Former Aptose Biosciences (OTC: APTOF) director relinquishes shares in Hammi acquisition

Rhea-AI Filing Summary

Aptose Biosciences Inc. former director Erich Platzer reported the disposition of all his remaining equity interests in connection with the company’s acquisition by Hammi Pharmaceuticals Co. Ltd. On June 30, 2026, he returned 1,122 Common Shares to the issuer at $1.72 per share, reflecting the converted Canadian acquisition price.

On the same date, Platzer also disposed of multiple director and stock option grants covering underlying Common Shares, all as “Disposition to issuer” transactions tied to the Hammi business arrangement agreement under which a Hammi subsidiary acquired all outstanding Aptose shares at C$2.41 per share. Following these transactions, the filing shows no remaining Aptose common shares or option positions for Platzer.

Insights

Equity compensation analyst

All Aptose equity held by a former director was canceled in a cash acquisition.

The filing shows former director Erich Platzer disposing of his remaining Aptose equity on June 30, 2026. He returned 1,122 Common Shares at $1.72 per share and surrendered several director stock option grants, each marked as a Disposition to issuer.

Footnotes state these actions occurred under a board, shareholder and court‑approved business arrangement in which a Hammi Pharmaceuticals subsidiary acquired all outstanding Aptose shares at C$2.41 per share. With total_shares_following_transaction reported as zero for each line and no remaining derivative positions, this appears to be a mechanical clean‑up of holdings following the closing of the Hammi deal, rather than discretionary trading activity.

Insider Trade Summary

11 transactions reported

Mixed 11 txns

Insider PLATZER ERICH

Role null

Type	Security	Shares	Price	Value
Disposition	Director Stock Option (Right to Buy)	3,333	$0.00	--
Disposition	Director Stock Option (Right to Buy)	100,000	$0.00	--
Disposition	Director Stock Option (Right to Buy)	50,000	$0.00	--
Disposition	Director Stock Option (Right to Buy)	50,000	$0.00	--
Disposition	Director Option Grant	50,000	$0.00	--
Disposition	Director Option Grant	135,000	$0.00	--
Disposition	Stock Options (Right to Buy)	40,000	$0.00	--
Disposition	Director Stock Option	10,000	$0.00	--
Disposition	Director Stock Option (Right to Buy)	5,000	$0.00	--
Disposition	Director Stock Option (Right to Buy)	60,000	$0.00	--
Disposition	Common Shares	1,122	$1.72	$2K

Holdings After Transaction: Director Stock Option (Right to Buy) — 0 shares (Direct, null); Director Option Grant — 0 shares (Direct, null); Stock Options (Right to Buy) — 0 shares (Direct, null); Director Stock Option — 0 shares (Direct, null); Common Shares — 0 shares (Direct, null)

Footnotes (1)

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

Key Figures

Common Shares disposed: 1,122 shares at $1.72 Acquisition price: C$2.41 per share Option grant disposed: 60,000 options at $2.80 +3 more

6 metrics

Common Shares disposed 1,122 shares at $1.72 Disposition to issuer on June 30, 2026

Acquisition price C$2.41 per share Hammi subsidiary acquisition of all outstanding Aptose shares

Option grant disposed 60,000 options at $2.80 Director Stock Option (Right to Buy), expires January 19, 2028

Large option grant disposed 135,000 options at $6.91 Director Option Grant, expires January 30, 2030

Low‑strike option grant disposed 100,000 options at $0.66 Director Stock Option (Right to Buy), expires January 19, 2033

Exchange rate used C$1.4 = US$1.00 Conversion of C$2.41 per share to approximately $1.72

Key Terms

business arrangement agreement, Disposition to issuer, Director Stock Option (Right to Buy), exchange rate

4 terms

business arrangement agreement regulatory

"Disposed of pursuant to a board, shareholder and court‑approved business arrangement agreement between the Issuer and Hammi Pharmaceuticals Co. Ltd."

Disposition to issuer regulatory

"Each transaction is coded with the description "Disposition to issuer" for the reported shares and options."

