Spark I Acquisition Corp

As filed with the U.S. Securities and Exchange Commission on October 21, 2026.

Registration No. 333-299215

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION** **

Washington, D.C. 20549

AMENDMENT NO. 1

to

FORM****S-4

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

**Spark I Acquisition Corp*oration

(Exact name of registrant as specified in its charter)

For co-registrants, see**“Table of Co-Registrants”**** on the following page.**

3790 El Camino Real

Unit #570

(650) 353-7082

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Bernard Moon

Secretary

3790 El Camino Real

Unit #570

(650) 353-7082

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

**Approximate date of commencement of proposed sale to the public:**As soon as practicable after (i) this registration statement is declared effective and (ii) upon completion of the applicable transactions described in the enclosed proxy statement/prospectus.

If the securities being registered on this Form are being offered in connection with the formation of a holding company and there is compliance with General Instruction G, check the following box:☐

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering:☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering:☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company, or an emerging growth company. See the definitions of“large accelerated filer,” “accelerated filer,” “smaller reporting company,” and“emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.☐

If applicable, place an X in the box to designate the appropriate rule provision relied upon in conducting this transaction:

Exchange Act Rule 13e-4(i) (Cross-Border Issuer Tender Offer)☐

Exchange Act Rule 14d-1(d) (Cross-Border Third-Party Tender Offer)☐

The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the registration statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

TABLE OF CO-REGISTRANTS

20050 SW 112th Ave

Tel: (503) 399-3517

Tod Higinbotham

Chief Executive Officer

20050 SW 112th Ave

Tel: (503) 399-3517

The information in this preliminary proxy statement/prospectus is not complete and may be changed. These securities may not be issued until the registration statement filed with the U.S. Securities and Exchange Commission is effective. This preliminary proxy statement/prospectus is not an offer to sell these securities and does not constitute the solicitation of an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

PRELIMINARY PROXY STATEMENT — SUBJECT TO COMPLETION DATED** OCTOBER 21****, 2026**

PROXY STATEMENT FOR EXTRAORDINARY GENERAL MEETING OF

(A CAYMAN ISLANDS EXEMPTED COMPANY)

AND

PROSPECTUS FOR SHARES OF COMMON STOCK

AND

WARRANTS TO PURCHASE SHARES OF COMMON STOCK OF

(TO BE RENAMED “ZINCFIVE, INC.” FOLLOWING DOMESTICATION IN

THE STATE OF DELAWARE AND IN CONNECTION WITH THE BUSINESS COMBINATION DESCRIBED IN THIS PROXY STATEMENT/PROSPECTUS)

The board of directors of Spark I Acquisition Corporation, a Cayman Islands exempted company with limited liability (“SPKL”), has unanimously approved the business combination between SPKL and ZincFive, Inc., a Delaware corporation (referred to in this proxy statement/prospectus prior to the Business Combination (as defined below) as “Legacy ZincFive”), pursuant to which: (i) SPKL will deregister as an exempted company registered under the laws of the Cayman Islands with limited liability and register by way of continuation and domestication as a corporation under the laws of the State of Delaware (the “Domestication”) in accordance with the Delaware General Corporation Law (“DGCL”) and the Companies Act (As Revised) of the Cayman Islands (the “Companies Act”) and the plan of domestication (as may be amended, supplemented or otherwise modified from time to time in accordance with its terms, the “Plan of Domestication”), attached to this proxy statement/prospectus as Annex B(the post-Domestication company will be referred to in this proxy statement/prospectus as “ZincFive”); (ii) at the closing of the transactions contemplated by the Merger Agreement (as defined below) (the “Closing”) and at least one day following the Domestication, Spark I Acquisition Corporation Sub I Inc., a Delaware corporation (“Merger Sub I”), will merge with and into Legacy ZincFive (the “First Merger”), with Legacy ZincFive continuing as the surviving corporation (the “Surviving Corporation”), and, immediately following the First Merger, Legacy ZincFive, as the Surviving Corporation, will merge with and into Spark I Acquisition Corporation Sub II LLC, a Delaware limited liability company (“Merger Sub II”) (the “Second Merger” and, together with the First Merger, the “Mergers”), with Merger Sub II continuing as the surviving entity and a direct wholly owned subsidiary of ZincFive, in each case, pursuant and subject to the terms and conditions set forth in the Merger Agreement, dated as of June 11, 2026 (the “Signing Date”), attached to this proxy statement/prospectus as Annex A(as it may be further amended, supplemented or otherwise modified from time to time in accordance with its terms, the “Merger Agreement”), by and among SPKL, Merger Sub I, Merger Sub II and Legacy ZincFive; and (iii) the other transactions contemplated by the Merger Agreement and other related documents will be consummated (such transactions, together with the Mergers and the Domestication, the “Business Combination”). Prior to the Domestication, Legacy ZincFive will be renamed “ZincFive Technologies, Inc.”

In connection with the Domestication and in accordance with the Plan of Domestication, attached to this proxy statement/prospectus as Annex B: (i) each Class A ordinary share of SPKL, par value $0.0001 per share (the “SPKL Class A Ordinary Share”) issued and outstanding immediately prior to the Domestication will remain outstanding and will automatically convert, on a one-for-one basis, into one share of common stock of ZincFive, par value $0.0001 per share (the “ZincFive Common Stock”); (ii) each Public Warrant (as defined below) and Private Placement Warrant (as defined below), each exercisable for one SPKL Class A Ordinary Share at an exercise price of $11.50 per share, subject to adjustment (the “SPKL Warrant”), will be automatically converted into one share of redeemable warrant exercisable for one share of ZincFive Common Stock (the “ZincFive Warrant”) on the same terms as the SPKL Warrants; and (iii) each unit sold in SPKL’s initial public offering (“IPO”), each consisting of one SPKL Class A Ordinary Share and one-half of one Public Warrant (the “SPKL Unit”), issued and outstanding will automatically be cancelled and each holder thereof will be entitled, per SPKL Unit, to one share of ZincFive Common Stock and one-half of one ZincFive Warrant. No fractional ZincFive Warrants will be issued in the process described in this clause (iii).

In connection with the Domestication and subject to the satisfaction or waiver of the conditions set forth in the Merger Agreement, including approval of the Condition Precedent Proposals (as defined elsewhere in this proxy statement/prospectus) by SPKL’s shareholders: (i) the governing documents of SPKL will be replaced by the Proposed Certificate of Incorporation and the Proposed Bylaws (the “Proposed Organizational Documents”), attached to this proxy statement/prospectus as Annex Cand Annex D, respectively, and (ii) SPKL will be renamed “ZincFive, Inc.”

At Closing, pursuant to the terms of the Merger Agreement:

(a)in connection with the Mergers, the value of the aggregate consideration to be paid to Legacy ZincFive Securityholders will be $600,000,000 (the“Equity Value”), which consideration will be paid entirely in shares of ZincFive Common Stock with a value equal to $10.00 per share, options to purchase shares of ZincFive Common Stock or restricted stock units of ZincFive, as applicable;

(b)other than Excluded Shares (as defined in the Merger Agreement) and Dissenting Shares (as defined in the Merger Agreement), each share of Series F preferred stock, Series F-1 preferred stock, Series F-2 preferred stock, Series F-3-A preferred stock, Series F-3-B preferred stock, Series F-3-C preferred stock, Series F-3-D preferred stock and Series F-3-W preferred stock of Legacy ZincFive (collectively,“Legacy ZincFive Series** **F Stock”) issued and outstanding immediately prior to the date and time that the First Merger becomes effective (the“First Effective Time”) will be automatically surrendered and retired, and each holder of shares of Legacy ZincFive Series F Stock will receive a number of shares of ZincFive Common Stock equal to (i) such holder’s Aggregate Series F Preference Amount (as defined in the Merger Agreement) divided by (ii) $10.00, rounded up or down to the nearest whole share of ZincFive Common Stock (with 0.5 of a share or greater rounded up);

(c)each share of Class A common stock, par value $0.001 per share, of Legacy ZincFive (the“Legacy ZincFive Class** A Common Stock”) and Class B common stock, par value $0.001 per share, of Legacy ZincFive (the“Legacy ZincFive Class **B Common Stock” and, together with the Legacy ZincFive Class A Common Stock, the“Legacy ZincFive Common Stock”) issued and outstanding immediately prior to the First Effective Time (after giving effect to the Conversion (as defined below) and the exercise of any warrants to purchase shares of Legacy ZincFive capital stock (the“Legacy ZincFive Warrants”), but other than Excluded Shares and Dissenting Shares) will be automatically cancelled and converted into the right to receive a number of shares of ZincFive Common Stock equal to the Exchange Ratio (as defined in the Merger Agreement); and

(d)each Legacy ZincFive Warrant outstanding as of immediately prior to the Mergers shall expire or be exercised for the applicable number of shares of Legacy ZincFive’s Series A preferred stock, Series B preferred stock, Series C preferred stock, Series D preferred stock, Series E preferred stock and Legacy ZincFive Series F Stock, each with a par value of $0.001 per share (collectively, the“Legacy ZincFive Preferred Stock”) or Legacy ZincFive Common Stock, and such shares shall be canceled and converted into the right to receive the applicable consideration in respect of such shares pursuant to the terms of the Merger Agreement.

