In Matrixx Initiatives Inc. v. Siracusano, the Supreme Court considered “[w]hether a plaintiff can state a claim under § 10(b) of the Securities Exchange Act and SEC Rule 10b-5 based on a pharmaceutical company’s nondisclosure of adverse event reports even though the reports are not alleged to be statistically significant.”
The Court said "yes," and argued that a reasonable investor might want to know of such reports if they are sufficiently extensive and disturbing that they could prompt the FDA to take some action or might lead to costly lawsuits. Thus, even non-statistically significant information can be material and enough to trigger a legal duty to disclose.
In Trapped in the Matrixx: The U.S. Supreme Court and the Need for Statistical Significance, David Kaye (Penn St.) defends the Court's interpretation of the pleading rule but argues for a narrow reading of dicta in the opinion about proof of causation in product liability cases. Kaye's paper "suggests that the unanimous opinion conflates issues of study design with statistical significance. Disentangling these concepts shows that the Court’s remarks do not address the limited value of adverse event reports in establishing causation in toxic tort litigation."