X0306 4 2022-02-01 0 0001595974 MAGNITE, INC. MGNI 0001523288 Day David C/O MAGNITE, INC. 1250 BROADWAY, 15TH FLOOR NEWYORK NY 10001 0 1 0 0 Chief Financial Officer Common Stock 2022-02-01 4 A 0 96819 0.00 A 345719 D Common Stock 2022-02-01 4 A 0 55325 0.00 A 401044 D Employee Stock Option (right to buy) 13.90 2022-02-01 4 A 0 68886 0.00 A 2032-02-01 Common Stock 68886 68886 D Represents restricted stock units (the "RSUs") that vest as follows: 25% of the total number of shares underlying the RSU will vest on February 15, 2023 and the remaining shares vest in 12 equal quarterly installments on the 15th of every May, August, November and February thereafter, subject to continued service to the Issuer through each vesting date. This equity grant may be subject to accelerated vesting in the event the Reporting Person's employment is terminated under certain circumstances. Equity grant under the Company's 2014 Equity Incentive Plan. Represents RSUs that vest as follows: 50% of the total number of shares underlying the RSU will vest on February 1, 2023 and 50% of the total number of shares underlying the RSU will vest on February 1, 2024, subject to continued service to the Issuer through each vesting date. This equity grant may be subject to accelerated vesting in the event the Reporting Person's employment is terminated under certain circumstances. 25% of the total number of shares underlying this option will vest on February 1, 2023 and the remaining shares vest 1/36 per month over the next 36 months thereafter, subject to continued service to the Issuer through each vesting date. This equity grant may be subject to accelerated vesting in the event the Reporting Person's employment is terminated under certain circumstances. /s/ Aaron Saltz, attorney-in-fact 2022-02-03