secwatch.observer — SEC 8-K summary
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Issuer:     MAGNITE, INC. (MGNI)
CIK:        0001595974
Form:       8-K
Filed at:   2026-09-21T21:05:19+00:00
Accession:  0001595974-26-000032
Event type: leadership
Sentiment:  neutral
Materiality: 0.60
Item codes: 5.02, 9.01
LLM model:  deepseek-v4-flash:cloud@v2

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

Source:
  EDGAR index:    https://www.sec.gov/Archives/edgar/data/1595974/000159597426000032/0001595974-26-000032-index.htm
  Primary doc:    https://www.sec.gov/Archives/edgar/data/1595974/000159597426000032/mgni-20260921.htm
  HTML page:      https://secwatch.observer/filing/0001595974-26-000032

License: Source filings: public domain (SEC EDGAR). Summaries (headline + bullets): CC-BY-4.0; attribute https://secwatch.observer