Sandstorm Gold Ltd N (SAND) had the highest return between 2008 and 2010 by a mid-cap US stock, returning 649,100%.

ASSET	YEARS	% RETURN
Sandstorm Gold Ltd N (SAND)	2008-2010	649,100%
Aris Mining (ARMN)	2008-2010	139,761.18%
Weatherford International (WFRD)	2008-2010	15,400%
Amneal Pharmaceuticals, Inc Class A Common Stock (AMRX)	2008-2010	704.4%
Mesoblast (MESO)	2008-2010	619.47%
Northern Oil & Gas (NOG)	2008-2010	318.61%
Nova (NVMI)	2008-2010	233.73%
Hawkins (HWKN)	2008-2010	223.73%
Pegasystems (PEGA)	2008-2010	213.78%
Steven Madden (SHOO)	2008-2010	213.37%
Eldorado Gold (EGO)	2008-2010	211.93%
Cirrus Logic (CRUS)	2008-2010	203.8%
First Majestic Silver (AG)	2008-2010	201.87%
Credit Acceptance (CACC)	2008-2010	199.33%
Trex (TREX)	2008-2010	177.31%
ICL Israel Chemicals (ICL)	2008-2010	177.02%
Bausch Health Companies (BHC)	2008-2010	164.84%
Dorman Products (DORM)	2008-2010	158.86%
Boston Beer (SAM)	2008-2010	153.37%
Westlake Chemical (WLK)	2008-2010	135.96%
LivaNova (LIVN)	2008-2010	135.71%
Formula Systems 1985 Ltd ADR (FORTY)	2008-2010	134.61%
NewMarket (NEU)	2008-2010	134.59%
Balchem (BCPC)	2008-2010	130.18%
Alaska Air (ALK)	2008-2010	128.41%

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