---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-23-093126"
form_type: "8-K"
ticker: "MIRM"
cik: "0001759425"
company_name: "Mirum Pharmaceuticals, Inc."
filed_at: "2023-04-06T23:59:59+00:00"
generated_at: "2026-06-17T05:15:50.065913+00:00"
event_type: "leadership"
sentiment: "neutral"
materiality_score: 0.45
calibrated_materiality_score: 0.45
confidence: "high"
source: SEC EDGAR
---

# Mirum appoints Timothy Walbert to Board; Niall O'Donnell to resign at 2023 annual meeting

## Summary
- Timothy Walbert appointed to Board as Class I director effective April 5, 2023.
- Walbert receives option for 34,000 shares vesting over 3 years and $45,000 annual cash retainer.
- Niall O'Donnell resigns as director and from Nominating and Corporate Governance Committee, effective at 2023 annual meeting, no dispute.
- Walbert will serve until 2023 annual meeting and then be eligible for annual option grant of 17,000 shares.

## SEC filing metadata
- accession: 0001193125-23-093126
- form_type: 8-K
- ticker: MIRM
- cik: 0001759425
- company_name: Mirum Pharmaceuticals, Inc.
- filed_at: 2023-04-06T23:59:59+00:00
- event_type: leadership
- sentiment: neutral
- materiality_score: 0.45
- calibrated_materiality_score: 0.45
- confidence: high
- sec_items: 5.02
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1759425/000119312523093126/0001193125-23-093126-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1759425/000119312523093126/d462977d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-23-093126
- JSON: https://secwatch.observer/filing/0001193125-23-093126.json
- Plain text: https://secwatch.observer/filing/0001193125-23-093126.txt

## Key facts
- Executive change
  Niall O'Donnell resigned as Director at Mirum Pharmaceuticals, Inc..
  - Action: resigned
  - Role: Director
  source text: On April 5, 2023, Niall O’Donnell, Ph.D., notified the board of directors (the “Board”) of Mirum Pharmaceuticals, Inc. (the “Company”) of his resignation as a director of the Company and as a member of the Nominating and Corporate Governance Committee of the Board, in each case, effective as of the date of the Company’s 2023 Annual Meeting of Stockholders.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1759425/000119312523093126/0001193125-23-093126-index.htm
- Executive change
  Timothy Walbert was appointed as Director at Mirum Pharmaceuticals, Inc..
  - Action: appointed
  - Role: Director
  source text: On April 5, 2023, the Board, upon recommendation of the Nominating and Corporate Governance Committee of the Board, appointed Timothy Walbert to the Board, effective immediately.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1759425/000119312523093126/0001193125-23-093126-index.htm

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