Tesla (TSLA) had the highest return between 2012 and 2014 by a US stock in the S&P 500 (GSPC), returning 668.5%.

ASSET	YEARS	% RETURN
Tesla (TSLA)	2012-2014	668.53%
Regeneron Pharmaceuticals (REGN)	2012-2014	625.98%
Delta Air Lines (DAL)	2012-2014	505.67%
DexCom (DXCM)	2012-2014	478.26%
Micron Technology (MU)	2012-2014	427.26%
Axon Enterprise (AXON)	2012-2014	405.34%
Corpay (CPAY)	2012-2014	396.2%
Southwest Airlines (LUV)	2012-2014	395.1%
Netflix (NFLX)	2012-2014	386.07%
Incyte (INCY)	2012-2014	385.78%
NXP Semiconductors (NXPI)	2012-2014	384.16%
Constellation Brands Inc Class A (STZ)	2012-2014	368.37%
Gilead Sciences (GILD)	2012-2014	354.7%
Seagate Technology (STX)	2012-2014	343.19%
Skyworks Solutions (SWKS)	2012-2014	333.22%
HCA (HCA)	2012-2014	320.22%
Western Digital (WDC)	2012-2014	269.1%
Broadcom (AVGO)	2012-2014	260.41%
Huntington Ingalls Industries (HII)	2012-2014	260.25%
Tyler Technologies (TYL)	2012-2014	254.52%
Vertex Pharmaceuticals (VRTX)	2012-2014	251.27%
United Airlines (UAL)	2012-2014	247.84%
EPAM Systems (EPAM)	2012-2014	247.27%
Smurfit WestRock (SW)	2012-2014	243.82%
Monolithic Power Systems (MPWR)	2012-2014	240.47%