$AMPH

$25.57 +$0.10 (0.39%) Close

$AMPH Overview Financial Statements SEC Filings Executives News Red Flags Capital Raising Ownership Insider Transactions Congressional Trades

Ownership

13F as of Q2 2026 · 42.5M shares outstanding

Who owns AMPH?

By type of holder

Institutions 66.4% Insiders 25.1% Everyone else 8.6%

Concentration Top 10 holders own 38.8%

BlackRock, Inc. 12.3% · Dimensional Fund Advisors LP 5.4%

Institutional ownership

66.4%

-9.6 pts vs last qtr

Institutional holders

208

-6 vs last qtr

Net shares bought

−4.1M

by institutions in Q2 2026

New / sold out

32 / 38

positions opened vs closed

How is ownership changing?

Institutions, last 8 quarters

Biggest buyers in Q2 2026

HRT Financial LP +331.3K
Dimensional Fund Advisors LP +277.2K

Biggest sellers in Q2 2026

TD Asset Management Inc SOLD OUT −1.5M
Boston Trust Walden Corp SOLD OUT −944.8K

Who is planning to sell?

Notices of proposed sale, last 12 months

$1.54M

7 notices from 5 people

Shares covered

51.4K

0.12% of the company

Arranged in advance

of the value is under a 10b5-1 plan

Under a 10b5-1 plan No plan

Largest proposed sellers

Floyd Petersen Director $818K
Rong Zhou Officer $500K

Every notice on Red Flags →

A Form 144 is notice of a planned sale, not the sale itself. What insiders actually sold is on Insider Transactions.

Is your stake being diluted?

Diluted share count, FY2016–FY2025

+1.5%

+0.17% a year

Each share's claim on the business

−1.5%

shrank without buying or selling a share

Spent on buybacks vs paid in stock

$400M vs $195M

over 10 fiscal years

Diluted shares, split-adjusted

Buybacks Stock-based comp

How patient are the owners?

Institutional shares by how long they've been held

5+ years73% 3–5 years7% 1–3 years15% Under 1 year5%

Quarterly turnover

14.5%

of institutional shares changed hands

Top 10 managers, median time held

5 years

Super Investors

Investment managers reporting AMPH on Form 13F

Holder	Shares	% of company	Change vs last qtr	Held since	% of their book
B BlackRock, Inc.	5.2M	12.28%	−196.4K (−3.6%)	≤2021	0.0%
Shares held by quarter Peak holding6.1M (Q1'25) Change over 8 quarters−807.8K Share of the company12.280% BlackRock, Inc.'s full portfolio →
DF Dimensional Fund Advisors LP	2.3M	5.42%	+277.2K (+13.7%)	≤2021	0.0%
Shares held by quarter Peak holding2.3M (Q2'26) Change over 8 quarters+1.2M Share of the company5.420% Dimensional Fund Advisors LP's full portfolio →

BlackRock, Inc.

5.2M

% of company

12.28%

Change vs last qtr

−196.4K (−3.6%)

Held since

≤2021

Dimensional Fund Advisors LP

2.3M

% of company

5.42%

Change vs last qtr

+277.2K (+13.7%)

Held since

≤2021

28 more super investors behind a free account

See every manager holding Amphastar Pharmaceuticals, Inc., how their position has changed, and how long they've held it.

Institutional Funds

Mutual funds and ETFs reporting AMPH on Form N-PORT; together they hold 38.0% of the company

Fund	Position value	Shares	% of company	% of the fund	As of
IC iShares Core S&P Small-Cap ETF iShares Trust	$41.3M	2.0M	4.81%	0.04%	June 30, 2026
VT Vanguard Total Stock Market Index Fund Vanguard Index Funds	$21.3M	1.1M	2.48%	0.00%	June 30, 2026

iShares Core S&P Small-Cap ETF

iShares Trust

Position value

$41.3M

% of company

4.81%

% of the fund

0.04%

As of

June 30, 2026

Vanguard Total Stock Market Index Fund

Vanguard Index Funds

Position value

$21.3M

% of company

2.48%

% of the fund

0.00%

As of

June 30, 2026

23 more funds behind a free account

See every fund holding Amphastar Pharmaceuticals, Inc. and how much of the fund the position is.

Insiders and 5%+ holders

From Forms 3/4/5 and Schedules 13D/G

Holder	Shares	% of company	Change vs last qtr	8 quarters	Held since	% of their book
ZR Zhou Rong Insider	179.2K	0.42%	—	—	—	—
Insider holdings come from Form 3/4/5 filings, which are not quarterly. Share of the company0.420% Zhou Rong's insider activity →
PW Peters William J Insider	168.7K	0.40%	—	—	—	—
Insider holdings come from Form 3/4/5 filings, which are not quarterly. Share of the company0.400% Peters William J's insider activity →

Zhou Rong

Insider

179.2K

% of company

0.42%

Change vs last qtr

—

Held since

—

Peters William J

Insider

168.7K

% of company

0.40%

Change vs last qtr

—

Held since

—

9 more holders behind a free account

See every insider and 5%+ holder of Amphastar Pharmaceuticals, Inc..

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