X0306 4 2023-01-01 0 0001595974 MAGNITE, INC. MGNI 0001100612 BARRETT MICHAEL G. C/O MAGNITE, INC. 1250 BROADWAY,15TH FLOOR NEW YORK NY 10001 1 1 0 0 CEO Common Stock 2023-01-01 4 A 0 121951 0.00 A 1552187 D Performance Stock Units 2023-01-01 4 A 0 169173 0.00 A Common Stock 169173 169173 D Stock Option (Right to Buy) 10.59 2023-01-01 4 A 0 129870 0.00 A 2033-01-01 Common Stock 129870 129870 D Represents restricted stock units that vest as follows: 33,028 on February 15, 2024, 7,622 on each May 15, August 15, November 15, and February 15 thereafter until November 15, 2026 and 5,081 on February 15, 2027, 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. Each performance stock unit ("PSU") represents a contingent right to receive on vesting one share of the Issuer's common stock. Vesting of the PSU will be determined based on the Issuer's total stockholder return ("TSR") for the three-year period beginning on the grant date of the award relative to the TSRs of the companies in the Russell 2000 index over that period. The number of PSUs reported in column 5 reflects the target number of PSUs subject to the award. The award is eligible to vest as to 0% to 150% of the target number of PSUs. 25% of the total number of shares underlying this option will vest on January 1, 2024 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 2023-01-04