Amerant Bancorp (AMTB) had the highest return between 2002 and 2021 by a small-cap US stock, returning 10,854,266.7%.

ASSET	YEARS	% RETURN
Amerant Bancorp (AMTB)	2002-2021	10,854,266.67%
OPTIMIZERx (OPRX)	2002-2021	621,000%
Integra Resources (ITRG)	2002-2021	429,900%
Immatics (IMTX)	2002-2021	268,700%
Know Labs (KNW)	2002-2021	172,673.54%
USANA Health Sciences (USNA)	2002-2021	31,048.05%
Metalla Royalty & Streaming (MTA)	2002-2021	26,017.05%
Encore Capital (ECPG)	2002-2021	23,788.46%
Diversified Energy (DEC)	2002-2021	22,800%
Universal Insurance (UVE)	2002-2021	19,735.85%
Insteel Industries (IIIN)	2002-2021	17,867.73%
Diamond Hill Investment (DHIL)	2002-2021	14,348.51%
Ziff Davis (ZD)	2002-2021	13,366.96%
EVI Industries (EVI)	2002-2021	12,762.49%
Nutex Health (NUTX)	2002-2021	8,140%
Helios Technologies (HLIO)	2002-2021	7,756.31%
Gentherm (THRM)	2002-2021	7,728.83%
Mesa Laboratories (MLAB)	2002-2021	7,010.7%
eXp World (EXPI)	2002-2021	6,649.66%
UFP Technologies (UFPT)	2002-2021	6,466.36%
Cryoport (CYRX)	2002-2021	6,296.76%
Transcat (TRNS)	2002-2021	6,274.48%
Lightwave Logic (LWLG)	2002-2021	5,852%
HIVE Blockchain Technologies (HIVE)	2002-2021	5,589.66%
China Yuchai International (CYD)	2002-2021	5,118.68%

Small-cap stocks are treated as having a market cap between $300M and $2B.