Keystone Acquisition Corp.

06/10/2026 | Press release | Distributed by Public on 06/10/2026 13:08

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM (Form 8-K)

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Board of Directors and Shareholders of
Keystone Acquisition Corp.:

Opinion on the Financial Statement

We have audited the accompanying balance sheet of Keystone Acquisition Corp. (the "Company") as of June 4, 2026, and the related notes (collectively referred to as the "financial statement"). In our opinion, the financial statement presents fairly, in all material respects, the financial position of the Company as of June 4, 2026, in conformity with accounting principles generally accepted in the United States of America.

Basis for Opinion

This financial statement is the responsibility of the Company's management. Our responsibility is to express an opinion on the Company's financial statement based on our audit. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (the "PCAOB") and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audit in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statement is free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audit, we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company's internal control over financial reporting. Accordingly, we express no such opinion.

Our audit included performing procedures to assess the risks of material misstatement of the financial statement, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statement. Our audit also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statement. We believe that our audit provides a reasonable basis for our opinion.

/s/ WithumSmith+Brown, PC

We have served as the Company's auditor since 2025.

New York, New York
June 10, 2026

F-2

KEYSTONE ACQUISITION CORP.
BALANCE SHEET

JUNE 4, 2026

Assets
Current assets
Cash $ 1,950,000
Prepaid expenses 78,050
Total current assets 2,028,050
Cash held in Trust Account 288,218,750
Total Assets $ 290,246,800
Liabilities, Class A Ordinary Shares Subject to Possible Redemption, and Shareholders' Deficit
Current liabilities
Accrued expenses $ 63,475
Accrued offering costs 402,944
Advances from related party 5,877
Promissory note - related party 300,000
Total current liabilities 772,296
Deferred underwriting fee 11,500,000
Total Liabilities 12,272,296
Commitments and Contingencies (Note 7)
Class A Ordinary Shares Subject to Possible Redemption
Class A ordinary shares subject to possible redemption, $0.0001 par value; 28,750,000 shares at redemption value of $10.025 per share 288,218,750
Shareholders' Deficit
Preference shares, $0.0001 par value; 5,000,000 shares authorized; none issued or outstanding -
Class A ordinary shares, $0.0001 par value; 500,000,000 shares authorized; none issued or outstanding (excluding 28,750,000 shares subject to possible redemption) -
Class B ordinary shares, $0.0001 par value; 50,000,000 shares authorized; 9,583,333 shares issued and outstanding 958
Additional paid-in capital -
Accumulated deficit (10,245,204 )
Total Shareholders' Deficit (10,244,246 )
Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption, and Shareholders' Deficit $ 290,246,800

The accompanying notes are an integral part of the financial statement.

F-3

KEYSTONE ACQUISITION CORP.
NOTES TO FINANCIAL STATEMENT
JUNE 4, 2026

NOTE 1. DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS

Keystone Acquisition Corp. (the "Company") is a blank check company incorporated in the Cayman Islands on November 28, 2025. The Company was formed for the purpose of effecting a merger, amalgamation, share exchange, asset acquisition, share purchase, reorganization or similar business combination with one or more businesses (a "Business Combination"). The Company may pursue an initial Business Combination in any business or industry. The Company is an early stage and emerging growth company and, as such, the Company is subject to all of the risks associated with early stage and emerging growth companies.

As of June 4, 2026, the Company had not commenced any operations. All activity for the period from November 28, 2025 (inception) through June 4, 2026 relates to the Company's formation and the initial public offering ("Initial Public Offering"), which is described below. The Company will not generate any operating revenues until after the completion of a Business Combination, at the earliest. The Company will generate non-operating income in the form of interest income from the proceeds derived from the Initial Public Offering. The Company has selected December 31 as its fiscal year end.

The registration statement for the Company's Initial Public Offering was declared effective on June 2, 2026. On June 4, 2026, the Company consummated the Initial Public Offering of 28,750,000 units (the "Units" and, with respect to the Class A ordinary shares included in the Units being offered, the "Public Shares") at $10.00 per Unit, generating gross proceeds of $287,500,000. Each Unit consists of one Class A Ordinary Share, par value $0.0001 per share, and one-half of one redeemable warrant (the "Public Warrants"). Each whole Public Warrant entitles the holder thereof to purchase one Class A Ordinary Share at an exercise price of $11.50 per share, subject to adjustment.

Simultaneously with the closing of the Initial Public Offering, the Company consummated the sale of 8,468,750 warrants (the "Private Placement Warrants") at a price of $1.00 per Private Placement Warrant, in a private placement to the Company's sponsor, Keystone International Acquisition Management LLC, ("Sponsor"), and Cohen & Co., the representative of the underwriters, generating gross proceeds of $8,468,750. Of those 8,468,750 Private Placement Warrants, the Sponsor purchased 5,593,750 Private Placement Warrants and the underwriters purchased 2,875,000 Private Placement Warrants. Each whole Private Placement Warrant entitles the holder thereof to purchase one Class A Ordinary Share at an exercise price of $11.50 per share, subject to adjustment. The Private Placement Warrants will become exercisable 30 days after the completion of the initial Business Combination.

Transaction costs amounted to $17,871,474, consisting of $5,750,000 of cash underwriting fees, $11,500,000 of deferred underwriting fees, and $621,474 of other offering costs.

The Company's management has broad discretion with respect to the specific application of the net proceeds of the Initial Public Offering and the sale of the Private Placement Warrants, although substantially all of the net proceeds are intended to be applied generally toward consummating a Business Combination. There is no assurance that the Company will be able to complete a Business Combination successfully. The Company must complete a Business Combination with one or more target businesses that together have an aggregate fair market value of at least 80% of the value of the Trust Account (as defined below) (excluding the deferred underwriting commissions and taxes payable on income earned on the Trust Account) at the time of the agreement to enter into an initial Business Combination. The Company will only complete a Business Combination if the post-transaction company owns or acquires 50% or more of the outstanding voting securities of the target or otherwise acquires a controlling interest in the target sufficient for it not to be required to register as an investment company under the Investment Company Act of 1940, as amended (the "Investment Company Act").

