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WILLIAM K HEIDEN

CIK 1214939 · President & CEO · last filed 2026-06-11

WILLIAM K HEIDEN is a President & CEO who has filed 53 SEC Form 4 insider transactions across 4 companies since 2009. The most recent filing, for ATRA, was dated Jun 11, 2026. Across all open-market trades the lifetime net is −$7.0M, making them a net seller over the disclosed history. Current disclosed insider exposure totals $708.8K 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

$708.8K

Companies

4

Total Filings

53

Lifetime Open-Market Net

-$6.99M

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
ATRA Director 34,188 $7.81 $267.0K $25.3K 14 2026-06-11
MGNX Director 114,750 $3.85 $441.8K $150.5K 7 2026-05-20
AMAG PHARMACEUTICALS, INC. (AMAG) Delisted President & CEO 424,612 — — -$7.16M 30 2020-03-04
GTC BIOTHERAPEUTICS INC (GTCB) Delisted Director — — — $0 1 2009-10-05

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
2026-06-11 ATRA Grant (A) +12,000 $0 EDGAR
2026-05-20 MGNX Mixed +3,750 $0 EDGAR
2025-08-21 MGNX Buy (P) +100,000 $150.5K EDGAR
2025-06-12 ATRA Grant (A) +7,828 $0 EDGAR
2025-05-22 MGNX Mixed +6,500 $0 EDGAR
2024-05-23 MGNX Grant (A) — $0 EDGAR
2024-05-22 MGNX Exer (M) +4,500 $0 EDGAR
2024-04-02 ATRA Grant (A) +150,000 $0 EDGAR
2023-11-14 ATRA Buy (P) +100,000 $25.3K EDGAR
2023-06-02 MGNX Grant (A) — $0 EDGAR
Showing 1–10 of 53
Page 1 of 6
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.