Travere Therapeutics (TVTX) had the lowest return in May 2021 by a mid-cap US stock, returning -39.7%.

ASSET	MONTH	% RETURN
Travere Therapeutics (TVTX)	May 2021	-39.68%
Riot Blockchain (RIOT)	May 2021	-36.73%
Praxis Precision Medicines (PRAX)	May 2021	-36.35%
New Oriental Education & Technology (EDU)	May 2021	-32.7%
Alkami Technology (ALKT)	May 2021	-30.82%
Compass (COMP)	May 2021	-30.61%
TAL Education (TAL)	May 2021	-29.8%
QuantumScape Corporation Class A Common Stock (QS)	May 2021	-29.59%
Arcus Biosciences (RCUS)	May 2021	-28.06%
Magnite (MGNI)	May 2021	-27.03%
Hut 8 Corp Common Stock (HUT)	May 2021	-26.86%
Appian (APPN)	May 2021	-25.83%
Vipshop (VIPS)	May 2021	-25.7%
Arcutis Biotherapeutics (ARQT)	May 2021	-25.31%
TG Therapeutics (TGTX)	May 2021	-22.94%
Opendoor Technologies (OPEN)	May 2021	-22.9%
CleanSpark (CLSK)	May 2021	-22.66%
Veracyte (VCYT)	May 2021	-22.21%
Recursion Pharmaceuticals (RXRX)	May 2021	-22.03%
Glaukos (GKOS)	May 2021	-21.92%
Terns Pharmaceuticals (TERN)	May 2021	-21.62%
Miniso Group Holding (MNSO)	May 2021	-21.37%
Twist Bioscience (TWST)	May 2021	-20.9%
VNET Group Inc DRC (VNET)	May 2021	-20.82%
Ocular Therapeutix (OCUL)	May 2021	-20.65%

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