Argan (AGX) had the highest return between 1995 and 1996 by a mid-cap US stock, returning 6,101%.

ASSET	YEARS	% RETURN
Argan (AGX)	1995-1996	6,101.01%
AutoNation (AN)	1995-1996	1,832.58%
Alkermes (ALKS)	1995-1996	994.12%
Bausch Health Companies (BHC)	1995-1996	876.19%
Onto Innovation (ONTO)	1995-1996	660%
CBIZ (CBZ)	1995-1996	646.15%
Viavi Solutions (VIAV)	1995-1996	624.15%
Semtech (SMTC)	1995-1996	552.22%
Penn National Gaming (PENN)	1995-1996	533.16%
Sanmina (SANM)	1995-1996	318.52%
Comstock Resources (CRK)	1995-1996	285.18%
Patterson-UTI Energy (PTEN)	1995-1996	281.46%
ACI Worldwide (ACIW)	1995-1996	272.02%
Hexcel (HXL)	1995-1996	271.43%
Dycom Industries (DY)	1995-1996	269.97%
Transocean (RIG)	1995-1996	257.63%
Weatherford International (WFRD)	1995-1996	233.33%
Adtalem Global Education (ATGE)	1995-1996	208.2%
Zions Bancorporation (ZION)	1995-1996	205.44%
National Beverage (FIZZ)	1995-1996	200%
SLM (SLM)	1995-1996	198.01%
Belden (BDC)	1995-1996	191.5%
Robert Half International (RHI)	1995-1996	185.85%
WSFS Financial (WSFS)	1995-1996	181.06%
Synovus Financial (SNV)	1995-1996	179.58%

Mid-cap stocks are treated as having a market cap between $2B and $10B.