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Nucor

nucor.com
CONFIRMED

Official SEC Form 8-K Item 1.05 disclosure filed by Nucor regarding a material cybersecurity incident.

Observable Status CONFIRMED
Industry / Sector Technology & Commercial
Incident Classification Material Cybersecurity Incident
Attributed Threat Actor Unattributed / Unknown
Affected Population Scope Under Audit
First Seen 2025-06-20
Last Updated 2025-06-20
OPEN WEIGHTS TELEMETRY • DETERMINISTIC CONFIDENCE

Confidence & Source Corroboration

80% CONFIDENCE
1. Primary Authority CONFIRMED BY REGULATOR Base weight: 65%
2. Evidence Specificity +15% Statutory Filing Verified
3. Corroboration Curve +0% 1 independent domain
4. Timeline & Staleness +0% 2 milestones logged
Corroborated Source Domains:
sec.gov
STATUTORY REGULATORY DISCLOSURES

Official Regulatory Filings & Legal Compliance Records

2 Verified Statutory Filings
Regulatory Ground Truth Standard: The disclosures below represent formal statutory filings and enforcement records submitted to government regulatory authorities (SEC, State Attorneys General, HHS OCR, FTC, FCC, EU/UK DPAs). In accordance with repository principles, this data is captured exactly as filed by the reporting entity and is never modified, overridden, or synthesized by AI models.
SEC

Form 8-K Item 1.05

CONFIRMED BY REGULATOR
Docket / Accession ID 0001193125-25-143135
Statutory Filing Date 2025-06-20
Disclosed Impact Scope Under Audit
Evidence Standard Regulatory Ground Truth
Statutory Filing Details & Summary (Preserved As Filed):

Item 1.05 regarding the cybersecurity incident disclosed on the Original Form 8-K,

and should be read in conjunction with the Original Form 8-K.

View Official Regulatory Filing Document https://www.sec.gov/Archives/edgar/data/73309/000119312525143135/0001193125-25-143135-index.htm
SEC

Form 8-K Item 1.05

CONFIRMED BY REGULATOR
Docket / Accession ID 0001193125-25-119311
Statutory Filing Date 2025-05-14
Disclosed Impact Scope Under Audit
Evidence Standard Regulatory Ground Truth
Statutory Filing Details & Summary (Preserved As Filed):

Item 1.05.

Material Cybersecurity Incidents.

Nucor Corporation (the "Company") recently identified a cybersecurity incident involving unauthorized third party access to certain information technology systems used by the Company. Upon detecting the incident, the Company began promptly taking steps to contain and respond to the incident, including activating its incident response plan, proactively taking potentially affected systems offline and implementing other containment, remediation, or recovery measures. The Company is actively investigating the incident with the assistance of leading external cybersecurity experts and has notified federal law enforcement authorities. As of the date of this filing and in an abundance of caution, the Company temporarily and proactively halted certain production operations at various locations. However, the Company is currently in the process of restarting the affected operations.

As the investigation of the incident is ongoing, the Company will continue to monitor the timing and materiality of the incident.

Forward-Looking Statements

Certain statements made in this report, or in other public filings, press releases, or other written or oral communications made by Nucor, which are not historical facts are forward-looking statements subject to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. These forward-looking statements involve risks and uncertainties which we expect will or may occur in the future and may impact our business, financial condition and results of operations. The words "anticipate," "believe," "expect," "intend," "project," "may," "will," "should," "could" and similar expressions are intended to identify those forward-looking statements. These forward-looking statements reflect the Company's best judgment based on current information, and, although we base these statements on circumstances that we believe to be reasonable when made, there can be no assurance that future events will not affect the accuracy of such forward-looking information. As such, the forward-looking statements are not guarantees of future performance, and actual results may vary materially from the projected results and expectations discussed in this report. Factors that might cause the Company's actual results to differ materially from those anticipated in forward-looking statements include, but are not limited to: the Company's ongoing assessment of the impacts of the cybersecurity incident, including the Company's potential discovery of additional information related to the incident in connection with its investigation or otherwise; the Company's expectations regarding its ability to contain and remediate the cybersecurity incident; the impact of the cybersecurity incident on the Company's relationships with customers, employees, and governmental regulators; the legal, reputational, and financial risks resulting from the cybersecurity incident, including as may arise from any potential regulatory inquiries and/or litigation to which the Company may become subject in connection with the incident; remediation and other additional costs that may be incurred by the Company in connection with the investigation and remediation of the incident; and the risks discussed in "Item 1A. Risk Factors" of the Company's Annual Report on Form 10-K

for the year ended December 31, 2024, as may be supplemented by "Item 1A. Risk Factors" in the Company's subsequent Quarterly Reports on Form 10-Q

and in the Company's other periodic and current reports filed with the SEC.

1

View Official Regulatory Filing Document https://www.sec.gov/Archives/edgar/data/73309/000119312525119311/0001193125-25-119311-index.htm

Technical Forensic Briefing

Incident Overview

Nucor, within its operating sector, has been subject to a cybersecurity incident disclosed to federal securities regulators. Ground-truth telemetry indicates the event prompted statutory disclosure under SEC cybersecurity reporting mandates.

Official SEC Form 8-K Item 1.05 disclosure filed by Nucor regarding a material cybersecurity incident.

Compromised Assets & Data Scope

The specific volume of affected customer, employee, or organizational records remains under active technical audit or disclosed in primary filings. Primary online perimeter and corporate domains include nucor.com.

Specific classes of compromised records, infrastructure, or operational systems are detailed in the official statutory filings below.

Statutory Disclosures & Compliance

  • SEC Filing: Form 8-K Item 1.05 (0001193125-25-143135) - Filing Link

Milestone Timeline (2 events logged)

2025-06-20 16:00 UTC
CONFIRMED BY REGULATOR

SEC Form 8-K Item 1.05 Disclosure

2025-05-14 16:00 UTC
CONFIRMED BY REGULATOR

SEC Form 8-K Item 1.05 Disclosure

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