Keystone Acquisition Corp. (KEYYU) director discloses 35,000 Class B shares

Rhea-AI Filing Summary

Keystone Acquisition Corp. director Martin J. Payne filed an initial Form 3 showing beneficial ownership of 35,000 Class B ordinary shares. These Class B shares are directly held, are convertible into the company’s Class A ordinary shares, and, according to the disclosure, have no expiration date.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Payne Martin J.

Role null

Type	Security	Shares	Price	Value
holding	Class B Ordinary Shares	--	--	--

Holdings After Transaction: Class B Ordinary Shares — 35,000 shares (Direct, null)

Footnotes (1)

1. [object Object]

Key Figures

Class B shares owned: 35,000 shares Underlying Class A shares: 35,000 shares Exercise price: $0.00 per share

3 metrics

Class B shares owned 35,000 shares Total Class B ordinary shares directly owned after reported holding

Underlying Class A shares 35,000 shares Class A ordinary shares underlying the Class B ordinary shares

Exercise price $0.00 per share Conversion/exercise price disclosed for Class B into Class A

Key Terms

Class B ordinary shares, Class A ordinary shares, Registration Statement on Form S-1, beneficial ownership

4 terms

Class B ordinary shares financial

"The Class B ordinary shares are convertible for the Issuer's Class A ordinary shares"

Class B ordinary shares are a type of ownership stake in a company that typically come with different voting rights or privileges compared to other share classes. For investors, they represent a way to hold part of the company’s value and influence its decisions, often with fewer voting rights than Class A shares. Understanding these shares helps investors assess their level of control and potential returns within a company.

Class A ordinary shares financial

"convertible for the Issuer's Class A ordinary shares as described under the heading"

Class A ordinary shares are a type of ownership stake in a company that typically grants voting rights to shareholders, allowing them to have a say in important company decisions. They often come with priority in receiving dividends or profits, making them attractive to investors seeking influence and potential income. These shares help distinguish different levels of ownership and rights within a company's stock structure.

Registration Statement on Form S-1 regulatory

"as described under the heading "Description of Securities" in the Issuer's Registration Statement on Form S-1"

A registration statement on Form S-1 is a detailed filing a company submits to the U.S. securities regulator to register new shares for public sale; it includes a plain-language prospectus, financial statements, business description and risk factors. For investors it matters because it provides the official, comprehensive blueprint of the offering — like an owner’s manual — allowing buyers to assess risks, inspect financial health and compare valuation before deciding to invest.

beneficial ownership financial

"filed an initial Form 3 showing beneficial ownership of 35,000 Class B ordinary shares"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

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Understanding Insider Trading Forms →

Available on EDGAR 06/12/2026 - 08:39 AM Accepted by SEC EDGAR 06/02/2026 - 09:54 PM Learn about SEC filing dates

SEC Form 3

FORM 3

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

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0104
Estimated average burden
hours per response:			0.5

1. Name and Address of Reporting Person^*

Payne Martin J.

(Last) (First) (Middle)

C/O KEYSTONE ACQUISITION CORP.

142 WEST 57TH STREET, 11TH FLOOR

(Street)

NEW YORK NEW YORK 10019

(City) (State) (Zip)

UNITED STATES

(Country)

2. Date of Event Requiring Statement (Month/Day/Year)
06/02/2026

3. Issuer Name and Ticker or Trading Symbol
Keystone Acquisition Corp. [ KEYY ]

3a. Foreign Trading Symbol

5. If Amendment, Date of Original Filed (Month/Day/Year)

4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Class B Ordinary Shares	(1)	(1)	Class A Ordinary Shares	35,000	(1)	D

Explanation of Responses:

1. The Class B ordinary shares are convertible for the Issuer's Class A ordinary shares as described under the heading "Description of Securities" in the Issuer's Registration Statement on Form S-1 (File No. 333-295539) (the "Registration Statement") and have no expiration date.

Remarks:

See Exhibit 24.1 - Power of Attorney.

	/s/ Claudia Hanover, Attorney-in-Fact	06/02/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 5 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 3: SEC 1473 (03-26)

FAQ

What does the Keystone Acquisition Corp. (KEYYU) Form 3 for Martin J. Payne report?

The Form 3 reports that director Martin J. Payne beneficially owns 35,000 Class B ordinary shares of Keystone Acquisition Corp. These shares are directly held and represent his initial reported ownership position as an insider of the company.

How many Keystone Acquisition Corp. Class B shares does Martin J. Payne hold?

Martin J. Payne holds 35,000 Class B ordinary shares of Keystone Acquisition Corp. The filing shows this as his total direct ownership following the reported holding entry, establishing his baseline insider position in the company’s equity.

Are Martin J. Payne’s Class B shares in Keystone Acquisition Corp. convertible?

Yes. The filing states that the Class B ordinary shares are convertible into Keystone Acquisition Corp.’s Class A ordinary shares, as described in the company’s Form S-1 Registration Statement, linking these founder-style shares to the publicly traded class.

Do the Keystone Acquisition Corp. Class B shares reported have an expiration date?

The disclosure specifies that the Class B ordinary shares have no expiration date. This means Payne’s 35,000 Class B shares remain outstanding and convertible into Class A ordinary shares without a stated time limit in the reported terms.

Is the Keystone Acquisition Corp. Form 3 for Martin J. Payne a buy or sell transaction?

The Form 3 is an initial beneficial ownership report, not a buy or sell trade. It records Martin J. Payne’s existing direct ownership of 35,000 Class B ordinary shares when he became a reporting insider of Keystone Acquisition Corp.