Who owns Keystone Acquisition Corp.?
Prices and market caps: Cboe delayed data, at least 15 minutes delayed. Not real-time. Fundamentals from company filings.
Institutional ownership of KEYYU from SEC Form 13F filings across 29 reporting managers. All positions are from one synchronized reporting period — 2026-06-30 books, filed up to 45 days after quarter end — so every row is comparable.
As of the 2026-06-30 reporting period, 29 institutions disclosed 13.5M shares of Keystone Acquisition Corp. worth $135.2M — about 53.9% of shares outstanding; the largest disclosed holder is Magnetar Financial LLC. Source: SEC Form 13F filings, parsed by EvidInvest.
29
13F holders
$135.2M
value, 2026 filers
53.9%
of shares outstanding (13.5M sh)
29
new positions (2026 filers)
Top institutional holders
ordered by shares owned · positions as of 2026-06-30 · % of fund = share of the manager's own book · % of co. = share of KEYYU's shares outstanding
| # | Manager | Shares | Value | % of fund | % of co. | Δ shares QoQ |
|---|---|---|---|---|---|---|
| 1 | Magnetar Financial LLCNEW | 2.0M | $20.1M | 0.2% | 8% | new |
| 2 | AQR Arbitrage LLCNEW | 1.7M | $17.3M | 0.2% | 6.9% | new |
| 3 | LMR Partners LLPNEW | 1.3M | $13.1M | 0.0% | 5.2% | new |
| 4 | HEALTHCARE OF ONTARIO PENSION PLAN TRUST FUNDNEW | 1.3M | $12.6M | 0.0% | 5% | new |
| 5 | HGC Investment Management Inc.NEW | 800,000 | $8.0M | 1.6% | 3.2% | new |
| 6 | Alberta Investment Management CorpNEW | 800,000 | $8.0M | 0.0% | 3.2% | new |
| 7 | Fort Baker Capital Management LPNEW | 600,000 | $6.0M | 0.4% | 2.4% | new |
| 8 | BNP PARIBAS FINANCIAL MARKETSNEW | 526,725 | $5.3M | 0.0% | 2.1% | new |
| 9 | MILLENNIUM MANAGEMENT LLCNEW | 500,000 | $5.0M | 0.0% | 2% | new |
| 10 | Radcliffe Capital Management, L.P.NEW | 499,900 | $5.0M | 0.4% | 2% | new |
| 11 | Centiva Capital, LPNEW | 425,000 | $4.3M | 0.0% | 1.7% | new |
| 12 | PICTON MAHONEY ASSET MANAGEMENTNEW | 400,000 | $4.0M | 0.0% | 1.6% | new |
| 13 | Decagon Asset Management LLPNEW | 375,000 | $3.8M | 0.7% | 1.5% | new |
| 14 | WHITEBOX ADVISORS LLCNEW | 350,000 | $3.5M | 0.0% | 1.4% | new |
| 15 | MOORE CAPITAL MANAGEMENT, LPNEW | 300,000 | $3.0M | 0.0% | 1.2% | new |
| 16 | Lineage Point Capital LPNEW | 295,719 | $3.0M | 0.6% | 1.2% | new |
| 17 | Calamos Advisors LLCNEW | 200,000 | $2.0M | 0.0% | 0.8% | new |
| 18 | Schonfeld Strategic Advisors LLCNEW | 200,000 | $2.0M | 0.0% | 0.8% | new |
| 19 | RIVERNORTH CAPITAL MANAGEMENT, LLCNEW | 200,000 | $2.0M | 0.1% | 0.8% | new |
| 20 | TORONTO DOMINION BANKNEW | 199,900 | $2.0M | 0.0% | 0.8% | new |
| 21 | Ghisallo Capital Management LLCNEW | 150,000 | $1.5M | 0.0% | 0.6% | new |
| 22 | ARISTEIA CAPITAL, L.L.C.NEW | 144,062 | $1.4M | 0.0% | 0.6% | new |
| 23 | DLD Asset Management, LPNEW | 100,000 | $1.0M | 0.1% | 0.4% | new |
| 24 | SUSQUEHANNA INTERNATIONAL GROUP, LLPNEW | 40,000 | $401,600 | 0.0% | 0.2% | new |
| 25 | ABC ARBITRAGE SANEW | 30,000 | $301,200 | 0.0% | 0.1% | new |
Source: SEC Form 13F-HR filings (institutional managers over $100M in US-listed positions). 13Fs disclose long positions only, up to 45 days after quarter end; each manager's latest filed quarter is shown per row and dollar values are the manager's filed marks. Aggregates labeled "2026 filers" count only managers whose latest book is a 2026 quarter. Related: valuation · options positioning · supply chain. Research, not investment advice.