Lundin Mining Corp. v. Markowich — Supreme Court of Canada upholds investor’s leave to pursue timely-disclosure class action over mine rockslide

Case
Lundin Mining Corporation, Paul K. Conibear, Marie Inkster, Paul McRae, Lukas H. Lundin and Stephen Gatley v. Dov Markowich
Court
Supreme Court of Canada (Canada)
Date Decided
November 28, 2025
Citation
2025 SCC 39
Topics
Securities law, timely disclosure, material change, secondary market liability
Source
Read the full opinion

Background

Lundin Mining Corporation, a publicly listed Canadian mining company, detected pit wall instability at its premier open-pit mine. Within days the instability triggered a localized rockslide, forcing at least a partial mine shutdown and a 20 percent downward revision to the mine’s annual production forecast. Rather than disclosing these developments immediately, Lundin waited approximately one month and folded the news into its regular periodic updates. When the disclosure finally came, the company’s share price fell 16 percent in a single day, erasing more than $1 billion in market capitalization.

Dov Markowich, an investor who had purchased Lundin shares after the rockslide but before the disclosure, commenced a proposed class proceeding against Lundin and several of its officers and directors. He alleged a violation of the continuous disclosure obligations in Ontario’s Securities Act, R.S.O. 1990, c. S.5, arguing that the pit wall instability and rockslide each constituted a “material change” in Lundin’s business, operations, or capital that required immediate (“forthwith”) disclosure under s. 75(1). He sought leave under s. 138.8(1) to pursue the statutory cause of action and also moved for class certification.

The motion judge denied leave, reasoning that because Lundin remained a mining company throughout, neither event amounted to a “change” in its business, operations, or capital. The Ontario Court of Appeal reversed, holding that a more generous reading of those terms supported a reasonable possibility of success, and remitted certification to the lower court. Lundin appealed to the Supreme Court of Canada.

The Court’s Holding

The Supreme Court dismissed the appeal 8–1 (Côté J. dissenting), affirming that Markowich should be granted leave to pursue his statutory claim. Writing for the majority, Justice Jamal held that the motion judge erred by importing restrictive definitions of “change,” “business,” “operations,” and “capital” — terms the Ontario legislature intentionally left undefined so the legislation could apply flexibly across widely varying industries and corporate structures. Because the uncontested evidence showed that the pit wall instability and rockslide directly impacted Lundin’s mine operations and required revisions to its production forecast, a plausible application of the legislation to those facts demonstrated a reasonable or realistic chance that the action could succeed at trial.

The majority clarified the test for leave under s. 138.8(1): a court must be satisfied that the action is brought in good faith and that there is a reasonable possibility — meaning a realistic chance, not merely a theoretical possibility — that the action will be resolved in the plaintiff’s favour. That assessment requires a plausible application of the relevant statutory provisions to the available facts and evidence, combined with some credible evidence in support of the claim. Critically, the correct statutory interpretation must be applied at the leave stage; the court cannot simply accept any arguable reading of the statute as good enough.

On the substantive law, the majority held that “material change” and “material fact” serve distinct purposes. A material fact is static — a snapshot of an issuer’s affairs at a moment in time — while a material change is dynamic, requiring a comparison of the issuer’s position before and after a development. The change must be internal to the issuer and must be reasonably expected to have a significant effect on the market price or value of the issuer’s securities. The term “change” carries its ordinary meaning and need not be fundamental, core, or substantial; the magnitude and significance of a development go to materiality, not to whether a change has occurred at all. Whether a material change exists is always a highly contextual question of mixed fact and law.

Key Takeaways

  • The terms “change,” “business,” “operations,” and “capital” in the Ontario Securities Act definition of “material change” must be read in their ordinary sense without judicially imposed qualifiers such as “core,” “fundamental,” or “important”; restrictive glosses that limit the legislation’s reach are inconsistent with the legislature’s intent.
  • The leave threshold under s. 138.8(1) requires a plausible application of the statute to the facts — not merely a plausible interpretation of the statute — plus some credible supporting evidence; statutory interpretation at this stage must be correct and is not conducted on a relaxed standard.
  • A material change is dynamic and internal to the issuer; it differs from a material fact (which can be an external, static condition) in that it compares the issuer’s affairs at two points in time and relates to changes in the issuer’s own business, operations, or capital.
  • A development’s magnitude goes to materiality (i.e., whether it would reasonably be expected to have a significant effect on market price), not to whether a “change” within the meaning of the statute has occurred at all.
  • Lundin’s failure to immediately disclose a rockslide that shut down part of its mine and cut its annual production forecast by 20 percent presented a sufficiently plausible case of material change to survive the leave screen, notwithstanding that Lundin remained a going-concern mining company throughout.

Why It Matters

This is the Supreme Court of Canada’s most significant pronouncement on secondary-market securities liability in a decade. By rejecting a restrictive reading of “material change” and reaffirming that the leave filter under s. 138.8(1) is a genuine but not insurmountable threshold, the decision strengthens the hand of investors seeking to hold public companies accountable for delayed disclosure of operationally significant events. Issuers in extractive industries — and beyond — can no longer rely on the argument that a development is merely operational rather than structural to defer mandatory disclosure.

The dissent’s warning that the majority’s approach effectively collapses the “material change”/”material fact” distinction and will generate over-disclosure and compliance costs will likely animate regulatory guidance and future litigation. Securities practitioners across Canada should expect the decision to recalibrate how issuers, their counsel, and regulators assess disclosure obligations whenever an event materially disrupts an issuer’s production, revenue, or business activities, even if the company’s overall character or business model remains unchanged.

⬇ Download the original opinion (PDF)Archived from the court's official source.
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