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Sean Patrick Buckley

CIK 1865116 · See Remarks · last filed 2026-08-18

Sean Patrick Buckley is a corporate insider who has filed 64 SEC Form 4 insider transactions across 1 company since 2021. The most recent filing, for MGNI, was dated Aug 18, 2026. Across all open-market trades the lifetime net is −$8.3M, making them a net seller over the disclosed history. Current disclosed insider exposure totals $7.0M across reported positions.

"Disclosed insider exposure" sums this person's most-recently-reported share counts across each company they're an insider in, multiplied by the current underlying price. It is not net worth — it misses retail holdings, private investments, real estate, index funds, and any company where the person isn't an SEC-reporting insider. For informational purposes only.

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Disclosed Exposure

$7.03M

Companies

1

Total Filings

64

Lifetime Open-Market Net

-$8.32M

Filer Profile

Reported Address
C/O MAGNITE, INC.
6080 CENTER DRIVE, 4TH FLOOR
LOS ANGELES, MA 90045
Profile details as reported on the filer's SEC submissions — for individual insiders the address is often in care of the issuer. Related filers are identified from jointly filed SEC submissions and shared reported addresses. View filings on SEC EDGAR.

Holdings By Company

Latest on-record share count from this person's most recent non-derivative Form 4 transaction in each company. Disclosed exposure = shares × current underlying price.
Symbol Role Shares Price Disclosed Exposure Lifetime OM Net Filings Latest Filed
MGNI See Remarks 295,819 $23.77 $7.03M -$8.32M 40 2026-08-18

Recent Filings

64 filings
Insider activity across all companies, newest first. Form 4 rows are post-trade confirmations (buys, sells, grants, exercises). Notice (144) rows are pre-trade notices of intent to sell restricted or control stock under Rule 144 — they may not all execute. Compare adjacent dates to see which notices became actual sales.
Filed Symbol Action Net Shares Net $ Link
2026-08-18 MGNI Notice (144) −2,759 -$66.7K EDGAR
2026-08-18 MGNI Mixed −22,745 -$559.8K EDGAR
2026-08-17 MGNI Notice (144) −8,271 -$204.5K EDGAR
2026-08-07 MGNI Mixed −38,476 -$1.25M EDGAR
2026-08-07 MGNI Mixed −38,476 -$1.25M EDGAR
2026-08-06 MGNI Notice (144) −67,179 -$1.39M EDGAR
2026-07-09 MGNI Sell (S) −19,233 -$404.5K EDGAR
2026-07-07 MGNI Notice (144) −19,233 -$400.8K EDGAR
2026-06-18 MGNI Sell (S) −19,233 -$365.4K EDGAR
2026-06-17 MGNI Notice (144) −19,233 -$356.8K EDGAR
Showing 1–10 of 64
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Form 4 codes: P = open-market purchase · S = open-market sale · A = grant/award · M = option exercise · F = tax withholding at vest · G = bona-fide gift · D = disposition to issuer · J = other (see filing footnote). Only P / S codes carry directional signal.
Notice (144 / 144/A): Form 144 is a notice of intent to sell restricted/control stock under Rule 144, filed before the sale; 144/A is an amendment. Many notices are pre-scheduled under Rule 10b5-1 plans. A Form 4 with code S typically follows within a few days when the planned sale executes; missing follow-up Form 4s suggest the notice was cancelled or modified.