initial Shareholders, ESS and/or their directors, officers, advisors or respective affiliates who have agreed to vote in favor of this transaction purchase shares in privately negotiated transactions from public shareholders who have already elected to exercise their redemption rights, such selling shareholder would be required to revoke their prior elections to redeem their shares. The purpose of such share purchases and other transactions would be to increase the likelihood of satisfaction of the requirements that (i) the Business Combination Proposal, the Election of Directors Proposal, the Governance Proposals, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal and the Adjournment Proposal are approved by the affirmative vote of at least a majority of the votes cast by the holders of the issued ordinary shares present in person or represented by proxy at the extraordinary general meeting and entitled to vote on such matter (ii) the Domestication Proposal and the Charter Proposal are approved by the affirmative vote of at least a two-thirds (2/3) majority of the votes cast by the holders of the issued ordinary shares present in person or represented by proxy at the extraordinary general meeting and entitled to vote on such matter, (iii) otherwise limit the number of public shares electing to redeem their public shares and (iv) New ESS’ net tangible assets (as determined in accordance with Rule 3a51-1(g)(1) of the Exchange Act) being at least $5,000,001 after giving effect to the transactions contemplated by the Merger Agreement and the PIPE Financing.

If such transactions are effected, the consequence could be to cause the Business Combination to be consummated in circumstances where such consummation could not otherwise occur. Purchases of shares by the persons described above would allow them to exert more influence over the approval of the proposals to be presented at the extraordinary general meeting and would likely increase the chances that such proposals would be approved. We will file or submit a Current Report on Form 8-K to disclose any material arrangements entered into or significant purchases made by any of the aforementioned persons that would affect the vote on the proposals to be put to the extraordinary general meeting or the redemption threshold.

Any such report will include descriptions of any arrangements entered into or significant purchases by any of the aforementioned persons.

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Individuals call toll-free:

Banks and brokers call:

Email:

You also may obtain additional information about STWO from documents filed with the SEC by following the instructions in the section entitled “Where You Can Find More Information; Incorporation by Reference.” If you are a holder of public shares and you intend to seek redemption of your public shares, you will need to deliver your public shares (either physically or electronically) to Continental, STWO’s transfer agent, at the address below prior to the extraordinary general meeting. Holders must complete the procedures for electing to redeem their public shares in the manner described above prior to                , Eastern Time, on                , 2021 (two business days before the extraordinary general meeting) in order for their shares to be redeemed. If you have questions regarding the certification of your position or delivery of your stock, please contact:

Continental Stock Transfer & Trust Company

1 State Street, 30th Floor

New York, New York 10004

Attention:

E-mail:

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