X0306 4 2022-03-21 0 0001595974 MAGNITE, INC. MGNI 0001575492 PEARSON DAVID T. C/O MAGNITE, INC. 1250 BROADWAY, 15TH FLOOR NEW YORK NY 10001 1 0 0 0 Common Stock 2022-03-21 4 A 0 32422 0.00 A 32422 D Represents restricted stock units of which, (i) 30,145 shares will vest in three equal annual increments on each of March 21, 2023, March 21, 2024 and March 21, 2025 or, if earlier, upon a change of control of the Issuer; and (ii) 2,277 shares will vest on the date of the 2022 annual meeting of the Issuer's stockholders. Granted as compensation for services. /s/ Aaron Saltz, Attorney-in-Fact 2022-03-23