[Form 4] MAGNITE, INC. Insider Trading Activity

Rhea-AI Filing Summary

Magnite, Inc. (MGNI) reported an insider equity transaction involving its chief technology officer. On 11/15/2025, 7,129 shares of common stock were forfeited in a non-discretionary transaction to cover tax withholding obligations tied to the vesting of restricted stock units. After this tax-related forfeiture, the reporting person beneficially owned 231,824 shares of Magnite common stock. This total includes 324 shares acquired on November 15, 2025 under the company’s Employee Stock Purchase Plan.

SEC Form 4

FORM 4

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
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

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

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Buonasera David

(Last) (First) (Middle)

C/O MAGNITE, INC.

1250 BROADWAY, 9TH FLOOR

(Street)

NEW YORK NY 10001

(City) (State) (Zip)

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)
	CHIEF TECHNOLOGY OFFICER

3. Date of Earliest Transaction (Month/Day/Year)
11/15/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	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	11/15/2025		F(1)		7,129	D	$14.15	231,824(2)	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 (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	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 (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (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: 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

Explanation of Responses:

1. Represents the non-discretionary forfeiture of shares on behalf of the Reporting Person pursuant to an arrangement mandated by the Issuer to cover the tax withholding obligations associated with the vesting of restricted stock units.

2. Includes 324 shares acquired by the Reporting Person on November 15, 2025 under the Issuer's Employee Stock Purchase Plan.

	/s/ Aaron Saltz, attorney-in-fact	11/18/2025
	** Signature of Reporting Person	Date
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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What insider transaction did Magnite (MGNI) report in this Form 4?

The filing reports that the chief technology officer had 7,129 shares of Magnite common stock forfeited on 11/15/2025 to satisfy tax withholding obligations related to vested restricted stock units.

Was the Magnite Form 4 transaction a discretionary sale by the insider?

No. The filing states the 7,129-share disposition represents a non-discretionary forfeiture of shares mandated by Magnite to cover tax withholding on vested restricted stock units.

How many Magnite (MGNI) shares does the reporting person own after this transaction?

Following the reported tax-related forfeiture, the reporting person beneficially owns 231,824 shares of Magnite common stock.

Does the Magnite insider’s share count include Employee Stock Purchase Plan shares?

Yes. The reported 231,824 shares include 324 shares acquired by the reporting person on November 15, 2025 under Magnite’s Employee Stock Purchase Plan.

What is the reported price associated with the Magnite Form 4 share forfeiture?

The Form 4 shows the 7,129 forfeited shares at a price of $14.15 per share in the transaction table.

What role does the reporting person hold at Magnite (MGNI)?

The reporting person is identified as an officer of Magnite, serving as the company’s chief technology officer.