Sean Patrick Buckley - 06 Aug 2026 Form 4 Insider Report for MAGNITE, INC. (MGNI)

Reporting relationship: President, Revenue & Market Strategy
Issuer ticker: MGNI
Reported as of: 06 Aug 2026
Net transaction value: -$1,645,316
SEC form: 4
Accepted by SEC: 07 Aug 2026, 17:14:08 UTC
Prior SEC filing: 09 Jul 2026
Source filing: View source filing
Reporting owner signature: /s/ Aaron Saltz, attorney-in-fact

Key filing fact

Sean Patrick Buckley filed Form 4 for MAGNITE, INC. (MGNI) on 07 Aug 2026.

Key facts

This page summarizes Sean Patrick Buckley's Form 4 filing for MAGNITE, INC. (MGNI).
4 reported transactions and 1 derivative row are listed below.
Accepted by SEC: 07 Aug 2026, 17:14.

Change

Previous filing in this sequence was filed on 09 Jul 2026.
Current net transaction value: -$1,645,316.

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 0001865116 Primary reporting owner

Buckley Sean Patrick

Relationship: President, Revenue & Market Strategy
Address: C/O MAGNITE, INC., 1250 BROADWAY, 9TH FLOOR, NEW YORK
Signature: /s/ Aaron Saltz, attorney-in-fact
Signature date: 07 Aug 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: +28,703
Change %: +8.1%
Price: $13.90^*
Shares after: 382,984
Date: 06 Aug 2026
Ownership: Direct
Footnotes: F1

MGNI transaction

Common Stock

Sale

Transaction value: $1,202,865
Shares: -47,942
Change %: -13%
Price: $25.09
Shares after: 335,042
Date: 06 Aug 2026
Ownership: Direct
Footnotes: F1

MGNI transaction

Common Stock

Sale

Transaction value: $442,451
Shares: -19,237
Change %: -5.7%
Price: $23.00
Shares after: 315,805
Date: 06 Aug 2026
Ownership: Direct
Footnotes: F1

Reported derivative securities

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

MGNI transaction Derivative

Stock Option (right to buy)

Options Exercise

Transaction value
Shares: -28,703
Change %: -33%
Price: $0.000000^*
Shares after: 57,405
Date: 06 Aug 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 28,703
Exercise price: $13.90
Footnotes: F1, F2, F3

^* 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 3 footnotes

Footnote F1

The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on September 10, 2025.

Footnote F2

The stock options have fully vested and are immediately exercisable.

Footnote F3

Granted as compensation for services.

SEC remarks

President, Revenue & Market Strategy