DRDGOLD Limited ADR (DRD) had the highest return in January 2016 by a mid-cap US stock, returning 66.7%.

ASSET	MONTH	% RETURN
DRDGOLD Limited ADR (DRD)	January 2016	66.66%
Alphatec (ATEC)	January 2016	51.64%
Sibanye Gold Ltd ADR (SBSW)	January 2016	45.01%
Ollie's Bargain Outlet Hldg (OLLI)	January 2016	33.59%
Skyline (SKY)	January 2016	31.58%
Mercurity Fintech Holding Inc ADR (MFH)	January 2016	26.81%
Terex (TEX)	January 2016	23.48%
Cirrus Logic (CRUS)	January 2016	18.3%
Golar LNG (GLNG)	January 2016	18.07%
MSC Industrial Direct (MSM)	January 2016	17.32%
Macy’s (M)	January 2016	17.3%
Applied Digital (APLD)	January 2016	15.38%
Columbia Sportswear (COLM)	January 2016	15.2%
Chesapeake Utilities (CPK)	January 2016	13.89%
PLDT Inc ADR (PHI)	January 2016	13.33%
One Gas (OGS)	January 2016	13.21%
Inter Parfums (IPAR)	January 2016	12.82%
Euronet Worldwide (EEFT)	January 2016	12.23%
Cal-Maine Foods (CALM)	January 2016	12.05%
Five Below (FIVE)	January 2016	11.98%
Uniqure (QURE)	January 2016	11.57%
Banco Macro SA B ADR (BMA)	January 2016	11.17%
Pampa Energia SA ADR (PAM)	January 2016	10.57%
Fortuna Silver Mines (FSM)	January 2016	10.39%
American States Water (AWR)	January 2016	10.27%

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