Erich Platzer - 30 Jun 2026 Form 4 Insider Report for Aptose Biosciences Inc. (APTOF)

Reporting relationship: FORMER DIRECTOR
Issuer ticker: APTOF
Reported as of: 30 Jun 2026
Net transaction value: $0
SEC form: 4
Accepted by SEC: 01 Jul 2026, 16:55:06 UTC
Prior SEC filing: 07 Feb 2024
Source filing: View source filing
Reporting owner signature: /s/ Erich Platzer

Key filing fact

Erich Platzer filed Form 4 for Aptose Biosciences Inc. (APTOF) on 01 Jul 2026.

Key facts

This page summarizes Erich Platzer's Form 4 filing for Aptose Biosciences Inc. (APTOF).
10 reported transactions and 9 derivative rows are listed below.
Accepted by SEC: 01 Jul 2026, 16:55.

Change

Previous filing in this sequence was filed on 07 Feb 2024.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001275087 Primary reporting owner

PLATZER ERICH

Relationship: FORMER DIRECTOR
Address: C/O APTOSE BIOSCIENCES INC, 251 CONSUMERS ROAD, SUITE 1105, TORONTO, ONTARIO, CANADA
Signature: /s/ Erich Platzer
Signature date: 01 Jul 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

APTOF transaction

Common Shares

Disposed to Issuer

Transaction value
Shares: -1,122
Change %: -100%
Price: $1.72^*
Shares after: 0
Date: 30 Jun 2026
Ownership: Direct
Footnotes: F1, F2

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

APTOF transaction Derivative

Director Stock Option (Right to Buy)

Disposed to Issuer

Transaction value
Shares: -3,333
Change %: -100%
Price: $0.000000^*
Shares after: 0
Date: 30 Jun 2026
Ownership: Direct
Underlying class: Common Shares
Underlying amount: 3,333
Exercise price: $2.00
Footnotes: F1, F3

APTOF transaction Derivative

Director Stock Option (Right to Buy)

Disposed to Issuer

Transaction value
Shares: -100,000
Change %: -100%
Price: $0.000000^*
Shares after: 0
Date: 30 Jun 2026
Ownership: Direct
Underlying class: Common Shares
Underlying amount: 100,000
Exercise price: $0.6600
Footnotes: F1, F3

APTOF transaction Derivative

Director Stock Option (Right to Buy)

Disposed to Issuer

Transaction value
Shares: -50,000
Change %: -100%
Price: $0.000000^*
Shares after: 0
Date: 30 Jun 2026
Ownership: Direct
Underlying class: Common Shares
Underlying amount: 50,000
Exercise price: $1.34
Footnotes: F1, F3

APTOF transaction Derivative

Director Option Grant

Disposed to Issuer

Transaction value
Shares: -50,000
Change %: -100%
Price: $0.000000^*
Shares after: 0
Date: 30 Jun 2026
Ownership: Direct
Underlying class: Common Shares
Underlying amount: 50,000
Exercise price: $7.08
Footnotes: F1, F3

APTOF transaction Derivative

Director Option Grant

Disposed to Issuer

Transaction value
Shares: -135,000
Change %: -100%
Price: $0.000000^*
Shares after: 0
Date: 30 Jun 2026
Ownership: Direct
Underlying class: Common Shares
Underlying amount: 135,000
Exercise price: $6.91
Footnotes: F1, F3

APTOF transaction Derivative

Stock Options (Right to Buy)

Disposed to Issuer

Transaction value
Shares: -40,000
Change %: -100%
Price: $0.000000^*
Shares after: 0
Date: 30 Jun 2026
Ownership: Direct
Underlying class: Common Shares
Underlying amount: 40,000
Exercise price: $1.91
Footnotes: F1, F3

APTOF transaction Derivative

Director Stock Option

Disposed to Issuer

Transaction value
Shares: -10,000
Change %: -100%
Price: $0.000000^*
Shares after: 0
Date: 30 Jun 2026
Ownership: Direct
Underlying class: Common Shares
Underlying amount: 10,000
Exercise price: $1.14
Footnotes: F1, F3

APTOF transaction Derivative

Director Stock Option (Right to Buy)

Disposed to Issuer

Transaction value
Shares: -5,000
Change %: -100%
Price: $0.000000^*
Shares after: 0
Date: 30 Jun 2026
Ownership: Direct
Underlying class: Common Shares
Underlying amount: 5,000
Exercise price: $1.03
Footnotes: F1, F3

APTOF transaction Derivative

Director Stock Option (Right to Buy)

Disposed to Issuer

Transaction value
Shares: -60,000
Change %: -100%
Price: $0.000000^*
Shares after: 0
Date: 30 Jun 2026
Ownership: Direct
Underlying class: Common Shares
Underlying amount: 60,000
Exercise price: $2.80
Footnotes: F1, F3

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Section 16 status

Erich Platzer is no longer subject to Section 16 filing requirements. Form 4 or Form 5 obligations may still apply in specific circumstances.

Explanation of responses 3 footnotes

Footnote F1

Disposed of pursuant to a board, shareholder and court-approved business arrangement agreement between the Issuer and Hammi Pharmaceuticals Co. Ltd., a South Korean corporation ("Hammi") whereby a subsidiary of Hammi acquired all outstanding shares of the Issuer at a price of C$2.41 per share.

Footnote F2

Converted from Canadian price of C$2.41 per share using an exchange rate of C$1.4 = US$1.00.

Footnote F3

Options vest 50% on the first anniversary of grant date; remaining options vest 1/3 annually beginning on the second anniversary of the grant date.

SEC remarks

TOTAL OPTIONS AND OPTION EXERCISE PRICE SUBJECT TO ADJUSTMENT AS A RESULT OF THE ISSUER'S 1:30 REVERSE STOCK SPLIT ON 2/25/25 AND 1:15 REVERSE STOCK SPLIT ON 6/6/2023