Aris Mining (ARMN) had the best month in 2010 by a mid-cap US stock in October 2010, returning 196,508.5%.

ASSET	MONTH	% RETURN
Aris Mining (ARMN)	October 2010	196,508.54%
Arrowhead Pharmaceuticals (ARWR)	March 2010	111.11%
Novanta (NOVT)	March 2010	102.04%
Sharplink Gaming (SBET)	October 2010	88.32%
First Bancorp (FBP)	December 2010	84%
Uranium Energy (UEC)	November 2010	77.22%
Applied Digital (APLD)	December 2010	75%
Energy Fuels (UUUU)	October 2010	69.48%
Riot Blockchain (RIOT)	April 2010	69.33%
ACADIA Pharmaceuticals (ACAD)	December 2010	69.01%
Green Brick Partners (GRBK)	September 2010	68.65%
Energy Fuels (UUUU)	July 2010	64.89%
Sharplink Gaming (SBET)	February 2010	63.93%
Energy Fuels (UUUU)	September 2010	61.26%
Catalyst Pharmaceuticals (CPRX)	April 2010	60.71%
Radian (RDN)	March 2010	57.98%
Applied Digital (APLD)	February 2010	55.56%
Jazz Pharmaceuticals (JAZZ)	November 2010	54.74%
MakeMyTrip (MMYT)	August 2010	54.55%
Casella Waste Systems (CWST)	December 2010	52.8%
First Majestic Silver (AG)	November 2010	52.31%
Mesoblast (MESO)	January 2010	51.66%
Radian (RDN)	February 2010	51.36%
Cirrus Logic (CRUS)	April 2010	51.31%
Western Alliance Bancorporation (WAL)	April 2010	51.04%

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