Comparable stake leader
Hanmi Pharmaceutical Co., Ltd.
SEC ownership of Aptose Biosciences Inc.
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0000882361.
Disclosed value leader
Donald R. Wilson Jr.
Comparable rows
3/16
Latest evidence
30 Jun 2026
- Public ticker
- APTOF
- Parsed ownership sources
-
13D/G, 3/4/5, and 13F
Source: Parsed SEC ownership filingsUse: Compare filing families carefully
- Largest SEC-reported holder
-
Hanmi Pharmaceutical Co., Ltd.
Ranking: Comparable ownership first, then disclosed value
- Comparable ownership rows
-
3 of 16
Meaning: Rows with safely comparable ownership %
- Latest 13D/G holder
-
Hanmi Pharmaceutical Co., Ltd.
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
- 0000882361
- Issuer location
- Toronto
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 Aptose Biosciences Inc. (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
Hanmi Pharmaceutical Co.,...
Disclosed value leader
Donald R. Wilson Jr.
Comparable rows
3/16
Latest evidence
30 Jun 2026
13D/G
3/4/5
13F
Lead comparable stake: 20%
13 rows are not safely comparable across share classes.
13D/G row: Hanmi Pharmaceutical Co., Ltd.
Showing 1-8 of 16 holder rows.
Quick read
Hanmi Pharmaceutical Co., Ltd. leads the comparable SEC ownership view at 20%.
3 of 16 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 Hanmi Pharmaceutical Co., Ltd.'s linked filing trail.
Comparable ownership
Top 3
Hanmi Pharmaceutical Co., Ltd.
20%
ARMISTICE CAPITAL, LLC
5%
Bleichroeder LP
1.6%
Ownership % is shown only when SEC disclosures are safely comparable across share classes.
Detailed SEC evidence table Showing 1-8 of 16 holder rows
| Holder | Evidence | Ownership % | Position | 12M Net Δ | As of |
|---|---|---|---|---|---|
| Hanmi Pharmaceutical Co., Ltd. |
13D/G
3/4/5
10%+ Owner
|
20%
|
$115,375
508,710 shares
|
$0 | 18 Mar 2025 |
| ARMISTICE CAPITAL, LLC |
13D/G
|
5%
|
$112,779
1,025,267 shares
|
$0 | 31 Dec 2024 |
| Bleichroeder LP |
13D/G
|
1.6%
|
$4,583
41,666 shares
|
-$13,350 | 30 Jun 2025 |
| Donald R. Wilson Jr. |
3/4/5
10%+ Owner
|
—
class O/S missing
|
$12,885,141
8,892,437 shares
|
— | 03 Aug 2021 |
| DRW Securities, LLC |
13F
Company
|
—
class O/S missing
|
$32,012
19,761 shares
|
— | 30 Jun 2026 |
| Gleason Group, Inc. |
13F
Company
|
—
class O/S missing
|
$6,341
4,206 shares
|
— | 30 Jun 2026 |
| CALDWELL SUTTER CAPITAL, INC. |
13F
Company
|
—
class O/S missing
|
$327
202 shares
|
— | 30 Jun 2026 |
| Farther Finance Advisors, LLC |
13F
Company
|
—
class O/S missing
|
$15
10 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 27 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 1-14 of 14 reporting-owner rows connected to Aptose Biosciences Inc.. Open a relationship link for the CIK-to-CIK filing trail.
Rows
14
Largest Forms 3/4/5 holder
Donald R. Wilson Jr.
Net 12M change
$0
Latest report
30 Jun 2026
| Name | Relationship | Holdings Value | Past Year Net Change | Change % | Valuation | Report Date |
|---|---|---|---|---|---|---|
| Donald R. Wilson Jr. | 10%+ Owner | $12,885,141 | Mixed | 03 Aug 2021 | ||
| Hanmi Pharmaceutical Co., Ltd. | 10%+ Owner | $101,742 | Mixed | 18 Mar 2025 | ||
| Erich Platzer | Former Director | $0 | Mixed | 30 Jun 2026 | ||
| Rafael Bejar | Former SVP&Ch Medical Officer | $0 | Mixed | 30 Jun 2026 | ||
| Bernd R. Seizinger | Former Director | $0 | Mixed | 30 Jun 2026 | ||
| Warren Whitehead | Former Director | $0 | Mixed | 30 Jun 2026 | ||
| Fletcher Payne | Former Svp And Cfo | $0 | Mixed | 30 Jun 2026 | ||
| Mark D. Vincent | Former Director | $0 | Mixed | 30 Jun 2026 | ||
| Denis R. Burger | Former Director | $0 | Mixed | 30 Jun 2026 | ||
| William G. Rice | Chair, President & CEO, Director | $0 | Mixed | 30 Jun 2026 | ||
| Philippe Ledru | Former Officer | Mixed | 23 Feb 2024 | |||
| Carol Gail Ashe | Director | Mixed | 05 Feb 2024 | |||
| Caroline M. Loewy | Former Director | Mixed | 31 May 2022 | |||
| Jotin Marango | Senior VP, CFO, and CBO | Mixed | 18 Jan 2022 |
Recent insider transactions for Aptose Biosciences Inc.
