Katie Seitz Evans - 09 Jan 2026 Form 4 Insider Report for MAGNITE, INC. (MGNI)

Role: President, Operations
Signature: /s/ Aaron Saltz, attorney-in-fact
Issuer symbol: MGNI
Transactions as of: 09 Jan 2026
Net transactions value: -$433,938
Form type: 4
Filing time: 12 Jan 2026, 16:30:13 UTC
Previous filing: 05 Jan 2026
Next filing: 18 Feb 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Evans Katie Seitz	President, Operations	C/O MAGNITE, INC., 1250 BROADWAY, 9TH FLOOR, NEW YORK	/s/ Aaron Saltz, attorney-in-fact	12 Jan 2026	0001700262

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	MGNI	Common Stock	Options Exercise	$0	+51,300	+10%	$0.000000	562,308	09 Jan 2026	Direct	F1
transaction	MGNI	Common Stock	Tax liability	$433,938	-26,836	-4.8%	$16.17	535,472	09 Jan 2026	Direct	F2

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
transaction	MGNI	Performance Stock Units	Options Exercise	$0	-51,300	-100%	$0.000000	0	09 Jan 2026	Common Stock	51,300		Direct	F1, F3, F4

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	Equity grant under the Company's Amended and Restated 2014 Equity Incentive Plan.
F2	Represents the non-discretionary forfeiture of shares on behalf of the Reporting Person pursuant to an arrangement mandated by the Issuer to cover the tax withholding obligations associated with the vesting of the performance stock units ("PSUs") being reported herein.
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 51,300 shares.