Legacy ZincFive will take all actions necessary or appropriate so that, immediately prior to the Closing, all shares of Legacy ZincFive Preferred Stock (other than Legacy ZincFive Series F Stock) will be converted into shares of Legacy ZincFive Common Stock (the “Conversion”) pursuant to the terms of the Merger Agreement. See the section entitled “Description of ZincFive’s Securities” for more information regarding the ZincFive Common Stock. Following the Conversion, no shares of Legacy ZincFive Preferred Stock (other than Legacy ZincFive Series F Stock) will be outstanding and each holder of Legacy ZincFive Preferred Stock (other than Legacy ZincFive Series F Stock) will thereafter cease to have any rights with respect to any shares of Legacy ZincFive Preferred Stock.

Concurrently with the execution of the Merger Agreement, SPKL entered into the Sponsor Agreement, dated June 11, 2026, with SLG SPAC Fund LLC, a Delaware limited liability company (the “Sponsor”), SPKL, certain stockholders of SPKL and Legacy ZincFive (as amended by the Amendment to Sponsor Agreement, dated September 28, 2026, the “Sponsor Agreement”), pursuant to which the Sponsor agreed to, among other things: (i) vote in favor of adoption of the SPKL Stockholder Matters;(ii) vote against any Acquisition Transaction (as defined in the Merger Agreement) and any merger agreement or merger other than the Merger Agreement and the Business Combination; and (iii) convert all outstanding SPKL Class B Ordinary Shares held by the Sponsor into SPKL Class A Ordinary Shares immediately prior to the Domestication. In addition, the Sponsor separately agreed to forfeit, immediately following the Closing, (i) 3,500,000 shares of ZincFive Common Stock to be issued to Alyeska Master Fund, L.P. (the “Lead Purchaser”) as a condition to the Lead Purchaser’s participation in the Series A Preferred Investment; (ii) 922,078 shares of ZincFive Common Stock to be issued to the investors (the “First Tranche Bridge Investors”) who provided bridge financing to Legacy ZincFive in the form of secured promissory notes (the “Bridge Notes”) pursuant to the Note Purchase Agreement, dated April 23,

2026, by and among Legacy ZincFive and the investor parties thereto (the “Bridge Investors”) before the public announcement of the Business Combination and 1,458,400 ZincFive Warrants to be issued to certain of the Bridge Investors; and (iii) 2,786,867 ZincFive Warrants and 50% of any ZincFive Warrants issued as a result of the conversion of $1,500,000 of the unpaid principal balance of the Convertible Note (as defined below) into Working Capital Warrants (as defined below) to be reserved for issuance as stock options under the ZincFive, Inc. 2026 Equity Incentive Plan (the “2026 Plan”).

Pursuant to the Proposed Bylaws of ZincFive to be in effect at the First Effective Time, and subject to certain exceptions, stockholders of ZincFive will not be permitted to, from the Closing Date until the earlier of 11:59 p.m., New York time, on (x) the date that is the later of one hundred eighty (180) days after the date that a registration statement (the “Resale Registration Statement”) covering the resale of Registrable Securities (as defined in the A&R Registration Rights Agreement) initially becomes effective and days after the Closing Date, or, in the case of affiliates of ZincFive as of the Closing Date, twelve (12) months after the date the Resale Registration Statement becomes effective, and (y) the date on which ZincFive completes a liquidation, merger, stock exchange or other similar transaction that results in all of its stockholders having the right to exchange their shares of ZincFive Common Stock for cash, securities or other property, (i) exchange, transfer, assign, lend, sell, offer to sell, contract or agree to sell, hypothecate, pledge, grant any option to purchase or otherwise dispose of or agree to dispose of, directly or indirectly, or establish or increase a put equivalent position or liquidate or decrease a call equivalent position within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and the rules and regulations of the U.S. Securities and Exchange Commission (the “SEC”) promulgated thereunder with respect to, any shares of ZincFive Common Stock (A)issued as consideration pursuant to the Merger Agreement held by any such holders as of the Closing, (B) issued upon the settlement or exercise of options, restricted stock units or other equity awards or warrants outstanding as of immediately prior to the Closing that are assumed by ZincFive held by any such holders as of the Closing, (C) issued to employees of ZincFive, or (D) otherwise held by Sponsor, the officers and directors of Sponsor or ZincFive, or its and their respective affiliates as of the Closing (such shares, the“Lock-Up Shares”; provided that shares of ZincFive Common Stock issued pursuant to the ZincFive, Inc. 2026 Employee Stock Purchase Plan (the“ESPP”) will not constitute Lock-Up Shares), (ii) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of any Lock-Up Shares, whether any such transaction is to be settled by delivery of such securities, in cash or otherwise, or (iii) publicly announce any intention to effect any transaction specifiedin clause (i) or (ii).

The Proposed Bylaws provide for certain customary permitted transfers, including transfers to certain affiliates, members, partners, family members, or for estate planning purposes. Further, if the volume- weighted average price (“VWAP”) of ZincFive Common Stock equals or exceeds $12.00 for twenty (20) trading days within any period of thirty (30) consecutive trading days commencing at least one hundred eighty (180) days after the date the Resale Registration Statement becomes effective, then the transfer restrictions applicable to the Lock-Up Shares will expire. Notwithstanding the foregoing, the board of directors of ZincFive (the “ZincFive Board”) may grant a discretionary waiver or termination of the lockup restrictions. Any such discretionary waiver or termination shall apply to each other holder of Lock-Up Shares in the same proportion that the number of Lock-Up Shares held by the holder of Lock-Up Shares with respect to which such lockup restrictions are being terminated or waived bears to the total number of Lock-Up Shares then held by such holder (a “Pro-Rata Release”). A Pro-Rata Release shall not apply or be required in the case of an early release from the lockup restrictions if such early release is made (i) with respect to a number of shares of ZincFive Common Stock equal to $2,500 for each holder of Lock-Up Shares, calculated as of the Closing Date, rounded up to the nearest share, to the extent that a holder of such shares is not an affiliate of SPKL or ZincFive; (ii) solely for the purposes of complying with certain initial and continued listing requirements of Nasdaq or to comply with ZincFive’s obligations under the Series A Securities Purchase Agreement; or (iii) due to circumstances of an emergency or hardship, each as determined by the ZincFive Board or any duly authorized committee thereof in its sole judgment.

Prior to the Closing, Legacy ZincFive intends to enter into lockup agreements with each Legacy ZincFive stockholder that will receive 1% or more of the shares of ZincFive Common Stock distributable to Legacy ZincFive stockholders pursuant to the Merger Agreement. The lockup agreements are expected to provide for a restriction on transfers of Lock-Up Shares for up to twelve (12) months after the date the Resale Registration Statement becomes effective and otherwise on substantially identical terms as the lockup restrictions contained in the Proposed Bylaws that are applicable to affiliates of ZincFive as of the Closing Date.

