Magnite (MGNI) insider forfeits shares to cover RSU taxes

Rhea-AI Filing Summary

MAGNITE, INC. (MGNI) disclosed that Chief Accounting Officer Brian Gephart had 3,789 shares of common stock withheld on 2026-08-15 under a non-discretionary arrangement mandated by the company to cover tax withholding obligations arising from the vesting of restricted stock units. The shares were valued at $24.73 per share for this purpose, and Gephart now holds 102,328 shares of Magnite common stock directly.

Insider Trade Summary

Net Seller: 3,789 shares

Net Sell 1 txn

Insider Gephart Brian

Role CHIEF ACCOUNTING OFFICER

Type	Security	Shares	Price	Value
Tax Withholding	Common Stock F1	3,789	$24.73	$94K

Holdings After Transaction: Common Stock — 102,328 shares (Direct)

Footnotes (1)

1. F1. 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.

Key Figures

Shares forfeited for tax withholding: 3,789 shares Per-share value for tax withholding: $24.73 per share Shares owned after transaction: 102,328 shares

3 metrics

Shares forfeited for tax withholding 3,789 shares Non-discretionary forfeiture to cover tax obligations on RSU vesting

Per-share value for tax withholding $24.73 per share Value used in the tax-withholding disposition of 3,789 shares

Shares owned after transaction 102,328 shares Common stock directly owned by Brian Gephart following the transaction

Key Terms

restricted stock units, tax withholding obligations, non-discretionary forfeiture

3 terms

restricted stock units financial

"associated with the vesting of restricted stock units"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

tax withholding obligations financial

"to cover the tax withholding obligations associated with the vesting"

non-discretionary forfeiture financial

"Represents the non-discretionary forfeiture of shares on behalf"

FAQ

What insider transaction did MGNI report for Brian Gephart on this Form 4?

MAGNITE, INC. reported that Brian Gephart had 3,789 shares of common stock forfeited to cover tax withholding obligations tied to RSU vesting, at a value of $24.73 per share, under a non-discretionary, issuer-mandated arrangement.

Did the MGNI insider transaction represent an open-market sale of shares?

No. The Form 4 states the 3,789 shares represent a non-discretionary forfeiture to satisfy tax withholding obligations from RSU vesting, not an open-market sale, and was mandated by MAGNITE, INC. rather than initiated as a discretionary trade.

How many MGNI shares does Brian Gephart hold after this reported transaction?

After the tax-related share forfeiture, Brian Gephart directly holds 102,328 shares of MAGNITE, INC. common stock. This figure is reported as the total shares beneficially owned following the transaction in the Form 4 data.

What price per share was used for the MGNI tax-withholding transaction?

The transaction used a value of $24.73 per share for the 3,789 Magnite shares withheld. This reflects the per-share figure reported for the payment of tax liability by delivering or withholding securities linked to RSU vesting.

What is the transaction code used in this MGNI Form 4 and what does it mean?

The transaction code is F, which the Form 4 describes as payment of a tax liability by delivering or withholding securities. A footnote clarifies it as a non-discretionary forfeiture mandated by MAGNITE, INC. for RSU-related tax withholding.

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 08/18/2026 - 04:20 PM Accepted by SEC EDGAR 08/18/2026 - 04:20 PM Learn about SEC filing dates

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).

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, 9TH FLOOR

(Street)

NEW YORK NEW YORK 10001

(City) (State) (Zip)

UNITED STATES

(Country)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
08/15/2026

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

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

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

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	08/15/2026		F(1)		3,789	D	$24.73	102,328	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.

Remarks:

	/s/ Aaron Saltz, attorney-in-fact	08/18/2026
	** 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.
* Form 4: SEC 1474 (03-26)