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AMPH Insider Trading & Form 4 Activity

Amphastar Pharmaceuticals, Inc.
Last filing: Sep 23, 2026·1mo ago· Data may be outdated
BEARISH · LAST 90 DAYS
0%
buyers
$0
0 buys
$477K
3 sells
-$477K
net selling
2
insiders
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Net flow — last 12 months

Monthly net of insider buys minus sells. Green months indicate net buying; red months indicate net selling.

Most active insiders

Ranked by total transaction value over the last 90 days.

INSIDERBOUGHTSOLDNET
Zhou Rong
SENIOR EVP, PRODUCTION CENTER
—
$315K
-$315K
Peters William J
CFO, EVP & TREASURER
—
$287K
-$287K
Prins Richard K
Director
—
$162K
-$162K

Recent transactions

Every Form 4 transaction for AMPH, newest first.

SELL10b5-1
Peters William J · CFO, EVP & TREASURER
Tx Sep 21·Filed Sep 23·EDGAR ↗
4,139 sh @ $25.00
$103K
SELL
Zhou Rong · SENIOR EVP, PRODUCTION CENTER
Tx Sep 16·Filed Sep 17·EDGAR ↗
10,000 sh @ $23.94
$239K
EXERCISE
Zhou Rong · SENIOR EVP, PRODUCTION CENTER
Tx Sep 16·Filed Sep 17·EDGAR ↗
10,000 sh @ $13.35
$134K
SELL
Zhou Rong · SENIOR EVP, PRODUCTION CENTER
Tx Sep 2·Filed Sep 3·EDGAR ↗
3,187 sh @ $23.63
$75K
SELL
Prins Richard K · Director
Tx Aug 11·Filed Aug 12·EDGAR ↗
7,973 sh @ $20.30
$162K
SELL10b5-1
Peters William J · CFO, EVP & TREASURER
Tx Aug 7·Filed Aug 11·EDGAR ↗
8,180 sh @ $22.48
$184K
EXERCISE10b5-1
Peters William J · CFO, EVP & TREASURER
Tx Aug 7·Filed Aug 11·EDGAR ↗
5,053 sh @ $19.79
$100K
AWARD
Pierce Anthony T · Director
Tx Jul 9·Filed Jul 13·EDGAR ↗
7,886 sh
—
TAX
Lee Howard · Director
Tx Jun 2·Filed Jun 3·EDGAR ↗
769 sh @ $18.45
$14K
AWARD
Zasloff Michael A · Director
Tx Jun 1·Filed Jun 3·EDGAR ↗
8,143 sh
—
AWARD
Prins Richard K · Director
Tx Jun 1·Filed Jun 3·EDGAR ↗
8,143 sh
—
AWARD
Gaugh David Russell · Director
Tx Jun 1·Filed Jun 3·EDGAR ↗
8,143 sh
—
AWARD
Deflin Gayle · Director
Tx Jun 1·Filed Jun 3·EDGAR ↗
8,143 sh
—
AWARD
Lee Howard · Director
Tx Jun 1·Filed Jun 3·EDGAR ↗
8,143 sh
—
AWARD
Gerst Diane G. · Director
Tx Jun 1·Filed Jun 3·EDGAR ↗
8,143 sh
—
GIFT
Prins Richard K · Director
Tx Aug 19·Filed Jun 3·EDGAR ↗
1,500 sh
—

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About AMPH insider trading data

Form 4 is the SEC filing required when an officer, director, or 10% owner of a public company buys or sells the company's stock. By law, these filings must be submitted within two business days of the trade. Tracenotes pulls every Form 4 filing for AMPH from EDGAR, parses it, and surfaces the activity on this page.

What insider buying tells you. Open-market purchases by insiders are widely studied as a meaningful signal. Unlike stock awards (which are compensation, not conviction), an executive spending their own money to buy shares of the company they run is a vote of confidence. Studies have found insider-buying clusters — three or more insiders buying within a short window — outperform the broader market over the following year.

What insider selling tells you. Selling is noisier. Many sales are pre-scheduled under SEC Rule 10b5-1 plans, which let insiders sell on a fixed schedule regardless of company news. We label these "10b5-1" so you can see them. Discretionary sales — sales not tied to a plan — are more meaningful, especially when multiple insiders sell in quick succession.

Tracenotes methodology. We scan EDGAR daily for new Form 4 filings, parse them into individual transactions, and detect clusters when three or more distinct insiders buy or sell within a 14-day window. The data on this page covers the last 12 months. For deeper analysis, Tracenotes also runs language-change detection on 10-K and 10-Q filings — that's our core product.

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Frequently asked questions

What is a Form 4 filing?

Form 4 is the SEC disclosure required when a company insider — an officer, director, or 10% owner — buys or sells the company's stock. By law these filings must be submitted within two business days of the trade.

Is insider buying AMPH always bullish?

Open-market purchases by insiders are widely viewed as a bullish signal because executives are spending their own money. Stock awards and option exercises are part of compensation and don't carry the same weight, which is why we treat them separately on this page.

What is a 10b5-1 trade?

A trade made under SEC Rule 10b5-1, which lets insiders pre-schedule sales weeks or months in advance. These sales execute on a fixed plan regardless of company news, so they're a weaker signal than discretionary sales. We label them with a "10b5-1" tag.

What is an insider cluster?

A cluster is when three or more distinct insiders buy or sell within a 14-day window. Clusters are studied as stronger signals than single trades because multiple people independently reach the same view. We surface active clusters on Amphastar Pharmaceuticals, Inc. (AMPH) when they form.

Where does AMPH insider trading data come from?

Every Form 4 filing for AMPH is sourced directly from SEC EDGAR. Tracenotes scans EDGAR daily, parses each Form 4 into individual transactions, and updates this page within hours of new filings.

Nothing on this page constitutes investment advice. Form 4 data is sourced from SEC EDGAR and provided for research purposes only.

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