---
schema_version: "secwatch.filing_event.v1"
accession: "0001595974-26-000032"
form_type: "8-K"
ticker: "MGNI"
cik: "0001595974"
company_name: "MAGNITE, INC."
filed_at: "2026-09-21T21:05:19+00:00"
generated_at: "2026-09-21T21:06:09.399573+00:00"
event_type: "leadership"
sentiment: "neutral"
materiality_score: 0.6
calibrated_materiality_score: 0.6
confidence: "high"
source: SEC EDGAR
---

# Magnite promotes Brian Gephart to CFO, Haas Sullivan to CAO, effective Oct 1, 2026

## Summary
- Brian Gephart, CAO since June 2021, becomes CFO on Oct 1, 2026, succeeding retiring David Day (10-year tenure).
- Gephart receives equity award worth $2.25M: 70% RSUs ($1.575M) vesting over 4 years with 1-year cliff; 30% PSUs ($675k) granted in 2027.
- Haas Sullivan, VP of Accounting since April 2020, becomes CAO on Oct 1, 2026; gets RSUs valued at ~$600k, 4-year vest, 1-year cliff.
- Both appointments trigger amended or new Executive Severance Agreements; Gephart gets 12-month severance terms, Sullivan 3-month (6-month on sale).
- Prior roles: Gephart was CFO of Leaf Group; Sullivan held VP Accounting at Magnite and audit at Deloitte.

## SEC filing metadata
- accession: 0001595974-26-000032
- form_type: 8-K
- ticker: MGNI
- cik: 0001595974
- company_name: MAGNITE, INC.
- filed_at: 2026-09-21T21:05:19+00:00
- event_type: leadership
- sentiment: neutral
- 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/1595974/000159597426000032/0001595974-26-000032-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1595974/000159597426000032/mgni-20260921.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001595974-26-000032
- JSON: https://secwatch.observer/filing/0001595974-26-000032.json
- Plain text: https://secwatch.observer/filing/0001595974-26-000032.txt

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