Insmed (INSM) had the lowest return in August 2014 by a large-cap US stock, returning -18.3%.

ASSET	MONTH	% RETURN
Insmed (INSM)	August 2014	-18.3%
Las Vegas Sands (LVS)	August 2014	-9.52%
T-Mobile US (TMUS)	August 2014	-8.85%
Vale SA ADR (VALE)	August 2014	-8.8%
Cognizant Technology Solutions Corp Class A (CTSH)	August 2014	-6.9%
Ares Management (ARES)	August 2014	-6.9%
Motorola Solutions (MSI)	August 2014	-6.9%
Super Micro Computer (SMCI)	August 2014	-6.81%
Flutter Entertainment (FLUT)	August 2014	-6.57%
Orix Corp Ads (IX)	August 2014	-6.46%
Banco Santander Chile (BSAC)	August 2014	-6.17%
Logitech International (LOGI)	August 2014	-5.95%
YPF Sociedad Anonima (YPF)	August 2014	-5.6%
Hologic (HOLX)	August 2014	-4.79%
Apollo Global Management LLC Class A (APO)	August 2014	-4.73%
Teck Resources Ltd Class B (TECK)	August 2014	-4.65%
Elbit Systems (ESLT)	August 2014	-4.58%
Expeditors International of Washington (EXPD)	August 2014	-4.51%
Wheaton Precious Metals (WPM)	August 2014	-4.49%
ICON (ICLR)	August 2014	-4.16%
Smurfit WestRock (SW)	August 2014	-3.79%
Aramark (ARMK)	August 2014	-3.77%
James Hardie Industries PLC ADR (JHX)	August 2014	-3.7%
CNH Industrial (CNH)	August 2014	-3.64%
InterContinental Hotels Group PLC ADR (IHG)	August 2014	-3.61%

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