MIST · Milestone Pharmaceuticals Inc.

This option will vest in twelve (12) equal monthly installments, beginning on July 10, 2026, provided that the option will in any case be fully vested on the date of next annual meeting of the stockholders of the Issuer, subject to the Reporting Person continuing to provide service through each such vesting date.

This option will vest in twelve (12) equal monthly installments, beginning on July 10, 2026, provided that the option will in any case be fully vested on the date of next annual meeting of the stockholders of the Issuer, subject to the Reporting Person continuing to provide service through each such vesting date.

This option will vest in twelve (12) equal monthly installments, beginning on July 10, 2026, provided that the option will in any case be fully vested on the date of next annual meeting of the stockholders of the Issuer, subject to the Reporting Person continuing to provide service through each such vesting date.

This option will vest in twelve (12) equal monthly installments, beginning on July 10, 2026, provided that the option will in any case be fully vested on the date of next annual meeting of the stockholders of the Issuer, subject to the Reporting Person continuing to provide service through each such vesting date.

This option will vest in twelve (12) equal monthly installments, beginning on July 10, 2026, provided that the option will in any case be fully vested on the date of next annual meeting of the stockholders of the Issuer, subject to the Reporting Person continuing to provide service through each such vesting date.

This option will vest in twelve (12) equal monthly installments, beginning on July 10, 2026, provided that the option will in any case be fully vested on the date of next annual meeting of the stockholders of the Issuer, subject to the Reporting Person continuing to provide service through each such vesting date.

This option will vest in twelve (12) equal monthly installments, beginning on July 10, 2026, provided that the option will in any case be fully vested on the date of next annual meeting of the stockholders of the Issuer, subject to the Reporting Person continuing to provide service through each such vesting date.

This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on September 30, 2025.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $2.25 to $2.28 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold each separate price within the range set forth in this footnote.

The exercise price on the initial filings was incorrectly stated.

One-fourth (1/4th) of the shares subject to the option vest on February 2, 2027, and one thirty-sixth (1/36th) of the remaining shares subject to this option shall vest each month thereafter, subject to the Reporting Person continuing to provide service through each such date.

The exercise price on the initial filings was incorrectly stated.

One-fourth (1/4th) of the shares subject to the option vest on February 2, 2027, and one thirty-sixth (1/36th) of the remaining shares subject to this option shall vest each month thereafter, subject to the Reporting Person continuing to provide service through each such date.

The exercise price on the initial filings was incorrectly stated.

One-fourth (1/4th) of the shares subject to the option vest on February 2, 2027, and one thirty-sixth (1/36th) of the remaining shares subject to this option shall vest each month thereafter, subject to the Reporting Person continuing to provide service through each such date.

The exercise price on the initial filings was incorrectly stated.

One-fourth (1/4th) of the shares subject to the option vest on February 2, 2027, and one thirty-sixth (1/36th) of the remaining shares subject to this option shall vest each month thereafter, subject to the Reporting Person continuing to provide service through each such date.

The exercise price on the initial filings was incorrectly stated.

One-fourth (1/4th) of the shares subject to the option vest on February 2, 2027, and one thirty-sixth (1/36th) of the remaining shares subject to this option shall vest each month thereafter, subject to the Reporting Person continuing to provide service through each such date.

Each RSU represents a contingent right to receive one common share.

Represents shares sold pursuant to a sell-to-cover arrangement for the purpose of satisfying income tax liabilities incurred upon vesting of PSUs or restricted stock unit ("RSU") awards only, respectively.

The price reported is a weighted average price. These shares were sold in multiple transactions. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

Represents shares sold pursuant to a sell-to-cover arrangement for the purpose of satisfying income tax liabilities incurred upon vesting of PSUs or restricted stock unit ("RSU") awards only, respectively.

The price reported is a weighted average price. These shares were sold in multiple transactions. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

Each RSU represents a contingent right to receive one common share.

Each RSU represents a contingent right to receive one common share.

One-fourth (1/4th) of the shares subject to the RSU award vested or will vest on each of January 26, 2026, January 26, 2027, January 26, 2028 and January 26, 2029, subject to the Reporting Person continuing to provide service through each such date.

Each RSU represents a contingent right to receive one common share.

Represents shares sold pursuant to a sell-to-cover arrangement for the purpose of satisfying income tax liabilities incurred upon vesting of PSUs or restricted stock unit ("RSU") awards only, respectively.

The price reported is a weighted average price. These shares were sold in multiple transactions. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

Each RSU represents a contingent right to receive one common share.

One-fourth (1/4th) of the shares subject to the RSU award vested or will vest on each of January 26, 2026, January 26, 2027, January 26, 2028 and January 26, 2029, subject to the Reporting Person continuing to provide service through each such date.

Each RSU represents a contingent right to receive one common share.

One-fourth (1/4th) of the shares subject to the RSU award vested or will vest on each of January 26, 2026, January 26, 2027, January 26, 2028 and January 26, 2029, subject to the Reporting Person continuing to provide service through each such date.

Each RSU represents a contingent right to receive one common share.

One-fourth (1/4th) of the shares subject to the RSU award vested or will vest on each of January 26, 2026, January 26, 2027, January 26, 2028 and January 26, 2029, subject to the Reporting Person continuing to provide service through each such date.

Each RSU represents a contingent right to receive one common share.

Represents shares sold pursuant to a sell-to-cover arrangement for the purpose of satisfying income tax liabilities incurred upon vesting of PSUs or restricted stock unit ("RSU") awards only, respectively.

