Milestone Pharmaceuticals Inc.

Rule 10b5-1 Trading Arrangements

None of our directors or executive officers (as defined in Rule 16a-1(f) under the Exchange Act) adopted, modified orterminated a “Rule 10b5-1 trading arrangement” or “non-Rule-10b5-1 trading arrangement,” aseach term isdefined in Item 408(a) of Regulation S-K, during the three months ended March 31, 2026.

Controlled Equity Offering

On May 13, 2026, we entered into a Controlled Equity Offering SM Sales Agreement, or the "Sales Agreement," with Cantor Fitzgerald & Co., as sales agent, or the "Sales Agent," pursuant to which we may, from time to time, sell common shares, without par value per share, through the Sales Agent, or the “ATM Offering”. We are not obligated to, and cannot provide any assurances that we will make any sales of our shares under the Sales Agreement.

Upon delivery of a placement notice and subject to the terms and conditions of the Sales Agreement, the Sales Agent may sell the shares by methods deemed to be an "at-the-market" offering as defined in Rule 415(a)(4) promulgated under the Securities Act. Subject to the terms and conditions of the Sales Agreement, the Sales Agent will use commercially reasonable efforts consistent with its normal trading and sales practices to sell the shares from time to time, based upon our instructions. The Sales Agreement contains customary representations, warranties and agreements, indemnification rights and obligations of the parties. We will pay the Sales Agent a commission for its services as Sales Agent of 3.0% of the aggregate gross proceeds from each sale of the common shares sold through the Sales Agent pursuant to the Sales Agreement.

The common shares being offered pursuant to the Sales Agreement will be offered and sold pursuant to a shelf registration statement on Form S-3 and prospectus relating to the ATM Offering that we will file with the SEC.

The offering of shares pursuant to the Sales Agreement will terminate upon the termination of the Sales Agreement in accordance with its terms.

The foregoing description of the Sales Agreement is not complete and is qualified in its entirety by reference to the full text of the Sales Agreement, a copy of which is filed as Exhibit 10.3 to this Quarterly Report on Form 10-Q.