Alnylam Pharmaceuticals (ALNY) had the highest return between 2012 and 2013 by a large-cap US stock, returning 671.9%.

ASSET	YEARS	% RETURN
Alnylam Pharmaceuticals (ALNY)	2012-2013	671.91%
Genmab A-S (GMAB)	2012-2013	498.47%
Insmed (INSM)	2012-2013	444.87%
Netflix (NFLX)	2012-2013	423.86%
Tesla (TSLA)	2012-2013	419.81%
Regeneron Pharmaceuticals (REGN)	2012-2013	387.06%
American Airlines (AAL)	2012-2013	385.58%
Cheniere Energy (LNG)	2012-2013	385.04%
Sarepta Therapeutics (SRPT)	2012-2013	349.67%
Corpay (CPAY)	2012-2013	290.96%
Smurfit WestRock (SW)	2012-2013	281.83%
DexCom (DXCM)	2012-2013	271.95%
Saia (SAIA)	2012-2013	271.81%
Zillow (ZG)	2012-2013	263.24%
Gilead Sciences (GILD)	2012-2013	262.28%
Seagate Technology (STX)	2012-2013	261.93%
Illumina (ILMN)	2012-2013	256.74%
Builders FirstSource (BLDR)	2012-2013	239.52%
Incyte (INCY)	2012-2013	236.41%
Constellation Brands Inc Class A (STZ)	2012-2013	235.78%
Delta Air Lines (DAL)	2012-2013	235.49%
AerCap (AER)	2012-2013	231.46%
Tyler Technologies (TYL)	2012-2013	230.84%
Lloyds Banking Group PLC ADR (LYG)	2012-2013	228.38%
Micron Technology (MU)	2012-2013	227.56%

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