National HealthCare (NHC) had the highest return between 1990 and 1994 by a small-cap US stock, returning 1,459.4%.

ASSET	YEARS	% RETURN
National HealthCare (NHC)	1990-1994	1,459.42%
Shyft (SHYF)	1990-1994	706.79%
Polaris Industries (PII)	1990-1994	657.81%
CONMED (CNMD)	1990-1994	562.51%
Great Southern Bancorp (GSBC)	1990-1994	549.84%
Photronics (PLAB)	1990-1994	480.5%
ODP (ODP)	1990-1994	480.22%
Digi International (DGII)	1990-1994	469.61%
Vicor (VICR)	1990-1994	442.11%
PAMT (PAMT)	1990-1994	433.25%
Cohu (COHU)	1990-1994	419.46%
Marten Transport (MRTN)	1990-1994	400.12%
Oppenheimer (OPY)	1990-1994	354.52%
Heartland Express (HTLD)	1990-1994	328.59%
OFG Bancorp (OFG)	1990-1994	327.89%
Mesa Laboratories (MLAB)	1990-1994	321.84%
REX American Resources (REX)	1990-1994	319.33%
LCI Industries (LCII)	1990-1994	318.69%
Owens & Minor (OMI)	1990-1994	296.42%
NPK International (NPKI)	1990-1994	291.85%
Callaway Golf (MODG)	1990-1994	271.17%
Vishay Intertechnology (VSH)	1990-1994	265.18%
Lsb Industries (LXU)	1990-1994	264.13%
Wolverine World Wide (WWW)	1990-1994	254.27%
Cracker Barrel Old Country Store (CBRL)	1990-1994	245.66%

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