Sean Patrick Buckley - 15 Aug 2026 Form 4 Insider Report for MAGNITE, INC. (MGNI)

Reporting relationship: President, Revenue & Market Strategy
Issuer ticker: MGNI
Reported as of: 15 Aug 2026
Net transaction value: -$270,043
SEC form: 4
Accepted by SEC: 18 Aug 2026, 16:14:39 UTC
Prior SEC filing: 07 Aug 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 18 Aug 2026.

Key facts

This page summarizes Sean Patrick Buckley's Form 4 filing for MAGNITE, INC. (MGNI).
3 reported transactions and 0 derivative rows are listed below.
Accepted by SEC: 18 Aug 2026, 16:14.

Change

Previous filing in this sequence was filed on 07 Aug 2026.
Current net transaction value: -$270,043.

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: 18 Aug 2026

Reported non-derivative transactions

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

MGNI transaction

Common Stock

Tax liability

Transaction value
Shares: -11,715
Change %: -3.7%
Price: $24.73^*
Shares after: 304,090
Date: 15 Aug 2026
Ownership: Direct
Footnotes: F1

MGNI transaction

Common Stock

Sale

Transaction value: $201,068
Shares: -8,271
Change %: -2.7%
Price: $24.31
Shares after: 295,819
Date: 17 Aug 2026
Ownership: Direct
Footnotes: F2, F3

MGNI transaction

Common Stock

Sale

Transaction value: $68,975
Shares: -2,759
Change %: -0.93%
Price: $25.00
Shares after: 293,060
Date: 18 Aug 2026
Ownership: Direct
Footnotes: F2

^* 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

Represents the non-discretionary forfeiture of shares on behalf of the Reporting Person pursuant to an arrangement mandated by the Issuer to cover the tax withholding obligations associated with the vesting of restricted stock units.

Footnote F2

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

Footnote F3

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $24.05 to $24.55, 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.

SEC remarks

President, Revenue & Market Strategy