---
schema_version: "secwatch.filing_event.v1"
accession: "0001619856-24-000071"
form_type: "8-K"
ticker: "CRBU"
cik: "0001619856"
company_name: "Caribou Biosciences, Inc."
filed_at: "2024-09-03T23:59:59+00:00"
generated_at: "2026-05-31T06:37:57.394220+00:00"
event_type: "leadership"
sentiment: "negative"
materiality_score: 0.6
calibrated_materiality_score: 0.6
confidence: "high"
source: SEC EDGAR
---

# CFO Jason O'Byrne resigns effective Sept 27; Ryan Fischesser named principal accounting officer

## Summary
- Jason O'Byrne resigns as CFO effective Sept 27, 2024, to pursue other opportunity; no disagreement with company.
- Company has initiated search for new CFO.
- Ryan Fischesser, VP Finance and Controller, will assume principal accounting officer role Sept 27.
- Fischesser previously served as principal accounting officer from IPO through Dec 2022.

## SEC filing metadata
- accession: 0001619856-24-000071
- form_type: 8-K
- ticker: CRBU
- cik: 0001619856
- company_name: Caribou Biosciences, Inc.
- filed_at: 2024-09-03T23:59:59+00:00
- event_type: leadership
- sentiment: negative
- materiality_score: 0.6
- calibrated_materiality_score: 0.6
- confidence: high
- sec_items: 5.02, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1619856/000161985624000071/0001619856-24-000071-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1619856/000161985624000071/crbu-20240901.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001619856-24-000071
- JSON: https://secwatch.observer/filing/0001619856-24-000071.json
- Plain text: https://secwatch.observer/filing/0001619856-24-000071.txt

## Key facts
- Executive change
  Jason O'Byrne resigned as Chief Financial Officer at Caribou Biosciences, Inc..
  - Action: resigned
  - Role: Chief Financial Officer
  source text: On September 1, 2024, Jason O’Byrne, the Chief Financial Officer of Caribou Biosciences, Inc. (the “Company”), informed the Company of his intent to resign from his position, effective September 27, 2024, to pursue another opportunity.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1619856/000161985624000071/0001619856-24-000071-index.htm
- Executive change
  Ryan Fischesser was appointed as principal accounting officer at Caribou Biosciences, Inc..
  - Action: appointed
  - Role: principal accounting officer
  source text: The Company intends to appoint Ryan Fischesser, the Company’s current Vice President of Finance and Controller, to assume the role of the Company’s principal accounting officer, effective as of the close of business on September 27, 2024.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1619856/000161985624000071/0001619856-24-000071-index.htm

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