X0306 4 2021-08-09 0 0001595974 MAGNITE, INC. MGNI 0001807986 Saltz Aaron C/O MAGNITE, INC. 6080 CENTER DRIVE, 4TH FLOOR LOS ANGELES CA 90045 0 1 0 0 General Counsel Common Stock 2021-08-09 4 M 0 1791 3.61 A 264897 D Common Stock 2021-08-09 4 S 0 5000 33.81 D 259897 D Stock Option (Right to Buy) 3.61 2021-08-09 4 M 0 1791 0.00 D 2028-02-27 Common Stock 1791 43600 D This exercise and subsequent sales were made pursuant to a Rule 10b5-1 Trading Plan adopted by the Reporting Person. 25% of the total number of shares underlying this option vested on February 14, 2019 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. Equity grant under the Company's 2014 Equity Incentive Plan. /s/ Aaron Saltz 2021-08-11