Former Aptose Biosciences (APTOF) director exits in Hammi acquisition

Rhea-AI Filing Summary

Aptose Biosciences Inc. former director Bernd R. Seizinger reported disposing of his remaining stake in connection with the company’s sale to Hammi Pharmaceuticals Co. Ltd.

On June 30, 2026, he transferred 17,000 Common Shares at about $1.72 per share (the U.S. equivalent of C$2.41) and surrendered an additional 153,333 stock options with exercise prices of $0.74, $0.66 and $2.00 per share back to the issuer. These actions occurred under a board, shareholder and court-approved business arrangement in which a Hammi subsidiary acquired all outstanding Aptose shares at C$2.41 per share. Following these transactions, Seizinger holds no Aptose common shares or options.

Insights

Biotech equity analyst

Form 4 shows a clean director exit as Aptose is acquired at a fixed cash price.

The filing details how former director Bernd R. Seizinger disposed of all his Aptose Biosciences holdings when a Hammi Pharmaceuticals subsidiary acquired every outstanding share at C$2.41 per share. His 17,000 common shares were valued around $1.72 each using a stated exchange rate.

He also surrendered 153,333 stock options with exercise prices between $0.66 and $2.00, ending with zero common shares and zero options. The transaction reflects the completion of a board, shareholder and court-approved business arrangement, rather than discretionary open-market trading by the insider.

Insider Trade Summary

Net Seller: 17,000 shares

Net Sell 4 txns

Insider Seizinger Bernd R.

Role Insider

Type	Security	Shares	Price	Value
Disposition	Director Stock Option (Right to Buy)	3,333	$0.00	$0.00
Disposition	Stock Option (right to buy)	100,000	$0.00	$0.00
Disposition	Stock Option (right to buy)	50,000	$0.00	$0.00
Disposition	Common Shares	17,000	$1.72	$29K

Holdings After Transaction: Director Stock Option (Right to Buy) — 0 shares (Direct); Stock Option (right to buy) — 0 shares (Direct); Common Shares — 0 shares (Direct)

Footnotes (3)

1. 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.
2. F2. Converted from Canadian price of C$2.41 per share using an exchange rate of C$1.4 = US$1.00.
3. F3. Options vest 50% on first anniversary of grant date; remaining options vest 1/3 annually beginning on second anniversary of the grant date.

Key Figures

Common shares disposed: 17,000 shares Share acquisition price: C$2.41 per share U.S. dollar equivalent: $1.72 per share +5 more

8 metrics

Common shares disposed 17,000 shares Common Shares transferred to issuer on June 30, 2026

Share acquisition price C$2.41 per share Cash consideration paid by Hammi subsidiary for all outstanding shares

U.S. dollar equivalent $1.72 per share Converted from C$2.41 using C$1.4 = US$1.00

Options disposed 153,333 options Total stock options surrendered back to issuer

Option exercise price $0.74 per share Exercise price for 50,000 stock options

Option exercise price $0.66 per share Exercise price for 100,000 stock options

Director option exercise price $2.00 per share Exercise price for 3,333 Director Stock Options

Exchange rate used C$1.4 = US$1.00 Rate used to convert C$2.41 into approximately $1.72

Key Terms

Disposition to issuer, business arrangement agreement, Stock Option (right to buy), Director Stock Option (Right to Buy), +1 more

5 terms

Disposition to issuer financial

"transaction_code_description: Disposition to issuer"

business arrangement agreement financial

"Disposed of pursuant to a board, shareholder and court-approved business arrangement agreement"

Stock Option (right to buy) financial

"security_title: Stock Option (right to buy)"

Director Stock Option (Right to Buy) financial

"security_title: Director Stock Option (Right to Buy)"

vest 50% on first anniversary financial

"Options vest 50% on first anniversary of grant date"

FAQ

What insider transaction did former Aptose Biosciences (APTOF) director Bernd R. Seizinger report?

He reported disposing of all his Aptose Biosciences holdings. This included 17,000 Common Shares and 153,333 stock options, all transferred back to the issuer as part of a business arrangement when a Hammi subsidiary acquired all outstanding Aptose shares.

At what price were Aptose Biosciences shares acquired in the Hammi transaction?

All outstanding Aptose Biosciences shares were acquired at C$2.41 per share. The Form 4 notes this Canadian price and references an exchange rate, translating to approximately $1.72 per share for Seizinger’s 17,000 disposed Common Shares.

How many Aptose Biosciences shares did Bernd R. Seizinger dispose of in the Form 4?

He disposed of 17,000 Common Shares of Aptose Biosciences. These shares were transferred back to the issuer at an implied U.S. price of about $1.72 per share, based on the C$2.41 per share cash consideration in the Hammi acquisition.

What happened to Bernd R. Seizinger’s Aptose Biosciences stock options?

He surrendered stock options covering 153,333 Aptose common shares. These included options with exercise prices of $0.74, $0.66, and $2.00 per share, all disposed of back to the issuer in connection with the Hammi acquisition transaction.

Does Bernd R. Seizinger still hold any Aptose Biosciences (APTOF) securities after this Form 4?

According to the Form 4 data, he holds no Aptose securities after the transactions. Post-transaction share and option balances are shown as zero, indicating his complete exit from both Common Shares and stock options upon closing of the Hammi business arrangement.

What agreement linked Seizinger’s Aptose Biosciences Form 4 transactions to Hammi Pharmaceuticals?

The dispositions occurred under a board, shareholder and court-approved business arrangement agreement between Aptose and Hammi Pharmaceuticals Co. Ltd. A Hammi subsidiary acquired all outstanding Aptose shares at C$2.41 per share, triggering the reported share and option disposals.

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 07/02/2026 - 11:02 AM Accepted by SEC EDGAR 07/02/2026 - 11:01 AM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

X

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Seizinger Bernd R.

(Last) (First) (Middle)

C/O APTOSE BIOSCIENCES INC.

251 CONSUMERS ROAD, SUITE 1105

(Street)

TORONTO M5J 4R3

(City) (State) (Zip)

ONTARIO, CANADA

(Country)

2. Issuer Name and Ticker or Trading Symbol
Aptose Biosciences Inc. [ APTO ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
	Officer (give title below)	X	Other (specify below)
			FORMER DIRECTOR

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/30/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Shares	06/30/2026		D(1)		17,000	D	$1.72(2)	0	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Director Stock Option (Right to Buy)	$2	06/30/2026		D(1)			3,333	(3)	02/05/2034	Common Shares	3,333	$0	0	D
Stock Option (right to buy)	$0.66	06/30/2026		D(1)			100,000	(3)	01/19/2033	Common Shares	100,000	$0	0	D
Stock Option (right to buy)	$0.74	06/30/2026		D(1)			50,000	(3)	09/14/2032	Common Shares	50,000	$0	0	D

Explanation of Responses:

1. 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.

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

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

Remarks:

TOTAL OPTIONS AND OPTION EXERCISE PRICE SUBJECT TO ADJUSTMENT AS A RESULT OF THE ISSUER'S 1:30 REVERSE STOCK SPLIT ON 2/26/2025 AND 1:15 REVERSE STOCK SPLIT ON 6/6/2023.

	/s/ Bernd R. Seizinger	07/02/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)