Concurrently with the execution of the Merger Agreement, on June 11, 2026, SPKL and Legacy ZincFive entered into the Series A Securities Purchase Agreement (the “Series A Securities Purchase Agreement”) with certain institutional and accredited investors (the “Series A Preferred Investors”). Pursuant to the Series A Securities Purchase Agreement, the Series A Preferred Investors have agreed to purchase, concurrently with the Closing, an aggregate of 10,441,174 shares of the 12.0% Series A Cumulative Convertible Preferred Stock of ZincFive, par value $0.0001 per share (the “Series A Preferred Stock”), having the rights, preferences and privileges set forth in the Certificate of Designation of Preferences, Rights and Limitations of 12.0% Series A

Cumulative Convertible Preferred Stock (the “Certificate of Designation”) and warrants to purchase a number of shares of ZincFive Common Stock equal to the number of shares into which such shares of ZincFive Common Stock underlying such investor’s Series A Preferred Stock are initially convertible (the “Series A Preferred Investor Warrants”), for an aggregate purchase price of $106.5 million (the “Series A Preferred Investment”). Certain Series A Preferred Investors will satisfy their purchase price obligations through the cancellation of their Bridge Notes in exchange for shares of Series A Preferred Stock and Series A Preferred Investor Warrants. The consummation of the Series A Preferred Investment is conditioned upon the satisfaction or waiver of certain customary closing conditions, including the Available Closing SPAC Cash (as defined in the Merger Agreement) being not less than $100,000,000 at the Closing.

The following table illustrates the pro forma ownership in ZincFive immediately following the consummation of the Business Combination, under each of: (i) the No Redemption Scenario and (ii) the Maximum Redemption Scenario, each as defined below and excluding the dilutive effect of: (a) the Private Placement Warrants (as defined below); (b) the Public Warrants (as defined below); (c) the Working Capital Warrants into which the Convertible Note (as defined below) can be converted; and (d) the Series A Preferred Investor Warrants:

For more information, please see the sections of this proxy statement/prospectus entitled “Unaudited Pro Forma Condensed Combined Financial Information” and “Beneficial Ownership of Securities.”

The Memorandum and Articles of Association provide that SPKL must complete its initial business combination by March 29, 2027, or such earlier date as the SPKL Board may approve, or such later date as the shareholders of SPKL may approve in accordance with the Memorandum and Articles of Association (the “Combination Period”). If SPKL is unable to complete the Business Combination or another initial business combination by such date, SPKL will: (i) cease all operations except for the purpose of winding up; (ii) as promptly as reasonably possible but not more than ten business days thereafter, redeem the Public Shares, at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the trust account of SPKL (the “Trust Account”), including interest earned on the funds held in the Trust Account (less taxes payable and up to $100,000 of interest to pay dissolution expenses), divided by the number of the then-outstanding Public Shares, which redemption will completely extinguish rights of Public Shareholders (as defined below) as shareholders (including the right to receive further liquidation distributions, if any); and (iii) as promptly as reasonably possible following such redemption, subject to the approval of SPKL’s remaining shareholders and the SPKL Board, liquidate and dissolve, subject in the case of clauses(ii) and (iii) to SPKL’s obligations under Cayman Islands law to provide for claims of creditors and the requirements of other applicable law. The Sponsor and SPKL’s officers and directors have entered into an agreement with SPKL, pursuant to which they have waived their rights to liquidating distributions from the Trust Account with respect to their Founder Shares if SPKL fails to consummate an initial business combination within the Combination Period.

The SPKL Units, SPKL Class A Ordinary Shares and Public Warrants are currently listed on The Nasdaq Stock Market LLC (“Nasdaq”) under the symbols “SPKLU,” “SPKL” and “SPKLW,” respectively. On September 30, 2026, SPKL received a written notice (the “Delisting Notice”) from the Listing Qualifications Department of Nasdaq stating that the SPKL Units, SPKL Class A Ordinary Shares and Public Warrants will be delisted from Nasdaq because SPKL did not complete its initial business combination by September 29, 2026, which is 36 months from the effectiveness of SPKL’s registration statement for the IPO. Accordingly, trading in the SPKL Units, SPKL Class A Ordinary Shares and Public Warrants on Nasdaq was suspended at the opening of business on October 7, 2026, and Nasdaq will file a Form 25-NSE with the SEC, which will remove such securities from listing and registration on Nasdaq. Following the delisting, SPKL expects that the SPKL Units, SPKL Class A Ordinary Shares and Public Warrants will be quoted on the Pink Limited Market operated on the OTC Market systems (the “OTC Market”) under the symbols “SPKLU,” “SPKLF” and “SPKLW,” respectively.

Pursuant to the terms of the Merger Agreement, SPKL is required to cause the ZincFive Common Stock issued in the Domestication to be approved for listing on the NYSE, Nasdaq, or such other stock exchange as mutually agreed to by SPKL and Legacy ZincFive (the “Stock Exchange”). There can be no assurance that such listing condition will be met. If the listing condition is not met, the Business Combination will not be consummated unless the listing condition is waived by the parties to the Merger Agreement. Following the Closing, ZincFive Common Stock and ZincFive Warrants will be listed, subject to the approval of the Stock Exchange, under the proposed symbols “ZFIV” and “ZFIVW,” respectively. We may not have received confirmation from a Stock Exchange of approval of the listing of the ZincFive Common Stock and ZincFive Warrants at the time of the Extraordinary General Meeting or prior to the Closing. The listing condition to the Closing may be waived by the parties to the Merger Agreement. As a result, you may be asked to vote to approve the Business Combination and the other proposals included in this proxy statement/prospectus without such confirmation. Further, it is possible that such confirmation may never be received, and the Business Combination could still be consummated if such condition is waived. In such event, the ZincFive Common Stock and ZincFive Warrants may not be listed on any Stock Exchange.

Material Financing Transactions of SPKL

Prior to the IPO, the Sponsor paid $25,000, or approximately $0.004 per share, to cover certain expenses on our behalf in consideration of 6,870,130 Class B ordinary shares of SPKL, par value $0.0001 per share (“SPKL Class B Ordinary Shares”, together with the SPKL Class A Ordinary Shares, “SPKL Ordinary Shares”, and such SPKL Class B Ordinary Shares initially issued to the Sponsor, the “Founder Shares”), and on April 1, 2022, the Sponsor sold and transferred a total of 850,000 Founder Shares to certain of SPKL’s officers and directors, at a purchase price equal to the par value per share. Up to 448,052 Founder Shares were subject to forfeiture by the Sponsor depending on the extent to which the underwriter’s over-allotment option was exercised, and, pursuant to that certain letter agreement, dated as of October 5, 2023, by and among SPKL, the Sponsor and the members of SPKL’s board of directors and management team party thereto (the “Letter Agreement”), and up to 3,435,065 Founder Shares were subject to forfeiture if the Forward Purchaser (as defined in the Letter Agreement) exercises its right to terminate or reduce its commitment to purchase forward purchase securities pursuant to that certain forward purchase agreement, dated as of October 5, 2023, by and between SPKL and SparkLabs Group Management, LLC (the “Forward Purchase Agreement”) or in the event of SPKL’s liquidation and subsequent dissolution. On October 10, 2023, at the request of SPKL, Cantor Fitzgerald & Co. (“Cantor”) informed SPKL that it would not be exercising the over-allotment option. As a result, the Sponsor forfeited an aggregate of 448,052 Founder Shares, and such forfeited shares were cancelled by SPKL prior to the consummation of the IPO. Additionally, pursuant to the Sponsor Agreement, the Letter Agreement was amended to provide that the Sponsor will not be obligated to surrender any Founder

Shares (or any SPKL Class A Ordinary Share issued upon conversion thereof) as a result of the Forward Purchaser not fulfilling its commitment under the Forward Purchase Agreement. Accordingly, no forfeiture of Founder Shares as contemplated under the Letter Agreement will occur in connection with the Business Combination regardless of whether the Forward Purchaser fulfills its commitment.

