Soleno Therapeutics (SLNO) had the highest return on December 30, 2019 by a mid-cap US stock, returning 9.5%.

ASSET	DATE	% RETURN
Soleno Therapeutics (SLNO)	12/30/2019	9.54%
DRDGOLD Limited ADR (DRD)	12/30/2019	5.36%
Grupo Simec SAB de CV ADR (SIM)	12/30/2019	5.29%
Corporacion America Airports (CAAP)	12/30/2019	5.26%
Hut 8 Corp Common Stock (HUT)	12/30/2019	4.77%
Dianthus Therapeutics (DNTH)	12/30/2019	4.16%
CNX Resources (CNX)	12/30/2019	3.6%
Immunitybio (IBRX)	12/30/2019	3.5%
Comstock Resources (CRK)	12/30/2019	3.49%
NovaGold Resources (NG)	12/30/2019	3.31%
Intercorp Financial Services (IFS)	12/30/2019	3.18%
Boot Barn (BOOT)	12/30/2019	3.07%
Fortuna Silver Mines (FSM)	12/30/2019	3.02%
Alpha Metallurgical Resources (AMR)	12/30/2019	2.96%
360 DigiTech (QFIN)	12/30/2019	2.96%
Torm PLC Class A (TRMD)	12/30/2019	2.9%
Eldorado Gold (EGO)	12/30/2019	2.87%
Apellis Pharmaceuticals (APLS)	12/30/2019	2.86%
Signet Jewelers (SIG)	12/30/2019	2.72%
Celcuity LLC (CELC)	12/30/2019	2.67%
Fluor (FLR)	12/30/2019	2.61%
Scorpio Tankers (STNG)	12/30/2019	2.61%
SSR Mining (SSRM)	12/30/2019	2.56%
Teekay Tankers (TNK)	12/30/2019	2.53%
Silvercorp Metals (SVM)	12/30/2019	2.46%

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