Which has grown faster, AMPH or CSTL?

Over the past five years, CSTL grew revenue faster — AMPH at a 13.71% CAGR versus CSTL at 35.55%.

Is AMPH or CSTL more profitable?

AMPH runs the higher net margin — AMPH at 10.76% versus CSTL at -5.43%.

How have AMPH and CSTL total returns compared?

Over the past 5 years, AMPH delivered 6.13% and CSTL delivered -10.28% annualized total return. Past performance doesn't predict future results.

Amphastar Pharmaceuticals, Inc. (AMPH) vs Castle Biosciences, Inc. (CSTL)

A side-by-side comparison of Amphastar Pharmaceuticals, Inc. and Castle Biosciences, Inc. across valuation, profitability, dividends, and growth — built entirely from reported fundamentals, as of October 6, 2026. Differences are shown without an overall score or investment verdict.

AMPH

Amphastar Pharmaceuticals, Inc.

$1.11B

$25.16HealthcareDelayed quote: Oct 6, 2026, 10:05 AM EDT

CSTL

Castle Biosciences, Inc.

$1.11B

$36.29HealthcareDelayed quote: Oct 6, 2026, 10:05 AM EDT

Total return — AMPH vs CSTL

growth of $100 · dividends reinvested · last 7y

AMPH +31.9% (+4.0%/yr)CSTL +71.3% (+8.0%/yr)CSTL compounded faster over this window

AMPH CSTL

AMPH vs CSTL: by the numbers

•AMPH is the larger company ($1.11B vs $1.11B market cap).
•AMPH is profitable (10.76% net margin) while CSTL runs a net loss (-5.43%).
•CSTL grew revenue faster over the past five years (35.55% vs 13.71% CAGR).

Metrics side by side

Valuation

Metric	AMPH	CSTL
P/E ratio	14.89	N/A
Forward P/E	8.47	N/A
PEG ratio	0.11	N/A
P/S ratio	1.52	3.10
P/B ratio	1.44	2.36
EV / EBITDA	8.77	N/A
FCF yield	13.78%	N/A

Profitability

Metric	AMPH	CSTL
Gross margin	47.68%	77.26%
Operating margin	15.66%	-8.99%
Net margin	10.76%	-5.43%
ROE	10.23%	-4.13%
ROIC	5.93%	-6.33%

Growth (annualized)

Metric	AMPH	CSTL
Revenue CAGR (5Y)	13.71%	35.55%
EPS CAGR (5Y)	134.23%	N/A
FCF CAGR (5Y)	23.90%	N/A
Total return CAGR (5Y)	6.13%	-10.28%

Frequently asked

Which has grown faster, AMPH or CSTL?: Over the past five years, CSTL grew revenue faster — AMPH at a 13.71% CAGR versus CSTL at 35.55%.
Is AMPH or CSTL more profitable?: AMPH runs the higher net margin — AMPH at 10.76% versus CSTL at -5.43%.
How have AMPH and CSTL total returns compared?: Over the past 5 years, AMPH delivered 6.13% and CSTL delivered -10.28% annualized total return. Past performance doesn't predict future results.

Go deeper

Full AMPH analysis Full CSTL analysis Interactive comparison tool

Dig into the metrics

Amphastar Pharmaceuticals P/E ratio Amphastar Pharmaceuticals ROE Castle Biosciences ROE Amphastar Pharmaceuticals operating margin Castle Biosciences operating margin Amphastar Pharmaceuticals revenue growth Castle Biosciences revenue growth Amphastar Pharmaceuticals free cash flow Castle Biosciences free cash flow

Amphastar Pharmaceuticals & Castle Biosciences appear in these rankings

Fastest Revenue Growth Stocks Highest FCF Yield Stocks Lowest P/E Ratio Stocks

Figures are sourced from reported fundamentals and the latest end-of-day price. This comparison is informational only and is not investment advice. Past performance does not predict future results. See our methodology. Compiled by TGMCharts Research · data verified October 6, 2026.