On November 28, 2025, the Supreme Court of Canada released its highly anticipated decision Lundin Mining Corporation v. Markowich,[1] addressing the meaning of “material change” in Canadian securities law. The Supreme Court determined that the definition of a “material change” is broad and contextual, and involves a consideration of both the nature and the magnitude of the change. The Supreme Court also clarified the test for leave to proceed with a securities class action under s. 138.8 of the Ontario Securities Act (the Act), finding that a plaintiff seeking leave under s. 138.8(1) of the Act must establish a reasonable or realistic chance of success based on a plausible analysis of the legislation and some credible evidence.
[1] 2025 SCC 39.
