Netflix (NFLX) had the highest return in January 2013 by a large-cap US stock, returning 73.6%.

ASSET	MONTH	% RETURN
Netflix (NFLX)	January 2013	73.55%
Ionis Pharmaceuticals (IONS)	January 2013	36.69%
Best Buy (BBY)	January 2013	33.94%
Zillow (ZG)	January 2013	33.85%
Sony (SONY)	January 2013	30.36%
Boston Scientific (BSX)	January 2013	27.47%
Alnylam Pharmaceuticals (ALNY)	January 2013	27.34%
Apollo Global Management LLC Class A (APO)	January 2013	25.32%
Valero Energy (VLO)	January 2013	25.01%
Marvell Technology (MRVL)	January 2013	24.16%
Evercore Partners (EVR)	January 2013	23.57%
HCA (HCA)	January 2013	22.84%
Stellantis (STLA)	January 2013	21.79%
Centrais Elétricas Brasileiras SA - Eletrobrás (EBR.B)	January 2013	21.77%
Somnigroup International (SGI)	January 2013	21.3%
Infosys Ltd ADR (INFY)	January 2013	21.22%
Copart (CPRT)	January 2013	19.73%
Carlyle (CG)	January 2013	18.96%
Smurfit WestRock (SW)	January 2013	18.33%
Super Micro Computer (SMCI)	January 2013	18.02%
Neurocrine Biosciences (NBIX)	January 2013	17.97%
STMicroelectronics NV ADR (STM)	January 2013	17.89%
LPL Financial (LPLA)	January 2013	17.75%
Tenet Healthcare (THC)	January 2013	17.06%
Hologic (HOLX)	January 2013	16.46%

Large-cap stocks are treated as having a market cap of $10B+.