Facebook (META) had the highest return in July 2013 by a US stock in the S&P 500 (GSPC), returning 47.4%.

ASSET	MONTH	% RETURN
Facebook (META)	July 2013	47.38%
ONEOK (OKE)	July 2013	27.35%
F5 Networks (FFIV)	July 2013	25.43%
Tesla (TSLA)	July 2013	22.79%
Fortinet (FTNT)	July 2013	21.36%
CoStar (CSGP)	July 2013	20.58%
Air Products and Chemicals (APD)	July 2013	18.72%
Genesis Healthcare (GEN)	July 2013	18.37%
Gilead Sciences (GILD)	July 2013	18.15%
Boston Scientific (BSX)	July 2013	17.17%
Regeneron Pharmaceuticals (REGN)	July 2013	16.61%
Hologic (HOLX)	July 2013	16.41%
Align Technology (ALGN)	July 2013	16.29%
Generac (GNRC)	July 2013	16.13%
Palo Alto Networks (PANW)	July 2013	15.89%
S&P Global (SPGI)	July 2013	15.5%
Take-Two Interactive Software (TTWO)	July 2013	15.34%
CDW (CDW)	July 2013	15.28%
Rockwell Automation (ROK)	July 2013	15.15%
Principal Financial (PFG)	July 2013	14.89%
Smurfit WestRock (SW)	July 2013	14.88%
L3Harris Technologies (LHX)	July 2013	14.88%
Netflix (NFLX)	July 2013	14.45%
Eastman Chemical (EMN)	July 2013	14.31%
Cognizant Technology Solutions Corp Class A (CTSH)	July 2013	14.18%