Question 1

Who are the insiders buying Amphastar Pharmaceuticals, Inc. stock?

Accepted Answer

InsiderAct tracks all open-market purchases of Amphastar Pharmaceuticals, Inc. stock by corporate insiders — including officers, directors, and shareholders owning more than 10% — sourced from public SEC Form 4 filings.

Question 2

What does insider buying at a company mean?

Accepted Answer

When a corporate officer, director, or major shareholder purchases their own company's stock on the open market using personal funds, it signals confidence in the company's outlook. This is especially meaningful when multiple insiders buy within the same 7–14 day window (cluster buying) or when the purchase size exceeds $100,000.

Question 3

How do I find cluster buying signals for a company?

Accepted Answer

InsiderAct automatically detects cluster buying — two or more insiders independently purchasing shares within a 14-day window. When a cluster buy signal is active for a company, it appears prominently on the company's InsiderAct page and on the Signals tab.

Question 4

Has Amphastar Pharmaceuticals, Inc. had any recent large insider purchases?

Accepted Answer

InsiderAct tracks all open-market purchases of $100,000 or more at Amphastar Pharmaceuticals, Inc.. Large insider purchases are flagged as high-conviction signals because they represent meaningful personal capital commitments by executives or directors who have direct visibility into the company's operations and prospects.

Question 5

Where do the insider transactions on this page come from?

Accepted Answer

All transactions shown on InsiderAct company pages are sourced directly from SEC EDGAR Form 4 filings — the mandatory public disclosures that corporate insiders must submit within 2 business days of any stock transaction. InsiderAct ingests these filings in near real time and filters for open-market purchases and sales.


2026-09-23	2026-09-21	Peters William J	CFO	Sale	4,139	$25.00	$103,475
2026-09-17	2026-09-16	Zhou Rong	EVP	Sale	10,000	$23.94	$239,400
2026-09-17	2026-09-16	Zhou Rong	EVP	Exercise Conversion	10,000	$13.35	$133,500
2026-09-17	2026-09-16	Zhou Rong	EVP	Exercise Conversion	10,000	$13.35	$133,500
2026-09-03	2026-09-02	Zhou Rong	EVP	Sale	3,187	$23.63	$75,306
2026-08-12	2026-08-11	Prins Richard K	Director	Sale	7,973	$20.30	$161,852
2026-08-11	2026-08-07	Peters William J	CFO	Exercise Conversion	5,053	$19.79	$99,999
2026-08-11	2026-08-07	Peters William J	CFO	Sale	8,180	$22.48	$183,886
2026-08-11	2026-08-07	Peters William J	CFO	Exercise Conversion	5,053	$19.79	$99,999
2026-07-13	2026-07-09	Pierce Anthony T	Director	Award	7,886	$0.00	$0

AMPH

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