Sec Form 4 Filing - Saltz Aaron @ MAGNITE, INC. - 2021-09-08

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Saltz Aaron 2. Issuer Name and Ticker or Trading Symbol MAGNITE, INC. [ MGNI] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) General Counsel (Last) (First) (Middle) C/O MAGNITE, INC., 6080 CENTER DRIVE, 4TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 09/08/2021 (Street) LOS ANGELES, CA90045 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 09/08/2021 M 5,410 A $ 7.74 263,826 D Common Stock 09/08/2021 M 28,852 A $ 5.46 292,678 D Common Stock 09/10/2021 M 965 A $ 5.28 293,643 D Common Stock 09/10/2021 M 8,264 A $ 3.61 301,907 D Common Stock 09/10/2021 M 4,575 A $ 5.16 306,482 D Common Stock 09/10/2021 S 40,004 D $ 30.21 ( 1 ) 266,478 D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Stock Option (Right to Buy) $ 7.74 09/08/2021 M 5,410 ( 2 ) 07/31/2023 Common Stock 5,410 $ 0 ( 3 ) 0 D Stock Option (Right to Buy) $ 5.46 09/08/2021 M 28,852 ( 2 ) 03/05/2023 Common Stock 28,852 $ 0 ( 3 ) 0 D Stock Option (Right to Buy) $ 5.28 09/10/2021 M 965 ( 4 ) 04/01/2030 Common Stock 965 $ 0 ( 3 ) 29,911 D Stock Option (Right to Buy) $ 3.61 09/10/2021 M 8,264 ( 5 ) 02/27/2028 Common Stock 8,264 $ 0 ( 3 ) 35,336 D Stock Option (Right to Buy) $ 5.16 09/10/2021 M 4,575 ( 6 ) 02/28/2029 Common Stock 4,575 $ 0 ( 3 ) 22,872 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Saltz Aaron C/O MAGNITE, INC. 6080 CENTER DRIVE, 4TH FLOOR LOS ANGELES, CA90045 General Counsel Signatures /s/ Aaron Saltz 09/10/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $30.15 to $30.33, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. ( 2 )This option is fully vested and immediately exercisable. ( 3 )Equity grant under the Company's 2014 Equity Incentive Plan. ( 4 )25% of the total number of shares underlying this option vested on April 1, 2021 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. ( 5 )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. ( 6 )25% of the total number of shares underlying this option vested on February 14, 2020 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.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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