Magnite, Inc. (MGNI) executive sells 67,179 shares under 10b5-1 plan

Rhea-AI Filing Summary

MAGNITE, INC. executive Sean Patrick Buckley, President, Revenue & Market Strategy, exercised 28,703 stock options at $13.90 per share on August 6, 2026, acquiring the same number of common shares, then sold 67,179 shares at prices from $23.00 to $25.09. Following the exercise, 57,405 stock options remain outstanding and are fully vested and immediately exercisable. All reported transactions were effected under a Rule 10b5-1 trading plan adopted on September 10, 2025.

Insider Trade Summary 10b5-1

Exercise and sale activity reported; no spread calculated

Exercise and Sale 4 txns

Insider Buckley Sean Patrick

Role See Remarks

Sold 67,179 shs ($1.65M)

Approx. gross sale proceeds $1.65M

Approx. exercise cost $399K

Type	Security	Shares	Price	Value
Exercise	Stock Option (right to buy) F1, F3, F2	28,703	$0.00	$0.00
Exercise	Common Stock F1	28,703	$13.90	$399K
Sale	Common Stock F1	47,942	$25.09	$1.20M
Sale	Common Stock F1	19,237	$23.00	$442K

Holdings After Transaction: Stock Option (right to buy) — 57,405 shares (Direct); Common Stock — 315,805 shares (Direct)

Footnotes (3)

1. F1. The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on September 10, 2025.
2. F2. The stock options have fully vested and are immediately exercisable.
3. F3. Granted as compensation for services.

Key Figures

Options exercised: 28,703 shares Exercise price: $13.90 per share Shares sold (tranche 1): 47,942 shares at $25.09 +4 more

7 metrics

Options exercised 28,703 shares Stock options exercised on 2026-08-06 at $13.90 per share, converting into common stock

Exercise price $13.90 per share Exercise price for 28,703 stock options exercised on 2026-08-06

Shares sold (tranche 1) 47,942 shares at $25.09 Common stock sale on 2026-08-06

Shares sold (tranche 2) 19,237 shares at $23.00 Second common stock sale on 2026-08-06

Total shares sold 67,179 shares Aggregate common shares sold across two sales on 2026-08-06

Remaining stock options 57,405 shares Stock options remaining after exercise; fully vested and immediately exercisable, expiring 2032-02-01

Rule 10b5-1 plan adoption date September 10, 2025 Date Buckley adopted the trading plan governing these transactions

Key Terms

Rule 10b5-1 trading plan, Stock Option (right to buy), Exercise or conversion of derivative security

3 terms

Rule 10b5-1 trading plan regulatory

"reported transaction was effected pursuant to a Rule 10b5-1 trading plan"

A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.

Stock Option (right to buy) financial

"security_title: Stock Option (right to buy) with 28,703 underlying shares"

Exercise or conversion of derivative security financial

"transaction_code_description: Exercise or conversion of derivative security"

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 08/07/2026 - 05:14 PM Accepted by SEC EDGAR 08/07/2026 - 05:14 PM Learn about SEC filing dates

FAQ

What insider transactions did Magnite (MGNI) executive Sean Patrick Buckley report?

Sean Patrick Buckley reported exercising 28,703 stock options at $13.90 per share and selling 67,179 common shares on August 6, 2026. The trades were made pursuant to a Rule 10b5-1 trading plan adopted on September 10, 2025.

How many Magnite (MGNI) shares did Buckley sell, and at what prices?

Buckley sold a total of 67,179 Magnite common shares on August 6, 2026. He sold 47,942 shares at $25.09 per share and 19,237 shares at $23.00 per share under his Rule 10b5-1 trading plan.

What stock options did Buckley exercise in this Magnite (MGNI) Form 4?

He exercised 28,703 stock options with an exercise price of $13.90 per share, converting them into an equal number of Magnite common shares. These options are described as fully vested and immediately exercisable and have an expiration date of February 1, 2032.

Does this Magnite (MGNI) Form 4 involve a Rule 10b5-1 trading plan?

Yes. The filing states the transactions were effected under a Rule 10b5-1 trading plan adopted by Sean Patrick Buckley on September 10, 2025. The document’s 10b5-1 checkbox is also marked to affirm plan-based trading.

How many stock options does Buckley still hold after these Magnite (MGNI) transactions?

After exercising 28,703 options, Buckley is reported as holding 57,405 stock options on the same grant. These remaining options are fully vested and immediately exercisable and carry an expiration date of February 1, 2032.

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^*

Buckley Sean Patrick

(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)
	See Remarks

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
08/06/2026

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	08/06/2026		M(1)		28,703	A	$13.9	382,984	D
Common Stock	08/06/2026		S(1)		47,942	D	$25.09	335,042	D
Common Stock	08/06/2026		S(1)		19,237	D	$23	315,805	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
Stock Option (right to buy)	$13.9	08/06/2026		M(1)			28,703	(2)	02/01/2032	Common Stock	28,703	$0(3)	57,405	D

Explanation of Responses:

1. The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on September 10, 2025.

2. The stock options have fully vested and are immediately exercisable.

3. Granted as compensation for services.

Remarks:

President, Revenue & Market Strategy

	/s/ Aaron Saltz, attorney-in-fact	08/07/2026
	** 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)