---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-24-045328"
form_type: "8-K"
ticker: "MCRB"
cik: "0001609809"
company_name: "Seres Therapeutics, Inc."
filed_at: "2024-02-26T23:59:59+00:00"
generated_at: "2026-06-05T15:12:16.125185+00:00"
event_type: "leadership"
sentiment: "neutral"
materiality_score: 0.6
calibrated_materiality_score: 0.6
confidence: "high"
source: SEC EDGAR
---

# Seres Therapeutics appoints Marella Thorell as CFO; David Arkowitz retires March 15

## Summary
- Marella Thorell named EVP and CFO effective March 25, 2024; David Arkowitz retires as CFO on March 15.
- CEO Eric Shaff serves as interim principal financial and accounting officer from March 15 to March 25.
- Thorell receives $480,000 base salary, $80,000 sign-on bonus, and option to purchase 700,000 shares.
- Arkowitz gets 12 months base salary, COBRA coverage, and $500/hour advisory fee for up to 10 hours/month for 6 months.

## SEC filing metadata
- accession: 0001193125-24-045328
- form_type: 8-K
- ticker: MCRB
- cik: 0001609809
- company_name: Seres Therapeutics, Inc.
- filed_at: 2024-02-26T23:59:59+00:00
- event_type: leadership
- sentiment: neutral
- materiality_score: 0.6
- calibrated_materiality_score: 0.6
- confidence: high
- sec_items: 5.02, 7.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1609809/000119312524045328/0001193125-24-045328-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1609809/000119312524045328/d784620d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-24-045328
- JSON: https://secwatch.observer/filing/0001193125-24-045328.json
- Plain text: https://secwatch.observer/filing/0001193125-24-045328.txt

## Key facts
- Executive change
  David Arkowitz retired as Chief Financial Officer at Seres Therapeutics, Inc..
  - Action: retired
  - Role: Chief Financial Officer
  source text: Mr. Arkowitz’s retirement effective as of March 15, 2024 (the “Retirement Date”).
  evidence_url: https://www.sec.gov/Archives/edgar/data/1609809/000119312524045328/0001193125-24-045328-index.htm
- Executive change
  Marella Thorell was appointed as Executive Vice President and Chief Financial Officer at Seres Therapeutics, Inc..
  - Action: appointed
  - Role: Executive Vice President and Chief Financial Officer
  source text: On February 24, 2024, the Board of Directors (the “Board”) of Seres Therapeutics, Inc. (the “Company”) appointed Marella Thorell to succeed David Arkowitz as the Company’s Executive Vice President and Chief Financial Officer, effective as of the commencement of her employment with the Company, which is expected to be on or about March 25, 2024 (the “Effective Date”), following Mr. Arkowitz’s retirement effective as of March 15, 2024 (the “Retirement Date”).
  evidence_url: https://www.sec.gov/Archives/edgar/data/1609809/000119312524045328/0001193125-24-045328-index.htm

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