Magnite trust plans $888K stock sale under Rule 144

Trustee-related holders of Magnite, Inc. common stock have filed a Rule 144 notice to resell 37,337 shares, with prior 10b5-1 sales also reported.

Rhea-AI Filing Summary

MAGNITE, INC. (MGNI) is the issuer for a planned resale of common stock disclosed by Douglas S. Knopper and Abigail L. Knopper, as trustees of the Knopper Joint Management Trust dated November 15, 2013, under Rule 144. The notice covers 37,337 shares of common stock, originally acquired as Restricted Stock Units granted on November 6, 2019 by the issuer. The proposed sale is to be executed through Morgan Stanley Smith Barney LLC Executive Financial Services, with an aggregate market value stated as $887,873.86 and trading on NASDAQ referenced as of September 17, 2026. The filing also lists Rule 10b5-1 sales of Magnite common stock during the prior three months for related accounts.

Key Figures

Shares to be sold under Rule 144: 37,337 shares Aggregate market value of shares to be sold: $887,873.86 Original grant date of Restricted Stock Units: November 6, 2019 +4 more

7 metrics

Shares to be sold under Rule 144 37,337 shares Magnite common stock covered by the notice

Aggregate market value of shares to be sold $887,873.86 Planned Rule 144 sale of Magnite common stock

Original grant date of Restricted Stock Units November 6, 2019 Acquisition date for RSUs underlying the 37,337 shares

Shares sold for Douglas Knopper in last 3 months 19,128 shares 10b5-1 sale of Magnite common stock on August 6, 2026

Proceeds from Douglas Knopper August 6, 2026 sale $434,588.16 10b5-1 sale of Magnite common stock

Shares sold for Knopper Joint Management Trust in last 3 months 18,209 shares 10b5-1 sale of Magnite common stock on August 6, 2026

Proceeds from Trust August 6, 2026 sale $413,708.48 10b5-1 sale of Magnite common stock

Key Terms

Rule 144, Restricted Stock Units, 10b5-1

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

"Common | 11/06/2019 | 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 DOUGLAS KNOPPER 1250 Broadway"

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.

FAQ

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

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

The filing reports a planned Rule 144 resale of 37,337 shares of Magnite common stock by Douglas and Abigail Knopper, as trustees of the Knopper Joint Management Trust, with an aggregate market value of $887,873.86 and trading on NASDAQ referenced as of September 17, 2026.

Who is selling MAGNITE, INC. (MGNI) shares under this Rule 144 notice?

The shares are to be sold for the account of Douglas S. Knopper and Abigail L. Knopper, trustees of the Knopper Joint Management Trust dated November 15, 2013, with Magnite, Inc. as the issuer of the common stock.

How many MAGNITE, INC. (MGNI) shares are covered by this Form 144?

The notice covers 37,337 shares of Magnite, Inc. common stock. These shares are linked to Restricted Stock Units originally granted on November 6, 2019 by the issuer.

What is the stated market value of the MAGNITE, INC. (MGNI) shares to be sold?

The planned sale of 37,337 Magnite common shares has an aggregate market value stated as $887,873.86, with NASDAQ trading referenced as of September 17, 2026.

What prior MAGNITE, INC. (MGNI) share sales are reported in the last three months?

The filing lists 10b5-1 sales on August 6, 2026: 19,128 Magnite common shares for $434,588.16 for Douglas Knopper, and 18,209 shares for $413,708.48 for the Knopper Joint Management Trust co-trustees.

When were the MAGNITE, INC. (MGNI) securities originally acquired?

The 37,337 Magnite common shares covered by this notice are tied to Restricted Stock Units with an acquisition date of November 6, 2019, and the acquisition source is listed as the issuer.

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

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Available on EDGAR 09/17/2026 - 04:36 PM Accepted by SEC EDGAR 09/17/2026 - 04:35 PM 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	0001350876
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	Douglas S. Knopper & Abigail L. Knopper TTEES of the Knopper Joint Mgmt Trust 11/15/13
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	Director

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	37337	887873.86	143424157	09/17/2026	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	11/06/2019	Restricted Stock Units	Issuer			37337	11/06/2019	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 DOUGLAS KNOPPER 1250 Broadway, 9th Floor New York NY 10001	Common	08/06/2026	19128	434588.16
10b5-1 Sales for D S KNOPPER & A L KNOPPER CO-TTEEKNOPPER JOINT MANAGEMENT TRUSTU/T/A DTD 11/15/2013 1250 Broadway, 9th Floor New York NY 10001	Common	08/06/2026	18209	413708.48

144: Remarks and Signature

Remarks
Date of Notice	09/17/2026
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	12/12/2025
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/ Douglas Knopper
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)