X0202 SCHEDULE 13G 0001903360 XXXXXXXX LIVE Common Stock 03/11/2026 0001374339 ProMIS Neurosciences, Inc. 74346M505 Suite 200, 1920 Yonge Street Toronto Z4 M4S 3E2 Rule 13d-1(c) Wellington Biomedical Innovation Master Investors (Cayman) II, L.P. X1 0 895877 0 895877 895877.00 9.99 PN ProMIS Neurosciences, Inc. Suite 200, 1920 Yonge Street, Toronto ON M4S 3E2 Wellington Biomedical Innovation Master Investors (Cayman) II, L.P. c/o Wellington Management Company LLP, 280 Congress Street, Boston MA 02210 Cayman Islands Y 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. 9.99 0 895,877 0 895,877 Y Y Y Y Y N 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. Wellington Biomedical Innovation Master Investors (Cayman) II, L.P. Ihsan Speede 03/18/2026 Wellington Alternative Investments LLC; Its General Partner Signature: Ihsan Speede Name/Title: Authorized Person Date: 03/18/2026