X0508 4 2025-11-15 0001595974 MAGNITE, INC. MGNI 0001966857 Buonasera David C/O MAGNITE, INC. 1250 BROADWAY, 9TH FLOOR NEW YORK NY 10001 false true false false CHIEF TECHNOLOGY OFFICER 0 Common Stock 2025-11-15 4 F 0 7129 14.15 D 231824 D 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 restricted stock units. Includes 324 shares acquired by the Reporting Person on November 15, 2025 under the Issuer's Employee Stock Purchase Plan. /s/ Aaron Saltz, attorney-in-fact 2025-11-18