RTW Investments and Roderick Wong reported beneficial ownership of 12,356,953 common shares of Milestone Pharmaceuticals, representing 9.99% of the class. The cover pages assume exercise of warrants to purchase 6,025,952 shares subject to a 9.99% beneficial ownership cap.
The filing bases percentages on 117,667,277 shares outstanding as of March 20, 2026. The Reporting Persons state shared voting and dispositive power over the 12,356,953 shares. The statement is an amended Schedule 13G/A signed on May 15, 2026.
Positive
None.
Negative
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Insights
Large passive stake disclosed with warrant exercise cap and shared control.
The filing lists 12,356,953 Shares and a reported ownership percentage of 9.99%, calculated using 117,667,277 Shares outstanding as of March 20, 2026. It also notes warrants exercisable for 6,025,952 Shares but subject to a 9.99% ownership limit.
Cash‑flow treatment and disposition plans are not stated; future trading or voting activity will depend on the Reporting Persons and is not described in this excerpt.
Amendment clarifies beneficial ownership and power structure for regulatory record.
The cover page rows show shared voting and shared dispositive power for both RTW Investments and Roderick Wong over the same 12,356,953 Shares. The filing reiterates the 9.99% cap on warrant exercises "to the extent" exercisable.
This filing is a disclosure of ownership under Section 13; it does not by itself indicate transactions or changes in holdings beyond the warrant exercise assumption.
Key Figures
Shares reported:12,356,953 sharesPercent of class:9.99%Warrants assumed exercisable:6,025,952 shares+2 more
5 metrics
Shares reported12,356,953 sharesshared voting and dispositive power reported
Percent of class9.99%reported ownership percentage for RTW Investments and Dr. Wong
Warrants assumed exercisable6,025,952 sharesmaximum exercisable given current outstanding shares, subject to 9.99% cap
Shares outstanding used117,667,277 sharesas of <date>March 20, 2026</date>
Filing date / signature05/15/2026Schedule 13G/A amendment signature date
A Schedule 13G/A is an amended public filing with the U.S. securities regulator that updates a previous Schedule 13G, disclosing when an individual or group holds a substantial (typically over 5%) stake in a company and is claiming a passive, non‑controlling intent. Investors monitor these updates because rising or falling holdings can signal changing confidence, potential future moves, or shifts in voting power — like watching a public ledger where large shareholders quietly adjust their positions.
Shared Dispositive Powerfinancial
"Shared Dispositive Power 12,356,953.00"
Warrantsfinancial
"exercise of warrants (the "Warrants") held by the Reporting Persons to purchase 6,025,952 Shares"
Warrants are special documents that give you the right to buy a company's stock at a set price before a certain date. They are often used as a way for companies to attract investors or raise money, and their value can increase if the company's stock price goes up.
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This statement is filed by:
(i) RTW Investments, LP ("RTW Investments"), a Delaware limited partnership and the investment adviser to certain funds (the "RTW Funds"), with respect to the Common Shares, no par value per share (the "Shares") of Milestone Pharmaceuticals Inc. (the "Company") directly held by the RTW Funds; and
(ii) Roderick Wong, M.D. ("Dr. Wong"), the Managing Partner and Chief Investment Officer of RTW Investments, with respect to the Shares directly held by the RTW Funds.
The foregoing persons are hereinafter sometimes collectively referred to as the "Reporting Persons."
The filing of this statement should not be construed as an admission that any of the foregoing persons or any Reporting Person is, for the purposes of Section 13 of the Securities Exchange Act of 1934, as amended, the beneficial owner of the Shares reported herein.
(b)
Address or principal business office or, if none, residence:
The address of the business office of each of the Reporting Persons is 40 10th Avenue, Floor 7, New York, New York 10014.
(c)
Citizenship:
RTW Investments is a Delaware limited partnership. Dr. Wong is a citizen of the United States.