Following the closing of the Initial Public Offering on June 4, 2026, an amount of $288,218,750 ($10.025 per Unit) from the net proceeds of the sale of the Units, and a portion of the proceeds of the sale of the Private Placement Warrants, were placed in a trust account ("Trust Account"), located in the United States with Efficiency, INC. acting as trustee and invested only in U.S. government treasury obligations with a maturity of 185 days or less or in money market funds meeting certain conditions under Rule 2a-7 under the Investment Company Act, which invest only in direct U.S. government treasury obligations, until the earlier of (i) the completion of a Business Combination and (ii) the distribution of the funds held in the Trust Account, as described below.

The Company will provide its holders of the outstanding Public Shares (the "public shareholders") with the opportunity to redeem all or a portion of their Public Shares upon the completion of a Business Combination either (i) in connection with a shareholder meeting called to approve the Business Combination or (ii) by means of a tender offer. The decision as to whether the Company will seek shareholder approval of a Business Combination or conduct a tender offer will be made by the Company, solely in its discretion. The public shareholders will be entitled to redeem their Public Shares for a pro rata portion of the amount then in the Trust Account (initially anticipated to be $10.025 per Public Share, plus any pro rata interest earned on the funds held in the Trust Account and not previously released to the Company to pay its tax obligations). There will be no redemption rights upon the completion of a Business Combination with respect to the Company's warrants. The Public Shares subject to redemption were recorded at redemption value and classified as temporary equity upon the completion of the Initial Public Offering in accordance with the Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") Topic 480, Distinguishing Liabilities from Equity ("ASC 480").

F-4

KEYSTONE ACQUISITION CORP.
NOTES TO FINANCIAL STATEMENT
JUNE 4, 2026

NOTE 1. DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS (cont.)

The Company will proceed with a Business Combination only if a majority of the shares voted are voted in favor of the Business Combination. If a shareholder vote is not required by law and the Company does not decide to hold a shareholder vote for business or other reasons, the Company will, pursuant to its amended and restated memorandum and articles of association (the "Amended and Restated Memorandum and Articles of Association"), conduct the redemptions pursuant to the tender offer rules of the U.S. Securities and Exchange Commission ("SEC") and file tender offer documents with the SEC prior to completing a Business Combination. If, however, shareholder approval of the transaction is required by law, or the Company decides to obtain shareholder approval for business or other reasons, the Company will offer to redeem shares in conjunction with a proxy solicitation pursuant to the proxy rules and not pursuant to the tender offer rules. If the Company seeks shareholder approval in connection with a Business Combination, the Sponsor has agreed to vote its Founder Shares (as defined in Note 6) and any Public Shares purchased during or after the Initial Public Offering in favor of approving a Business Combination. Additionally, each public shareholder may elect to redeem their Public Shares irrespective of whether they vote for or against the proposed transaction or don't vote at all.

Notwithstanding the above, if the Company seeks shareholder approval of a Business Combination and the Company does not conduct redemptions pursuant to the tender offer rules, the Amended and Restated Memorandum and Articles of Association provides that a public shareholder, together with any affiliate of such shareholder or any other person with whom such shareholder is acting in concert or as a "group" (as defined under Section 13 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), will be restricted from redeeming its shares with respect to more than an aggregate of 15% or more of the Public Shares, without the prior consent of the Company.

The Sponsor has agreed to waive redemption rights with respect to any Founder Shares (as defined in Note 6) held and any Public Shares they may acquire during or after the Initial Public Offering in connection with the completion of Business Combination, except that Public Shares held by the initial shareholders will be subject to mandatory redemption upon any diminution of the Trust Account in connection with an extension, and such shares will be entitled to redemption at a price equal to the per share redemption value then held in the Trust Account in connection therewith.

The Company will have until 21 months from the closing of the Initial Public Offering to complete a Business Combination. However, the Company anticipates that it may not be able to consummate a Business Combination within such period, the Company may, but is not obligated to, by resolution of the board if requested by the initial shareholders, extend the period of time to consummate a Business Combination the Company may seek shareholder approval to amend the Amended and Restated Memorandum and Articles of Association to extend the date by which the Company must consummate the initial Business Combination. If the Company seeks shareholder approval for an extension, holders of public shares will be offered an opportunity to redeem their shares, regardless of whether they abstain, vote for, or against, the Company's initial Business Combination, at a per share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest earned thereon (which interest shall be net of taxes paid or payable, divided by the number of then issued and outstanding public shares, subject to applicable law.

There is no limit on the number or length of extensions that the Company may seek; however, the Company does not expect to extend the time period to consummate the initial Business Combination beyond 36 months from the closing of the Initial Public Offering. If the Company determine not to or are unable to extend the time period to consummate the initial Business Combination or fail to obtain shareholder approval to extend, the Sponsor, management team and other initial shareholders will lose their entire investment in the Founder Shares, except to the extent they entitle the holders thereof to receive liquidating distributions from assets outside the Trust Account.

F-5

KEYSTONE ACQUISITION CORP.
NOTES TO FINANCIAL STATEMENT
JUNE 4, 2026

NOTE 1. DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS (cont.)

In order to protect the amounts held in the Trust Account, the Sponsor has agreed that it will be liable to the Company if and to the extent any claims by a third party for services rendered or products sold to the Company, or a prospective target business with which the Company has entered into a written letter of intent, confidentiality or other similar agreement or business combination agreement, reduce the amount of funds in the Trust Account to below the lesser of (i) $10.025 per Public Share and (ii) the actual amount per Public Share held in the Trust Account as of the date of the liquidation of the Trust Account, if less than $10.025 per Public Share due to reductions in the value of the trust assets, in each case less taxes payable and up to $100,000 of interest to pay liquidation expenses, provided that such liability will not apply to any claims by a third party or prospective target business who executed a waiver of any and all rights to the monies held in the Trust Account (whether or not such waiver is enforceable) nor will it apply to any claims under the indemnity of the underwriters of the Initial Public Offering against certain liabilities, including liabilities under the Securities Act of 1933, as amended (the "Securities Act").

NOTE 2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Presentation

The accompanying financial statement is presented in conformity with accounting principles generally accepted in the United States of America ("US GAAP") and pursuant to the rules and regulations of the SEC.

