Magnite (MGNI) CAO forfeits shares for RSU tax withholding in Form 4 filing

Rhea-AI Filing Summary

MAGNITE, INC. chief accounting officer Brian Gephart reported a routine share disposition tied to taxes. On the vesting of restricted stock units, 3,789 shares of common stock were forfeited at an indicated value of $12.82 per share to cover mandated tax withholding obligations. This non-discretionary forfeiture was executed under an arrangement required by the company, rather than as an open-market sale. Following the transaction, Gephart directly holds 118,596 shares of Magnite common stock.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Gephart Brian

Role CHIEF ACCOUNTING OFFICER

Type	Security	Shares	Price	Value
Tax Withholding	Common Stock	3,789	$12.82	$49K

Holdings After Transaction: Common Stock — 118,596 shares (Direct, null)

Footnotes (1)

1. [object Object]

Key Figures

Tax-withholding shares forfeited: 3,789 shares Indicated value per share: $12.82 per share Shares held after transaction: 118,596 shares +2 more

5 metrics

Tax-withholding shares forfeited 3,789 shares Common stock delivered to cover RSU tax obligations

Indicated value per share $12.82 per share Value used for tax-withholding disposition

Shares held after transaction 118,596 shares Direct holdings following Form 4 transaction

Transaction code F Payment of tax liability by delivering securities

Tax-withholding transactions 1 transaction, 3,789 shares Summary of non-discretionary tax forfeiture

Key Terms

restricted stock units, tax withholding obligations, non-discretionary forfeiture, Form 4, +1 more

5 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 of the Reporting Person"

Form 4 regulatory

"INSIDER FILING DATA (Form 4):"

Form 4 is a official document that company insiders, such as executives or major shareholders, file with regulators whenever they buy or sell company shares. It provides transparency about how those with inside knowledge are trading, helping investors see if insiders are confident in the company's prospects or may be selling for personal reasons. This information can influence investor decisions by revealing insiders' perspectives on the company's value.

Payment of exercise price or tax liability by delivering securities regulatory

"transaction_code_description": "Payment of exercise price or tax liability by delivering securities"

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).

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)
05/15/2026

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	05/15/2026		F(1)		3,789	D	$12.82	118,596	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.

	/s/ Aaron Saltz, attorney-in-fact	05/19/2026
	** 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)

FAQ

What insider transaction did Magnite (MGNI) report for Brian Gephart?

Magnite reported that chief accounting officer Brian Gephart had 3,789 common shares forfeited to cover tax withholding on vested restricted stock units. This was a non-discretionary, company-mandated arrangement rather than an open-market trade, and it reflects standard handling of equity compensation taxes.

Was the Magnite (MGNI) Form 4 transaction an open-market sale?

No, the Form 4 shows a non-discretionary forfeiture of shares to satisfy tax withholding obligations on restricted stock unit vesting. The shares were delivered back under an issuer-mandated arrangement, not sold by the insider on the open market for investment or timing reasons.

How many Magnite (MGNI) shares does Brian Gephart hold after this Form 4?

After the tax-withholding forfeiture of 3,789 shares, Brian Gephart directly holds 118,596 shares of Magnite common stock. This indicates the transaction affected only a small portion of his total direct holdings, consistent with routine equity compensation tax treatment.

What does the F transaction code mean in the Magnite (MGNI) Form 4?

The F code indicates shares were disposed of to pay an exercise price or tax liability. In this case, shares were forfeited to cover tax withholding on restricted stock units, reflecting compensation-related tax settlement rather than a discretionary buy or sell decision by the insider.

Why were Magnite (MGNI) shares forfeited for Brian Gephart on this date?

The shares were forfeited because restricted stock units vested and triggered income taxes. Under a company-mandated arrangement, 3,789 shares were delivered to satisfy tax withholding obligations, simplifying tax payment and avoiding the need for a separate cash transaction by the executive.