Magnite CTO sells 1,165 shares at $24

MAGNITE’s CTO reported a small Rule 10b5-1 planned sale of 1,165 shares, retaining 245,155 shares afterward.

Available on EDGAR 09/16/2026 - 04:23 PM EDT Accepted by SEC EDGAR 09/16/2026 - 04:23 PM EDT Learn about SEC filing dates

Rhea-AI Filing Summary

MAGNITE, INC. (MGNI) Chief Technology Officer David Buonasera reported a sale of 1,165 shares of common stock on September 14, 2026 at $24.00 per share, in an open-market or private transaction. Following this sale, he directly holds 245,155 shares of MAGNITE common stock. The transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on June 13, 2026.

Insider Trade Summary 10b5-1

Net Seller: 1,165 shares

Net Sell 1 txn

Insider Buonasera David

Role CHIEF TECHNOLOGY OFFICER

Sold 1,165 shs ($28K)

Share of Position Sold 0.47%

Type	Security	Shares	Price	Value
Sale	Common Stock F1	1,165	$24.00	$28K

Holdings After Transaction: Common Stock — 245,155 shares (Direct)

Holdings Before and After: Common Stock, 246,320 to 245,155 shares (Direct)

Other Insiders: 6 other insiders reported open-market sales of this stock in the 30 days up to this filing.

Footnotes (1)

1. F1. The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on June 13, 2026.

Key Figures

Shares sold: 1,165 shares Sale price per share: $24.00 per share Shares held after transaction: 245,155 shares +3 more

6 metrics

Shares sold 1,165 shares Common Stock sale reported for September 14, 2026

Sale price per share $24.00 per share Price for the 1,165 shares of Common Stock sold

Shares held after transaction 245,155 shares Direct Common Stock holdings of CTO after the sale

Transactions reported as sales 1 sale Form 4 transaction summary for this filing

Net shares sold 1,165 shares Net buy/sell direction is net-sell for this Form 4

Rule 10b5-1 plan adoption date June 13, 2026 Plan under which the reported sale was effected

Key Terms

Rule 10b5-1 trading plan, Common Stock, open market or private transaction

3 terms

Rule 10b5-1 trading plan regulatory

"The 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.

Common Stock financial

"security title is listed as Common Stock for the transaction"

Common stock represents ownership shares in a company, giving investors a stake in its success and a say in important decisions through voting rights. It is the most common type of stock traded on markets and can provide income through dividends, as well as potential for value growth. For investors, holding common stock means sharing in the company’s profits and risks.

open market or private transaction financial

"transaction code description notes a Sale in open market or private transaction"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did MAGNITE, INC. (MGNI) disclose for its CTO?

MAGNITE’s CTO, David Buonasera, reported selling 1,165 shares of common stock on September 14, 2026 at $24.00 per share in an open-market or private transaction.

How many MGNI shares does the CTO hold after this reported sale?

After the reported transaction, Chief Technology Officer David Buonasera directly holds 245,155 shares of MAGNITE, INC. common stock.

Was the MGNI insider sale made under a Rule 10b5-1 trading plan?

Yes. The filing states the sale was effected pursuant to a Rule 10b5-1 trading plan adopted by David Buonasera on June 13, 2026, and the plan status checkbox is affirmed.

What price did the MAGNITE (MGNI) CTO receive per share in this transaction?

The transaction reports a sale price of $24.00 per share for 1,165 shares of MAGNITE, INC. common stock on September 14, 2026.

Is this MAGNITE (MGNI) Form 4 transaction a purchase or a sale?

It is a sale transaction. The Form 4 reports the disposition of 1,165 shares of MAGNITE common stock, coded as a sale in an open-market or private transaction.

Does the MGNI Form 4 show any derivative securities activity?

No. The Form 4’s structured data show no derivative transactions and an empty derivative positions summary, indicating only this common stock sale was reported.

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

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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^*

Buonasera David

(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 TECHNOLOGY OFFICER

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/14/2026

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	09/14/2026		S(1)		1,165	D	$24	245,155	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. The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on June 13, 2026.

Remarks:

	/s/ Aaron Saltz, attorney-in-fact	09/16/2026
	** 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)