---
schema_version: "secwatch.filing_event.v1"
accession: "0001288847-25-000063"
form_type: "8-K"
ticker: "FIVN"
cik: "0001288847"
company_name: "Five9, Inc."
filed_at: "2025-03-24T23:59:59+00:00"
generated_at: "2026-05-24T06:22:07.416253+00:00"
event_type: "leadership"
sentiment: "neutral"
materiality_score: 0.4
calibrated_materiality_score: 0.4
confidence: "high"
source: SEC EDGAR
---

# Five9: Director Acosta to leave board; Mariner moves to Class II; board size reduced to nine

## Summary
- Jack Acosta not nominated for re-election at May 21, 2025 annual meeting.
- Jonathan Mariner resigned Class III, reappointed Class II director effective March 19.
- Board size to be reduced to nine directors, Class II to three, at conclusion of annual meeting.
- Maria Walker to succeed as Audit Committee chair after the annual meeting.

## SEC filing metadata
- accession: 0001288847-25-000063
- form_type: 8-K
- ticker: FIVN
- cik: 0001288847
- company_name: Five9, Inc.
- filed_at: 2025-03-24T23:59:59+00:00
- event_type: leadership
- sentiment: neutral
- materiality_score: 0.4
- calibrated_materiality_score: 0.4
- confidence: high
- sec_items: 5.02, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1288847/000128884725000063/0001288847-25-000063-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1288847/000128884725000063/fivn-20250319.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001288847-25-000063
- JSON: https://secwatch.observer/filing/0001288847-25-000063.json
- Plain text: https://secwatch.observer/filing/0001288847-25-000063.txt

## Key facts
- Executive change
  Jack Acosta departed as Director at Five9, Inc..
  - Action: not nominated for re-election
  - Role: Director
  source text: The board of directors (the “Board”) of the Company has determined that Mr. Jack Acosta, who is currently a Class II director, will not be nominated to stand for re-election as a Class II director at the Annual Meeting.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1288847/000128884725000063/0001288847-25-000063-index.htm
- Executive change
  Jonathan Mariner was appointed as Director, Class II at Five9, Inc..
  - Action: resigned from Class III and reappointed as Class II director
  - Role: Director, Class II
  source text: The Board accepted Mr. Mariner’s resignation, reduced Class III to three members, increased Class II to four members and immediately reappointed Mr. Mariner as a Class II director with a term set to expire at the Annual Meeting.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1288847/000128884725000063/0001288847-25-000063-index.htm

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