Wellington reports 9.99% stake in ProMIS Neurosciences

ProMIS Neurosciences reports that Wellington Biomedical Innovation Master Investors (Cayman) II, L.P. beneficially owns 895,877 shares of Common Stock, representing 9.99% of the outstanding common shares.

Rhea-AI Filing Summary

ProMIS Neurosciences reports that Wellington Biomedical Innovation Master Investors (Cayman) II, L.P. beneficially owns 895,877 shares of Common Stock, representing 9.99% of the outstanding common shares.

That 895,877 figure comprises 696,378 shares held directly and 199,499 shares issuable upon warrants; an issuance limitation on certain warrants prevents exercise that would result in ownership above 9.99%. The filing bases percentages on approximately 8,967,740 shares outstanding, reflecting a one-for-twenty-five reverse split effective November 28, 2025 and shares reported as issued as of February 3, 2026.

Insights

Institutional Ownership Analyst

Wellington holds a near-10% passive position via direct shares and warrant exposure.

Wellington Biomedical Innovation Master Investors (Cayman) II, L.P. beneficially owns 895,877 shares, split between 696,378 directly held shares and 199,499 shares underlying warrants. The filing states an issuance limitation that caps exercise to avoid exceeding 9.99%.

Cash-flow treatment and sale intentions are not disclosed in the excerpt; subsequent filings would show any trading or disposition activity.

Corporate Governance Specialist

The position is disclosed with explicit ownership limits tied to warrant exercise mechanics.

The filing explains that 496,879 warrant shares are excluded from beneficial ownership due to an issuance limitation that prevents exercises that would push ownership over 9.99%. This is a contractual cap described verbatim in the filing.

Regulatory or governance consequences are not stated here; the ownership percentage and the warrant limitation are the primary governance-relevant facts disclosed.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What stake does Wellington hold in ProMIS Neurosciences (PMN)?

Wellington beneficially owns 895,877 shares, equal to 9.99% of the common stock. This total includes 696,378 directly held shares and 199,499 shares issuable upon warrants as stated in the filing.

How is the 9.99% ownership calculated for PMN?

The percentage uses approximately 8,967,740 shares outstanding. That figure reflects a one-for-twenty-five reverse split effective November 28, 2025 and shares reported as issued as of February 3, 2026, per the filing.

Do the warrants owned by Wellington automatically increase its stake above 9.99%?

No. The filing states certain warrants contain an issuance limitation that prohibits exercise to the extent it would result in ownership above 9.99%, limiting immediate dilution from those warrants.

How many shares does Wellington hold directly versus via warrants?

Wellington holds 696,378 shares directly and has 199,499 shares underlying warrants reported in this filing, totaling 895,877 shares beneficially owned.

Does the filing disclose whether Wellington will sell or buy more PMN shares?

The filing does not disclose any purchase or sale intentions. It reports beneficial ownership of 895,877 shares and the warrant exercise limitation, without describing trading plans.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 03/18/2026 - 12:26 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

ProMIS Neurosciences, Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

74346M505

(CUSIP Number)

03/11/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 74346M505

1

Names of Reporting Persons

Wellington Biomedical Innovation Master Investors (Cayman) II, L.P.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 895,877.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 895,877.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

895,877.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

9.99 %

12

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: ProMIS Neurosciences, Inc.
(b)	Address of issuer's principal executive offices: Suite 200, 1920 Yonge Street, Toronto ON M4S 3E2
Item 2.
(a)	Name of person filing: Wellington Biomedical Innovation Master Investors (Cayman) II, L.P.
(b)	Address or principal business office or, if none, residence: c/o Wellington Management Company LLP, 280 Congress Street, Boston MA 02210
(c)	Citizenship: Cayman Islands
(d)	Title of class of securities: Common Stock
(e)	CUSIP Number(s): 74346M505
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: Wellington Biomedical Innovation Master Investors (Cayman) II L.P. may be deemed to beneficially own an aggregate of 895,877 shares (the "Shares") of Common Stock, of ProMIS Neurosciences Inc. (the "Issuer"). The 895,877 Shares reported as beneficially owned on this Schedule 13G consists of (i) 696,378 Shares held directly by Wellington Biomedical Innovation Master Investors (Cayman) II L.P., (ii) 199,499 Shares underlying warrants (the "Warrants") held directly by Wellington Biomedical Innovation Master Investors (Cayman) II L.P. The securities beneficially owned by each Filer excludes 496,879 Shares underlying Warrants which contain an issuance limitation that prohibits the holder from exercising the Warrants to the extent that after giving effect to such issuance after the exercise, the holder (together with the holder's affiliates and any other persons acting as a group together with the holder or any of the holder's affiliates, including the other Filers) would beneficially own in excess of 9.99% of the Shares outstanding immediately after giving effect to the issuance of the Shares issuable upon exercise of the Warrants. As a result, Wellington Biomedical Innovation Master Investors (Cayman) II L.P. beneficially owns 9.99% of the outstanding Shares of the Issuer. Ownership percentages are based on approximately 8,967,740 shares of Common Stock outstanding, comprised of (i) 2,152,444 shares of Common Shares outstanding, following a one-for-twenty-five reverse stock split effective as of November 28, 2025 reported by the Issuer in Exhibit 99.1 to its Form 8-K filed with the SEC on November 24, 2025 and (ii) 6,815,296 shares of Common Stock reported by the Issuer as issued as of February 3, 2026 in the Issuer's Form 8-K filed with the SEC on January 30, 2026.
(b)	Percent of class: 9.99 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 0
	(ii) Shared power to vote or to direct the vote: 895,877
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 895,877
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.
	Not Applicable
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 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.

Wellington Biomedical Innovation Master Investors (Cayman) II, L.P.

Signature:	Ihsan Speede
Name/Title:	Authorized Person
Date:	03/18/2026

Comments accompanying signature: Wellington Alternative Investments LLC; Its General Partner Signature: Ihsan Speede Name/Title: Authorized Person Date: 03/18/2026