Paycom Soft (PAYC) had the highest return in August 2014 by a large-cap US stock, returning 39.6%.

ASSET	MONTH	% RETURN
Paycom Soft (PAYC)	August 2014	39.56%
Monster Beverage (MNST)	August 2014	37.6%
EXACT Sciences (EXAS)	August 2014	33.83%
Centrais Electricas Brasileiras (EBR)	August 2014	32.5%
Axon Enterprise (AXON)	August 2014	30.47%
United Therapeutics (UTHR)	August 2014	30%
Alnylam Pharmaceuticals (ALNY)	August 2014	28.64%
Veeva Systems Inc Class A (VEEV)	August 2014	27.42%
Arista Networks (ANET)	August 2014	27.39%
MercadoLibre (MELI)	August 2014	24.27%
Petróleo Brasileiro SA - Petrobras (PBR.A)	August 2014	23.14%
Gold Fields Ltd ADR (GFI)	August 2014	22.84%
Petroleo Brasileiro Petrobras SA ADR (PBR)	August 2014	22.7%
Neurocrine Biosciences (NBIX)	August 2014	20.19%
Tesla (TSLA)	August 2014	19.29%
MACOM Technology Solutions (MTSI)	August 2014	19.11%
Banco Bradesco SA ADR (BBD)	August 2014	18.76%
Ubiquiti Networks (UI)	August 2014	18.74%
Itau Unibanco Banco (ITUB)	August 2014	18.23%
Gilead Sciences (GILD)	August 2014	18.2%
Texas Pacific Land Trust (TPL)	August 2014	17.99%
Molina Healthcare (MOH)	August 2014	17.72%
Broadcom (AVGO)	August 2014	17.41%
DexCom (DXCM)	August 2014	17.18%
Ross Stores (ROST)	August 2014	16.95%

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