Since the IPO, the following material financing transactions have occurred or will occur in connection with the consummation of the Business Combination: (i) simultaneously with the consummation of the IPO, the Sponsor purchased an aggregate of 8,490,535 warrants, each exercisable to purchase one SPKL Class A Ordinary Share, or, following the Domestication, one share of ZincFive Common Stock, at an exercise price of $11.50 per share (the “Private Placement Warrants”), at a price of $1.00 per warrant in a private placement, generating total proceeds of $8,490,535; (ii) on January 28, 2025, SPKL issued a convertible unsecured promissory note (the “Convertible Note”) in the principal amount of up to $1,900,000 to the Sponsor, of which $1,900,000 is outstanding, which does not bear interest and is repayable upon the consummation of the Business Combination, with the Sponsor having the option to convert up to $1,500,000 of the outstanding principal balance into warrants with terms identical to the Private Placement Warrants (the “Working Capital Warrants”), at a price of $1.00 per warrant upon consummation of the Business Combination; (iii) on June 25, 2025, SPKL issued a non-convertible unsecured promissory note (the “Non-Convertible Note”) in the principal amount of up to $2,500,000 to the Sponsor, of which $ was outstanding as of , 2026, which does not bear interest and is repayable upon the earlier of the consummation of the Business Combination and the last day that SPKL has to complete a business combination; (iv) following the approval of a proposal to amend the Memorandum and Articles of Association to extend the date by which we have to consummate an initial business combination from July 11, 2025 to September 29, 2026 (the “First Extension”) at the extraordinary general meeting of SPKL’s shareholders held on July 8, 2025 (the “First Extension Meeting”), SPKL committed to make monthly deposits (the “First Extension Contributions”) into the Trust Account in an amount equal to the lesser of (A) $0.015 for each outstanding SPKL Class A Ordinary Share and (B) $55,000, up to a maximum aggregate amount of $825,000, to extend SPKL’s time period to consummate a business combination from July 11, 2025 to September 29, 2026; (v) following the approval of a proposal to amend the Memorandum and Articles of Association to extend the date by which we have to consummate an initial business combination from September 29, 2026 to March 29, 2027 (the “Second Extension”) at the extraordinary general meeting of SPKL’s shareholders held on September 25, 2026 (the “Second Extension Meeting”), SPKL committed to make monthly deposits (the “Second Extension Contributions” and together with the First Extension Contributions, the “Contributions”) into the Trust Account in an amount equal to $0.015 for each outstanding SPKL Class A Ordinary Share, up to a maximum aggregate amount of $201,304, to extend SPKL’s time period to consummate a business combination from September 29, 2026 to March 29, 2027, with aggregate deposits of $ having been made into the Trust Account through , 2026; and (vi) the Series A Preferred Investment. The Non-Convertible Note, which includes the aggregate amount of the Contributions deposited into the Trust Account, and $of the Convertible Note will be repaid upon the consummation of the Business Combination, except that, with respect to the Convertible Note, up to $1,500,000 of the outstanding principal balance may be converted at the Sponsor’s option into Working Capital Warrants with terms identical to the Private Placement Warrants at a price of $1.00 per warrant, pursuant to the Sponsor Agreement.

Sponsor Compensation

The Sponsor currently holds 4,000,000 SPKL Class A Ordinary Shares and 1,572,078 SPKL Class B Ordinary Shares. The compensation and securities received or to be received by the Sponsor in connection with the Business Combination and related transactions upon the consummation of the Business Combination is:(i) 1,150,000 shares of ZincFive Common Stock issuable upon a one-for-one conversion of all of the SPKL Ordinary Shares held by Sponsor, with an implied aggregate market value of $ million (based upon the closing price of SPKL Class A Ordinary Shares of $ on the OTC Market on , 2026, the most recent practicable date prior to the date of this proxy statement/prospectus), which reflects the forfeiture of (a) 3,500,000 shares to be issued to the Lead Purchaser and (b) 922,078 shares to be issued to the First Tranche Bridge Investors, each pursuant to the Sponsor Agreement; (ii) 4,245,268 ZincFive Warrants, issuable upon a one-for-one conversion of all of the Private Placement Warrants held by the Sponsor, with an implied aggregate market value of $ million (based upon the closing price of the Public Warrants, each exercisable for one SPKL Class A Ordinary Share or, following the Domestication, one share of ZincFive Common Stock, at an exercise price of $11.50 (the“Public Warrants”), of $ on the OTC Market on, 2026, the most recent practicable date prior to the date of this proxy statement/prospectus), which reflects the forfeiture of (a) 2,786,867 ZincFive Warrants to be reserved for issuance as stock options under the 2026 Plan and (b) 1,458,400 ZincFive Warrants to be issued to certain of the Bridge Investors, each pursuant to the Sponsor Agreement; (iii) 750,000 ZincFive Warrants issuable upon a one-for- one conversion of all of the Working Capital Warrants to be held by the Sponsor, assuming full conversion of $1,500,000 of the unpaid principal balance of the Convertible Note into Working Capital Warrants, of which $ million is outstanding as of , 2026, the most recent practicable date prior to the date of this proxy statement/prospectus, which ZincFive Warrants would have an implied aggregate market value of $ million (based upon the closing price of the Public Warrants of $ on the OTC Market on , 2026, the most recent practicable date prior to the date of this proxy statement/prospectus), which reflects the forfeiture of 50% of such warrants to be reserved for issuance

as stock options under the 2026 Plan pursuant to the Sponsor Agreement; (iv) $ representing repayment of the remainder of the outstanding balance of the Convertible Note; (v) $ representing repayment of the Non-Convertible Note, of which $ million is outstanding, which includes an aggregate of $ in Contributions deposited into the Trust Account; and (vi) $ representing reimbursement of out-of-pocket expenses incurred by the Sponsor in connection with identifying, investigating and completing an initial business combination, as further described below, each as of , 2026, the most recent practicable date prior to the date of this proxy statement/prospectus. In no event will the Sponsor or any of SPKL’s existing officers or directors or any of their respective affiliates be paid any finder’s fee, consulting fee or other compensation prior to, or for any services rendered to effectuate, the completion of the Business Combination, other than the fees, and reimbursement of out-of-pocket expenses described herein.

Set forth below is a summary of the price paid and the amount of compensation and securities received or to be received by the Sponsor in connection with the Business Combination and related transactions:

OTC Market on , 2026, the most recent practicable date prior to the date of this proxy statement/prospectus), which reflects the forfeiture of (i) 3,500,000 shares of ZincFive Common Stock to be issued to the Lead Purchaser as a condition to the Lead Purchaser’s participation in the Series A Preferred Investment and (ii) 922,078 shares of ZincFive Common Stock to be issued to the First Tranche Bridge Investors, each pursuant to the Sponsor Agreement as described in the section entitled “The Business Combination Proposal — Certain Agreements Related to the Business Combination — Sponsor Agreement.”

Currently, holders of the SPKL Class A Ordinary Shares sold in the IPO (the “Public Shareholders” and such shares, the “Public Shares”) hold SPKL Class A Ordinary Shares subject to possible redemption. To the extent that the Sponsor elects to receive the repayment of the Convertible Note in Working Capital Warrants and subsequently exercises such warrants to acquire ZincFive Common Stock, the resulting issuances of ZincFive Common Stock may result in material dilution of the non-redeeming Public Shareholders.

Further** detail regarding the compensation and securitiesreceived or to be received by the Sponsor and its affiliates, ****and the extent of any potential dilution that may be caused thereby to the non-redeeming holders of SPKL Class A Ordinary Shares, is provided in the sections of this proxy statement/prospectus entitled “Questions and Answers for Shareholders of SPKL — What equity stake will current SPKL shareholders and Legacy ZincFive Securityholders hold in ZincFive immediately after the Closing?” and “**Summary of the Proxy Statement/Prospectus — The Proposals to be Submitted at the Extraordinary General Meeting — The Business Combination Proposal — Dilution.”

In no event will the Sponsor or any of SPKL’s existing officers or directors or any of their respective affiliates, be paid any finder’s fee, consulting fee or other compensation in connection with the Business Combination or related transactions. However, SPKL’s officers and certain directors are entitled to compensation in the form of consulting fees in connection with consulting and board services as described in “Information About SPKL.” SPKL also pays an affiliate of the Sponsor a total of $1,000 per month for office space, telecommunication services, security, utilities, maintenance, and other administrative services. In addition, the Sponsor and SPKL’s officers anddirectors, or their respective affiliates, are entitled to reimbursement for any out-of-pocket expenses related to identifying, investigating and completing an initial business combination. In addition, the Sponsor is entitled to reimbursement for transaction expenses advanced and/or paid by the Sponsor on behalf of SPKL or Legacy ZincFive. As of , 2026, the most recent practicable date prior to the date of this proxy statement/prospectus, the Sponsor and SPKL’s officers and directors are awaiting reimbursement for $ of such expenses which would be reimbursed at Closing.