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 |
|---|---|---|---|---|---|---|---|---|---|---|
| Bernd R. Seizinger | APTOF | Common Shares | Disposed to Issuer | -100% | -17,000 | 0 | 30 Jun 2026 | Direct | ||
| Bernd R. Seizinger | APTOF | Stock Option (right to buy) | Disposed to Issuer | -100% | -150,000 | 0 | 30 Jun 2026 | Direct | ||
| Bernd R. Seizinger | APTOF | Director Stock Option (Right to Buy) | Disposed to Issuer | -100% | -3,333 | 0 | 30 Jun 2026 | Direct | ||
| Warren Whitehead | APTOF | Common Shares | Disposed to Issuer | -100% | -33 | 0 | 30 Jun 2026 | Direct | ||
| Warren Whitehead | APTOF | Stock Options (Right to Buy) | Disposed to Issuer | -100% | -40,000 | 0 | 30 Jun 2026 | Direct | ||
| Warren Whitehead | APTOF | Director Option Grant | Disposed to Issuer | -100% | -302,500 | 0 | 30 Jun 2026 | Direct | ||
| Warren Whitehead | APTOF | Director Stock Option (Right to Buy) | Disposed to Issuer | -100% | -106,333 | 0 | 30 Jun 2026 | Direct | ||
| Mark D. Vincent | APTOF | Stock Options (Right to Buy) | Disposed to Issuer | -100% | -40,000 | 0 | 30 Jun 2026 | Direct | ||
| Mark D. Vincent | APTOF | Director Option Grant | Disposed to Issuer | -100% | -204,000 | 0 | 30 Jun 2026 | Direct | ||
| Mark D. Vincent | APTOF | Director Stock Option (Right to Buy) | Disposed to Issuer | -100% | -228,333 | 0 | 30 Jun 2026 | Direct | ||
| William G. Rice | APTOF | Common Shares | Disposed to Issuer | -100% | -613,252 | 0 | 30 Jun 2026 | Direct | ||
| William G. Rice | APTOF | Common Shares | Disposed to Issuer | -100% | -400,000 | 0 | 30 Jun 2026 | Direct | ||
| William G. Rice | APTOF | Stock Options (Right to Buy) | Disposed to Issuer | -100% | -400,000 | 0 | 30 Jun 2026 | Direct | ||
| William G. Rice | APTOF | Employee Option Grant | Disposed to Issuer | -100% | -2,700,000 | 0 | 30 Jun 2026 | Direct | ||
| William G. Rice | APTOF | Performance Stock Options | Disposed to Issuer | -100% | -600,000 | 0 | 30 Jun 2026 | Direct | ||
| William G. Rice | APTOF | Warrants | Disposed to Issuer | -100% | -50,000 | 0 | 30 Jun 2026 | Direct | ||
| William G. Rice | APTOF | Employee Stock Option (Right to Buy) | Disposed to Issuer | -100% | -1,263,000 | 0 | 30 Jun 2026 | Direct | ||
| Erich Platzer | APTOF | Common Shares | Disposed to Issuer | -100% | -1,122 | 0 | 30 Jun 2026 | Direct | ||
| Erich Platzer | APTOF | Director Stock Option | Disposed to Issuer | -100% | -10,000 | 0 | 30 Jun 2026 | Direct | ||
| Erich Platzer | APTOF | Stock Options (Right to Buy) | Disposed to Issuer | -100% | -40,000 | 0 | 30 Jun 2026 | Direct | ||
| Erich Platzer | APTOF | Director Option Grant | Disposed to Issuer | -100% | -185,000 | 0 | 30 Jun 2026 | Direct | ||
| Erich Platzer | APTOF | Director Stock Option (Right to Buy) | Disposed to Issuer | -100% | -218,333 | 0 | 30 Jun 2026 | Direct | ||
| Fletcher Payne | APTOF | Common Shares | Disposed to Issuer | -100% | -22 | 0 | 30 Jun 2026 | Fletcher Payne 2019 Trust | ||
| Fletcher Payne | APTOF | Common Shares | Disposed to Issuer | -100% | -222 | 0 | 30 Jun 2026 | Direct | ||
| Fletcher Payne | APTOF | Common Stock (Option) | Disposed to Issuer | -100% | -1,000,000 | 0 | 30 Jun 2026 | Direct | ||
| Fletcher Payne | APTOF | Employee Stock Option (Right to Buy) | Disposed to Issuer | -100% | -255,000 | 0 | 30 Jun 2026 | Direct | ||
| Denis R. Burger | APTOF | Common Shares | Disposed to Issuer | -100% | -70 | 0 | 30 Jun 2026 | Direct | ||
| Denis R. Burger | APTOF | Stock Options (Right to Buy) | Disposed to Issuer | -100% | -40,000 | 0 | 30 Jun 2026 | Direct | ||
| Denis R. Burger | APTOF | Director Stock Option (Right to Buy) | Disposed to Issuer | -100% | -388,667 | 0 | 30 Jun 2026 | Direct | ||
| Rafael Bejar | APTOF | Common Shares | Disposed to Issuer | -100% | -244 | 0 | 30 Jun 2026 | Direct | ||
| Rafael Bejar | APTOF | Employee Option Grant | Disposed to Issuer | -100% | -200,000 | 0 | 30 Jun 2026 | Direct | ||
| Rafael Bejar | APTOF | Performance Stock Option | Disposed to Issuer | -100% | -400,000 | 0 | 30 Jun 2026 | Direct | ||
| Rafael Bejar | APTOF | Employee Stock Option | Disposed to Issuer | -100% | -200,000 | 0 | 30 Jun 2026 | Direct | ||
| Rafael Bejar | APTOF | Employee Stock Option (Right to Buy) | Disposed to Issuer | -100% | -778,000 | 0 | 30 Jun 2026 | Direct | ||
| Mark D. Vincent | APTOF | Common Shares | Disposed to Issuer | -100% | -14 | 0 | 13 Jun 2026 | Direct |
* marks a reported price that did not pass the local price check.