Liquidity and Capital Resources

The Company's liquidity needs up to June 4, 2026 had been satisfied through the loan under an unsecured promissory note from the Sponsor of up to $300,000 (Note 6). As of June 4, 2026, the Company had $1,950,000 in cash and a working capital of $1,255,754.

In order to finance transaction costs in connection with the initial Business Combination, the Sponsor or an affiliate of the Sponsor or certain of the Company's officers and directors may, but are not obligated to, loan the Company funds as may be required. If the Company completes the initial Business Combination, the Company will repay such loaned amounts. In the event that the initial Business Combination does not close, the Company may use a portion of the working capital held outside the Trust Account to repay such loaned amounts, including the repayment of loans from the Sponsor to pay for any amount deposited to pay for any extension of the time to complete the initial Business Combination, but no proceeds from the Trust Account would be used for such repayment. Up to $1,500,000 of such loans may be convertible into warrants, at a price of $1.00 per warrant at the option of the lender, upon consummation of the initial Business Combination. The warrants would be identical to the Private Placement Warrants. The terms of such loans by the Company's officers and directors, if any, have not been determined and no written agreements exist with respect to such loans. There are no such outstanding related party loans as of June 4, 2026.

In connection with the Company's assessment of going concern considerations in accordance with FASB ASC 205-40, Presentation of Financial Statements - Going Concern, the Company does not believe it will need to raise additional funds in order to meet the expenditures required for operating its business. However, if the estimate of the costs of identifying a target business, undertaking in-depth due diligence and negotiating a Business Combination are less than the actual amount necessary to do so, the Company may have insufficient funds available to operate its business prior to the initial Business Combination. The Company has the Completion Window to complete the initial Business Combination. Management has determined that the Company has sufficient funds to finance the working capital needs of the Company within one year from the date of issuance of the financial statement.

F-6

KEYSTONE ACQUISITION CORP.
NOTES TO FINANCIAL STATEMENT
JUNE 4, 2026

NOTE 2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (cont.)

Further, Section 102(b)(1) of the JOBS Act exempts emerging growth companies from being required to comply with new or revised financial accounting standards until private companies (that is, those that have not had a Securities Act registration statement declared effective or do not have a class of securities registered under the Exchange Act) are required to comply with the new or revised financial accounting standards. The JOBS Act provides that a company can elect to opt out of the extended transition period and comply with the requirements that apply to non-emerging growth companies but any such election to opt out is irrevocable. The Company has elected not to opt out of such extended transition period which means that when a standard is issued or revised and it has different application dates for public or private companies, the Company, as an emerging growth company, can adopt the new or revised standard at the time private companies adopt the new or revised standard. This may make comparison of the Company's financial statement with another public company which is neither an emerging growth company nor an emerging growth company which has opted out of using the extended transition period difficult or impossible because of the potential differences in accounting standards used.

Use of Estimates

The preparation of the financial statement in conformity with US GAAP requires the Company's management to make estimates and assumptions that affect the reported amounts of assets and liabilities.

Making estimates requires management to exercise significant judgment. It is at least reasonably possible that the estimate of the effect of a condition, situation or set of circumstances that existed at the date of the financial statement, which management considered in formulating its estimate, could change in the near term due to one or more future confirming events. Accordingly, the actual results could differ from those estimates.

Cash and Cash Equivalents

The Company considers all short-term investments with an original maturity of three months or less when purchased to be cash equivalents. The Company had cash of $1,950,000 and did not have any cash equivalents as of June 4, 2026.

Cash Held in Trust Account

As of June 4, 2026, the assets held in the Trust Account, amounting to $288,218,750, were held in cash. Subsequently, the assets held in the Trust Account were invested in U.S. government treasury obligations with a maturity of 185 days or less or in money market funds meeting certain conditions under Rule 2a-7 under the Investment Company Act, which invest only in direct U.S. government treasury obligations.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to concentrations of credit risk consist of a cash account in a financial institution, which, at times, may exceed the Federal Deposit Insurance Corporation coverage limit of $250,000. Any loss incurred or a lack of access to such funds could have a significant adverse impact on the Company's financial condition, results of operations, and cash flows.

Offering Costs

The Company complies with the requirements of FASB ASC 340-10-S99-1 and SEC Staff Accounting Bulletin Topic 5A, Expenses of Offering. Offering costs consist principally of professional and registration fees that are related to the Initial Public Offering. FASB ASC 470-20, Debt with Conversion and Other Options, addresses the allocation of proceeds from the issuance of convertible debt into its equity and debt components. The Company applies this guidance to allocate Initial Public Offering proceeds from the Units between Public Shares and warrants, prorate, allocating the Initial Public Offering proceeds to the assigned value of the warrants and to the Public Shares. Offering costs allocated to the Public Shares were charged to temporary equity and offering costs allocated to the Public and Private Placement Warrants were charged to shareholders' deficit as Public and Private Placement Warrants, after management's evaluation, were accounted for under equity treatment.

Income Taxes

The Company accounts for income taxes under FASB ASC 740, Income Taxes ("ASC 740"). FASB ASC 740 requires the recognition of deferred tax assets and liabilities for both the expected impact of differences between the financial statement and tax basis of assets and liabilities and for the expected future tax benefit to be derived from tax loss and tax credit carryforwards. FASB ASC 740 additionally requires a valuation allowance to be established when it is more likely than not that all or a portion of deferred tax assets will not be realized.

FASB ASC 740 also clarifies the accounting for uncertainty in income taxes recognized in an enterprise's financial statement and prescribes a recognition threshold and measurement process for financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination by taxing authorities. FASB ASC 740 also provides guidance on derecognition, classification, interest and penalties, accounting in interim period, disclosure and transition.

Based on the Company's evaluation, it has been concluded that there are no significant uncertain tax positions requiring recognition in the Company's financial statement.

F-7

KEYSTONE ACQUISITION CORP.
NOTES TO FINANCIAL STATEMENT
JUNE 4, 2026

NOTE 2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (cont.)

The Company recognizes accrued interest and penalties related to unrecognized tax benefits as income tax expense. There were no unrecognized tax benefits and no amounts accrued for interest and penalties as of June 4, 2026. The Company is currently not aware of any issues under review that could result in significant payments, accruals or material deviation from its position. There are no taxes in the Cayman Islands, and accordingly, income taxes are not levied on the Company. Consequently, income taxes are not reflected in the Company's financial statement.