In connection with the IPO, the Sponsor and SPKL’s directors and executive officers agreed to vote their SPKL Ordinary Shares in favor of the Business Combination Proposal (as defined elsewhere in this proxy statement/prospectus). Further, concurrently with the execution of the Merger Agreement, the Sponsor entered into the Sponsor Agreement. Pursuant to the terms and conditions of the Sponsor Agreement, the Sponsor agreed to, among other things, vote its SPKL Ordinary Shares in favor of each Shareholder Proposal (as defined elsewhere in this proxy statement/prospectus) being presented at the Extraordinary General Meeting (as defined elsewhere in this proxy statement/prospectus). As of , 2026 (the “Record Date”), the Sponsor owns approximately % of the total outstanding SPKL Ordinary Shares. When you consider the recommendation of these proposals by the board of directors of SPKL (the “SPKL Board”), you should keep in mind that the Sponsor and certain of SPKL’s directors and officers have interests in the Business Combination that may be different from, or in addition to, your interests as a shareholder, and there may be actual or potential material conflicts of interest between or among (i) the Sponsor, SPKL, SPKL’s officers and directors, and Legacy ZincFive’s officers and directors and (ii) unaffiliated security holders of SPKL. Such conflicts of interest may include a material conflict of interest arising in determining whether to proceed with the Business Combination and the compensation of the Sponsor in connection with the Business Combination. For instance, the Sponsor and certain of SPKL’s officers and directors will benefit from the completion of an initial business combination and may be incentivized to complete an acquisition of a less favorable target company or on terms less favorable to shareholders rather than liquidating the Trust Account. Legacy ZincFive’s directors and executive officers have interests in the Business Combination that are different from, or in addition to, those of the SPKL shareholders generally. See the sections of this proxy statement/prospectus entitled “The Business Combination Proposal — Certain Interests of SPKL’s Directors and Officers and Others in the Business Combination” and “The Business Combination Proposal — Certain Interests of Legacy ZincFive’s Directors and Officers in the Business Combination” for a further discussion of these considerations.

This proxy statement/prospectus covers: (i) shares of ZincFive Common Stock (including shares that are to be issued or may be issuable upon the conversion of SPKL Ordinary Shares into ZincFive Common Stock), which number is based on the assumptions set forth in the section of this proxy statement/ prospectus entitled “Frequently Used Terms — Share Calculations and Ownership Percentages”; and (ii)ZincFive Warrants.

SPKL will hold an extraordinary general meeting to consider matters relating to the Business Combination at , Eastern Time, on , 2026, electronically at (the “Extraordinary General Meeting”). There is no requirement to attend the Extraordinary General Meeting in person. You or your proxyholder will be able to attend and vote at the Extraordinary General Meeting in-person or online by visiting and using a control number assigned by Continental Stock Transfer & Trust Company, SPKL’s transfer agent. To register and receive access to the Extraordinary General Meeting, registered shareholders and beneficial shareholders (those holding shares through a stock brokerage account or by a bank or other holder of record) will need to follow the instructions applicable to them provided in this proxy statement/prospectus.

After careful consideration, the SPKL Board has unanimously approved the Merger Agreement and the other proposals described in this proxy statement/prospectus. The SPKL Board has also determined that it is advisable to consummate the Business Combination and that the Business Combination is in the best interests of the Public Shareholders. The SPKL Board took into account the oral opinion of Houlihan Capital, LLC (“Houlihan Capital”) (subsequently confirmed in writing), rendered on June 10, 2026, to the effect that, as of such date and based upon and subject to the procedures followed, assumptions made, qualifications and limitations on the review undertaken, and other matters considered by Houlihan Capital in preparing its opinion, the Business Combination and related transactions are fair, from a financial point of view, to the unaffiliated shareholders of SPKL. A copy of the written opinion is attached as Annex Mto this proxy statement/prospectus. Please see the section entitled “The Business Combination Proposal — Fairness Opinion of Houlihan Capital, LLC” for further information. The SPKL Board recommends that you vote “FOR” each proposal described in this proxy statement/prospectus.

If you have any questions or need assistance voting your SPKL Ordinary Shares, please contact Advantage Proxy, Inc., the proxy solicitor for SPKL, by calling 877-870-8565 (toll-free), or banks and brokers can call 206-870-8565, or by emailing ksmith@advantageproxy.com.

The notice of the Extraordinary General Meeting and this proxy statement/prospectus will be available at.

This proxy statement/prospectus provides shareholders of SPKL with detailed information about the Business Combination and other matters to be considered at the Extraordinary General Meeting. We encourage you to read this entire document, including the annexes and other documents referred to in this proxy statement/ prospectus, carefully and in their entirety. It also contains or references information about SPKL, Legacy ZincFive and ZincFive and certain related matters. In particular, when you consider the recommendation regarding the proposals by the SPKL Board, you should keep in mind that the Sponsor and certain of SPKL’s directors and officers have interests in the Business Combination that may be different from, or in addition to, your interests as a shareholder, and there may be actual or potential material conflicts of interest between or among (i) the Sponsor, SPKL, SPKL’s officers and directors, and Legacy ZincFive’s officers and directors and (ii) unaffiliated security holders of SPKL. Such conflicts of interest may include a material conflict of interest arising in determining whether to proceed with the Business Combination and the compensation of the Sponsor in connection with the Business Combination. For instance, the Sponsor and certain of SPKL’s officers and directors will benefit from the completion of an initial business combination and may be incentivized to complete an acquisition of a less favorable target company or on terms less favorable to shareholders rather than liquidating the Trust Account. Legacy ZincFive’s directors and executive officers have interests in the Business Combination that are different from, or in addition to, those of the SPKL shareholders generally. See the sections of this proxy statement/prospectus entitled “The Business Combination Proposal — Certain Interests of SPKL’s Directors and Officers and Others in the Business Combination” and “The Business Combination Proposal – Certain Interests of Legacy ZincFive’s Directors and Officers in the Business Combination” for a further discussion of these considerations. You should also carefully consider the risk factors described under the heading “Risk Factors” beginning on page67** of this proxy statement/prospectus.**

NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES REGULATORY AGENCY HAS APPROVED OR DISAPPROVED THE TRANSACTIONS DESCRIBED IN THIS PROXY STATEMENT/PROSPECTUS, PASSED UPON THE MERITS OR FAIRNESS OF

THE BUSINESS COMBINATION OR PASSED UPON THE ADEQUACY OR ACCURACY OF THE DISCLOSURE IN THIS PROXY STATEMENT/PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY CONSTITUTES A CRIMINAL OFFENSE.

This proxy statement/prospectus is dated , 2026, and is first being mailed to SPKL’s shareholders on or about , 2026.

SPARK I ACQUISITION CORPORATION

A Cayman Islands Exempted Company

3790 El Camino Real, Unit #570

NOTICE OF EXTRAORDINARY GENERAL MEETING TO BE HELD ON , 2026

TO THE SHAREHOLDERS OF SPARK I ACQUISITION CORPORATION:

NOTICE IS GIVEN that an extraordinary general meeting (including any adjournments or postponements of the extraordinary general meeting, the “Extraordinary General Meeting”) of Spark I Acquisition Corporation, a Cayman Islands exempted company with limited liability (“SPKL”), will be held on 2026, at , Eastern Time, electronically at .

The Extraordinary General Meeting will be held for the following purposes:

**Proposal No. 1 — The Business Combination Proposal —**To consider and vote upon a proposal to approve by ordinary resolution, and adopt the Merger Agreement, dated as of June 11, 2026, attached to the accompanying proxy statement/prospectus as Annex A(as amended, supplemented or otherwise modified from time to time in accordance with its terms, the “Merger Agreement”), by and among SPKL, Spark I Acquisition Corporation Sub I Inc., a Delaware corporation (“Merger Sub I”), Spark I Acquisition Corporation Sub II LLC, a Delaware limited liability company (“Merger Sub II”), and ZincFive, Inc., a Delaware corporation (“Legacy ZincFive”), pursuant to which, at the closing of the transactions contemplated by the Merger Agreement (the “Closing”) and at least one day following the Domestication (as defined below), Merger Sub I will merge with and into Legacy ZincFive (the “First Merger”), with Legacy ZincFive continuing as the surviving corporation (the “Surviving Corporation”), and, immediately following the First Merger, Legacy ZincFive, as the Surviving Corporation, will merge with and into Merger Sub II (the “Second Merger” and, together with the First Merger, the “Mergers”), with Merger Sub II continuing as the surviving entity and a direct wholly owned subsidiary of ZincFive (as defined below). The transactions contemplated by the Merger Agreement are described in more detail in the accompanying proxy statement/prospectus and are referred to as the “Business Combination.” We refer to this proposal as the “Business Combination Proposal.”

