Magnite officer proposes $130K sale of common shares

The shares designated for sale came from restricted stock units that vested between February 15 and May 15, 2025.

Available on EDGAR 11/05/2026 - 04:31 PM EST Accepted by SEC EDGAR 11/05/2026 - 04:28 PM EST Learn about SEC filing dates

Rhea-AI Filing Summary

Magnite, Inc. officer David Buonasera reported a proposed sale of 5,706 common shares, with an aggregate market value of $130,039.74, through Morgan Stanley Smith Barney LLC, for an approximate sale date of November 5, 2026. The shares came from restricted stock units that vested during February 15, 2025 through May 15, 2025. The notice also lists four sales during the prior three months: 1,165 shares on September 14, 2026; 1,043 on September 2, 2026; 5,371 on September 1, 2026; and 7,649 on August 6, 2026.

Key Figures

Proposed shares: 5,706 shares Aggregate market value: $130,039.74 Shares outstanding: 143,559,468 shares +4 more

7 metrics

Proposed shares 5,706 shares Approximate sale date November 5, 2026

Aggregate market value $130,039.74 Proposed sale

Shares outstanding 143,559,468 shares Reported in the securities information

Past sale, September 14, 2026 1,165 shares; $27,960.00 Sale reported during the prior three months

Past sale, September 2, 2026 1,043 shares; $26,075.00 Sale reported during the prior three months

Past sale, September 1, 2026 5,371 shares; $125,788.82 Sale reported during the prior three months

Past sale, August 6, 2026 7,649 shares; $179,445.54 Sale reported during the prior three months

Key Terms

Rule 144, Restricted Stock Units, 10b5-1 Sales

3 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

"acquired upon 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.

10b5-1 Sales regulatory

"10b5-1 Sales for David Buonasera"

10b5-1 sales are pre-arranged stock-trading plans that let company insiders automatically buy or sell shares according to a fixed schedule or formula, even if they later learn confidential information. Think of it as setting up an automatic thermostat for trades: it creates a clear, documented path that can protect insiders from insider-trading accusations and gives investors a signal about predictable insider activity—though it can also simply be a way for insiders to diversify or raise cash.

FAQ

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

How many MGNI shares did David Buonasera report for sale?

David Buonasera reported a proposed sale of 5,706 common shares, with an aggregate market value of $130,039.74, through Morgan Stanley Smith Barney LLC.

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

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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	0001966857
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	DAVID BUONASERA
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	5706	130039.74	143559468	11/05/2026	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	02/15/2025	Restricted Stock Units	Issuer			5706	02/15/2025	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 DAVID BUONASERA 1250 Broadway, 9th Floor New York NY 10001	Common	09/14/2026	1165	27960.00
DAVID BUONASERA 1250 Broadway, 9th Floor New York NY 10001	Common	09/02/2026	1043	26075.00
DAVID BUONASERA 1250 Broadway, 9th Floor New York NY 10001	Common	09/01/2026	5371	125788.82
DAVID BUONASERA 1250 Broadway, 9th Floor New York NY 10001	Common	08/06/2026	7649	179445.54

144: Remarks and Signature

Remarks	The securities to be sold were acquired upon the vesting of restricted stock units during the period of 02/15/2025 through 05/15/2025.
Date of Notice	11/05/2026
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	06/13/2026
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/ David Matthew Buoanesera
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)