Class A Ordinary Shares Subject to Possible Redemption

The Public Shares issued as part of the Initial Public Offering contain a redemption feature which allows for the redemption of such Public Shares in connection with the Company's liquidation, if there is a shareholder vote or tender offer in connection with the Business Combination and in connection with certain amendments to the Company's Amended and Restated Memorandum and Articles of Association. In accordance with FASB ASC Topic 480-10-S99, the Company classifies Public Shares subject to possible redemption outside of permanent equity as the redemption provisions are not solely within the control of the Company. The Company recognizes changes in redemption value immediately as they occur and will adjust the carrying value of redeemable shares to equal the redemption value at the end of each reporting period. Immediately upon the closing of the Initial Public Offering, the Company recognized the accretion from initial book value to redemption value. The change in the carrying value of redeemable shares will result in charges against additional paid-in capital (to the extent available) and accumulated deficit. Accordingly, as of June 4, 2026, Public Shares subject to possible redemption are presented at redemption value as temporary equity, outside of the shareholders' deficit section of the Company's balance sheet. As of June 4, 2026, the Public Shares subject to possible redemption reflected in the balance sheet are reconciled in the following table:

Gross proceeds $ 287,500,000
Less:
Proceeds allocated to Public Warrants (6,281,875 )
Public Shares issuance costs (17,463,588 )
Plus:
Remeasurement of carrying value to redemption value 24,464,213
Public Shares subject to possible redemption, June 4, 2026 $ 288,218,750

Fair Value of Financial Instruments

The fair value of the Company's assets and liabilities, which qualify as financial instruments under FASB ASC Topic 820, Fair Value Measurement, approximates the carrying amounts represented in the accompanying balance sheet, primarily due to their short-term nature except for warrants (Note 8).

Share-Based Compensation

The Company accounts for share awards in accordance with FASB ASC 718, Compensation-Stock Compensation, which requires that all equity awards be accounted for at their "fair value." Fair value is measured on the grant date and is equal to the underlying value of the share. Costs equal to these fair values are recognized ratably over the requisite service period based on the number of awards that are expected to vest, in the period of grant for awards that vest immediately and have no future service condition, or in the period the awards vest immediately after meeting a performance condition becomes probable (i.e., the occurrence of a Business Combination). For awards that vest over time, cumulative adjustments in later periods are recorded to the extent actual forfeitures differ from the Company's initial estimates; previously recognized compensation cost is reversed if the service or performance conditions are not satisfied and the award is forfeited.

F-8

KEYSTONE ACQUISITION CORP.
NOTES TO FINANCIAL STATEMENT
JUNE 4, 2026

NOTE 2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (cont.)

Warrants

The Company accounts for warrants as either equity-classified or liability-classified instruments based on an assessment of the warrant's specific terms and applicable authoritative guidance in FASB ASC 480 and FASB ASC 815. The assessment considers whether the warrants are freestanding financial instruments pursuant to FASB ASC 480, meet the definition of a liability pursuant to FASB ASC 480, and whether the warrants meet all of the requirements for equity classification under FASB ASC 815, including whether the warrants are indexed to the Company's own ordinary shares, among other conditions for equity classification. This assessment, which requires the use of professional judgment, is conducted at the time of warrant issuance and as of each subsequent quarterly period end date while the warrants are outstanding.

For issued or modified warrants that meet all of the criteria for equity classification, the warrants are required to be recorded as a component of additional paid-in capital at the time of issuance. For issued or modified warrants that do not meet all the criteria for equity classification, the warrants are required to be recorded as liabilities at their initial fair value on the date of issuance, and each balance sheet date thereafter. Changes in the estimated fair value of the warrants are recognized as a non-cash gain or loss on the statement of operations.

The warrants are not precluded from equity classification and were accounted for as such on the date of issuance.

Recent Accounting Standards

Management does not believe that any recently issued, but not effective, accounting standards, if currently adopted, would have a material effect on the Company's financial statement.

NOTE 3. INITIAL PUBLIC OFFERING

Pursuant to the closing of Initial Public Offering on June 4, 2026, the Company sold 28,750,000 Units including 3,750,000 Units for the full close of the underwriters' overallotment option, at a purchase price of $10.00 per Unit, generating gross proceeds of $287,500,000. Each Unit consists of one Class A ordinary share and one-half of one Public Warrant. Each whole Public Warrant entitles the holder to purchase one Class A ordinary share at an exercise price of $11.50 per share, subject to adjustment (see Note 8).

NOTE 4. PRIVATE PLACEMENT

Simultaneously with the closing of the Initial Public Offering on June 4, 2026, the Sponsor and underwriters purchased an aggregate of 8,468,750 Private Placement Warrants, at a price of $1.00 per Private Placement Warrant, generating gross proceeds of $8,468,750. Of those 8,468,750 Private Placement Warrants, the Sponsor purchased 5,593,750 Private Placement Warrants and the underwriters purchased 2,875,000 Private Placement Warrants. Each whole Private Placement Warrant is exercisable to purchase one Class A ordinary share at a price of $11.50 per share, subject to adjustment, terms and limitations as described herein. A portion of the proceeds from the sale of the Private Placement Warrants were added to the net proceeds from the Initial Public Offering held in the Trust Account. If the Company does not complete a Business Combination, the proceeds from the sale of the Private Placement Warrants held in the Trust Account will be used to fund the redemption of the Public Shares (subject to the requirements of applicable law) and the Private Placement Warrants will expire worthless.

NOTE 5. SEGMENT INFORMATION

FASB ASC Topic 280, Segment Reporting, establishes standards for companies to report, in their financial statements, information about operating segments, products, services, geographic areas, and major customers. Operating segments are defined as components of an enterprise that engage in business activities from which it may recognize revenues and incur expenses, and for which separate financial information is available that is regularly evaluated by the Company's chief operating decision maker ("CODM"), or group, in deciding how to allocate resources and assess performance.

F-9

KEYSTONE ACQUISITION CORP.
NOTES TO FINANCIAL STATEMENT
JUNE 4, 2026

NOTE 5. SEGMENT INFORMATION (cont.)

