Eyepoint Pharmaceuticals (EYPT) had the highest return in April 2018 by a small-cap US stock, returning 105%.

ASSET	MONTH	% RETURN
Eyepoint Pharmaceuticals (EYPT)	April 2018	105%
Solid Biosciences LLC (SLDB)	April 2018	90.93%
American Battery Technology Company Common Stock (ABAT)	April 2018	71.43%
Baytex Energy (BTE)	April 2018	63.14%
Tandem Diabetes Care (TNDM)	April 2018	53.21%
Veritone (VERI)	April 2018	50.51%
Contango ORE (CTGO)	April 2018	47.45%
Verastem (VSTM)	April 2018	39.46%
CEA Industries (BNC)	April 2018	39.39%
Caledonia Mining (CMCL)	April 2018	39.27%
W&T Offshore (WTI)	April 2018	38.64%
Oil States International (OIS)	April 2018	38%
Nextdecade (NEXT)	April 2018	37.35%
Valhi (VHI)	April 2018	37.19%
Helix Energy Solutions (HLX)	April 2018	35.68%
Vericel Corp Ord (VCEL)	April 2018	33.5%
OPTIMIZERx (OPRX)	April 2018	32.47%
BioLife Solutions (BLFS)	April 2018	31.45%
NPK International (NPKI)	April 2018	30.43%
Harrow Health (HROW)	April 2018	30.29%
Pulse Biosciences (PLSE)	April 2018	30.2%
Expro (XPRO)	April 2018	29.93%
Xunlei Ltd Adr (XNET)	April 2018	29.64%
OFG Bancorp (OFG)	April 2018	29.19%
Orthopediatrics (KIDS)	April 2018	28.9%

Small-cap stocks are treated as having a market cap between $300M and $2B.