Director Stock Option (Right to Buy) financial

"Several derivative entries are labeled as "Director Stock Option (Right to Buy)" with underlying Common Shares."

exchange rate financial

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

Exchange rate is the price of one currency expressed in another—for example, how many euros you receive for one US dollar. It matters to investors because changes in that price alter the reported profits, costs and value of assets for companies and portfolios that operate or hold money across borders; think of it like switching measurement units, where the same item can look bigger or smaller depending on the unit used.

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 07/01/2026 - 04:55 PM Accepted by SEC EDGAR 07/01/2026 - 04:55 PM 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^*

PLATZER ERICH

(Last) (First) (Middle)

C/O APTOSE BIOSCIENCES INC

251 CONSUMERS ROAD, SUITE 1105

(Street)

TORONTO M2J 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)		1,122	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
Director 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
Director Stock Option (Right to Buy)	$1.34	06/30/2026		D(1)			50,000	(3)	01/17/2032	Common Shares	50,000	$0	0	D
Director Stock Option (Right to Buy)	$4.37	06/30/2026		D(1)			50,000	(3)	01/04/2031	Common Shares	50,000	$0	0	D
Director Option Grant	$7.08	06/30/2026		D(1)			50,000	(3)	03/10/2030	Common Shares	50,000	$0	0	D
Director Option Grant	$6.91	06/30/2026		D(1)			135,000	(3)	01/30/2030	Common Shares	135,000	$0	0	D
Stock Options (Right to Buy)	$1.91	06/30/2026		D(1)			40,000	(3)	01/02/2029	Common Shares	40,000	$0	0	D
Director Stock Option	$1.14	06/30/2026		D(1)			10,000	(3)	03/28/2027	Common Shares	10,000	$0	0	D
Director Stock Option (Right to Buy)	$1.03	06/30/2026		D(1)			5,000	(3)	06/06/2027	Common Shares	5,000	$0	0	D
Director Stock Option (Right to Buy)	$2.8	06/30/2026		D(1)			60,000	(3)	01/19/2028	Common Shares	60,000	$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 the first anniversary of grant date; remaining options vest 1/3 annually beginning on the 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 2/25/25 AND 1:15 REVERSE STOCK SPLIT ON 6/6/2023

	/s/ Erich Platzer	07/01/2026
	** 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)

FAQ

What did former director Erich Platzer report in this Aptose (APTOF) Form 4?

Erich Platzer reported disposing of all his remaining Aptose equity. He returned 1,122 Common Shares and surrendered multiple director stock options back to the issuer as part of a completed acquisition by Hammi Pharmaceuticals at C$2.41 per share.

How many Aptose Biosciences shares did Erich Platzer dispose of and at what price?

Platzer disposed of 1,122 Common Shares at approximately $1.72 per share. The price reflects the Canadian acquisition consideration of C$2.41 per share, converted using an exchange rate of C$1.4 to US$1.00, as described in the filing’s footnotes.

What happened to Erich Platzer’s Aptose director stock options in this filing?

Platzer surrendered several director and stock option grants covering underlying Common Shares. Each option transaction is coded as a “Disposition to issuer,” and the Form 4 reports zero total derivative securities remaining after these transactions, indicating his Aptose option positions were fully canceled.

Why were Erich Platzer’s Aptose shares and options disposed of to the issuer?

The disposition occurred under a board, shareholder and court‑approved business arrangement between Aptose and Hammi Pharmaceuticals. A Hammi subsidiary acquired all outstanding Aptose shares at C$2.41 per share, and Platzer’s shares and options were surrendered to the issuer in connection with that transaction.

Does Erich Platzer hold any Aptose Biosciences shares or options after these transactions?

According to the Form 4, Platzer’s total shares following each reported transaction are zero, and no remaining derivative positions are listed. This indicates he no longer holds Aptose Common Shares or director stock options following completion of the Hammi Pharmaceuticals acquisition.

Is this Aptose (APTOF) Form 4 a market sale or part of the Hammi acquisition?

The transactions are coded as “Disposition to issuer,” not open‑market sales. Footnotes explain they were executed under a business arrangement where a Hammi Pharmaceuticals subsidiary acquired all outstanding Aptose shares, so these entries reflect deal‑related cancellations rather than discretionary trading.