Comparable stake leader
Whiteowl Holdings LLC
SEC ownership of Quantumsphere Acquisition Corp
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0002070900.
Disclosed value leader
MIZUHO SECURITIES USA LLC
Comparable rows
10/39
Latest evidence
31 Mar 2026
- Public ticker
- QUMS, QUMSR, QUMSU on Nasdaq
- Parsed ownership sources
-
3/4/5, 13D/G, and 13F
Source: Parsed SEC ownership filingsUse: Compare filing families carefully
- Largest SEC-reported holder
-
Whiteowl Holdings LLC
Ranking: Comparable ownership first, then disclosed value
- Comparable ownership rows
-
10 of 39
Meaning: Rows with safely comparable ownership %
- Latest 13D/G holder
-
Whiteowl Holdings LLC
Source: Latest parsed Schedule 13D/G stake
- Latest parsed ownership date
-
31 Mar 2026
Freshness: Most recent filing date in this holder set
- Issuer CIK
- 0002070900
- 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 Quantumsphere 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
Whiteowl Holdings LLC
Disclosed value leader
MIZUHO SECURITIES USA LLC
Comparable rows
10/39
Latest evidence
31 Mar 2026
3/4/5
13D/G
13F
Lead comparable stake: 27%
29 rows are not safely comparable across share classes.
13D/G row: Whiteowl Holdings LLC
Showing 1-8 of 39 holder rows.
Quick read
Whiteowl Holdings LLC leads the comparable SEC ownership view at 27%.
10 of 39 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 Whiteowl Holdings LLC's linked filing trail.
Comparable ownership
Top 5
Whiteowl Holdings LLC
27%
MIZUHO FINANCIAL GROUP INC
6.3%
WOLVERINE ASSET MANAGEMENT LLC
5%
MIZUHO SECURITIES USA LLC
6.4%
Karpus Management, Inc.
4.3%
Ownership % is shown only when SEC disclosures are safely comparable across share classes.
Detailed SEC evidence table Showing 1-8 of 39 holder rows
| Holder | Evidence | Ownership % | Position | 12M Net Δ | As of |
|---|---|---|---|---|---|
| Whiteowl Holdings LLC |
3/4/5
13D/G
10%+ Owner
|
27%
from 13D/G
|
—
3,126,650 shares
|
— | 05 Aug 2025 |
| MIZUHO FINANCIAL GROUP INC |
13D/G
|
6.3%
|
$7,188,041
718,086 shares
|
$0 | 31 Dec 2025 |
| WOLVERINE ASSET MANAGEMENT LLC |
13F
13D/G
Company
|
5%
from 13D/G
|
$6,146,121
739,197 shares
mixed-class rows
|
— | 31 Mar 2026 |
| MIZUHO SECURITIES USA LLC |
13F
Company
|
6.4%
|
$7,356,439
731,984 shares
|
— | 31 Mar 2026 |
| Karpus Management, Inc. |
13F
Company
|
4.3%
|
$4,998,015
493,875 shares
|
— | 31 Mar 2026 |
| Crossingbridge Advisors, LLC |
13F
Company
|
0.95%
|
$1,091,189
107,825 shares
|
— | 31 Mar 2026 |
| TWO SIGMA INVESTMENTS, LP |
13F
Company
|
0.31%
|
$357,145
35,291 shares
|
— | 31 Mar 2026 |
| Virtu Financial LLC |
13F
Company
|
0.2%
|
$226,000
22,303 shares
|
— | 31 Mar 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 21 Jun 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 1-5 of 5 reporting-owner rows connected to Quantumsphere Acquisition Corp. Open a relationship link for the CIK-to-CIK filing trail.
Rows
5
Largest Forms 3/4/5 holder
Wei Zhang
Net 12M change
$0
Latest report
05 Aug 2025
| Name | Relationship | Holdings Value | Past Year Net Change | Change % | Valuation | Report Date |
|---|---|---|---|---|---|---|
| Wei Zhang | Director | Mixed | 05 Aug 2025 | |||
| Whiteowl Holdings LLC | 10%+ Owner | Mixed | 05 Aug 2025 | |||
| Qi Gong | Director | Mixed | 05 Aug 2025 | |||
| Ping Zhang | Chairman, CEO, and CFO, Director | Mixed | 05 Aug 2025 | |||
| Daniel M. McCabe | Director | Mixed | 05 Aug 2025 |
Recent insider transactions for Quantumsphere 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 |
|---|---|---|---|---|---|---|---|---|---|---|
| Whiteowl Holdings LLC | QUMS | Ordinary Shares, par value $0.0001 per share | 0 | 3,126,650 | 05 Aug 2025 | Direct | ||||
| Ping Zhang | QUMS | Ordinary Shares, par value $0.0001 per share | 0 | 3,126,650 | 05 Aug 2025 | See footnote |
* marks a reported price that did not pass the local price check.