Zillow (ZG) had the highest return in Q2 2014 by a large-cap US stock, returning 61.4%.

ASSET	QUARTER	% RETURN
Zillow (ZG)	Q2 2014	61.41%
Williams Companies (WMB)	Q2 2014	46.95%
Super Micro Computer (SMCI)	Q2 2014	44.57%
Targa Resources (TRGP)	Q2 2014	40.4%
Micron Technology (MU)	Q2 2014	38.21%
InterContinental Hotels Group PLC ADR (IHG)	Q2 2014	38.12%
Rambus (RMBS)	Q2 2014	33.15%
Vertex Pharmaceuticals (VRTX)	Q2 2014	32.75%
MPLX (MPLX)	Q2 2014	32.43%
Diamondback Energy (FANG)	Q2 2014	31.95%
JD Inc Adr (JD)	Q2 2014	31.08%
Western Midstream Partners (WES)	Q2 2014	28.44%
Cheniere Energy (LNG)	Q2 2014	28.4%
Charter Communications (CHTR)	Q2 2014	28.03%
Energy Transfer (ET)	Q2 2014	27.54%
Trip Group Ltd ADR (TCOM)	Q2 2014	26.99%
Agnico Eagle Mines (AEM)	Q2 2014	26.53%
Westlake Chemical (WLK)	Q2 2014	26.26%
Skyworks Solutions (SWKS)	Q2 2014	25.49%
Netflix (NFLX)	Q2 2014	25.26%
Franco-Nevada (FNV)	Q2 2014	24.98%
Entergy (ETR)	Q2 2014	24.26%
Grupo Aeroportuario del Pacifico SAB De CV ADR (PAC)	Q2 2014	23.93%
Banco Santander Brasil SA ADR (BSBR)	Q2 2014	23.24%
Electronic Arts (EA)	Q2 2014	23.14%

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