Insteel Industries (IIIN) had the lowest return between 1990 and 1999 by a small-cap US stock, returning -100%.

ASSET	YEARS	% RETURN
Insteel Industries (IIIN)	1990-1999	-100%
Bar Harbor Bankshares (BHB)	1990-1999	-100%
Gray Television (GTN)	1990-1999	-100%
Manitowoc (MTW)	1990-1999	-99.74%
McEwen Mining (MUX)	1990-1999	-98.71%
Caledonia Mining (CMCL)	1990-1999	-97.92%
Vaalco Energy (EGY)	1990-1999	-94.57%
Gentherm (THRM)	1990-1999	-92.73%
BioLife Solutions (BLFS)	1990-1999	-92.48%
Amarin (AMRN)	1990-1999	-92.24%
Vericel Corp Ord (VCEL)	1990-1999	-88.84%
China Yuchai International (CYD)	1990-1999	-88.01%
Taseko Mines (TGB)	1990-1999	-87.77%
XOMA (XOMA)	1990-1999	-87.3%
Hallador Energy (HNRG)	1990-1999	-86%
Avadel Pharmaceuticals (AVDL)	1990-1999	-81.91%
3D Systems (DDD)	1990-1999	-81.42%
BJs Restaurants (BJRI)	1990-1999	-79.89%
Safehold (SAFE)	1990-1999	-79.42%
G-III Apparel (GIII)	1990-1999	-75.04%
United States Antimony (UAMY)	1990-1999	-75.02%
Franklin BSP Realty Trust (FBRT)	1990-1999	-74.03%
Hudson Technologies (HDSN)	1990-1999	-73.33%
Winmark (WINA)	1990-1999	-73.33%
SIGA Technologies (SIGA)	1990-1999	-71.11%

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