UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE
SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported): June 418, 2026

KEYSTONE ACQUISITION CORP.

(Exact name of registrant as specified in its charter)

Cayman Islands		001-43320		N/A
(State or other jurisdiction of incorporation)		(Commission File Number)		(IRS Employer Identification No.)

142 West 57th Street

11th Floor

New York, New York 10019

(Address of principal executive offices, including zip code)

Registrant’s telephone number, including area code: (408) 482-7532

Not Applicable
(Former name or former address, if changed since last report)

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Units, each consisting of one Class A ordinary share, $0.0001 par value, and one-half of one redeemable warrant	KEYYU	The Nasdaq Stock Market LLC
Class A ordinary shares, par value $0.0001 per share	KEYY	The Nasdaq Stock Market LLC
Warrants, each whole warrant exercisable for one Class A ordinary share at an exercise price of $11.50 per share	KEYYW	The Nasdaq Stock Market LLC

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐	Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐	Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐	Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐	Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 8.01. Other Events.

AsOn ~~previously reported, on~~ June 418, 2026, Keystone Acquisition Corp. (the “Company”) ~~consummated~~issued ~~its~~a ~~initial~~press ~~public~~release, ~~offering~~a ~~(“IPO”)~~ copy of ~~28,750,000~~which ~~units~~is ~~(the~~attached ~~“Units”),~~as ~~including~~Exhibit ~~the~~99.1 ~~issuance~~to ofthis ~~3,750,000~~Current ~~Units~~Report on asForm a8-K, ~~result~~announcing ofthat the ~~underwriters’ exercise~~holders of ~~their~~the ~~over-allotment~~Company’s ~~option~~units in(the ~~full.~~“Units”) ~~Each~~may ~~Unit~~elect ~~consists~~to ofseparately ~~one~~trade ~~Class~~the Class A ordinary ~~share of the Company~~shares, par value $0.0001 per share (the “Class A Ordinary Shares”), and warrants (the “Warrants”) included in the Units commencing on or about June 22, 2026. Each Unit consists of one Class A Ordinary Share and one-half of one redeemable Warrant ~~warrant~~to ofpurchase ~~the~~one ~~Company~~Class ~~(each~~A ~~whole~~Ordinary ~~warrant,~~Share. aAny Units not separated will continue to trade on The Nasdaq Global Market under the symbol “~~Warrant~~KEYYU”), ~~with~~and ~~each~~the ~~Warrant~~Class ~~entitling~~A ~~the~~Ordinary ~~holder~~Shares ~~thereof~~and toWarrants ~~purchase~~will ~~one~~separately ~~Class~~trade Aon ~~Ordinary~~The ~~Share~~Nasdaq ~~for~~Global ~~$11.50~~Market ~~per~~under ~~share,~~the symbols ~~subject~~“KEYY” toand ~~adjustment~~“KEYYW,” respectively. ~~The~~No ~~Units~~fractional ~~were~~Warrants ~~sold~~will atbe aissued ~~price~~upon separation of ~~$10~~the Units and only whole Warrants will trade.00 ~~per~~Holders ~~Unit,~~of ~~generating~~Units ~~gross~~will ~~proceeds~~need to have their brokers contact Efficiency INC., the Company’s oftransfer ~~$287~~agent,~~500,000~~ in order to separate the Units into Class A Ordinary Shares and Warrants.

Also as previously reported, on June 4, 2026, simultaneously with the consummation of the IPO, the Company completed the private sale (the “Private Placement”) of an aggregate of 8,468,750 warrants (the “Private Placement Warrants”) to Keystone International Acquisition Management LLC (the “Sponsor”), Cohen & Company Capital Markets, a division of Cohen & Company Securities, LLC and Clear Street LLC, as representatives of the underwriters (the “Representatives”) at a purchase price of $1.00 per Private Placement Warrant, generating gross proceeds to the Company of $8,468,750. Of the 8,468,750 Private Placement Warrants, the Sponsor purchased 5,593,750 Private Placement Warrants and the Representatives purchased 2,875,000 Private Placement Warrants.

A total of $288,218,750 of the proceeds from the IPO and Private Placement, which amount includes up to $11,500,000 of the underwriters’ deferred commission, was placed in a U.S.-based trust account maintained by Efficiency INC., acting as trustee.

An audited balance sheet as of June 4, 2026 reflecting receipt of the proceeds upon consummation of the IPO and the Private Placement has been issued by the Company and is included as Exhibit 99.1 to this Current Report on Form 8-K.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

EXHIBIT INDEX

Exhibit No.		Description
99.1		~~Audited~~Press ~~Balance~~Release, ~~Sheet~~dated ~~as of~~ June 418, 2026.
104		Cover Page Interactive Data File (embedded within the Inline XBRL document).

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	KEYSTONE ACQUISITION CORP.
	By:	/s/ Richard Chin
		Name:	Richard Chin
		Title:	Chief Executive Officer
Dated: June 10, 2026
Dated: June 18, 2026

Filing Compare · Keystone Acquisition Corp.