The Company's CODM has been identified as the Chief Executive Officer, who reviews the operating results for the Company as a whole to make decisions about allocating resources and assessing financial performance. Accordingly, management has determined that the Company only has one reportable segment.

The measure of segment assets is reported on the balance sheet as total assets. When evaluating the Company's performance and making key decisions regarding resource allocation, the CODM reviews key metrics such as total assets, which include the following:

June 4,
2026
Cash $ 1,950,000
Cash held in Trust Account $ 288,218,750

The CODM reviews the position of total assets to assess if the Company has sufficient resources available to discharge its liabilities. The CODM is provided with details of cash and liquid resources available with the Company.

NOTE 6. RELATED PARTY TRANSACTIONS

Founder Shares

On December 10, 2025, the Sponsor was issued 9,583,333 Class B ordinary shares (the "Founder Shares") for an aggregate price of $25,000 paid to cover certain expenses on behalf of the Company. The Founder Shares include an aggregate of up to 1,250,000 Founder Shares subject to forfeiture to the extent that the underwriters' over-allotment option is not exercised in full or in part, so that the Sponsor will own, on an as-converted basis, 25% of the Company's issued and outstanding shares after the Initial Public Offering. On June 4, 2026, the underwriters exercised their over-allotment option in full as part of the closing of the Initial Public Offering. As a result, the 1,250,000 Founder Shares are no longer subject to forfeiture.

On December 12, 2025 and January 13, 2026, the Sponsor transferred an aggregate of 100,000 Founder Shares to three independent directors (with one receiving 40,000 Founder Shares, another receiving 25,000 Founder Shares and a third receiving 35,000 Founder Shares) at the same per-share price that the Sponsor purchased the Founder Shares, or approximately $0.003 per share. On December 22, 2025, as amended on March 25, 2026, the Sponsor transferred membership interest to the Company's officers equivalent to an aggregate of 1,100,000 Founder Shares and 550,000 Private Placement Warrants, resulting in the Sponsor holding 8,383,333 of the total 9,583,333 Founder Shares.

The transfer of the Founder Shares to the holders of such interests is in the scope of FASB ASC 718. Under FASB ASC 718, share-based compensation associated with equity classified awards is measured at fair value upon the assignment date. Since the transfer of the Founder Shares to the independent directors and officers occurred within a month from the date of incorporation and issuance of the Founder Share to the Sponsor and the Company had yet to file the registration statement publicly at the time the independent director and officers shares were transferred, the Company has determined the fair value of the Sponsor Founder Shares is the nearest and most appropriate value to use for the valuation of the 1,200,000 Founder Shares transferred to the independent directors and officers. Accordingly, the total fair value of the aggregate of 1,200,000 Founder Shares on June 4, 2026 was $3,130 or $0.003 per share. The membership interests in Founder Shares is subject to a performance condition (i.e., providing services through the Company's Initial Public Offering). The share-based compensation expense related to the transfer of membership interest in Founder Shares is recognized only when the performance condition is probable of occurrence under the applicable accounting literature. Share-based compensation was recognized upon the consummation of the Initial Public Offering, thus, the total fair value of $3,130 was recorded as compensation expense on June 4, 2026.

Additionally, the transfer of the Private Placement Warrants is in the scope of FASB ASC 718. Under FASB ASC 718, share-based compensation associated with equity classified awards is measured at fair value upon the assignment date. The total fair value of the 550,000 Private Placement Warrants on June 4, 2026 was $241,969 or $0.44 per Private Placement Warrant. The Private Placement Warrants were granted subject to a performance condition (i.e., providing services through the Company's Initial Public Offering). The share-based compensation expense related to the transfer of Private Placement Warrants is recognized only when the performance condition is probable of occurrence under the applicable accounting literature. Share-based compensation was recognized upon the consummation of the Initial Public Offering, thus, the total fair value of $241,969 was recorded as compensation expense on June 4, 2026. The Company established the initial fair value of the Private Placement Warrants on June 4, 2026, the date of the grant agreement, using a calculation prepared by a third party valuation team using Monte Carlo Simulation Model which takes into consideration the (i) underlying stock price of $9.81, (ii) volatility of 5%, (iii) remaining term of 6.75 years, (iv) risk-free rate of 4.21%, and (v) implied market adjustment of 35%.

F-10

KEYSTONE ACQUISITION CORP.
NOTES TO FINANCIAL STATEMENT
JUNE 4, 2026

NOTE 6. RELATED PARTY TRANSACTIONS (cont.)

The Founder Shares are designated as Class B ordinary shares and, except as described below, are identical to the Class A ordinary shares included in the units being sold in the Initial Public Offering, and holders of Founder Shares have the same shareholder rights as public shareholders, except that (i) the Founder Shares are subject to certain transfer restrictions, as described in more detail below, (ii) the Founder Shares are entitled to registration rights, (iii) the Company's Sponsor, officers and directors have entered into a letter agreement with the Company, pursuant to which they have agreed to (A) waive their redemption rights with respect to their Founder Shares and public shares in connection with the completion of the Company's initial Business Combination, (B) waive their redemption rights with respect to their Founder Shares and public shares in connection with a shareholder vote to approve an amendment to the Company's Amended and Restated Memorandum and Articles of Association (1) to modify the substance or timing of the Company's obligation to allow redemption in connection with the Company's initial Business Combination or to redeem 100% of the Company's public shares if the Company has not consummated an initial Business Combination within the completion window or (2) with respect to any other material provisions relating to shareholders' rights or pre-initial Business Combination activity; (C) waive their rights to liquidating distributions from the Trust Account with respect to their Founder Shares if the Company fails to complete the Company's initial Business Combination within the completion window, although they will be entitled to liquidating distributions from the Trust Account with respect to any public shares they hold if the Company fails to complete the initial Business Combination within such time period and to liquidating distributions from assets outside the Trust Account and (D) vote any Founder Shares held by them and any public shares purchased during or after the Initial Public Offering (including in open market and privately negotiated transactions) in favor of the initial Business Combination (including any proposals recommended by the Company's board of directors in connection with such Business Combination) (except with respect to any public shares which may not be voted in favor of approving the Business Combination transaction in accordance with the requirements of Rule 14e-5 under the Exchange Act and any SEC interpretations or guidance relating thereto), (iv) the Founder Shares are automatically convertible into Class A ordinary shares immediately prior to, concurrently with or immediately following the consummation of the Company's initial Business Combination or at any time prior thereto at the option of the holder on a one-for-one basis, subject to adjustment as described herein and in the Amended and Restated Memorandum and Articles of Association, and (v) prior to the closing of the Company's initial Business Combination, only holders of Class B ordinary shares will be entitled to vote on the appointment and removal of directors or continuing in a jurisdiction outside the Cayman Islands (including any special resolution required to amend the constitutional documents or to adopt new constitutional documents, in each case, as a result of approving a transfer by way of continuation in a jurisdiction outside the Cayman Islands).

