Insmed (INSM) had the highest return in June 2014 by a large-cap US stock, returning 52.2%.

ASSET	MONTH	% RETURN
Insmed (INSM)	June 2014	52.17%
MakeMyTrip (MMYT)	June 2014	37.76%
Vertex Pharmaceuticals (VRTX)	June 2014	31.21%
Ubiquiti Networks (UI)	June 2014	28.42%
Wheaton Precious Metals (WPM)	June 2014	27.9%
Agnico Eagle Mines (AEM)	June 2014	26.74%
Zillow (ZG)	June 2014	26.15%
EXACT Sciences (EXAS)	June 2014	26.15%
Williams Companies (WMB)	June 2014	25.1%
Franco-Nevada (FNV)	June 2014	25.03%
Western Midstream Partners (WES)	June 2014	22.51%
Veeva Systems Inc Class A (VEEV)	June 2014	22.3%
Targa Resources (TRGP)	June 2014	21.34%
Sprouts Farmers Market LLC (SFM)	June 2014	20.6%
Lithia Motors (LAD)	June 2014	19.7%
Entegris (ENTG)	June 2014	19.11%
ServiceNow (NOW)	June 2014	18.4%
DexCom (DXCM)	June 2014	17.9%
Super Micro Computer (SMCI)	June 2014	17.53%
CarMax (KMX)	June 2014	17.19%
Tyler Technologies (TYL)	June 2014	16.86%
Tesla (TSLA)	June 2014	15.79%
Diamondback Energy (FANG)	June 2014	15.34%
Trip Group Ltd ADR (TCOM)	June 2014	15.33%
Micron Technology (MU)	June 2014	15.17%

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