The standard of materiality articulated by the U.S. Supreme Court in TSC Industries v. Northway, 426 U.S. 438, 449 (1976) (a fact is material “if there is a substantial likelihood that a reasonable shareholder would consider it important” in making an investment decision or if it “would have been viewed by the reasonable investor as having significantly altered the ‘total mix’ of information made available” to the shareholder).
Source(s):
NIST SP 800-161r1 from TSC Industries v. Northway

  The materiality of cybersecurity risks or incidents depends upon their nature, extent, and potential magnitude, particularly as they relate to any compromised information or the business and scope of company operations. The materiality of cybersecurity risks and incidents also depends on the range of harm that such incidents could cause. This includes harm to a company’s reputation, financial performance, and customer and vendor relationships, as well as the possibility of litigation or regulatory investigations or actions, including regulatory actions by state and federal governmental authorities and non-U.S. authorities.
Source(s):
NIST SP 800-161r1 from Public Company Cybersecurity Disclosures