[Form 4] Magnite, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Brian Gephart, Chief Accounting Officer of Magnite, Inc. (MGNI), reported the sale of 27,671 shares of common stock on 09/04/2025. The sales were made pursuant to a Rule 10b5-1 trading plan adopted on 06/05/2025. The weighted-average price for the shares sold was reported as $24.71, with individual trade prices ranging from $24.26 to $24.94. After the reported disposition, the filing shows 92,898 shares beneficially owned by the reporting person. The Form 4 was signed by an attorney-in-fact on 09/05/2025.

Positive

• Sale executed under a Rule 10b5-1 plan, indicating a pre-established, compliant trading arrangement
• Transparent pricing disclosure including weighted-average price ($24.71) and detailed price range ($24.26–$24.94)
• Reporting provides remaining beneficial ownership (92,898 shares), showing continued stake

Negative

• Insider sale of 27,671 shares may be perceived negatively by some investors as an officer divestiture
• Form shows direct reduction in holdings which could be interpreted as reduced insider alignment, depending on context

Insights

Securities Analyst

TL;DR: Officer sale under a 10b5-1 plan reduces holdings but was pre-arranged, so market impact is likely limited.

The sale of 27,671 shares by the Chief Accounting Officer was executed under a pre-established Rule 10b5-1 plan adopted on 06/05/2025, which typically mitigates concerns about opportunistic timing. The weighted-average price of $24.71 and the disclosed price range provide transparency about execution. The remaining beneficial ownership of 92,898 shares maintains a meaningful residual stake, but continued monitoring of subsequent filings is prudent to assess ongoing insider selling activity.

Corporate Governance Expert

TL;DR: Structured insider sale shows adherence to governance procedures, though officer divestiture merits attention for signaling.

Disposing shares via a documented 10b5-1 plan indicates compliance with insider trading controls and reduces legal risk. From a governance perspective, the filing appropriately discloses the plan adoption date and price range. While a planned sale does not necessarily indicate negative firm-specific information, investors often interpret officer sales as a potential signal; the magnitude here is moderate relative to the officer's remaining holdings.

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^*

Gephart Brian

(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)
	CHIEF ACCOUNTING OFFICER

3. Date of Earliest Transaction (Month/Day/Year)
09/04/2025

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	09/04/2025		S(1)		27,671	D	$24.71(2)	92,898	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. These shares were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on June 5, 2025.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $24.26 to $24.94, 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.

	/s/ Aaron Saltz, attorney-in-fact	09/05/2025
	** 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 did MGNI insider Brian Gephart sell on the Form 4?

The filing reports the sale of 27,671 shares of Magnite (MGNI) common stock executed on 09/04/2025.

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

The weighted-average sale price was $24.71, with individual trade prices ranging from $24.26 to $24.94.

Was the sale by the MGNI officer part of a 10b5-1 plan?

Yes. The shares were sold pursuant to a Rule 10b5-1 trading plan adopted on 06/05/2025.

How many MGNI shares does the reporting person own after the sale?

After the reported transaction the filing shows 92,898 shares beneficially owned by the reporting person.

When was the Form 4 filed and who signed it?

The Form 4 was signed by an attorney-in-fact on 09/05/2025 and filed pursuant to Section 16 reporting requirements.