T-Mobile US (TMUS) had the lowest return in October 2009 by a US stock in the S&P 500 (GSPC), returning -31%.

ASSET	MONTH	% RETURN
T-Mobile US (TMUS)	October 2009	-31.01%
Caesars Entertainment (CZR)	October 2009	-29.08%
Boston Scientific (BSX)	October 2009	-23.25%
American International (AIG)	October 2009	-22.84%
Wynn Resorts (WYNN)	October 2009	-22.65%
United Airlines (UAL)	October 2009	-22.41%
Regions Financial (RF)	October 2009	-21.43%
Skyworks Solutions (SWKS)	October 2009	-21.28%
MGM Resorts International (MGM)	October 2009	-21.04%
ON Semiconductor (ON)	October 2009	-20.73%
Delta Air Lines (DAL)	October 2009	-20.22%
NVIDIA (NVDA)	October 2009	-20.17%
State Street (STT)	October 2009	-19.75%
Garmin (GRMN)	October 2009	-19.54%
Interpublic Group of Companies (IPG)	October 2009	-19.2%
Huntington Bancshares (HBAN)	October 2009	-18.76%
Regeneron Pharmaceuticals (REGN)	October 2009	-18.61%
Advanced Micro Devices (AMD)	October 2009	-18.15%
NRG Energy (NRG)	October 2009	-17.89%
PulteGroup (PHM)	October 2009	-17.64%
Live Nation Entertainment (LYV)	October 2009	-17.57%
First Solar (FSLR)	October 2009	-17.39%
Domino's Pizza Inc Common Stock (DPZ)	October 2009	-16.78%
Cadence Design Systems (CDNS)	October 2009	-16.53%
Biogen (BIIB)	October 2009	-16.48%