Inventrust Properties (IVT) had the highest return between 2014 and 2015 by a mid-cap US stock, returning 751,855%.

ASSET	YEARS	% RETURN
Inventrust Properties (IVT)	2014-2015	751,855%
Cidara Therapeutics (CDTX)	2014-2015	2,045%
Applied Digital (APLD)	2014-2015	580%
Green Brick Partners (GRBK)	2014-2015	510.53%
CleanSpark (CLSK)	2014-2015	350%
Amicus Therapeutics (FOLD)	2014-2015	312.77%
Pampa Energia SA ADR (PAM)	2014-2015	288.47%
RadNet (RDNT)	2014-2015	267.86%
Globant (GLOB)	2014-2015	223.36%
TG Therapeutics (TGTX)	2014-2015	201.26%
Galapagos NV ADR (GLPG)	2014-2015	197.39%
Transportadora de Gas del Sur SA ADR (TGS)	2014-2015	185.92%
BBVA Banco Frances SA ADR (BBAR)	2014-2015	174.98%
Agios Pharm (AGIO)	2014-2015	173%
Travere Therapeutics (TVTX)	2014-2015	168.29%
Grupo Financiero Galicia SA ADR (GGAL)	2014-2015	158.98%
Dycom Industries (DY)	2014-2015	153.48%
Qorvo (QRVO)	2014-2015	148.05%
Banco Macro SA B ADR (BMA)	2014-2015	145.31%
Ultragenyx (RARE)	2014-2015	144.93%
Tower Semiconductor (TSEM)	2014-2015	141.17%
MACOM Technology Solutions (MTSI)	2014-2015	137.04%
Silicon Motion Technology (SIMO)	2014-2015	133.32%
EPAM Systems (EPAM)	2014-2015	126.05%
ANI Pharmaceuticals (ANIP)	2014-2015	124.73%

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