0001595974 2020-01-01 2020-12-31 0001595974 2020-06-30 0001595974 2021-02-19 iso4217:USD shares CA 0001595974 true FY 10-K/A true 2020-12-31 --12-31 2020 false 001-36384 MAGNITE, INC. DE 20-8881738 6080 Center Drive, 4th Floor Los Angeles, 90045 310 207-0272 Common stock, par value $0.00001 per share MGNI NASDAQ No No Yes Yes Accelerated Filer false false true false 646300000 115570100 None. EXPLANATORY NOTE On February 25, 2021, Magnite, Inc. (the “Company”) filed its Annual Report on Form 10-K for the fiscal year ended December 31, 2020 (the “Original Form 10-K”). This Amendment No. 1 (the “Amendment”) amends Part III, Items 10 through 14 of the Original Form 10-K to include information previously omitted from the Original Form 10-K in reliance on General Instruction G(3) to Form 10-K. As a result of an administrative calendar oversight, the Company did not file a proxy statement involving the election of directors or an amendment to the Original Form 10-K before April 30, 2021, as required by the instructions. Accordingly, Part III of the Original Form 10-K is hereby amended as set forth below. In addition, as required by Rule 12b-15 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), new certifications by our principal executive officer and principal financial officer are filed as exhibits to this Amendment under Item 15 of Part IV hereof, which has been restated in its entirety. Except as stated herein, this Amendment does not reflect events occurring after the filing of the Original Form 10-K with the Securities and Exchange Commission on February 25, 2021 and no attempt has been made in this Amendment to modify or update other disclosures as presented in the Original Form 10-K.