**Proposal No. 2 — The Domestication Proposal —**To consider and vote upon a proposal to approve, by special resolution, and adopt the plan of domestication (as may be amended, supplemented or otherwise modified from time to time in accordance with its terms, the “Plan of Domestication”) attached to the accompanying proxy statement/prospectus as Annex B, and a change in the corporate domicile of SPKL, which will be accomplished by way of deregistering SPKL as an exempted company registered under the laws of the Cayman Islands with limited liability and registering SPKL by way of continuation and domestication as a corporation under the laws of the State of Delaware in accordance with the Plan of Domestication (the “Domestication”). The Domestication will be effected in accordance with the Plan of Domestication at least one day prior to the Closing by SPKL filing a certificate of corporate domestication and the proposed new certificate of incorporation of ZincFive, as the post-Business Combination company (the “Proposed Certificate of Incorporation”) with the Secretary of State of the State of Delaware and filing an application to deregister with the Registrar of Companies in the Cayman Islands. Upon the effectiveness of the Domestication, SPKL will continue as a Delaware corporation and under the corporate name “ZincFive, Inc.” (“ZincFive”). All outstanding securities of SPKL will become outstanding securities of ZincFive, as described in more detail in the accompanying proxy statement/prospectus. We refer to this proposal as the “Domestication Proposal.”

**Proposal No. 3 — The Stock Issuance Proposal —**To consider and vote upon a proposal to approve, by ordinary resolution, for purposes of complying with the applicable provisions of Nasdaq Listing Rule 5635, the issuance (or reservation for issuance) of: (i) shares of ZincFive Common Stock to the Legacy ZincFive Securityholders in connection with the Business Combination; (ii) shares of 12.0% Series A Cumulative Convertible Preferred Stock of ZincFive (the “Series A Preferred Stock”) and warrants to purchase a number of shares of ZincFive Common Stock equal to the number of shares into which such shares of ZincFive Common Stock underlying Series A Preferred Stock held by Series A Preferred Investors (as defined herein) are initially convertible (the “Series A Preferred Investor Warrants”) pursuant to that certain Series A Securities Purchase Agreement (the “Series A Securities Purchase Agreement”), dated as of June 11, 2026, by and among SPKL, Legacy ZincFive and the other purchasers identified on the signature pages thereto (the “Series A Preferred Investors”); (iii)shares of ZincFive Common Stock issuable upon conversion of Series A Preferred Stock and upon exercise of Series A Preferred Investor Warrants; (iv) shares of ZincFive Common Stock to the Lead Purchaser and certain Series A Preferred Investors pursuant to the Sponsor Agreement; and (v) any other preferred stock, common stock and securities convertible into or exercisable for common stock

pursuant to subscription, purchase or similar agreements that SPKL has entered, or may enter, into prior to the Closing. We refer to this proposal as the“Stock Issuance Proposal.”

**Proposal No. 4 — The Organizational Documents Proposal —**To consider and vote upon a proposal to approve, by special resolution, the Proposed Certificate of Incorporation and the Proposed Bylaws of ZincFive, as the post-Business Combination company (the “Proposed Bylaws” and, together with the Proposed Certificate of Incorporation, the “Proposed Organizational Documents”) in connection with the Domestication. We refer to this proposal as the “Organizational Documents Proposal.” The form of each of the Proposed Certificate of Incorporation and the Proposed Bylaws is attached to the accompanying proxy statement/prospectus as Annex Cand Annex D, respectively.

**Proposal No. 5 — The Advisory Organizational Documents Proposals —**To consider and vote upon the following five separate proposals (collectively, the “Advisory Organizational Documents Proposals”) to approve on an advisory non-binding basis and in accordance with applicable U.S. Securities and Exchange Commission (the “SEC”) guidance, by ordinary resolution, each of the following material differences between SPKL’s amended and restated memorandum and articles of association (the “Memorandum and Articles of Association”) and the Proposed Organizational Documents:

**Proposal No. 6 — The Incentive Plan Proposal —**To consider and vote upon a proposal to approve by ordinary resolution, the ZincFive, Inc. 2026 Equity Incentive Plan (the “2026 Plan”). A form of the 2026 Plan is attached to the accompanying proxy statement/prospectus as Annex H. We refer to this proposal as the “Incentive Plan Proposal.”

**Proposal No. 7 — The Employee Stock Purchase Plan Proposal —**To consider and vote upon a proposal to approve by ordinary resolution, the ZincFive, Inc. 2026 Employee Stock Purchase Plan (the “ESPP”). A form of the ESPP is attached to the

accompanying proxy statement/prospectus as Annex I. We refer to this proposal as the “Employee Stock Purchase Plan Proposal.”

**Proposal No. 8 — The Director Election Proposal —**To consider and vote upon a proposal to approve by ordinary resolution the election of directors to serve on the ZincFive Board, each until such director’s successor is duly elected and qualified or until such director’s earlier death, resignation or removal. We refer to this proposal as the “Director Election Proposal,” and, collectively with the Business Combination Proposal, the Domestication Proposal, the Stock Issuance Proposal, the Organizational Documents Proposal, the Incentive Plan Proposal and the Employee Stock Purchase Plan Proposal, the “Condition Precedent Proposals.”

**Proposal No. 9 — The Adjournment Proposal —**To consider and vote upon a proposal to approve by ordinary resolution, the adjournment of the Extraordinary General Meeting to a later date or dates, if necessary: (i) to permit further solicitation and vote of proxies in the event that there are insufficient votes for the approval of one or more proposals at the Extraordinary General Meeting; (ii) for the absence of a quorum; (iii) to allow reasonable additional time for the filing or mailing of any supplemental or amended disclosure that SPKL has determined in good faith after consultation with outside legal counsel is required under applicable law and for such supplemental or amended disclosure to be disseminated and reviewed by its shareholders prior to the Extraordinary General Meeting; or (iv) to engage with investors. We refer to this proposal as the “Adjournment Proposal.”

These items of business are described in the accompanying proxy statement/prospectus, which we encourage you to read carefully and in its entirety before voting.

Only holders of record of SPKL Class A Ordinary Shares, and SPKL Class B Ordinary Shares, including those held by SPKL’s sponsor, SLG SPAC Fund LLC, a Delaware limited liability company (the “Sponsor”), at the close of business on , 2026 (the “Record Date”) are entitled to notice of and to have their votes counted at the Extraordinary General Meeting.

The approval of each of the Domestication Proposal and the Organizational Documents Proposal requires a special resolution under the Companies Act (As Revised) of the Cayman Islands and the Memorandum and Articles of Association. A special resolution requires the affirmative vote of at least two-thirds of the votes cast by the holders of the issued SPKL Ordinary Shares, voting together as a single class, who are present in person, virtually or represented by proxy and entitled to vote. In regard to the Domestication Proposal, pursuant to Article 182 of the Memorandum and Articles of Association, holders of SPKL Class B Ordinary Shares will have ten votes for every SPKL Class B Ordinary Share and holders of SPKL Class A Ordinary Shares will have one vote for every SPKL Class A Ordinary Share.

The approval of each of the Business Combination Proposal, the Stock Issuance Proposal, the Advisory Organizational Documents Proposals, the Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal, the Director Election Proposal and the Adjournment Proposal requires an ordinary resolution, being the affirmative vote of at least a majority of the votes cast by the holders of the issued SPKL Ordinary Shares, who are present in person, virtually or represented by proxy and entitled to vote on the respective proposal at the Extraordinary General Meeting. In regard to the Director Election Proposal, pursuant to Article 96 of the Memorandum and Articles of Association, the approval of the Director Election Proposal requires an ordinary resolution of the holders of the SPKL Class B Ordinary Shares only, being the affirmative vote of at least a simple majority of the votes cast by the holders of the issued SPKL Class B Ordinary Shares, who are present in person, virtually or represented by proxy and entitled to vote at the Extraordinary General Meeting. As of the date of this proxy statement/prospectus, the Sponsor has agreed, and SPKL’s officers and directors intend, to vote the SPKL Class B Ordinary Shares owned by them in favor of the Director Election Proposal. As of the Record Date, the Sponsor and SPKL Insiders own all of the issued and outstanding SPKL Class B Ordinary Shares. As a result, approval of the Director Election Proposal will not require the affirmative vote of shareholders other than the vote of the Sponsor and the SPKL Insiders.

