Constantin Ionel Stefan

CIK 1940928 · Chief Technology Officer · last filed 2026-08-25

"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.

Disclosed Exposure

$7.54M

Companies

Total Filings

Lifetime Open-Market Net

-$11.24M

Charts

Trading activity, where the exposure sits, and each trade against the stock price.

AMPX.WS price and trades

Daily close with each Form 4 filing on this company marked: green = open-market buy, red = open-market sale, purple = grants, exercises, gifts and other non-market transactions. Marker size scales with the dollar value.

Shares held

Shares owned after each reported transaction on this company (direct holdings as reported).

Open-market buying and selling

by month

Dollar value of open-market purchases (code P, up) and sales (code S, down) across all companies, by filing month. Grants, exercises and gifts are excluded.

Exposure by company

latest

OfficerDirector10% owner* stale (no filing in 3 yrs)

Most recently reported shares × current price. Faded bars (*) have had no filing in 3 years, so the person may no longer hold them. Click a bar to chart that company.

Filer Profile

Reported Address

1180 PAGE AVENUE
FREMONT, CA 94538

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
AMPX	Chief Technology Officer	771,629	$7.80	$6.02M	-$306.9K	1	2026-08-25
AMPX.WS	Chief Technology Officer	801,310	$1.89	$1.51M	-$10.93M	22	2026-05-28

Recent Filings · Page 4 of 4

39 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
2024-05-24	AMPX.WS	Sell (S)	−9,393	-$12.6K	EDGAR
2024-03-19	AMPX.WS	Grant (A)	+374,570	$0	EDGAR
2023-09-18	AMPX.WS	Sell (S)	−80,000	-$300.2K	EDGAR
2023-09-15	AMPX	Notice (144)	−33,630	-$130.8K	EDGAR
2023-09-14	AMPX	Notice (144)	−46,370	-$169.5K	EDGAR
2023-09-12	AMPX.WS	Exer (M)	+80,000	$4.0K	EDGAR
2023-05-03	AMPX.WS	Tax (F)	−209	-$1.5K	EDGAR
2022-12-15	AMPX.WS	Exer (M)	+30,000	$1.5K	EDGAR
2022-09-16	—	Grant (A)	—	$0

Showing 31–39 of 39

Prev Page 4 of 4

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.