Best Buy (BBY) had the highest return in March 2013 by a US stock in the S&P 500 (GSPC), returning 28.4%.

ASSET	MONTH	% RETURN
Best Buy (BBY)	March 2013	28.43%
Texas Pacific Land Trust (TPL)	March 2013	27.46%
Deckers Outdoor (DECK)	March 2013	25.91%
Enphase Energy (ENPH)	March 2013	23.26%
Charter Communications (CHTR)	March 2013	21.46%
United Airlines (UAL)	March 2013	20.43%
Micron Technology (MU)	March 2013	19.89%
HP (HPQ)	March 2013	19.65%
Diamondback Energy (FANG)	March 2013	19.29%
Vertex Pharmaceuticals (VRTX)	March 2013	18.09%
Live Nation Entertainment (LYV)	March 2013	17.7%
Discover Financial Services (DFS)	March 2013	17.01%
Walgreens Boots Alliance (WBA)	March 2013	16.66%
Jacobs Solutions (J)	March 2013	16.58%
Biogen (BIIB)	March 2013	16.53%
Insulet (PODD)	March 2013	16.22%
Delta Air Lines (DAL)	March 2013	15.78%
Southwest Airlines (LUV)	March 2013	15.7%
Leidos (LDOS)	March 2013	14.83%
Gilead Sciences (GILD)	March 2013	14.8%
Mondelez International (MDLZ)	March 2013	14.63%
Seagate Technology (STX)	March 2013	14.13%
Kroger (KR)	March 2013	13.57%
DexCom (DXCM)	March 2013	13.2%
ServiceNow (NOW)	March 2013	12.91%