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John Joseph Johnston

CIK 1874850 · last filed 2026-06-22

John Joseph Johnston is a corporate insider who has filed 29 SEC Form 4 insider transactions across 1 company since 2021. The most recent filing, for MXCT, was dated Jun 22, 2026. Across all open-market trades the lifetime net is −$389.1K, making them a net seller over the disclosed history. Current disclosed insider exposure totals $251.0K 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

$251.0K

Companies

1

Total Filings

29

Lifetime Open-Market Net

-$389.1K

Filer Profile

Reported Address
C/O MAXCYTE, INC.
22 FIRSTFIELD ROAD, SUITE 110
GAITHERSBURG, MD 20878
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
MXCT Director 201,581 $1.25 $251.0K -$389.1K 23 2026-06-22

Recent Filings

29 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
2026-06-22 MXCT Grant (A) +30,421 $0 EDGAR
2025-06-23 MXCT Grant (A) +29,210 $0 EDGAR
2025-01-29 MXCT Mixed — -$5.1K EDGAR
2024-12-30 MXCT Mixed — -$3.2K EDGAR
2024-12-26 MXCT Notice (144) −12,000 -$49.3K EDGAR
2024-12-10 MXCT Mixed — -$4.0K EDGAR
2024-10-30 MXCT Mixed — -$2.4K EDGAR
2024-09-30 MXCT Mixed — -$2.7K EDGAR
2024-09-26 MXCT Notice (144) −9,000 -$34.3K EDGAR
2024-08-28 MXCT Mixed — -$4.1K EDGAR
Showing 1–10 of 29
Page 1 of 3
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.