The accompanying proxy statement/prospectus and proxy card are being provided to SPKL’s shareholders in connection with the solicitation of proxies to be voted at the Extraordinary General Meeting.Whether or not you plan to attend the Extraordinary General Meeting,all of SPKL’s shareholders are urged to read the accompanying proxy statement/prospectus,including the annexes and the documents referred to in the accompanying proxy statement/prospectus,carefully and in their entirety.You should also carefully consider the risk factors described under the heading “Risk Factors” beginning on page67** of the accompanying proxy statement/prospectus**.

After careful consideration, the board of directors of SPKL (the “SPKL Board”) has unanimously approved the Business Combination and unanimously recommends that shareholders vote “FOR” the adoption of the Merger Agreement and approval of the

transactions contemplated thereby, including the Domestication and the Business Combination, and “FOR” all other proposals presented to SPKL’s shareholders in the accompanying proxy statement/prospectus. When you consider the recommendation ofthese proposals by the SPKL Board, you should keep in mind that the Sponsor and certain of SPKL’s directorsand officers have interests in the Business Combination that may be different from, or in addition to, your interests as a shareholder, and there may be actual or potential material conflicts of interest between or among (i) the Sponsor, SPKL’s officers and directors, and Legacy ZincFive’s officers and directors and (ii) unaffiliated security holders of SPKL. Such conflicts of interest may include a material conflict of interest arising in determining whether to proceed with the Business Combination and the compensation of the Sponsor in connection with the Business Combination. For instance, the Sponsor and certain of SPKL’s officers and directors will benefit from the completion of an initial business combination and may be incentivized to complete an acquisition of a less favorable target company or on terms less favorable to shareholders rather than liquidating the Trust Account. Legacy ZincFive’s directors and executive officers have interests in the Business Combination that are different from, or in addition to, those of the SPKL shareholders generally. For instance, the Sponsor and certain of SPKL’s officers and directors will benefit from the completion of a business combination and may be incentivized to complete an acquisition of a less favorable target company or on terms less favorable to shareholders rather than liquidating SPKL. See the sections of the accompanying proxy statement/prospectus entitled “The* Business Combination Proposal — Certain Interests of SPKL’s Directors and Officers and Others in the Business Combination” and “The Business Combination Proposal — Certain Interests of Legacy ZincFive’s Directors and Officers in the Business Combination*”* *for a further discussion of these considerations.

In connection with the Business Combination, certain related agreements have been or will be entered into at or prior to the Closing, including the A&R Registration Rights Agreement and the Sponsor Agreement (each term as defined in the accompanying proxy statement/prospectus). See*“The Business Combination Proposal — Certain Agreements Related to the Business Combination”and “Certain Relationships and Related Party Transactions”* in the accompanying proxy statement/prospectus for more information.

Pursuant to the Memorandum and Articles of Association, a holder of SPKL Class A Ordinary Shares issued as part of the units (“SPKL Units”) issued in our initial public offering (“IPO”), whether purchased in our IPO or following our IPO in the open market (a “Public Shareholder,” and such shares, “Public Shares”), may request to redeem all or a portion of such holder’s Public Shares for cash if the Business Combination is consummated. As a holder of Public Shares, you will be entitled to receive cash for any Public Shares to be redeemed only if you:

Holders must complete the procedures for electing to redeem their Public Shares in the manner described above prior to 5:00 p.m., Eastern Time, on , 2026 (two business days before the initially scheduled date of the Extraordinary General Meeting) for their Public Shares to be redeemed (the “Redemption Deadline”).

The address of the Transfer Agent is listed under the question “Questions and Answers for Shareholders of SPKL — Who can help answer my questions?” of this proxy statement/prospectus.

Public Shareholders will be entitled to request that their Public Shares be redeemed for an amount equal to each Public Share’s pro rata portion of the aggregate amount then on deposit in the Trust Account in accordance with the Memorandum and Articles of Association (the “Redemption Price”). For illustrative purposes, as of , 2026, this would have amounted to approximately $ per issued and outstanding Public Share. However, the proceeds deposited in the Trust Account could become subject to the claims of SPKL’s creditors, if any, which could have priority over the claims of the Public Shareholders. 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, 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. The redemption of Public Shares will be effected while SPKL remains a Cayman

Islands exempted company, prior to the Domestication, and it is expected that the Redemption Price will be paid to Public Shareholders electing to redeem their Public Shares promptly after the Closing.

Any request for redemption, once made by a holder of Public Shares, may not be withdrawn following the Redemption Deadline, unless the SPKL Board determines (in its sole discretion) to permit such withdrawal of a redemption request (which it may do in whole or in part). Furthermore, if a holder of a Public Share delivers its share certificates (if any) along with the redemption forms in connection with an election of its redemption and subsequently decides prior to the Redemption Deadline not to elect to exercise such rights, it may simply request that SPKL permit the withdrawal of the request for redemption and instruct the Transfer Agent, to return the share certificates (physically or electronically). The holder can make such request by contacting the Transfer Agent at the address or email address listed in this proxy statement/ prospectus.

Any corrected or changed written exercise of redemption rights must be received by the Transfer Agent at least two business days prior to the initially scheduled date of the Extraordinary General Meeting. No request for redemption will be honored unless the holder’s certificates for Public Shares (if any) along with the redemption forms have been delivered (either physically or electronically) to the Transfer Agent, at least two business days prior to the initially scheduled date of the Extraordinary General Meeting.

If a holder of Public Shares properly makes a request for redemption and the certificates for Public Shares (if any) along with the redemption forms are delivered as described above, then, if the Business Combination is approved, SPKL will effect the redemption of such Public Shares while SPKL remains a Cayman Islands exempted company, and pay the Redemption Price, calculated as of two business days prior to the Closing, promptly following the Closing. If the Business Combination is not consummated, the Public Shares will be returned to the respective holder, broker or bank.

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

See the section of the accompanying proxy statement/prospectus entitled “Extraordinary General Meeting of SPKL — Redemption Rights” for a detailed description of the procedures to be followed if you wish to redeem your Public Shares.

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 Securities Exchange Act of 1934, as amended), will be restricted from redeeming its Public Shares with respect to more than an aggregate of 15% of the Public Shares sold in our IPO. Accordingly, if a Public Shareholder, alone or acting in concert or as a group, seeks to redeem more than 15% of the Public Shares sold in our IPO, then any such shares in excess of that 15% limit would not be redeemed for cash.

The Sponsor and each director and officer of SPKL who holds shares of SPKL have agreed to vote in favor of the Business Combination, and to waive their redemption rights in connection with the Closing with respect to any SPKL Ordinary Shares held by them. None of the Sponsor, directors or officers received separate consideration for their waiver of redemption rights. Further, concurrently with the execution of the Merger Agreement, the Sponsor entered into a Sponsor Agreement, dated June 11, 2026, with SPKL, Legacy ZincFive and certain shareholders of SPKL (as amended by the Amendment to Sponsor Agreement, dated September 28, 2026, the “Sponsor Agreement”). Pursuant to the terms and conditions of the Sponsor Agreement, the Sponsor agreed to, among other things, vote its SPKL Ordinary Shares in favor of each Shareholder Proposal (as defined in the accompanying proxy statement/ prospectus) being presented at the Extraordinary General Meeting. The SPKL Ordinary Shares held by the Sponsor will be excluded from the pro rata calculation used to determine the per-share Redemption Price. As of the Record Date, the Sponsor owns approximately % of the issued and outstanding SPKL Ordinary Shares.