(d)
Title of class of securities:
Common Shares, no par value per share
(e)
CUSIP No.:
59935V107
Item 3.
If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)
Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)
Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)
Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)
Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)
An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)
An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)
A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)
A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)
A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)
A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J),
please specify the type of institution:
(k)
Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.
Ownership
(a)
Amount beneficially owned:
The information required by Item 4(a) is set forth in Rows 5 - 9 of the cover page for each of the Reporting Persons and is incorporated herein by reference. The amounts reported herein assume the exercise of warrants (the "Warrants") held by the Reporting Persons to purchase 6,025,952 Shares, the maximum amount that may be exercised given the current number of outstanding Shares and the Shares held by the Reporting Persons. Pursuant to the terms of the Warrants, the Reporting Persons cannot exercise any of the Warrants to the extent the Reporting Persons would beneficially own, after any such exercise, more than 9.99% of the outstanding Shares. The percentages set forth in Row 11 of the cover pages are calculated based upon 117,667,277 Shares outstanding as of March 20, 2026, as reported in the Company's Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 20, 2026, and assume the exercise of Warrants held by the Reporting Persons to purchase 6,025,952 Shares.
(b)
Percent of class:
RTW Investments: 9.99%
Dr. Wong: 9.99%
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
RTW Investments: 0
Dr. Wong: 0
(ii) Shared power to vote or to direct the vote:
RTW Investments: 12,356,953 Shares
Dr. Wong: 12,356,953 Shares
(iii) Sole power to dispose or to direct the disposition of:
RTW Investments: 0
Dr. Wong: 0
(iv) Shared power to dispose or to direct the disposition of:
RTW Investments: 12,356,953 Shares
Dr. Wong: 12,356,953 Shares
Item 5.
Ownership of 5 Percent or Less of a Class.
Not Applicable
Item 6.
Ownership of more than 5 Percent on Behalf of Another Person.
If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required.
See Item 2. The RTW Funds have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the Shares reported herein. RTW Master Fund, Ltd., an RTW Fund, has the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of more than 5% of the Shares reported herein.
Item 7.
Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
Not Applicable
Item 8.
Identification and Classification of Members of the Group.
Not Applicable
Item 9.
Notice of Dissolution of Group.
Not Applicable
Item 10.
Certifications:
By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.
SIGNATURE
After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.
RTW Investments, LP
Signature:
/s/ Roderick Wong, M.D.
Name/Title:
Roderick Wong, M.D., Managing Partner
Date:
05/15/2026
Roderick Wong
Signature:
s/ Roderick Wong, M.D.
Name/Title:
Roderick Wong, M.D.
Date:
05/15/2026
Exhibit Information
Exhibit 99.1 Joint Filing Agreement (incorporated by reference to Exhibit 1 to the Reporting Persons' Schedule 13G filed with the SEC on February 12, 2021).
What stake does RTW Investments report in Milestone Pharmaceuticals (MIST)?
RTW Investments reports beneficial ownership of 12,356,953 shares, representing 9.99% of the class based on 117,667,277 shares outstanding as of March 20, 2026. The filing assumes exercise of certain warrants.
How many warrants are assumed exercisable by the Reporting Persons?
The filing assumes exercise of 6,025,952 warrants held by the Reporting Persons, described as the maximum exercisable given current outstanding shares and ownership constraints, subject to a 9.99% cap.
What voting and dispositive power do the Reporting Persons claim?
Both RTW Investments and Roderick Wong report shared voting power and shared dispositive power over 12,356,953 shares. They report no sole voting or sole dispositive power for those shares.
What outstanding share count is the percentage based on?
The percentage calculations use 117,667,277 shares outstanding as of March 20, 2026, cited from the company's Annual Report on Form 10‑K filed March 20, 2026.
Does the filing identify who receives dividends or sale proceeds?
The filing states the RTW Funds have the right to receive or direct dividends or sale proceeds, and that RTW Master Fund, Ltd. holds more than 5% of the reported Shares for that purpose.
