Patrick Industries (PATK) had the highest return between 2012 and 2017 by a mid-cap US stock, returning 3,683.5%.

ASSET	YEARS	% RETURN
Patrick Industries (PATK)	2012-2017	3,683.53%
Par Pacific (PARR)	2012-2017	3,113.33%
ACADIA Pharmaceuticals (ACAD)	2012-2017	2,637.27%
Celsius (CELH)	2012-2017	2,400%
Vipshop (VIPS)	2012-2017	1,853.31%
TAL Education (TAL)	2012-2017	1,793.08%
Caesars Entertainment (CZR)	2012-2017	1,663.3%
DXC Technology (DXC)	2012-2017	1,555.36%
Sarepta Therapeutics (SRPT)	2012-2017	1,128.26%
Ligand Pharmaceuticals (LGND)	2012-2017	1,041.08%
Travere Therapeutics (TVTX)	2012-2017	1,008.95%
Grupo Financiero Galicia SA ADR (GGAL)	2012-2017	1,000.75%
JOYY (JOYY)	2012-2017	976.76%
Nexstar Broadcasting (NXST)	2012-2017	969.48%
Repligen (RGEN)	2012-2017	948.55%
Nektar Therapeutics (NKTR)	2012-2017	945.88%
Builders FirstSource (BLDR)	2012-2017	937.62%
American Airlines (AAL)	2012-2017	934.47%
Transportadora de Gas del Sur SA ADR (TGS)	2012-2017	846.97%
IES (IESC)	2012-2017	845.21%
CleanSpark (CLSK)	2012-2017	838.47%
Trex (TREX)	2012-2017	826.41%
Western Alliance Bancorporation (WAL)	2012-2017	793.05%
Ambarella (AMBA)	2012-2017	775.56%
Radian (RDN)	2012-2017	775.44%

Mid-cap stocks are treated as having a market cap between $2B and $10B.