The consummation of the Business Combination is conditioned upon the satisfaction or written waiver (where permissible) by the parties to the Merger Agreement of certain customary closing conditions. These conditions include: (i) the adoption or approval, as applicable, by SPKL’s shareholders of: (A) the Merger Agreement and the Business Combination in accordance with applicable law and exchange rules and regulations; (B) the Domestication; (C) the Proposed Certificate of Incorporation and the Proposed Bylaws; (D)approval of the issuance of shares of ZincFive Common Stock as required by the listing rules of the applicable stock exchange; (E) the adoption by SPKL of the 2026 Plan and the ESPP; (F) the election of members of the ZincFive Board (in the form of an advisory vote, with the directors being elected by written resolution of the holders of the SPKL Class B Ordinary Shares in accordance with the SPKL’s organizational documents); (G) the amendment of SPKL’s organizational documents, effective immediately prior to the Closing, to remove references to the $5,000,001 net tangible assets requirements set forth in SPKL’s organizational documents; (H) any other proposals as the SEC (or staff members of the SEC) may indicate are necessary in its comments to the proxy statement

included in this proxy statement/prospectus or any related correspondence; (I) any proposals the parties to the Merger Agreement agree are necessary or desirable to consummate the Business Combination, and (J) adjournment of the special meeting, if necessary, to permit further solicitation of the proxies because there are not sufficient votes to approve and adopt any of the foregoing; (ii) the receipt of the requisite consent of the stockholders of Legacy ZincFive; (iii) any applicable waiting period or any extension of any applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 (and the rules and regulations promulgated under such Act) in respect of the Business Combination being expired or earlier terminated without the imposition of burdensome conditions; (iv) the Registration Statement becoming effective; (v) SPKL having filed with the applicable stock exchange an application or supplemental listing application for the listing of the ZincFive Common Stock, and such shares of ZincFive Common Stock having been approved for listing, subject to official notice of issuance; (vi) the accuracy of the representations and warranties of each of the parties to the Merger Agreement and the performance of the covenants and agreements of such parties subject, in each case, to customary standards; (vii) the completion of the Domestication; (viii) the Available Closing SPAC Cash (as defined in the Merger Agreement) not being less than $100,000,000; and (ix) approval by the SPKL shareholders to extend the time SPKL has to consummate an initial business combination pursuant to the terms of the SPKL organizational documents. For more information, see the section of this proxy statement/ prospectus entitled“The Business Combination Proposal* —** Merger Agreement** —** Conditions to* Closing — General Conditions.”

The SPKL Units, SPKL Class A Ordinary Shares and Public Warrants are currently listed on The Nasdaq Stock Market LLC (“Nasdaq”) under the symbols “SPKLU,” “SPKL” and “SPKLW,” respectively. On September 30, 2026, SPKL received a written notice (the “Delisting Notice”) from the Listing Qualifications Department of Nasdaq stating that the SPKL Units, SPKL Class A Ordinary Shares and Public Warrants will be delisted from Nasdaq because SPKL did not complete its initial business combination by September 29, 2026, which is 36 months from the effectiveness of SPKL’s registration statement for the IPO. Accordingly, trading in the SPKL Units, SPKL Class A Ordinary Shares and Public Warrants on Nasdaq was suspended at the opening of business on October 7, 2026, and Nasdaq will file a Form 25-NSE with the SEC, which will remove such securities from listing and registration on Nasdaq. Following the delisting, SPKL expects that the SPKL Units, SPKL Class A Ordinary Shares and Public Warrants will be quoted on the Pink Limited Market operated on the OTC Market systems (the “OTC Market”) under the symbols “SPKLU,” “SPKLF” and “SPKLW,” respectively.

Pursuant to the terms of the Merger Agreement, SPKL is required to cause the ZincFive Common Stock issued in the Domestication to be approved for listing on the NYSE, Nasdaq, or such other stock exchange as mutually agreed to by SPKL and Legacy ZincFive (the “Stock Exchange”). There can be no assurance that such listing condition will be met. If the listing condition is not met, the Business Combination will not be consummated unless the listing condition is waived by the parties to the Merger Agreement. Following the Closing, ZincFive Common Stock and ZincFive Warrants will be listed, subject to the approval of the Stock Exchange, under the proposed symbols “ZFIV” and “ZFIVW,” respectively. We may not have received confirmation from a Stock Exchange of approval of the listing of the ZincFive Common Stock and ZincFive Warrants at the time of the Extraordinary General Meeting or prior to the Closing. The listing condition to the Closing may be waived by the parties to the Merger Agreement. As a result, you may be asked to vote to approve the Business Combination and the other proposals included in the accompanying proxy statement/ prospectus without such confirmation. Further, it is possible that such confirmation may never be received, and the Business Combination could still be consummated if such condition is waived. In such event, the ZincFive Common Stock and ZincFive Warrants may not be listed on any Stock Exchange.

Your vote is very important. Whether or not you plan to attend the Extraordinary General Meeting, please vote as soon as possible by following the instructions in the accompanying proxy statement/ prospectus to make sure that your shares are represented at the Extraordinary General Meeting. If you hold your shares in “street name” through a bank, broker or other nominee, you will need to follow the instructions provided to you by your bank, broker or other nominee to ensure that your shares are represented and voted at the Extraordinary General Meeting. The transactions contemplated by the Merger Agreement will be consummated only if the Condition Precedent Proposals are approved at the Extraordinary General Meeting, and if the other conditions to closing are satisfied or waived. Each of the Condition Precedent Proposals is cross-conditioned on the approval of each other Condition Precedent Proposal. The Advisory Organizational Documents Proposals are conditioned on the approval of each of the Condition Precedent Proposals. The Adjournment Proposal is not conditioned upon the approval of any other proposal set forth in the accompanying proxy statement/prospectus.

If you sign, date and return your proxy card without indicating how you wish to vote, your proxy will be voted “FOR” each of the proposals presented at the Extraordinary General Meeting. If you fail to return your proxy card or fail to instruct your bank, broker or other nominee how to vote, and do not attend the Extraordinary General Meeting in person or virtually, the effect will be, among other things, that your shares will not be counted for purposes of determining whether a quorum is present at the Extraordinary General

Meeting and will not be voted. If you are a shareholder of record and you attend the Extraordinary General Meeting and wish to vote in person or virtually, you may withdraw your proxy and vote in person or virtually.

TO EXERCISE YOUR REDEMPTION RIGHTS, YOU MUST SUBMIT A WRITTEN REQUEST, INCLUDING THE LEGAL NAME, PHONE NUMBER AND ADDRESS OF THE BENEFICIAL OWNER OF THE SHARES FOR WHICH REDEMPTION IS REQUESTED, TO THE TRANSFER AGENT THAT YOUR PUBLIC SHARES BE REDEEMED FOR CASH. YOU MUST ALSO DELIVER YOUR PUBLIC SHARES TO THE TRANSFER AGENT, PHYSICALLY OR ELECTRONICALLY USING THE DTC’S DWAC (DEPOSIT WITHDRAWAL AT CUSTODIAN) SYSTEM IN ACCORDANCE WITH THE PROCEDURES AND DEADLINES DESCRIBED IN THE ACCOMPANYING PROXY STATEMENT/PROSPECTUS. IF THE BUSINESS COMBINATION IS NOT CONSUMMATED, THEN THE PUBLIC SHARES WILL NOT BE REDEEMED FOR CASH. IF YOU HOLD THE SHARES IN STREET NAME, TO EXERCISE YOUR REDEMPTION RIGHTS YOU MUST INSTRUCT THE ACCOUNT EXECUTIVE AT YOUR BANK OR BROKER TO WITHDRAW THE SHARES FROM YOUR ACCOUNT. SEE THE SECTION OF THE ACCOMPANYING PROXY STATEMENT/PROSPECTUS ENTITLED “EXTRAORDINARY GENERAL MEETING OF SPKL — REDEMPTION RIGHTS” FOR MORE SPECIFIC INSTRUCTIONS.

On behalf of the SPKL Board, I would like to thank you for your support and look forward to the successful completion of the Business Combination.

Sincerely,

James Rhee

Chief Executive Officer and Chairman of the Board of Directors

NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES REGULATORY AGENCY HAS APPROVED OR DISAPPROVED THE TRANSACTIONS DESCRIBED IN THE ACCOMPANYING PROXY STATEMENT/PROSPECTUS, PASSED UPON THE MERITS OR FAIRNESS OF THE BUSINESS COMBINATION OR RELATED TRANSACTIONS OR PASSED UPON THE ADEQUACY OR ACCURACY OF THE DISCLOSURE IN THE ACCOMPANYING PROXY STATEMENT/PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY CONSTITUTES A CRIMINAL OFFENSE.

The accompanying proxy statement/prospectus is dated , 2026 and is first being mailed to shareholders on or about , 2026.