What does materiality mean exactly?

This essay argues that materiality remains a foundational concept for cybersecurity risk forecasting across public, private, and government organizations despite legal uncertainty following the SEC’s cyber disclosure rule and the Supreme Court’s Chevron reversal. It reframes materiality beyond shareholder impact to encompass mission-critical consequences, urging leaders to prioritize company/mission killers and to define materiality specific to their context. For the U.S. Navy, it proposes four materiality threat vectors—loss of life, cyber espionage, physical infrastructure destruction, and mission degradation—as a starting point for first-principles security strategy.