ACADIA Pharmaceuticals (ACAD) had the highest return between 2012 and 2017 by a mid-cap US stock, returning 2,637.3%.

ASSET	YEARS	% RETURN
ACADIA Pharmaceuticals (ACAD)	2012-2017	2,637.27%
Vipshop (VIPS)	2012-2017	1,853.31%
TAL Education (TAL)	2012-2017	1,793.08%
Caesars Entertainment (CZR)	2012-2017	1,663.3%
Patrick Industries (PATK)	2012-2017	1,581.59%
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	1,000.76%
JOYY (JOYY)	2012-2017	976.76%
Nexstar Broadcasting (NXST)	2012-2017	969.5%
Repligen (RGEN)	2012-2017	948.55%
DXC Technology (DXC)	2012-2017	893.79%
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	793.06%
Ambarella (AMBA)	2012-2017	775.56%
Radian (RDN)	2012-2017	775.41%
Cidara Therapeutics (CDTX)	2012-2017	750%
Saia (SAIA)	2012-2017	720.77%
Marriot Vacations Worldwide (VAC)	2012-2017	714.75%
JBTMarel (JBTM)	2012-2017	647.75%
Axos Financial (AX)	2012-2017	634.64%

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