MGNI President, Revenue reports stock forfeiture and sale in Form 4

Rhea-AI Filing Summary

Magnite, Inc. insider transaction: A company officer, identified as President, Revenue, reported two transactions in Magnite, Inc. common stock. On 11/15/2025, 11,642 shares were forfeited at $14.15 per share to cover tax withholding obligations tied to the vesting of restricted stock units, as required by the company. On 11/18/2025, 4,426 shares were sold at a weighted average price of $13.36 per share under a pre‑arranged Rule 10b5‑1 trading plan adopted on November 24, 2023. After these transactions, the officer beneficially owned 271,125 shares of Magnite common stock directly.

Insider Trade Summary

Net Seller: 4,426 shares ($59,131)

Net Sell 2 txns

Insider Buckley Sean Patrick

Role President, Revenue

Sold 4,426 shs ($59K)

Type	Security	Shares	Price	Value
Sale	Common Stock	4,426	$13.36	$59K
Tax Withholding	Common Stock	11,642	$14.15	$165K

Holdings After Transaction: Common Stock — 271,125 shares (Direct)

Footnotes (1)

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. The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 24, 2023. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $13.14 to $13.50, 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 to this Form 4.

Form 4 Insider Transactions: What Each Field Means →

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

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

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

X

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^*

Buckley Sean Patrick

(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)
	President, Revenue

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)		11,642	D	$14.15	275,551	D
Common Stock	11/18/2025		S(2)		4,426	D	$13.36(3)	271,125	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. The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 24, 2023.

3. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $13.14 to $13.50, 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 to this Form 4.

	/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 activity did MGNI disclose in this Form 4 filing?

The filing reports that Magnite, Inc.'s President, Revenue had 11,642 shares forfeited on 11/15/2025 to cover tax withholding on vesting restricted stock units and sold 4,426 shares on 11/18/2025.

How many MGNI shares does the reporting person own after these transactions?

Following the reported transactions, the officer beneficially owns 271,125 shares of Magnite, Inc. common stock directly.

What was the purpose of the 11,642 MGNI shares forfeited on 11/15/2025?

The 11,642 Magnite shares were non-discretionary forfeitures required by the company to cover tax withholding obligations associated with the vesting of restricted stock units.

At what price were the 4,426 MGNI shares sold on 11/18/2025?

The 4,426 Magnite shares were sold at a weighted average price of $13.36 per share, in multiple trades between $13.14 and $13.50.

Was the MGNI stock sale made under a Rule 10b5-1 trading plan?

Yes. The 4,426-share sale on 11/18/2025 was effected under a Rule 10b5-1 trading plan adopted by the reporting person on November 24, 2023.

What is the role of the reporting person at Magnite, Inc.?

The reporting person is an officer of Magnite, Inc., serving as President, Revenue.