The price reported is a weighted average price. These shares were sold in multiple transactions. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

Each RSU represents a contingent right to receive one common share.

Each RSU represents a contingent right to receive one common share.

One-fourth (1/4th) of the shares subject to the RSU award vested or will vest on each of January 26, 2026, January 26, 2027, January 26, 2028 and January 26, 2029, subject to the Reporting Person continuing to provide service through each such date.

Represents shares sold pursuant to a sell-to-cover arrangement for the purpose of satisfying income tax liabilities incurred upon vesting of PSUs or restricted stock unit ("RSU") awards only, respectively.

The price reported is a weighted average price. These shares were sold in multiple transactions. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on September 30, 2025.

The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $2.25 to $2.265 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on September 30, 2025.

Represents shares sold pursuant to a sell-to-cover arrangement for the purpose of satisfying income tax liabilities incurred upon vesting of PSUs or restricted stock unit ("RSU") awards only, respectively.

The price reported is a weighted average price. These shares were sold in multiple transactions. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

Represents shares sold pursuant to a sell-to-cover arrangement for the purpose of satisfying income tax liabilities incurred upon vesting of PSUs or restricted stock unit ("RSU") awards only, respectively.

The price reported is a weighted average price. These shares were sold in multiple transactions. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

Represents shares sold pursuant to a sell-to-cover arrangement for the purpose of satisfying income tax liabilities incurred upon vesting of PSUs or restricted stock unit ("RSU") awards only, respectively.

The price reported is a weighted average price. These shares were sold in multiple transactions. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

Represents shares sold pursuant to a sell-to-cover arrangement for the purpose of satisfying income tax liabilities incurred upon vesting of PSUs or restricted stock unit ("RSU") awards only, respectively.

The price reported is a weighted average price. These shares were sold in multiple transactions. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

Represents shares sold pursuant to a sell-to-cover arrangement for the purpose of satisfying income tax liabilities incurred upon vesting of PSUs or restricted stock unit ("RSU") awards only, respectively.

The price reported is a weighted average price. These shares were sold in multiple transactions. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

50% of the option will vest on June 12, 2026 and 50% will vest on December 12, 2026, subject to the Reporting Person continuing to provide service through each such date.

Represents a performance stock unit ("PSU") award that vested upon the certification by the Compensation Committee of the Board of Directors of the Issuer that the U.S. Food and Drug Administration has provided a New Drug Application Approval Letter granting approval of Cardamyst (etripamil).

Each PSU represents a contingent right to receive one common share.

Represents a performance stock unit ("PSU") award that vested upon the certification by the Compensation Committee of the Board of Directors of the Issuer that the U.S. Food and Drug Administration has provided a New Drug Application Approval Letter granting approval of Cardamyst (etripamil).

Each PSU represents a contingent right to receive one common share.

50% of the option will vest on June 12, 2026 and 50% will vest on December 12, 2026, subject to the Reporting Person continuing to provide service through each such date.

Represents a performance stock unit ("PSU") award that vested upon the certification by the Compensation Committee of the Board of Directors of the Issuer that the U.S. Food and Drug Administration has provided a New Drug Application Approval Letter granting approval of Cardamyst (etripamil).

Each PSU represents a contingent right to receive one common share.

50% of the option will vest on June 12, 2026 and 50% will vest on December 12, 2026, subject to the Reporting Person continuing to provide service through each such date.

Represents a performance stock unit ("PSU") award that vested upon the certification by the Compensation Committee of the Board of Directors of the Issuer that the U.S. Food and Drug Administration has provided a New Drug Application Approval Letter granting approval of Cardamyst (etripamil).

Each PSU represents a contingent right to receive one common share.

50% of the option will vest on June 12, 2026 and 50% will vest on December 12, 2026, subject to the Reporting Person continuing to provide service through each such date.

Represents a performance stock unit ("PSU") award that vested upon the certification by the Compensation Committee of the Board of Directors of the Issuer that the U.S. Food and Drug Administration has provided a New Drug Application Approval Letter granting approval of Cardamyst (etripamil).

Each PSU represents a contingent right to receive one common share.

50% of the option will vest on June 12, 2026 and 50% will vest on December 12, 2026, subject to the Reporting Person continuing to provide service through each such date.

Represents a bona fide gift for no consideration to members of the Reporting Person's family outside the Reporting Person's household.

The reported securities are included within 50,000 Issuer Units purchased by the Reporting Person for $1.50 per Unit. Each Unit consists of one common share, one Series A common warrant and one Series B common warrant, each warrant represents the right to purchase 50,000 shares of common stock.

Fully vested and exercisable.

The reported securities are included within 50,000 Issuer Units purchased by the Reporting Person for $1.50 per Unit. Each Unit consists of one common share, one Series A common warrant and one Series B common warrant, each warrant represents the right to purchase 50,000 shares of common stock.

Fully vested and exercisable.

The reported securities are included within 66,666 Issuer Units purchased by the Reporting Person for $1.50 per Unit. Each Unit consists of one common share, one Series A common warrant and one Series B common warrant, each warrant represents the right to purchase 66,666 shares of common stock.

Fully vested and exercisable.

The reported securities are included within 66,666 Issuer Units purchased by the Reporting Person for $1.50 per Unit. Each Unit consists of one common share, one Series A common warrant and one Series B common warrant, each warrant represents the right to purchase 66,666 shares of common stock.

Fully vested and exercisable.