Form 4 for MGNI MAGNITE, INC.

Accepted 2026-01-12 00:00:00 ET · period of report 2026-01-09 · accession 0001523288-26-000002 · SEC index · Original document

Summary rows

Aggregated the way they appear in lists: one row per insider, transaction code and security table.

X	Filed	Traded	Ticker	Insider	Title	Type	Price	Qty	Owned	ΔOwn	Value
D	2026-01-12	2026-01-09	MGNI	Day David	CFO	M - OptEx	$0.00	+72.7K	573.2K	+15%	$0
D	2026-01-12	2026-01-09	MGNI	Day David	CFO	F - Tax	$16.17	-35.2K	538.1K	-6%	-$568.7K
D	2026-01-12	2026-01-09	MGNI	Day David	CFO	M - OptEx	$0.00	-72.7K	0	-100%	$0

Purchase Sale Sale after option exercise All abbreviations

#	Table	Security	Date	Code	A/D	Shares	Price	Owned after	Own	Exercise / expiry	Underlying	Footnotes
1	Common	Common Stock	2026-01-09	M	A	72,675	$0.00	573,245	D	—	—	(F1) Equity grant under the Company's Amended and Restated 2014 Equity Incentive Plan.
2	Common	Common Stock	2026-01-09	F	D	35,169	$16.17	538,076	D	—	—
3	Derivative	Performance Stock Units	2026-01-09	M	D	72,675	$0.00	0	D	— · — to —	72,675 Common Stock	(F1) Equity grant under the Company's Amended and Restated 2014 Equity Incentive Plan. (F3) Each PSU represents a contingent right to receive, on vesting, one share of the Issuer's common stock, subject to Issuer performance as more specifically described in Footnote 4 herein. (F4) Vesting of the PSU was determined based on the Issuer's total stockholder return ("TSR") for the three-year period beginning on January 1, 2023 relative to the TSRs of the companies in the Russell 2000 index over that period. The number of PSUs reported in column 5 on the Form 4 filed with the Securities and Exchange Commission on January 4, 2023 reflected the target number of PSUs initially subject to the award. The award was eligible to vest as to 0% to 150% of the target number of PSUs. On January 9, 2026, the Compensation Committee of the Issuer's Board of Directors determined that, based on 126.35% achievement, the Reporting Person actually vested 72,675 shares.