MGNI Form 4: CTO Buonasera Sells 7,834 Shares in Sell-to-Cover

Rhea-AI Filing Summary

Magnite insider sale to cover taxes from vested RSUs. David Buonasera, Chief Technology Officer, reported a sale of 7,834 shares of Magnite, Inc. (MGNI) on 08/18/2025 at a price of $23.85 per share. The filing states the sale was executed to satisfy tax-withholding obligations arising from the settlement of vested Restricted Stock Units and was mandated by the issuer's sell-to-cover election rather than a discretionary decision by the reporting person. After the transaction Buonasera beneficially owned 241,579 shares, held directly. The Form 4 was signed by attorney-in-fact Aaron Saltz on 08/20/2025.

Positive

• Clear disclosure that the sale was a mandated sell-to-cover to satisfy tax withholding on vested RSUs
• Timely and complete Form 4 filing signed by an attorney-in-fact, indicating compliance with Section 16 reporting

Negative

• None.

Insights

Financial Analyst

TL;DR: Routine sell-to-cover by an officer; small percentage of holdings, limited market impact.

The transaction represents a non-discretionary, tax-motivated sale of 7,834 shares at $23.85 to satisfy withholding on vested RSUs. Relative to the post-transaction direct holding of 241,579 shares, the sale is modest (about 3.2% of reported post-sale holdings). There is no indication of additional sales or derivative transactions in this filing. For investors, this filing documents compensation-related liquidity activity but provides no new operational or financial information about Magnite.

Corporate Governance Expert

TL;DR: Disclosure is clear and compliant; sale was mandated by company policy, not voluntary insider trading.

The Form 4 clearly states the sale was to cover tax withholding on vested RSUs and was not a discretionary trade by the reporting person. The filing includes the reporting persons role as CTO and shows timely reporting by an attorney-in-fact. From a governance perspective, the filing meets Section 16 disclosure requirements and clarifies the nature of the transaction, reducing ambiguity about insider intent.

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
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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, 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 TECHNOLOGY OFFICER

3. Date of Earliest Transaction (Month/Day/Year)
08/18/2025

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	08/18/2025		S(1)		7,834	D	$23.85	241,579	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 to cover the Reporting Person's tax obligation resulting from the settlement of vested Restricted Stock Units. The sale is mandated by the Issuer's election to require the satisfaction of tax withholding obligations to be funded by sell to cover transactions and does not represent a discretionary transaction by the Reporting Person.

	/s/ Aaron Saltz, attorney-in-fact	08/20/2025
	** 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 David Buonasera report on Form 4?

The filing reports a sale of 7,834 shares of Magnite (MGNI) on 08/18/2025 at $23.85 per share to cover tax withholding from vested RSUs.

Why were the shares sold according to the Form 4?

The sale was executed to satisfy tax-withholding obligations resulting from the settlement of vested Restricted Stock Units and was mandated by the issuers sell-to-cover election.

How many MGNI shares does David Buonasera own after the sale?

After the reported transaction, Buonasera beneficially owned 241,579 shares, held directly.

Who signed the Form 4 and when was it filed?

The Form 4 was signed by Aaron Saltz, attorney-in-fact and dated 08/20/2025.

Is this sale considered discretionary insider trading?

No. The filing states the sale was mandated by the issuer as a sell-to-cover for tax withholding and was not a discretionary transaction by the reporting person.