MGNI Insider David Day Plans 36k-Share Sale After Prior 73k Dispositions

Rhea-AI Filing Summary

Magnite, Inc. (MGNI) — Form 144 filing dated 06/26/2025

Officer David Day has filed a Form 144 indicating his intention to sell up to 36,000 common shares through Morgan Stanley Smith Barney on or about 06/26/2025. At the recent market price used in the filing, the shares are valued at $754,200. The company has 141,110,559 shares outstanding, so the proposed sale represents roughly 0.026 % of shares outstanding and poses no dilution risk to current shareholders.

Day adopted a Rule 10b5-1 trading plan on 03/13/2025, which pre-authorises trades and reduces the likelihood of trades being based on undisclosed information.

Form 144 also discloses that during the past three months Day sold:

• 38,146 shares on 06/18/2025 for $722,866.70
• 35,000 shares on 06/24/2025 for $698,250.00

Together with the new notice, the officer has sold or plans to sell 109,146 shares worth approximately $2.18 million, equal to about 0.077 % of shares outstanding.

Key Take-aways for investors

• The filing signals continued insider selling but under a 10b5-1 plan, indicating procedural compliance.
• The size of the sale is immaterial to the company’s capital structure but may be monitored as a sentiment indicator.

Positive

• The planned sale is conducted under a pre-arranged Rule 10b5-1 trading plan, demonstrating compliance with insider-trading regulations.
• The transaction accounts for only 0.026 % of total shares outstanding, posing no dilution or liquidity risk.

Negative

• Ongoing insider selling by a company officer may be interpreted as a bearish sentiment signal.
• Aggregate insider dispositions over the last three months total 109,146 shares worth about $2.18 million, which could concern sentiment-focused investors.

Insights

Insider Trading Analyst

TL;DR — Routine 10b5-1 insider sale; sentiment mildly negative, financial impact minimal.

The notice shows an officer using a pre-planned 10b5-1 arrangement to dispose of 36,000 shares, adding to 73,146 shares sold earlier in the quarter. While the dollar amount (~$754k) is respectable, it is immaterial versus Magnite’s 141 million-share float. From a governance standpoint, execution under a 10b5-1 plan limits concerns about information asymmetry. However, cumulative insider selling can weigh on market sentiment, especially when it comes from senior leadership. Overall, I view the filing as neutral on valuation but a modestly negative sentiment datapoint.

Portfolio Manager

TL;DR — Small, plan-based insider sale; I do not expect price impact.

The proposed 36k-share sale represents just 0.026 % of MGNI’s float and falls under a previously adopted 10b5-1 plan. Liquidity of Magnite stock is sufficient to absorb this volume without disruption. Insider sales become more concerning when they exceed 1-2 % of shares or occur outside a plan. Given the immaterial size and procedural safeguards, I classify the filing as a routine housekeeping disclosure with negligible impact on the investment thesis.

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	0001523288
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, 15th Floor New York NEW YORK 10001
Phone	(212) 243-2769
Name of Person for Whose Account the Securities are To Be Sold	DAVID DAY
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	36000	754200.00	141110559	06/26/2025	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	06/26/2025	Stock Option Exercise	ISSUER			36000	06/26/2025	Cash

* 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
DAVID DAY 1250 Broadway, 15th Floor New York NY 10001	Common	06/24/2025	35000	698250.00
DAVID DAY 1250 Broadway, 15th Floor New York NY 10001	Common	06/18/2025	38146	722866.70

144: Remarks and Signature

Remarks
Date of Notice	06/26/2025
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	03/13/2025
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/ David Day
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)

FAQ

How many Magnite (MGNI) shares does David Day plan to sell?

The Form 144 shows a proposed sale of 36,000 common shares.

What is the value of the planned MGNI insider sale?

Based on the filing, the shares are valued at approximately $754,200.

When is the proposed sale date for the MGNI shares?

The approximate sale date listed is 06/26/2025.

How many MGNI shares has the officer sold in the past three months?

Including the new notice, 109,146 shares have been sold or proposed for sale since 06/18/2025.

Was the sale arranged under a Rule 10b5-1 plan?

Yes. The trading plan was adopted on 03/13/2025, indicating pre-scheduled transactions.

What percentage of Magnite’s outstanding shares does the sale represent?

The 36,000 shares equal roughly 0.026 % of the 141,110,559 shares outstanding.