Northern Oil & Gas (NOG) had the highest return between 2000 and 2010 by a mid-cap US stock, returning 8,777,303.8%.

ASSET	YEARS	% RETURN
Northern Oil & Gas (NOG)	2000-2010	8,777,303.85%
Sandstorm Gold Ltd N (SAND)	2000-2010	649,100%
Aris Mining (ARMN)	2000-2010	326,680.13%
First Majestic Silver (AG)	2000-2010	63,584%
Companhia Siderurgica Nacional ADR (SID)	2000-2010	13,662.3%
Weatherford International (WFRD)	2000-2010	7,650%
Middleby (MIDD)	2000-2010	3,031.89%
Hudbay Minerals (HBM)	2000-2010	2,961.2%
HF Sinclair (DINO)	2000-2010	2,915.37%
CarMax (KMX)	2000-2010	2,733.78%
Alliance Resource Partners (ARLP)	2000-2010	2,218.49%
Cleveland-Cliffs (CLF)	2000-2010	2,201.49%
Balchem (BCPC)	2000-2010	2,165.92%
SSR Mining (SSRM)	2000-2010	2,157.58%
Gerdau SA ADR (GGB)	2000-2010	2,024.39%
Cal-Maine Foods (CALM)	2000-2010	1,991.05%
BRF SA ADR (BRFS)	2000-2010	1,989.51%
ICL Israel Chemicals (ICL)	2000-2010	1,599.26%
FTI Consulting (FCN)	2000-2010	1,577.62%
Credit Acceptance (CACC)	2000-2010	1,573.87%
RadNet (RDNT)	2000-2010	1,558.82%
Penn National Gaming (PENN)	2000-2010	1,539.87%
Dorman Products (DORM)	2000-2010	1,467.21%
DaVita HealthCare Partners (DVA)	2000-2010	1,444.22%
Methanex (MEOH)	2000-2010	1,393.44%

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