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Mark Thierer

CIK 1334925 · Interim Chief Exec Officer · last filed 2026-01-23

Mark Thierer is an Interim Chief Exec Officer who has filed 53 SEC Form 4 insider transactions across 6 companies since 2008. The most recent filing, for PIIIW, was dated Jan 23, 2026. Across all open-market trades the lifetime net is −$70.0M, making them a net seller over the disclosed history. Current disclosed insider exposure totals $1.4M 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

$1.39M

Companies

6

Total Filings

53

Lifetime Open-Market Net

-$70.02M

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
PIIIW Director 21,182 $0.01 $212 $0 5 2026-01-23
Discover Financial Services (DFS) Delisted Director 24,563 $200.05 $4.91M $0 10 2023-05-15
XERS Director — $8.24 — $0 2 2020-06-04
XRAY Interim Chief Exec Officer 103,198 $13.49 $1.39M $5.08M 5 2018-02-27
Catamaran Corp (CTRX) Delisted President & CEO 0 — — -$23.68M 12 2015-07-23
Catamaran Corp (SXCI) Delisted President & CEO 95,408 — — -$51.43M 19 2012-06-06

Recent Filings

53 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
2026-01-23 PIIIW Grant (A) +4,000 $0 EDGAR
2025-08-08 PIIIW Grant (A) +4,000 $0 EDGAR
2024-06-10 PIIIW Grant (A) — $0 EDGAR
2024-01-25 PIIIW Grant (A) +433,121 $0 EDGAR
2023-05-15 Discover Financial Services (DFS) Delisted Grant (A) +1,774 $0 EDGAR
2022-05-23 Discover Financial Services (DFS) Delisted Grant (A) +1,634 $0 EDGAR
2022-03-28 PIIIW Grant (A) — $0 EDGAR
2021-05-06 Discover Financial Services (DFS) Delisted Grant (A) +1,291 $0 EDGAR
2020-06-04 XERS Grant (A) — $0 EDGAR
2020-05-18 Discover Financial Services (DFS) Delisted Grant (A) +3,824 $0 EDGAR
Showing 1–10 of 53
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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.