Nebius (NBIS) had the lowest return in December 2014 by a large-cap US stock, returning -27%.

ASSET	MONTH	% RETURN
Nebius (NBIS)	December 2014	-26.99%
Petroleo Brasileiro Petrobras SA ADR (PBR)	December 2014	-21.25%
Veeva Systems Inc Class A (VEEV)	December 2014	-19.24%
Texas Pacific Land Trust (TPL)	December 2014	-18.62%
YPF Sociedad Anonima (YPF)	December 2014	-18.45%
Cemex SAB de CV ADR (CX)	December 2014	-18.02%
Arista Networks (ANET)	December 2014	-17.89%
Wayfair (W)	December 2014	-17.19%
Madrigal Pharmaceuticals (MDGL)	December 2014	-16.4%
Wynn Resorts (WYNN)	December 2014	-15.97%
EQT (EQT)	December 2014	-15.9%
Ecopetrol SA ADR (EC)	December 2014	-15.16%
Trip Group Ltd ADR (TCOM)	December 2014	-14.95%
Dr Reddy’s Laboratories Ltd ADR (RDY)	December 2014	-13.8%
Companhia de Saneamento Basico do Estado de Sao Paulo SABESP ADR (SBS)	December 2014	-13.48%
NRG Energy (NRG)	December 2014	-13.06%
Coca-Cola Femsa SAB de CV ADR (KOF)	December 2014	-12.76%
Exelixis (EXEL)	December 2014	-12.73%
Antero Resources (AR)	December 2014	-12.64%
Freeport-McMoran Copper & Gold (FCX)	December 2014	-12.54%
AerCap (AER)	December 2014	-12.49%
Five Below (FIVE)	December 2014	-12.19%
Wipro Limited ADR (WIT)	December 2014	-11.98%
Steel Dynamics (STLD)	December 2014	-11.86%
Ovintiv (OVV)	December 2014	-11.84%

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