The Founder Shares will automatically convert into Class A ordinary shares immediately prior to, concurrently with or immediately following the consummation of the initial Business Combination or at any time prior thereto at the option of the holder on a one-for-one basis, subject to adjustment for share subdivisions, share capitalizations, reorganizations, recapitalizations and the like, and subject to further adjustment as provided herein. In the case that additional Class A ordinary shares, or any other equity-linked securities, are issued or deemed issued in excess of the amounts sold in the Initial Public Offering and related to or in connection with the closing of the initial Business Combination, the ratio at which Class B ordinary shares convert into Class A ordinary shares will be adjusted (unless the holders of a majority of the outstanding Class B ordinary shares agree to waive such adjustment with respect to any such issuance or deemed issuance) so that the number of Class A ordinary shares issuable upon conversion of all Class B ordinary shares will equal, in the aggregate, 25% of the sum of (i) the total number of all Class A ordinary shares outstanding upon the completion of the Initial Public Offering (including any Class A ordinary shares issued pursuant to the underwriters' over-allotment option and excluding the Class A ordinary shares underlying the Private Placement Warrants issued to the Sponsor and the underwriter), plus (ii) all Class A ordinary shares and equity-linked securities issued or deemed issued in connection with the Company's initial Business Combination (excluding any shares or equity-linked securities issued, or to be issued, to any seller in the initial Business Combination and any private placement-equivalent warrants issued to the Company's Sponsor or any of its affiliates or to the Company's officers and directors upon conversion of working capital loans) minus (iii) any redemptions of Class A ordinary shares by public shareholders in connection with an initial Business Combination; provided that such conversion of Founder Shares will never occur on a less than one-for-one basis.

F-11

KEYSTONE ACQUISITION CORP.
NOTES TO FINANCIAL STATEMENT
JUNE 4, 2026

NOTE 6. RELATED PARTY TRANSACTIONS (cont.)

With certain limited exceptions, the Founder Shares are not transferable, assignable or saleable (except to the Company's officers and directors and other persons or entities affiliated with the Company's Sponsor, each of whom will be subject to the same transfer restrictions) until the earlier of (A) 180 days after the completion of the Company's initial Business Combination or earlier if, subsequent to the Company's initial Business Combination, the last sale price of the Class A ordinary shares equals or exceeds $12.00 per share (as adjusted for share subdivisions, share capitalizations, reorganizations, recapitalizations and the like) for any 20 trading days within any 30-trading day period commencing at least 150 days after the Company's initial Business Combination, and (B) the date following the completion of the Company's initial Business Combination on which the Company completes a liquidation, merger, share exchange or other similar transaction that results in all of the Company's shareholders having the right to exchange their Class A ordinary shares for cash, securities or other property.

Promissory Note - Related Party

On December 10, 2025, the Sponsor agreed to loan the Company an aggregate of up to $300,000 to cover expenses related to the Initial Public Offering pursuant to a promissory note (the "Promissory Note"). This loan was non-interest bearing and payable on the earlier of June 30, 2026 or the date on which the Company consummates the Initial Public Offering of its securities. On June 4, 2026, the Company had $300,000 outstanding borrowings under the Promissory Note which is now due on demand. On June 9, 2026, the Company repaid the $300,000 outstanding under the Promissory Note. Borrowings against the note are no longer available.

Advances from Related Party

As of June 4, 2026, the Company has $5,877 of advances from related party for expenses paid on the Company's behalf. On June 9, 2026, the Company repaid the $5,877 of advances from related party.

Administrative Services and Indemnification Agreement

The Company's Sponsor agreed, commencing on June 2, 2026 through the earlier of the Company's consummation of a Business Combination and its liquidation, to make available to the Company certain general and administrative services, including office space and administrative services, as the Company may require from time to time. The Company agreed to pay $20,000 per month to the Sponsor for these services during the 21-month period to complete a Business Combination. As of June 4, 2026, an amount of $2,000 has been accrued for these services in the Company's balance sheet.

In addition, pursuant to such agreement, the Company has agreed to indemnify the Sponsor from any claims arising out of or relating to the Initial Public Offering or the Company's operations or conduct of the Company's business or any claim against the Sponsor alleging any expressed or implied management or endorsement by the Sponsor of any of the Company's activities or any express or implied association between the Sponsor and the Company or any of its affiliates, which agreement provides that the indemnified parties cannot access the funds held in the Trust Account.

Related Party Loans

In order to finance transaction costs in connection with the initial Business Combination, the Sponsor or an affiliate of the Sponsor or certain of the Company's officers and directors may, but are not obligated to, loan the Company funds as may be required. If the Company completes the initial Business Combination, the Company will repay such loaned amounts. In the event that the initial Business Combination does not close, the Company may use a portion of the working capital held outside the Trust Account to repay such loaned amounts, including the repayment of loans from the Sponsor to pay for any amount deposited to pay for any extension of the time to complete the initial Business Combination, but no proceeds from the Trust Account would be used for such repayment. Up to $1,500,000 of such loans may be convertible into warrants, at a price of $1.00 per warrant at the option of the lender, upon consummation of the initial Business Combination. The warrants would be identical to the Private Placement Warrants. The terms of such loans by the Company's officers and directors, if any, have not been determined and no written agreements exist with respect to such loans. There are no such outstanding related party loans as of June 4, 2026.

