Comparable stake leader
Magnetar Financial LLC
SEC ownership of Keystone Acquisition Corp.
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0002102771.
Disclosed value leader
Magnetar Financial LLC
Comparable rows
33/50
Latest evidence
30 Jun 2026
- Public ticker
- KEYY, KEYYU on Nasdaq
- Parsed ownership sources
-
13D/G and 13F
Source: Parsed SEC ownership filingsUse: Compare filing families carefully
- Largest SEC-reported holder
-
Magnetar Financial LLC
Ranking: Comparable ownership first, then disclosed value
- Comparable ownership rows
-
33 of 50
Meaning: Rows with safely comparable ownership %
- Latest 13D/G holder
-
Magnetar Financial LLC
Source: Latest parsed Schedule 13D/G stake
- Latest parsed ownership date
-
30 Jun 2026
Freshness: Most recent filing date in this holder set
- Issuer CIK
- 0002102771
- Issuer location
- New York, NY
Ownership snapshot
CIK-linked ownership evidence from parsed SEC filings.
3 signals
Issuer
Names, identifiers, and filing context for this profile.
2 identity fields
Ownership snapshot
Top shareholders of Keystone Acquisition Corp. (13F + 13D/G + 3/4/5)
Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.
Comparable stake leader
Magnetar Financial LLC
Disclosed value leader
Magnetar Financial LLC
Comparable rows
33/50
Latest evidence
30 Jun 2026
13D/G
13F
Lead comparable stake: 7%
17 rows are not safely comparable across share classes.
13D/G row: Magnetar Financial LLC
Showing 1-8 of 50 holder rows.
Quick read
Magnetar Financial LLC leads the comparable SEC ownership view at 7%.
33 of 50 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.
Open SEC evidence
Opens Magnetar Financial LLC's linked filing trail.
Comparable ownership
Top 5
Magnetar Financial LLC
7%
AQR CAPITAL MANAGEMENT LLC
6%
AQR Arbitrage LLC
6%
LMR Partners LLP
4.5%
HEALTHCARE OF ONTARIO PENSION PLA...
4.4%
Ownership % is shown only when SEC disclosures are safely comparable across share classes.
Detailed SEC evidence table Showing 1-8 of 50 holder rows
| Holder | Evidence | Ownership % | Position | 12M Net Δ | As of |
|---|---|---|---|---|---|
| Magnetar Financial LLC |
13D/G
13F
Company
|
7%
|
$20,280,000
2,000,000 shares
|
$0 | 30 Jun 2026 |
| AQR CAPITAL MANAGEMENT LLC |
13D/G
|
6%
|
$16,991,492
1,723,275 shares
|
$0 | 30 Jun 2026 |
| AQR Arbitrage LLC |
13F
Company
|
6%
|
$17,301,681
1,723,275 shares
|
— | 30 Jun 2026 |
| LMR Partners LLP |
13F
Company
|
4.5%
|
$13,052,000
1,300,000 shares
|
— | 30 Jun 2026 |
| HEALTHCARE OF ONTARIO PENSION PLAN TRUST FUND |
13F
Company
|
4.4%
|
$12,575,000
1,250,000 shares
|
— | 30 Jun 2026 |
| Alberta Investment Management Corp |
13F
Company
|
2.8%
|
$8,048,000
800,000 shares
|
— | 30 Jun 2026 |
| HGC Investment Management Inc. |
13F
Company
|
2.8%
|
$8,032,000
800,000 shares
|
— | 30 Jun 2026 |
| First Trust Capital Management L.P. |
13F
Company
|
2.6%
|
$7,394,980
749,998 shares
|
— | 30 Jun 2026 |
How to read this table
Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.
Forms 3/4/5 flow
Insider trading overview
Insider buy and sell flow is broadly balanced over the last 12 months. No Buy or Sell transactions have been reported since 30 Aug 2025.
Buys
$0
Insiders: 0
Sells
$0
Insiders: 0
Net
$0
Shares: 0
Window
Last 12 months
4 rolling buckets
Buy value
Sell value
Shares: 0
Shares: 0
| Window (months) | Buy shares | Sell shares | Buy value | Sell value | Net value |
|---|---|---|---|---|---|
| 0-3 | 0 | 0 | $0 | $0 | $0 |
| 3-6 | 0 | 0 | $0 | $0 | $0 |
| 6-9 | 0 | 0 | $0 | $0 | $0 |
| 9-12 | 0 | 0 | $0 | $0 | $0 |
Reporting owners
Insider holders from Forms 3/4/5
Showing 1-7 of 7 reporting-owner rows connected to Keystone Acquisition Corp.. Open a relationship link for the CIK-to-CIK filing trail.
Rows
7
Largest Forms 3/4/5 holder
Keystone International Acquisition Management LLC
Net 12M change
$0
Latest report
02 Jun 2026
| Name | Relationship | Holdings Value | Past Year Net Change | Change % | Valuation | Report Date |
|---|---|---|---|---|---|---|
| Keystone International Acquisition Management LLC | Executive Chairman, Director, 10%+ Owner | Mixed | 02 Jun 2026 | |||
| Jae Hyun Park | Director, 10%+ Owner | Mixed | 02 Jun 2026 | |||
| Richard H. Chin | Chief Executive Officer | Mixed | 02 Jun 2026 | |||
| Jaiho Cho | Chief Financial Officer | Mixed | 02 Jun 2026 | |||
| John A. Boehner | Director | Mixed | 02 Jun 2026 | |||
| Paul Y. Cho | Director | Mixed | 02 Jun 2026 | |||
| Martin J. Payne | Director | Mixed | 02 Jun 2026 |
Recent insider transactions for Keystone Acquisition Corp.
Showing up to 300 recent insider transactions from the last 12 months.
| Insider | Symbol | Class | Transaction | % | SEC-reported value | SEC-reported price | Shares | Shares owned | Date | Ownership |
|---|---|---|---|---|---|---|---|---|---|---|
| No insider transactions were found in the last 12 months for this issuer. | ||||||||||
* marks a reported price that did not pass the local price check.