Every Form 4 that APTOSE BIOSCIENCES INC (APTOF) has filed with the SEC in the last 12 months is listed below, newest first, and each one links through to the document itself with the summary and the scores our analysis gives it.
A Form 4 covers the transactions officers, directors and large holders report, so if you follow APTOF and want that one kind of document rather than the whole filing history, this is the page to keep. The company's other filings, of every form, are on the full APTOF filings page.
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.
Former Aptose Biosciences director Warren Whitehead disposed of all his remaining interests in the company on June 30, 2026 as part of a business arrangement under which Hammi Pharmaceuticals acquired all outstanding Aptose shares. He returned 33 common shares at about $1.72 per share and multiple director stock options to the issuer, leaving him with no direct Aptose shares or options after the transactions.
Aptose Biosciences Inc. former director Vincent Mark D. reported multiple dispositions to the issuer of stock options and a small number of common shares. These transactions reflect cancellation of option awards and 14 common shares in connection with a business arrangement where a Hammi Pharmaceuticals Co. Ltd. subsidiary acquired all outstanding Aptose shares at C$2.41 per share. Following these dispositions, the filing shows no remaining direct holdings or derivative positions for this former director.
Aptose Biosciences Inc.’s Chair, President & CEO William G. Rice disposed of his equity holdings in connection with the company’s acquisition by Hammi Pharmaceuticals. He transferred 613,252 Common Shares at $1.72 per share, reflecting a Canadian price of C$2.41 converted at C$1.4 = US$1.00.
Rice also disposed of multiple stock option and warrant positions to the issuer on the same date, including large employee option grants and performance stock options with exercise prices ranging from $0.25 to $6.91 per share. Following these transactions, the filing shows zero shares and zero listed derivative awards remaining in his direct ownership, consistent with all outstanding shares of Aptose being acquired under a board, shareholder and court‑approved business arrangement with Hammi.
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.
Aptose Biosciences Inc. former SVP and CFO Fletcher Payne reported dispositions of all his equity interests in connection with the company’s acquisition by a subsidiary of Hammi Pharmaceuticals Co. Inc. A trust associated with Payne disposed of 22 common shares, and he disposed of 222 directly held common shares, each at approximately $1.72 per share, converted from C$2.41 using an exchange rate of C$1.4 = US$1.00. He also surrendered 1,000,000 stock options with a $0.8479 exercise price, 200,000 options at $0.66, and 55,000 options at $2.00 per share, all as dispositions to the issuer. Following these transactions, the filing shows zero common shares and zero options remaining in Payne’s reported holdings.
Aptose Biosciences Inc. former director Denis R. Burger reported the disposition of his remaining stake in connection with the company’s acquisition by Hammi Pharmaceuticals Co. Ltd.
On June 30, 2026, he disposed of 70 Common Shares at $1.72 per share, reflecting a Canadian purchase price of C$2.41 converted using an exchange rate of C$1.4 = US$1.00.
Burger also disposed of multiple stock option grants, including director stock options with exercise prices such as $1.14, $2.80, and $6.91 per share, with expirations running through 2034. After these issuer-directed dispositions, his reported holdings of Aptose common shares and related options were zero.
Aptose Biosciences Inc. former SVP and Chief Medical Officer Rafael Bejar reported the disposition of his remaining equity stake in connection with a completed acquisition of Aptose by Hammi Pharmaceuticals Co. Inc. A subsidiary of Hammi acquired all outstanding Aptose shares at C$2.41 per share, which the filing converts using an exchange rate of C$1.4 = US$1.00, consistent with a reported common share price of about $1.72 per share.
Bejar disposed of 244 common shares at $1.72 per share and multiple employee and performance stock option awards, each recorded as a Disposition to issuer. After these transactions, the filing shows he holds 0 common shares and no remaining stock options, fully exiting his reported ownership position following the transaction.