Magnite officer plans $66.7K stock sale for 2026

Rhea-AI Filing Summary

MAGNITE, INC. (MGNI) received a notice that officer Sean Buckley intends to sell common stock under Rule 144. The notice covers 2,759 shares of common stock, to be sold through Morgan Stanley Smith Barney LLC, with a reported transaction value of $66,740.21.

The shares derive from restricted stock units, with the planned sale date reported as August 18, 2026 and trading on NASDAQ. Over the prior three months, the notice lists additional Rule 10b5-1 sales by Sean Buckley totaling several tranches of common stock with reported transaction values in the hundreds of thousands of dollars.

Key Figures

Planned shares to be sold: 2,759 shares Reported value of planned sale: $66,740.21 10b5-1 sale on 08/17/2026: 8,271 shares; $201,106.06 +3 more

6 metrics

Planned shares to be sold 2,759 shares Common stock covered by the Form 144 notice for Sean Buckley

Reported value of planned sale $66,740.21 Transaction value reported for the 2,759 shares of common stock

10b5-1 sale on 08/17/2026 8,271 shares; $201,106.06 Common stock sold for Sean Buckley under a 10b5-1 plan

10b5-1 sale on 08/06/2026 67,179 shares; $1,645,076.07 Common stock sold for Sean Buckley under a 10b5-1 plan

10b5-1 sale on 07/07/2026 19,233 shares; $404,553.78 Common stock sold for Sean Buckley under a 10b5-1 plan

10b5-1 sale on 06/17/2026 19,233 shares; $365,427.00 Common stock sold for Sean Buckley under a 10b5-1 plan

Key Terms

Rule 144, Restricted Stock Units, 10b5-1, Executive Financial Services

4 terms

Rule 144 regulatory

"See the definition of "person" in paragraph (a) of Rule 144."

Rule 144 is a U.S. securities regulation that sets conditions under which restricted or insider-held shares can be legally resold to the public, such as required holding periods, availability of public information, limits on how much can be sold at once, and certain filing requirements. For investors it matters because it determines when previously locked-up shares can enter the market — like a release valve that can increase supply, affect share price, and signal insider intent.

Restricted Stock Units financial

"Common | 08/15/2026 | Restricted Stock Units | Issuer"

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.

10b5-1 regulatory

"10b5-1 Sales for SEAN BUCKLEY 1250 Broadway, 9th Floor"

A 10b5-1 plan is a pre-set schedule that lets company insiders buy or sell shares according to written instructions made when they do not possess material, nonpublic information. Think of it as a timed automatic payment for stock trades: it helps insiders avoid accusations of trading on secret information and gives outside investors a clearer signal about whether sales are routine or potentially informative about the company’s prospects.

Executive Financial Services financial

"Common | Morgan Stanley Smith Barney LLC Executive Financial Services"

FAQ

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

What does the Form 144 filing mean for MAGNITE, INC. (MGNI)?

The Form 144 reports that officer Sean Buckley plans to sell 2,759 MGNI common shares under Rule 144. This is an advance notice of a potential sale by an affiliate, not a transaction by Magnite itself.

How many MAGNITE (MGNI) shares is Sean Buckley planning to sell?

Sean Buckley’s notice covers 2,759 shares of MGNI common stock. The filing also reports a related transaction value of $66,740.21, reflecting the value associated with these shares as stated in the notice.

What is the source of the MAGNITE (MGNI) shares listed in this Form 144?

The Form 144 states the shares are from Restricted Stock Units. The securities to be sold section identifies the class as Common and the nature of acquisition as restricted stock units issued by Magnite.

Which broker is handling Sean Buckley’s planned sale of MAGNITE (MGNI) shares?

The notice lists Morgan Stanley Smith Barney LLC Executive Financial Services, located at 1 New York Plaza, 8th Floor, New York, NY, as the broker handling the planned sale of Magnite common shares.

What recent 10b5-1 sales in MAGNITE (MGNI) stock does the filing report?

The filing lists Rule 10b5-1 sales for Sean Buckley on 06/17/2026, 07/07/2026, 08/06/2026, and 08/17/2026, with share amounts from 8,271 to 67,179 and reported transaction values between hundreds of thousands and over a million dollars.

Is this MAGNITE (MGNI) Form 144 a sale by the company or by an individual?

The notice relates to Sean Buckley, an officer of Magnite, selling shares for his own account. It does not represent a sale of securities by Magnite, Inc. itself and does not describe primary capital raising.

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

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Accepted by SEC EDGAR 08/18/2026 - 04:21 PM EDT Learn about SEC filing dates

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK	0001865116
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	MAGNITE, INC.
SEC File Number	001-36384
Address of Issuer	1250 Broadway, 9th Floor New York NEW YORK 10001
Phone	2122432769
Name of Person for Whose Account the Securities are To Be Sold	SEAN BUCKLEY
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Officer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common	Morgan Stanley Smith Barney LLC Executive Financial Services 1 New York Plaza 8th Floor New York NY 10004	2759	66740.21	143424157	08/18/2026	NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common	08/15/2026	Restricted Stock Units	Issuer			2759	08/15/2026	N/A

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
10b5-1 Sales for SEAN BUCKLEY 1250 Broadway, 9th Floor New York NY 10001	Common	08/17/2026	8271	201106.06
10b5-1 Sales for SEAN BUCKLEY 1250 Broadway, 9th Floor New York NY 10001	Common	08/06/2026	67179	1645076.07
10b5-1 Sales for SEAN BUCKLEY 1250 Broadway, 9th Floor New York NY 10001	Common	07/07/2026	19233	404553.78
10b5-1 Sales for SEAN BUCKLEY 1250 Broadway, 9th Floor New York NY 10001	Common	06/17/2026	19233	365427.00

144: Remarks and Signature

Remarks
Date of Notice	08/18/2026
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	09/10/2025
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	/s/ Sean Buckley
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)