On May 23, 2023, during the Aptose Annual and Special Meeting of Shareholders, our shareholders voted to approve special resolutions providing for an amendment to our articles of incorporation to effect a reverse share split of our outstanding Common Shares at a ratio in the range of 1-for-10 to 1-for-20. Our Board of Directors then approved a ratio of 1-for-15 on May 23, 2023. On May 24, 2023, we filed articles of amendment under the Canada Business Corporations Act to give effect to the Reverse Stock Split. The Common Shares commenced trading on a post-Reverse Stock Split basis at market open on Tuesday, June 6, 2023. All references in this report to historical Common Share prices, numbers of Common Shares, and earnings per share calculations have been presented to reflect the effect of the Reverse Stock Split.

The Company has authorized share capital of an unlimited number of common voting shares.

(i) 2023 Committed Equity Facility ("Keystone Purchase Agreement")

On May 25, 2023, the Company and Keystone Capital Partners, LLC ("Keystone") entered into a committed equity facility, (the "Keystone Purchase Agreement"), which provides that subject to the terms and conditions set forth therein, we may sell to Keystone up to the lesser of (i) $25.0 million of the Common Shares and (ii) a number of Common Shares equal to 19.99% of the Common Shares outstanding immediately prior to the execution of the Keystone Purchase Agreement (subject to certain exceptions provided in the Purchase Agreement) (the “Total Commitment”), from time to time during the 24-month term of the Keystone Purchase Agreement. Additionally, on May 25, 2023, we entered into a Registration Rights Agreement with Keystone, pursuant to which the Company agreed to file a registration statement with the SEC covering the resale of Common Shares that are issued to Keystone under the Keystone Purchase Agreement. This registration statement became effective on June 30, 2023, and we commenced the Keystone Facility on July 10, 2023 (the “Commencement Date”)

Upon entering into the Keystone Purchase Agreement, the Company agreed to issue to Keystone an aggregate of 25,156 Common Shares (the “Commitment Shares”) as consideration for Keystone’s commitment to purchase Common Shares upon the Company’s direction under the Keystone Purchase Agreement. The Company issued 7,547 Common Shares, or

30% of the Commitment Shares, on the date of the Purchase Agreement (the “Initial Commitment Shares”). An additional 7,547 Common Shares, or 30% of the Commitment Shares, shall be issued to Keystone 90 days following the Commencement Date (the “First Back-End Commitment Shares”). The remaining 10,062 Common Shares, or 40% of the Commitment Shares, shall be issued to Keystone 180 days following the Commencement Date (the “Second Back-End Commitment Shares”, together with the First Back-End Commitment Shares, the “Back-End Commitment Shares”).

In the six months ended June 30, 2023, the Company's issuance of shares to Keystone was limited to the Initial Commitment Shares.

(ii) 2022 At-The-Market ("ATM") Facility

On December 9, 2022, the Company entered into an equity distribution agreement with Jones Trading acting as the agent under which the Company may, from time to time, sell Common Shares having an aggregate offering value of up to $50 million through Jones Trading on Nasdaq (the "2022 ATM Facility"). During the year ended December 31, 2022, the Company issued 4,836 shares under this 2022 ATM Facility at an average price of $10.81 for gross proceeds of $52 thousand ($51 thousand net of share issuance costs). During the six months ended June 30, 2023, the Company issued 171,253 shares under this 2022 ATM Facility at an average price of $6.88 for gross proceeds of $1.2 million ($1.1 million net of share issuance costs). Costs associated with the proceeds consisted of 3% cash commission.

(iii) 2020 At-The-Market Facility

On May 5, 2020, the Company entered an “at-the-market” equity distribution agreement with Piper Sandler & Co. (“Piper Sandler”) and Canaccord Genuity LLC (“Canaccord Genuity”) acting as co-agents (the “2020 ATM Facility”). Under the terms of the 2020 ATM Facility, the Company could, from time to time, sell Common Shares having an aggregate offering value of up to $75 million through Piper Sandler and Canaccord Genuity on Nasdaq. During the six months ended June 30, 2022, the Company issued 1,869 shares under the 2020 ATM Facility at an average price of $15.90 for gross proceeds of $30 thousand ($29 thousand net of share issue costs). During the year ended December 31, 2022, the Company issued 3,646 shares under the 2020 ATM Facility at an average price of $14.25 for gross proceeds of $52 thousand ($50 thousand net of share issue costs). As of October 31, 2022, the date the Agreement was terminated, the Company had raised a total of $89 thousand gross proceeds ($86 thousand net of share issuance costs) under the 2020 ATM Facility. Costs associated with the proceeds consisted of a 3% cash commission.

The effects of any potential exercise of the Company’s stock options outstanding during the three-month and six-month periods ended June 30, 2023, and June 30, 2022 have been excluded from the calculation of diluted loss per common share, since such securities would be anti‑dilutive.