MercadoLibre (MELI) had the highest return in December 2007 by a large-cap US stock, returning 67.5%.

ASSET	MONTH	% RETURN
MercadoLibre (MELI)	December 2007	67.49%
Hess (HES)	December 2007	40.97%
MSCI (MSCI)	December 2007	38.63%
Biomarin Pharmaceutical (BMRN)	December 2007	27.94%
Lululemon Athletica (LULU)	December 2007	26.97%
Archer-Daniels-Midland (ADM)	December 2007	26.86%
Lennox International (LII)	December 2007	22.91%
Petroleo Brasileiro Petrobras SA ADR (PBR)	December 2007	20.49%
CF Industries (CF)	December 2007	20.28%
Steel Dynamics (STLD)	December 2007	18.68%
Petróleo Brasileiro SA - Petrobras (PBR.A)	December 2007	18.56%
Contura Energy (CTRA)	December 2007	18.42%
Incyte (INCY)	December 2007	17.54%
Fomento Economico Mexicano (FMX)	December 2007	16.76%
YPF Sociedad Anonima (YPF)	December 2007	15.68%
Take-Two Interactive Software (TTWO)	December 2007	15.67%
Intercontinental Exchange (ICE)	December 2007	15.3%
ResMed (RMD)	December 2007	15.12%
Suncor Energy (SU)	December 2007	14.45%
T-Mobile US (TMUS)	December 2007	14.41%
Dr Reddy’s Laboratories Ltd ADR (RDY)	December 2007	14.28%
Canadian Natural Resources (CNQ)	December 2007	13.91%
Nasdaq (NDAQ)	December 2007	13.82%
Agnico Eagle Mines (AEM)	December 2007	13.81%
Stifel Financial (SF)	December 2007	13.59%

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