Aurinia Pharmaceuticals (AUPH) had the highest return between 2013 and 2014 by a mid-cap US stock, returning 5,587.5%.

ASSET	YEARS	% RETURN
Aurinia Pharmaceuticals (AUPH)	2013-2014	5,587.5%
Vipshop (VIPS)	2013-2014	986.12%
Globalstar, Inc Common Stock (GSAT)	2013-2014	759.38%
Catalyst Pharmaceuticals (CPRX)	2013-2014	582.76%
ACADIA Pharmaceuticals (ACAD)	2013-2014	564.23%
Plug Power (PLUG)	2013-2014	500%
Avadel Pharmaceuticals (AVDL)	2013-2014	472.91%
Nexstar Broadcasting (NXST)	2013-2014	389.92%
CleanSpark (CLSK)	2013-2014	374.36%
Pilgrims Pride (PPC)	2013-2014	346.12%
JOYY (JOYY)	2013-2014	329.93%
Ambarella (AMBA)	2013-2014	323.37%
TG Therapeutics (TGTX)	2013-2014	322.4%
Enphase Energy (ENPH)	2013-2014	269.25%
Qorvo (QRVO)	2013-2014	260.65%
Travere Therapeutics (TVTX)	2013-2014	260%
Astronics (ATRO)	2013-2014	250.96%
Saia (SAIA)	2013-2014	250.67%
Applied Digital (APLD)	2013-2014	248.28%
Skyworks Solutions (SWKS)	2013-2014	247.98%
Arrowhead Pharmaceuticals (ARWR)	2013-2014	241.67%
MGIC Investment (MTG)	2013-2014	237.68%
RadNet (RDNT)	2013-2014	234.9%
PTC Therapeutics (PTCT)	2013-2014	227.66%
Addus HomeCare (ADUS)	2013-2014	226.21%

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