Supreme Court of Canada Interprets “Material Change” in Securities Legislation: Implications for Disclosure of Dealings between Indigenous Communities and Public Companies
Press Release
December 9, 2025
On November 28, 2025, the Supreme Court of Canada issued Lundin Mining Corp. v Markowich. The decision provides guidance on the disclosure obligations of public companies in Canada, and establishes a broad interpretation of when events are considered a “material change” that requires prompt public disclosure under securities legislation.
This case is noteworthy for Indigenous communities that deal with public companies who may be subject to regulatory disclosure requirements for material information about their relationships with Indigenous peoples.
What is the Lundin Mining Corp. v Markowich Case About?
Lundin Mining Corp. (Lundin) is a mining company that trades its shares on the Toronto Stock Exchange and is subject to Ontario’s Securities Act.
On October 25, 2017, Lundin detected a pit wall instability at an open pit copper mine in Chile. Within days, on October 31, the pit wall instability caused a rockslide in the open pit mine. The rockslide required Lundin to shut down part of the mine for a time. The rockslide meant the mine’s production forecast went down by 20% for the next year.
Lundin did not immediately disclose the pit wall instability or the rockslide to its shareholders. It waited until after the close of trading on November 29, and then shared details about the pit wall instability and rockslide as part of Lundin’s regular operational updates news release. On November 30, the day after the news release was published, Lundin’s share price dropped 16%.
An investor who purchased shares in Lundin after the pit wall instability and rockslide and before Lundin published its news release started a class action against Lundin and several of its officers and directors. The class action alleged that the pit wall instability and rockslide were “material changes” under the Ontario Securities Act, and Lundin breached its continuous disclosure obligations by failing to promptly disclose those events.
Background Disclosure Obligations
Companies that issue shares on public stock exchanges in Canada are subject to disclosure requirements under securities legislation.
When a company first issues shares, it has to prepare a comprehensive disclosure document called a prospectus with a “full, true and plain disclosure of all material facts” relating to its business.[1]
Public companies also have continuous disclosure obligations. When a “material change” occurs in the affairs of the public company they must promptly issue a news release disclosing the change.[2] The definition of “material change” in Ontario’s Securities Act includes “a change in the business, operations or capital of the issuer that would reasonably be expected to have a significant effect on the market price or value of any of the securities of the issuer.”[3] There are similar obligations in provincial and territorial securities legislation across the country.
What Did the Lower Courts Say?
Initially, a motion judge refused to grant leave for the investor to pursue his case and dismissed the motion to certify the class action. The judge ruled neither the pit wall instability or the rockslide involved a “change” in Lundin’s business, operations or capital and not every development that requires additional expenditures is a “material change” under the Securities Act.[4]
On appeal, the Court of Appeal for Ontario overturned the motion judge’s decision. The Court of Appeal said the motion judge interpreted “change” “business”, “operations” and “capital” in the definition of “material change” too narrowly.[5] The Court of Appeal said the pit wall instability and rockslide could constitute a material change to Lundin’s operations.[6]
The Supreme Court of Canada Decision
The Majority of the Supreme Court of Canada agreed with the Court of Appeal that the motion judge had interpreted “material change” too narrowly. The Majority explained that the motion judge interpreted the word “change”, and the phrase “business, operations or capital” in the statutory definition of “material change” too restrictively. The motion judge erred by using a dictionary definition of “change” and relying on case law definitions of “business”, “operations” and “capital”, when those words could be understood with their ordinary meaning.[7] A “change is a change” and “business, operations and capital” are widely understood commercial concepts.[8] Those words should keep their ordinary commercial meaning and flexibility as required in specific factual circumstances.[9]
The Majority also dismissed lower court case law that added a requirement that an event must be “important and substantial” to constitute a change under the definition of “material change”, explaining that the narrower standard is inconsistent with the text of the legislation.[10]
The Majority said that instead interpretation of “material change” should be guided by the purpose of securities legislation to address information asymmetries between companies and investors.[11] Disclosure helps level the playing field of information between investors and companies, which then helps investors direct their money to the most deserving public companies.[12]
After a company has filed its prospectus full of material facts, it has to update its disclosure whenever there is a material change in its business, operations or capital.[13] Material changes are dynamic and internal to a company.[14] Mere negotiations or internal deliberations usually are not a material change.[15] However, a contractual dispute is an example of an internal development requiring disclosure as a material change.[16]
Takeaways from the Decision
This Supreme Court decision established a broad and flexible definition of “material changes” requiring immediate disclosure under securities legislation across Canada. This decision means that publicly traded companies will need to make disclosures in real time with developments in their businesses.
Indigenous communities dealing with publicly traded companies should be mindful that their relationship with a public company could be material to investors and a change to their relationship may require immediate disclosure. Indigenous communities should track information in prospectuses and subsequent disclosures published by the companies they deal with to ensure that they accurately and promptly convey information about their dealings to investors.
[1] Securities Act, RSO 1990, c S5, s. 56(1).
[2] Securities Act, RSO 1990, c S5, s. 75(1).
[3] Securities Act, RSO 1990, c S5, s. 1(1) “material change”.
[4] Lundin Mining Corp. v Markowich, 2025 SCC 39 at para 23 [Lundin Mining].
[5] Lundin Mining at para 26; Markowich v Lundin Mining Corporation, 2023 ONCA 359 at para 7.
[6] Lundin Mining at para 27; Markowich v Lundin Mining Corporation, 2023 ONCA 359 at paras 82-85.
[8] Lundin Mining at paras 71 and 92.
[10] Lundin Mining at paras 79-81.
[11] Lundin Mining at para 63.
[12] Lundin Mining at paras 35-37.
[13] Lundin Mining at para 49.
[14] Lundin Mining at paras 48 and 51.
[15] Lundin Mining at para 59.
[16] Lundin Mining at para 53.
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