NVR (NVR) had the highest return in January 1991 by a US stock, returning 183.3%.

ASSET	MONTH	% RETURN
NVR (NVR)	January 1991	183.33%
Light & Wonder (LNW)	January 1991	71.42%
Spectrum Brands (SPB)	January 1991	66.67%
Ark Restaurants (ARKR)	January 1991	63.64%
Natures Sunshine Products (NATR)	January 1991	63.33%
VOXX International (VOXX)	January 1991	60%
Hovnanian Enterprises (HOV)	January 1991	54.55%
ESCO Technologies (ESE)	January 1991	53.65%
Clean Harbors (CLH)	January 1991	51.11%
CECO Environmental (CECO)	January 1991	50%
Semtech (SMTC)	January 1991	50%
Celldex Therapeutics (CLDX)	January 1991	47.83%
Data I/O (DAIO)	January 1991	47.06%
Digi International (DGII)	January 1991	45.12%
Advanced Micro Devices (AMD)	January 1991	45%
Winnebago Industries (WGO)	January 1991	45%
PTC (PTC)	January 1991	43.14%
Mesa Laboratories (MLAB)	January 1991	42.4%
SunOpta (STKL)	January 1991	41.73%
Jack Henry & Associates (JKHY)	January 1991	41.07%
Daxor (DXR)	January 1991	40%
Pilgrims Pride (PPC)	January 1991	38.64%
Charles Schwab (SCHW)	January 1991	38.08%
Applied Materials (AMAT)	January 1991	37.23%
Mitek Systems (MITK)	January 1991	37.12%