Wellington Management Group LLP Acquires 9.99% Stake in ProMIS Neurosciences, Inc.

On May 15, 2026, Wellington Management Group LLP and its affiliated entities filed a Schedule 13G regarding their position in ProMIS Neurosciences, Inc. (PMN). The filing reveals that Wellington now beneficially owns 895,871 shares of common stock, representing a 9.99% ownership stake in the issuer. This position is comprised of 696,378 shares held directly by Wellington Biomedical Innovation Master Investors (Cayman) II L.P. and 199,493 shares underlying warrants. Notably, the reporting persons hold additional warrants for 496,885 shares that are currently unexercisable due to a 9.99% beneficial ownership blocker provision. The filing was made on behalf of a group of entities including Wellington Group Holdings LLP, Wellington Investment Advisors Holdings LLP, and Wellington Management Company LLP. The shares were acquired in the ordinary course of business, and the filing indicates a passive investment intent. This marks a significant increase from a zero-position reported in previous periods, establishing Wellington as a major institutional shareholder.