F-12

KEYSTONE ACQUISITION CORP.
NOTES TO FINANCIAL STATEMENT
JUNE 4, 2026

NOTE 7. COMMITMENTS AND CONTINGENCIES

Registration and Shareholder Rights Agreement

The holders of the (i) Founder Shares, which were issued in a private placement prior to the closing of the Initial Public Offering, (ii) Private Placement Warrants which were issued in a private placement simultaneously with the closing of the Initial Public Offering and the Class A ordinary shares underlying such Private Placement Warrants and (iii) Private Placement Warrants that may be issued upon conversion of working capital loans have registration rights to require the Company to register a sale of any of the Company's securities held by them and any other securities of the Company acquired by them prior to the consummation of the Company's initial Business Combination pursuant to a registration rights agreement on the effective date of the Initial Public Offering. The holders of these securities are entitled to make up to three demands, excluding short form demands, that the Company registers such securities. In addition, the holders have certain "piggyback" registration rights with respect to registration statements filed subsequent to the Company's completion of the Company's initial Business Combination. The Company will bear the expenses incurred in connection with the filing of any such registration statements.

Underwriting Agreement

The Sponsor and the executive officers, directors and advisors have agreed that, for a period of 180 days from the date of the Company's prospectus, will not, without the prior written consent of the representative, offer, sell, contract to sell, pledge, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend or otherwise transfer or dispose of, directly or indirectly, any units, warrants, ordinary shares or any other securities convertible into, or exercisable or exchangeable for, any units, ordinary shares, Founder Shares or warrants, subject to certain exceptions. The representatives in their discretion may release any of the securities subject to these lock-up agreements at any time without notice, other than in the case of the officers and directors, which shall be with notice. The Sponsor, officers, directors and advisors are also subject to separate transfer restrictions on their Founder Shares and Private Placement Warrants pursuant to the letter agreement described herein.

The Company granted the underwriters a 45-day option from the date of the Initial Public Offering to purchase up to 3,750,000 additional Units to cover over-allotments, if any, at the Initial Public Offering price less the underwriting discounts and commissions. On June 4, 2026, the underwriters exercised their over-allotment option, closing on the 3,750,000 additional Units simultaneously with the Initial Public Offering.

The underwriters were paid a cash underwriting discount of $5,750,000 following the closing of the Initial Public Offering on June 4, 2026. In addition, the underwriters were entitled to a deferred fee $11,500,000 in the aggregate. The deferred fee will become payable to the underwriters from the amounts held in the Trust Account solely in the event that the Company completes a Business Combination and shall be due to the underwriters solely on amounts remaining in the Trust Account following all properly submitted shareholder redemptions, including in connection with the consummation of the initial Business Combination, subject to the terms of the underwriting agreement.

F-13

KEYSTONE ACQUISITION CORP.
NOTES TO FINANCIAL STATEMENT
JUNE 4, 2026

NOTE 8. SHAREHOLDERS' DEFICIT

Preference shares - The Company is authorized to issue 5,000,000 preference shares with a par value of $0.0001 per share, with such designations, voting and other rights and preferences as may be determined from time to time by the Company's board of directors. As of June 4, 2026, there were no preference shares issued or outstanding.

Class A ordinary shares - The Company is authorized to issue 500,000,000 Class A ordinary shares with a par value of $0.0001 per share. Holders of the Company's Class A ordinary shares are entitled to one vote for each share. As of June 4, 2026, there were no Class A ordinary shares issued or outstanding, excluding the 28,750,000 shares subject to possible redemption.

Class B ordinary shares - The Company is authorized to issue 50,000,000 Class B ordinary shares with a par value of 0.0001 per share. Holders of the Company's Class B ordinary shares are entitled to one vote for each share. As of June 4, 2026, there were 9,583,333 Class B ordinary shares issued and outstanding.

Ordinary shareholders of record are entitled to one vote for each share held on all matters to be voted on by shareholders. Except as described below, holders of Class A ordinary shares and holders of Class B ordinary shares will vote together as a single class on all matters submitted to a vote of the Company's shareholders except as required by law. Prior to the closing of the initial Business Combination, only holders of Class B ordinary shares (i) will have the right to appoint and remove directors prior to or in connection with the completion of the initial Business Combination and (ii) will be entitled to vote on continuing the Company in a jurisdiction outside the Cayman Islands (including any special resolution required to amend constitutional documents or to adopt new constitutional documents, in each case, as a result of approving a transfer by way of continuation in a jurisdiction outside the Cayman Islands). On any other matters submitted to a vote of shareholders prior to or in connection with the completion of the initial Business Combination, holders of the Class B ordinary shares and holders of the Class A ordinary shares will vote together as a single class, except as required by law.

The Founder Shares will automatically convert into Class A ordinary shares immediately prior to, concurrently with or immediately following the consummation of a Business Combination, and may be converted at any time prior to the Business Combination, at the option of the holder, on a one-for-one basis (unless otherwise provided in the business combination agreement), subject to adjustment for share subdivisions, share dividends, reorganizations, recapitalizations and the like, and subject to further adjustment as provided herein. In the case that additional Class A ordinary shares or equity-linked securities are issued or deemed issued in connection with the Business Combination, the number of Class A ordinary shares issuable upon conversion of all Founder Shares will equal, in the aggregate, on an as-converted basis, approximately 25% of the total number of Class A ordinary shares outstanding after such conversion (not including the Class A ordinary shares underlying the Private Placement Warrants), including the total number of Class A ordinary shares issued, or deemed issued or issuable upon conversion or exercise of any equity-linked securities or rights issued or deemed issued, by the Company in connection with or in relation to the consummation of the Business Combination, excluding any Class A ordinary shares or equity-linked securities or rights exercisable for or convertible into Class A ordinary shares issued, or to be issued, to any seller in the Business Combination and any Private Placement Warrants issued to the Sponsor, officers or directors upon conversion of Working Capital Loans, provided that such conversion of Founder Shares will never occur on a less than one-for-one basis.

F-14

KEYSTONE ACQUISITION CORP.
NOTES TO FINANCIAL STATEMENT
JUNE 4, 2026

NOTE 8. SHAREHOLDERS' DEFICIT (cont.)

Warrants - There are 22,843,750 warrants currently outstanding, including 14,375,000 Public Warrants and 8,468,750 Private Placement Warrants as of June 4, 2026. Each whole Public Warrant entitles the registered holder to purchase one Class A ordinary share at a price of $11.50 per share, subject to adjustment as discussed below, at any time commencing 30 days after the completion of the initial Business Combination. Pursuant to the warrant agreement, a warrant holder may exercise its Public Warrants only for a whole number of Class A ordinary shares. No fractional Public Warrants will be issued upon separation of the units and only whole Public Warrants will trade.

