Magnite director sells 37,337 shares at $26.28

A MAGNITE, INC. director sold 37,337 shares under a pre-arranged Rule 10b5-1 trading plan, leaving him with 51,136 shares directly held.

Rhea-AI Filing Summary

MAGNITE, INC. (MGNI) director Douglas S. Knopper sold Common Stock in an open-market transaction on September 17, 2026. He sold 37,337 shares at a weighted average price of $26.28 per share, with actual trade prices ranging from $26.00 to $26.50. Following this sale, he directly holds 51,136 shares of MAGNITE, INC. common stock. The sale was effected pursuant to a Rule 10b5-1 trading plan adopted on December 12, 2025.

Insider Trade Summary 10b5-1

Net Seller: 37,337 shares

Net Sell 1 txn

Insider Knopper Douglas S

Role Director

Sold 37,337 shs ($981K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1, F2	37,337	$26.28	$981K

Holdings After Transaction: Common Stock — 51,136 shares (Direct)

Footnotes (2)

1. F1. The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on December 12, 2025.
2. F2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $26.00 to $26.50, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote to this Form 4.

Key Figures

Shares sold: 37,337 shares Weighted average sale price: $26.28 per share Sale price range: $26.00–$26.50 per share +3 more

6 metrics

Shares sold 37,337 shares Common Stock sold by director on September 17, 2026

Weighted average sale price $26.28 per share Average price for the 37,337 shares sold

Sale price range $26.00–$26.50 per share Range of prices for multiple sale transactions

Shares held after transaction 51,136 shares Director’s direct holdings after the sale

Rule 10b5-1 plan adoption date December 12, 2025 Date the trading plan governing the sale was adopted

Net shares sold in filing 37,337 shares Net selling activity reported across all transactions in this Form 4

Key Terms

Rule 10b5-1 trading plan, weighted average price, 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.

weighted average price financial

"The price reported in Column 4 is a weighted average price"

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

open market or private transaction market

"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) report on this Form 4?

MAGNITE, INC. reported that director Douglas S. Knopper sold 37,337 shares of common stock on September 17, 2026 in an open-market transaction, at a weighted average price of $26.28 per share.

How many MGNI shares does the director hold after the reported sale?

After the sale, director Douglas S. Knopper directly holds 51,136 shares of MAGNITE, INC. common stock, as reported in the Form 4.

At what prices were the MGNI shares sold in this Form 4 transaction?

The Form 4 states the sales occurred at a weighted average price of $26.28 per share. The shares were sold in multiple transactions at prices ranging from $26.00 to $26.50, inclusive.

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

Yes. The filing states the transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 12, 2025.

Is this MGNI Form 4 transaction a buy or a sell by the insider?

This Form 4 reports a sale of common stock by director Douglas S. Knopper, totaling 37,337 shares in an open-market transaction on September 17, 2026.

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

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Available on EDGAR 09/18/2026 - 04:05 PM Accepted by SEC EDGAR 09/18/2026 - 04:05 PM Learn about SEC filing dates

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^*

Knopper Douglas S

(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)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/17/2026

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	09/17/2026		S(1)		37,337	D	$26.28(2)	51,136	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 December 12, 2025.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $26.00 to $26.50, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote to this Form 4.

Remarks:

	/s/ Aaron Saltz, attorney-in-fact	09/18/2026
	** 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)