Magnite exec sells 43,385 shares in plan trade

Magnite executive Katie Seitz Evans exercised options and sold a total of 43,385 MGNI shares in pre-planned transactions under a Rule 10b5-1 trading plan.

Rhea-AI Filing Summary

MAGNITE, INC. (MGNI) reported that President, Product & Operations Katie Seitz Evans exercised employee stock options for 13,546 shares of common stock at $5.16 per share on September 8, 2026, then sold 32,285 shares that day at a weighted average price of $23.63, and sold an additional 11,100 shares on September 9, 2026 at a weighted average price of $23.46. All reported trades were made under a Rule 10b5-1 trading plan adopted on June 8, 2026.

Insider Trade Summary 10b5-1

Exercise and sale activity reported; no spread calculated

Exercise and Sale 4 txns

Insider Evans Katie Seitz

Role See Remarks

Sold 43,385 shs ($1.02M)

Approx. gross sale proceeds $1.02M

Approx. exercise cost $70K

Type	Security	Shares	Price	Value
Sale	Common Stock F1, F3	11,100	$23.46	$260K
Exercise	Employee Stock Option (Right to Buy) F1, F5, F4, F6	13,546	$0.00	$0.00
Exercise	Common Stock F1	13,546	$5.16	$70K
Sale	Common Stock F1, F2	32,285	$23.63	$763K

Holdings After Transaction: Employee Stock Option (Right to Buy) — 0 contracts (Direct); Common Stock — 455,797 shares (Direct)

Footnotes (6)

1. F1. The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on June 8, 2026.
2. F2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $23.465 to $23.91, 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.
3. F3. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $23.095 to $24.00, 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.
4. F4. The stock options have fully vested and are immediately exercisable.
5. F5. Granted as compensation for services.
6. F6. The amount reported in Column 9 reflects a correction to the number of derivative securities beneficially owned directly by the Reporting Person. A prior report inadvertently understated the number of derivative securities beneficially owned directly by the Reporting Person by 13,546 shares due to an administrative error. This correction does not reflect any purchase, sale or other transaction by the Reporting Person.

Key Figures

Shares sold September 8, 2026: 32,285 shares Shares sold September 9, 2026: 11,100 shares Options exercised: 13,546 shares +5 more

8 metrics

Shares sold September 8, 2026 32,285 shares Common stock sale at a weighted average price of $23.63 per share

Shares sold September 9, 2026 11,100 shares Common stock sale at a weighted average price of $23.46 per share

Options exercised 13,546 shares Employee stock options exercised for common stock on September 8, 2026

Option exercise price $5.16 per share Exercise price of employee stock options converted into 13,546 shares

Weighted average sale price September 8, 2026 $23.63 per share Common stock sold in multiple transactions within a disclosed price range

Weighted average sale price September 9, 2026 $23.46 per share Common stock sold in multiple transactions within a disclosed price range

Rule 10b5-1 plan adoption date June 8, 2026 Date Katie Seitz Evans adopted the trading plan governing the reported transactions

Option expiration date February 27, 2029 Expiration date of the employee stock options that were exercised

Key Terms

Rule 10b5-1 trading plan, weighted average price, Employee Stock Option, derivative securities

4 terms

Rule 10b5-1 trading plan regulatory

"The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on June 8, 2026."

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.

Employee Stock Option financial

"Employee Stock Option (Right to Buy)"

An employee stock option is a promise that lets a worker buy company shares later at a predetermined price, often after they stay for a certain period or meet performance goals — think of it like a coupon that locks in today's price for a future purchase. It matters to investors because options align employees’ incentives with company performance, can increase the number of shares outstanding (dilution) when exercised, and represent a compensation cost that affects reported profits and shareholder value.

derivative securities financial

"the number of derivative securities beneficially owned directly by the Reporting Person"

Financial contracts whose value is tied to the price or performance of another asset, such as a stock, bond, commodity, index, or currency; examples include options, futures and swaps. They matter to investors because they let you protect against price swings, bet on future moves or gain larger exposure with less upfront cash—like using a lever or insurance policy on an investment—so they can amplify gains and losses and help manage portfolio risk.

FAQ

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

What insider transactions did MGNI executive Katie Seitz Evans report on this Form 4?

Katie Seitz Evans reported exercising options for 13,546 shares of Magnite common stock on September 8, 2026 and selling a total of 43,385 shares of common stock on September 8 and 9, 2026, according to the Form 4.

How many MGNI shares did Katie Seitz Evans sell and at what prices?

She sold 32,285 shares of Magnite common stock on September 8, 2026 at a weighted average price of $23.63, and 11,100 shares on September 9, 2026 at a weighted average price of $23.46, with each sale executed in multiple transactions within disclosed price ranges.

What options did Katie Seitz Evans exercise in this MGNI Form 4 filing?

On September 8, 2026, she exercised employee stock options covering 13,546 shares of Magnite common stock at an exercise price of $5.16 per share. The options were fully vested and immediately exercisable and had an expiration date of February 27, 2029.

Were the reported MGNI insider trades by Katie Seitz Evans under a Rule 10b5-1 plan?

Yes. The filing states the reported transactions were effected pursuant to a Rule 10b5-1 trading plan adopted by Katie Seitz Evans on June 8, 2026, indicating the trades were pre-arranged under that plan.

Does the MGNI Form 4 indicate any correction related to Katie Seitz Evans’ derivative securities?

Yes. A footnote explains that the amount reported for derivative securities reflects a correction of 13,546 options previously understated due to an administrative error, and clarifies that this correction does not represent any purchase, sale, or other transaction.

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

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Available on EDGAR 09/10/2026 - 04:40 PM Accepted by SEC EDGAR 09/10/2026 - 04:39 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^*

Evans Katie Seitz

(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)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/08/2026

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	09/08/2026		M(1)		13,546	A	$5.16	499,182	D
Common Stock	09/08/2026		S(1)		32,285	D	$23.63(2)	466,897	D
Common Stock	09/09/2026		S(1)		11,100	D	$23.46(3)	455,797	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
Employee Stock Option (Right to Buy)	$5.16	09/08/2026		M(1)			13,546	(4)	02/27/2029	Common Stock	13,546	$0(5)	0(6)	D

Explanation of Responses:

1. The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on June 8, 2026.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $23.465 to $23.91, 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.

3. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $23.095 to $24.00, 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.

4. The stock options have fully vested and are immediately exercisable.

5. Granted as compensation for services.

6. The amount reported in Column 9 reflects a correction to the number of derivative securities beneficially owned directly by the Reporting Person. A prior report inadvertently understated the number of derivative securities beneficially owned directly by the Reporting Person by 13,546 shares due to an administrative error. This correction does not reflect any purchase, sale or other transaction by the Reporting Person.

Remarks:

President, Product & Operations

	/s/ Aaron Saltz, attorney-in-fact	09/10/2026
	** 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)