Katie Seitz Evans - 08 Sep 2026 Form 4 Insider Report for MAGNITE, INC. (MGNI)

Reporting relationship: President, Product & Operations
Issuer ticker: MGNI
Reported as of: 08 Sep 2026
Net transaction value: -$1,023,301
SEC form: 4
Accepted by SEC: 10 Sep 2026, 16:39:28 UTC
Prior SEC filing: 18 Aug 2026
Next SEC filing: 11 Sep 2026
Source filing: View source filing
Reporting owner signature: /s/ Aaron Saltz, attorney-in-fact

Key filing fact

Katie Seitz Evans filed Form 4 for MAGNITE, INC. (MGNI) on 10 Sep 2026.

Key facts

This page summarizes Katie Seitz Evans's Form 4 filing for MAGNITE, INC. (MGNI).
4 reported transactions and 1 derivative row are listed below.
Accepted by SEC: 10 Sep 2026, 16:39.

Change

Previous filing in this sequence was filed on 18 Aug 2026.
Current net transaction value: -$1,023,301.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001700262 Primary reporting owner

Evans Katie Seitz

Relationship: President, Product & Operations
Address: C/O MAGNITE, INC., 1250 BROADWAY, 9TH FLOOR, NEW YORK
Signature: /s/ Aaron Saltz, attorney-in-fact
Signature date: 10 Sep 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

MGNI transaction

Common Stock

Options Exercise

Transaction value
Shares: +13,546
Change %: +2.8%
Price: $5.16^*
Shares after: 499,182
Date: 08 Sep 2026
Ownership: Direct
Footnotes: F1

MGNI transaction

Common Stock

Sale

Transaction value: $762,895
Shares: -32,285
Change %: -6.5%
Price: $23.63
Shares after: 466,897
Date: 08 Sep 2026
Ownership: Direct
Footnotes: F1, F2

MGNI transaction

Common Stock

Sale

Transaction value: $260,406
Shares: -11,100
Change %: -2.4%
Price: $23.46
Shares after: 455,797
Date: 09 Sep 2026
Ownership: Direct
Footnotes: F1, F3

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

MGNI transaction Derivative

Employee Stock Option (Right to Buy)

Options Exercise

Transaction value
Shares: -13,546
Change %: -100%
Price: $0.000000^*
Shares after: 0
Date: 08 Sep 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 13,546
Exercise price: $5.16
Footnotes: F1, F4, F5, F6

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Rule 10b5-1 trading plan

These transactions were reported as open-market trades under a Rule 10b5-1 plan. The plan lets an insider set trading instructions in advance, which can reduce the risk of trading while in possession of material nonpublic information.

Original filing language: transaction made pursuant to a contract, instruction, or written plan intended to satisfy Rule 10b5-1(c).

Explanation of responses 6 footnotes

Footnote F1

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

Footnote 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.

Footnote 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.

Footnote F4

The stock options have fully vested and are immediately exercisable.

Footnote F5

Granted as compensation for services.

Footnote 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.

SEC remarks

President, Product & Operations