X0609 4 2026-05-15 0001595974 MAGNITE, INC. MGNI 0001100612 BARRETT MICHAEL G. false C/O MAGNITE, INC. 1250 BROADWAY, 9TH FLOOR NEW YORK NY 10001 true true false false CEO 0 Common Stock 2026-05-15 4 F 0 10404 12.82 D 403074 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 1,316 shares acquired by the Reporting Person on May 15, 2026 under the Issuer's Employee Stock Purchase Plan. /s/ Aaron Saltz, attorney-in-fact 2026-05-19