---
schema_version: "secwatch.filing_event.v1"
accession: "0001140361-23-024278"
form_type: "8-K"
ticker: "MDU"
cik: "0000067716"
company_name: "MDU RESOURCES GROUP INC"
filed_at: "2023-05-12T23:59:59+00:00"
generated_at: "2026-06-15T03:03:41.411432+00:00"
event_type: "other_material"
sentiment: "neutral"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# MDU Resources spin-off of Knife River corp; distribution ratio 1:4; effective May 31

## Summary
- Registration statement for Knife River spin-off declared effective by SEC.
- Distribution of ~90% of Knife River shares to MDU holders: 1 share KNF per 4 shares MDU.
- Record date May 22, distribution date May 31, 2023.
- KNF to trade on NYSE after spin-off; when-issued trading starts May 25 under 'KNF WI'.
- Investor day for Knife River scheduled for May 18, 2023.

## SEC filing metadata
- accession: 0001140361-23-024278
- form_type: 8-K
- ticker: MDU
- cik: 0000067716
- company_name: MDU RESOURCES GROUP INC
- filed_at: 2023-05-12T23:59:59+00:00
- event_type: other_material
- sentiment: neutral
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 7.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/67716/000114036123024278/0001140361-23-024278-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/67716/000114036123024278/ny20008720x1_8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001140361-23-024278
- JSON: https://secwatch.observer/filing/0001140361-23-024278.json
- Plain text: https://secwatch.observer/filing/0001140361-23-024278.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.