---
schema_version: "secwatch.filing_event.v1"
accession: "0000950170-23-047138"
form_type: "8-K"
ticker: "RARE"
cik: "0001515673"
company_name: "Ultragenyx Pharmaceutical Inc."
filed_at: "2023-09-08T23:59:59+00:00"
generated_at: "2026-06-10T22:07:58.957532+00:00"
event_type: "other"
sentiment: "neutral"
materiality_score: 0.1
calibrated_materiality_score: 0.1
confidence: "high"
source: SEC EDGAR
---

# Ultragenyx moves CFO start date to Oct 9 from Oct 16, 2023

## Summary
- Howard Horn's appointment as CFO & EVP, Corporate Strategy effective October 9, 2023, one week earlier than originally announced.
- Amendment No. 1 to offer letter dated September 6, 2023 changes only the start date; all other terms unchanged.
- Original effective date of October 16, 2023 was disclosed in the July 12, 2023 Form 8-K.

## SEC filing metadata
- accession: 0000950170-23-047138
- form_type: 8-K
- ticker: RARE
- cik: 0001515673
- company_name: Ultragenyx Pharmaceutical Inc.
- filed_at: 2023-09-08T23:59:59+00:00
- event_type: other
- sentiment: neutral
- materiality_score: 0.1
- calibrated_materiality_score: 0.1
- confidence: high
- sec_items: 5.02, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1515673/000095017023047138/0000950170-23-047138-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1515673/000095017023047138/rare-20230906.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0000950170-23-047138
- JSON: https://secwatch.observer/filing/0000950170-23-047138.json
- Plain text: https://secwatch.observer/filing/0000950170-23-047138.txt

## Key facts
- Executive change
  Howard Horn was appointed as Chief Financial Officer and Executive Vice President, Corporate Strategy at Ultragenyx Pharmaceutical Inc..
  - Action: appointed
  - Role: Chief Financial Officer and Executive Vice President, Corporate Strategy
  source text: Mr. Horn and the Company have modified the effective date of Mr. Horn’s appointment as the Company’s CFO and EVP, Corporate Strategy from October 16, 2023 to October 9, 2023 (the “Effective Date”).
  evidence_url: https://www.sec.gov/Archives/edgar/data/1515673/000095017023047138/0000950170-23-047138-index.htm

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