The Public Warrants will expire five years after the completion of the initial Business Combination, at 5:00 p.m., New York City time, or earlier upon redemption or liquidation.

The Company has agreed that as soon as practicable, but in no event later than 20 business days after the closing of the initial Business Combination, the Company will use commercially reasonable efforts to file with the SEC a post-effective amendment to the registration statement filed in connection with the Initial Public Offering or a new registration statement covering the registration, under the Securities Act, of the Class A ordinary shares issuable upon exercise of the warrants and thereafter will use the Company's commercially reasonable efforts to cause the same to become effective within 60 business days following the initial Business Combination and to maintain a current prospectus relating to the Class A ordinary shares issuable upon exercise of the warrants, until the expiration of the warrants in accordance with the provisions of the warrant agreement. If a registration statement covering the Class A ordinary shares issuable upon exercise of the warrants is not effective by the sixtieth (60) business day after the closing of the initial Business Combination, warrant holders may, until such time as there is an effective registration statement and during any period when the Company will have failed to maintain an effective registration statement, exercise warrants on a "cashless basis" in accordance with Section 3(a)(9) of the Securities Act or another exemption.

Once the warrant become exercisable, the Company may call the warrants for redemption for cash:

in whole and not in part;
at a price of $0.01 per warrant;
upon a minimum of 30 days' prior written notice of redemption;
if, and only if, the closing price of the Class A ordinary shares equals or exceeds $18.00 per share (as adjusted for adjustments to the number of shares issuable upon exercise or the exercise price of a warrant as described under the heading "Warrants") for any 20 trading days within a 30-trading day period commencing at least 30 days after completion of the Company's initial Business Combination and ending three business days before the Company sends the notice of redemption to the warrant holders.

If and when the warrants become redeemable by the Company for cash, the Company may exercise the redemption right even if the Company is unable to register or qualify the underlying securities for sale under all applicable state securities laws.

In addition, if (x) the Company issues additional Class A ordinary shares or equity-linked securities for capital raising purposes in connection with the closing of the initial Business Combination at an issue price or effective issue price of less than $9.20 per Class A ordinary shares (with such issue price or effective issue price to be determined in good faith by the Company's board of directors and, in the case of any such issuance to the initial shareholders or their affiliates, without taking into account any Founder Shares or Private Placement Shares held by the initial shareholders or such affiliates, as applicable, prior to such issuance) (the "Newly Issued Price"), (y) the aggregate gross proceeds from such issuances represent more than 60% of the total equity proceeds, and interest thereon, available for the funding of the initial Business Combination on the date of the consummation of the initial Business Combination (net of redemptions), and the volume weighted average trading price of the Class A ordinary shares during the 20 trading day period starting on the trading day after the day on which the Company consummate the initial Business Combination (such price, the "Market Value") is below $9.20 per share, the exercise price of the warrants will be adjusted (to the nearest cent) to be equal to 115% of the higher of the Market Value and the Newly Issued Price, and the $18.00 per share redemption trigger price will be adjusted (to the nearest cent) to be equal to 180% of the higher of the Market Value and the Newly Issued Price.

F-15

KEYSTONE ACQUISITION CORP.
NOTES TO FINANCIAL STATEMENT
JUNE 4, 2026

NOTE 8. SHAREHOLDERS' DEFICIT (cont.)

The Private Placement Warrants (including the Class A ordinary shares issuable upon exercise of the Private Placement Warrants) will not be transferable, assignable or salable until 30 days after the completion of the initial Business Combination. The Private Placement Warrants have terms and provisions that are identical to those of the Public Warrants being sold as part of the units in the Initial Public Offering.

The Company accounts for the warrants issued in connection with the Initial Public Offering in accordance with the guidance contained in FASB ASC 815-40. Such guidance provides that the warrants described above are not precluded from equity classification. Equity-classified contracts are initially measured at fair value (or allocated value). Subsequent changes in fair value are not recognized as long as the contracts continue to be classified in equity.

NOTE 9. FAIR VALUE MEASUREMENTS

Fair value is defined as the price that would be received for sale of an asset or paid for transfer of a liability in an orderly transaction between market participants at the measurement date. US GAAP establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). These tiers include:

Level 1, defined as observable inputs such as quoted prices (unadjusted) for identical instruments in active markets;
Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable such as quoted prices for similar instruments in active markets or quoted prices for identical or similar instruments in markets that are not active; and
Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions, such as valuations derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable. In some circumstances, the inputs used to measure fair value might be categorized within different levels of the fair value hierarchy. In those instances, the fair value measurement is categorized in its entirety in the fair value hierarchy based on the lowest level input that is significant to the fair value measurement.

The fair value of the Public Warrants issued in the Initial Public Offering is $6,281,875, or $0.44 per Public Warrant and was determined using Monte Carlo Simulation Model. The Public Warrants issued in the Initial Public Offering have been classified within shareholders' deficit and will not require remeasurement after issuance. The following table presents the quantitative information regarding market assumptions used in the Level 3 valuation of the Public Warrants issued in the Initial Public Offering:

June 4,
2026
Underlying stock price $ 9.81
Exercise price $ 11.50
Volatility 5.00 %
Remaining term (years) 6.75
Risk-free rate 4.21 %
Implied market adjustment 35.00 %

NOTE 10. SUBSEQUENT EVENTS

The Company evaluated subsequent events and transactions that occurred after the balance sheet date through the date that the financial statement was issued. Based on this review, other than noted below, the Company did not identify any subsequent events that would have required adjustment or disclosure in the financial statement.

On June 9, 2026, the Company repaid the $300,000 outstanding under the Promissory Note. Borrowings against the note are no longer available.

On June 9, 2026, the Company repaid the $5,877 of advance from related party.

F-16

Keystone Acquisition Corp. published this content on June 10, 2026, and is solely responsible for the information contained herein. Distributed via EDGAR on June 10, 2026 at 19:08 UTC. If you believe the information included in the content is inaccurate or outdated and requires editing or removal, please contact us at [email protected]