Sterling Infrastructure (STRL) had the best month in March 2011 by a large-cap US stock in March 2011, returning 28.3%.

ASSET	MONTH	% RETURN
Sterling Infrastructure (STRL)	March 2011	28.27%
Jazz Pharmaceuticals (JAZZ)	March 2011	27.81%
Harmony Gold Mining (HMY)	March 2011	27.2%
Insmed (INSM)	March 2011	25%
Regeneron Pharmaceuticals (REGN)	March 2011	23.36%
MercadoLibre (MELI)	March 2011	21.96%
Western Digital (WDC)	March 2011	21.7%
Westinghouse Air Brake Technologies (WAB)	March 2011	19.15%
Companhia de Saneamento Basico do Estado de Sao Paulo SABESP ADR (SBS)	March 2011	16.84%
Ulta Beauty (ULTA)	March 2011	16.26%
Huntington Ingalls Industries (HII)	March 2011	16.18%
Motorola Solutions (MSI)	March 2011	15.54%
Coca-Cola Consolidated (COKE)	March 2011	15.4%
Tesla (TSLA)	March 2011	15.39%
Incyte (INCY)	March 2011	15.36%
Netflix (NFLX)	March 2011	15.32%
Baidu (BIDU)	March 2011	15.11%
Woodside Energy (WDS)	March 2011	15.01%
Tractor Supply (TSCO)	March 2011	14.87%
Lululemon Athletica (LULU)	March 2011	14.83%
HEICO (HEI.A)	March 2011	14.77%
Seagate Technology (STX)	March 2011	14.18%
Expedia (EXPE)	March 2011	13.97%
Old Dominion Freight Line (ODFL)	March 2011	13.74%
Corcept Therapeutics (CORT)	March 2011	13.33%

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