Magnite (MGNI) officer reports two open-market sales totaling 40,000 shares

Rhea-AI Filing Summary

Magnite, Inc. (MGNI) insider sale disclosure: The Form 4 filed for Sean Patrick Buckley, President, Revenue, reports two open-market sales totaling 40,000 shares on 09/08/2025 and 09/09/2025. The first sale on 09/08/2025 disposed of 20,000 shares at a weighted-average price of $25.56 and the second on 09/09/2025 disposed of 20,000 shares at a weighted-average price of $24.61. Following these transactions, Mr. Buckley beneficially owns 287,193 shares, down from 307,193 prior to the second sale.

The filing includes footnotes clarifying that each reported price is a weighted average of multiple trades within specified ranges and offers to provide detailed per-trade quantities on request. The Form 4 was signed by an attorney-in-fact on 09/10/2025. No derivative transactions or other changes in beneficial ownership are reported in this filing.

Positive

• Continued substantial ownership: Reporting person still beneficially owns 287,193 shares after the sales
• Complete disclosure: Filing includes weighted-average price footnotes and offers to provide per-trade details on request

Negative

• Insider sales: Officer sold a total of 40,000 shares in two open-market transactions
• Decrease in direct holdings: Beneficial ownership fell from 307,193 to 287,193 shares

Insights

Securities Analyst

TL;DR: Officer sold 40,000 MGNI shares over two days, reducing direct holdings to 287,193 shares; transactions were open-market sales at weighted-average prices.

These transactions are routine insider dispositions disclosed on Form 4. The sales occurred across two consecutive trading dates and are reported with weighted-average prices and accompanying footnotes that state the trades occurred at prices within specified ranges. The reduction in beneficial ownership is clear and quantifiable: a decline of 20,000 shares after the first sale and a further 20,000 after the second, leaving 287,193 shares beneficially owned. There is no indication in this filing of derivative activity, option exercises, grants, or any planned Rule 10b5-1 trading plan.

Corporate Governance Expert

TL;DR: Disclosure is complete for reported open-market sales; footnotes provide weighted-price ranges and offer detailed breakdown if requested.

The Form 4 provides the legally required disclosure for changes in beneficial ownership by an officer. The explanatory footnotes comply with common practice by reporting weighted-average prices and offering to supply intrarange details on request. The filing was executed by an attorney-in-fact and includes the post-transaction beneficial ownership figure. From a governance and disclosure standpoint, the filing appears to meet Section 16 reporting requirements based on the information provided in this document.

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

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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^*

Buckley Sean Patrick

(Last) (First) (Middle)

C/O MAGNITE, INC.

1250 BROADWAY, 15TH 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)
09/08/2025

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	09/08/2025		S		20,000	D	$25.56(1)	307,193	D
Common Stock	09/09/2025		S		20,000	D	$24.61(2)	287,193	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. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $25.50 to $25.69, 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.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $24.51 to $25.07, 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	09/10/2025
	** 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).
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FAQ

What transactions did the Form 4 for MGNI report?

The Form 4 reports two open-market sales of MGNI common stock by Sean Patrick Buckley: 20,000 shares sold on 09/08/2025 and 20,000 shares sold on 09/09/2025.

At what prices were the MGNI shares sold by the reporting person?

The filing reports weighted-average prices: $25.56 for the 09/08/2025 trades (range $25.50–$25.69) and $24.61 for the 09/09/2025 trades (range $24.51–$25.07).

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

After the reported sales, the reporting person beneficially owns 287,193 shares of MGNI common stock.

Does the Form 4 show any derivative transactions or option exercises?

No. Table II for derivative securities shows no entries; only Non-Derivative common stock sales are reported.

Who signed the Form 4 and when?

The Form 4 was signed by /s/ Aaron Saltz, attorney-in-fact on 09/10/2025.