What the document says
On 26 July 2023, the Securities and Exchange Commission adopted rules requiring public companies to disclose material cybersecurity incidents. The SEC's press release describes a new Item 1.05 on Form 8-K, requiring a company to describe the material aspects of an incident's nature, scope and timing, and its material impact or reasonably likely material impact, generally within four business days of determining that the incident is material. Disclosure can be delayed if the Attorney General determines that immediate disclosure would pose a substantial risk to national security or public safety. A separate rulemaking page records that the rule took effect on 5 September 2023, with the 8-K disclosure obligation itself phased in from 18 December 2023, and that filings must use Inline XBRL formatting. The rule also added Item 106 to Regulation S-K, requiring an annual description, in Form 10-K, of a company's processes for assessing and managing cybersecurity risk, the material effects of such risks, and how the board oversees them.
An early example shows how the requirement worked in practice. VF Corporation, the apparel company, filed an Item 1.05 report on 18 December 2023, the day the requirement took effect, saying it had detected unauthorised activity on 13 December in which a threat actor deployed ransomware, encrypted some IT systems and stole data including personal data. The filing said the full scope, nature and impact of the incident were not yet known and that VF had not determined whether the incident would materially affect its financial results.
Confidence and limits
The rule's requirements and effective dates are established directly from the SEC's own materials. What an Item 1.05 filing must contain in the abstract, and what a company actually chose to disclose in its first days of investigating an incident, are two different things; VF's filing illustrates the latter, not a template every company follows identically.
Why it mattered
Before this rule, disclosure of a material cyber incident to investors depended on a company's own judgment about existing, more general disclosure obligations, with no specific clock attached. A four-business-day trigger tied to a materiality determination gives investors and regulators a benchmark against which a company's timeline can be measured, even though the materiality determination itself is still made by the company.
Defensive takeaway
If you work at a public company, confirm that your incident-response plan includes a defined path to a materiality determination, with named decision-makers, so that a security team's technical findings can reach the people who must start a four-business-day clock without unnecessary delay.
- Does your incident-response plan name who makes the materiality determination, and how quickly technical findings reach that person?
- Would your organisation's first Item 1.05-style disclosure, if drafted today, honestly state what is not yet known, the way VF Corporation's did?
- Is your board briefed on its oversight role for cybersecurity risk in a way that could support an annual Item 106 disclosure?
The rule creates a disclosure clock, not a security standard, and a company can comply with its timing requirements while still describing an incident whose full scope remains genuinely unknown at the time of filing.