Alpha Metallurgical Resources (AMR) had the highest return between 2021 and 2023 by a mid-cap US stock, returning 3,045.5%.

ASSET	YEARS	% RETURN
Alpha Metallurgical Resources (AMR)	2021-2023	3,045.55%
Applied Digital (APLD)	2021-2023	2,895.56%
Weatherford International (WFRD)	2021-2023	1,548.36%
Vista Oil Gas ADR (VIST)	2021-2023	1,039.38%
Peabody Energy (BTU)	2021-2023	898.49%
Trump Media & Technology (DJTWW)	2021-2023	843.46%
Tidewater (TDW)	2021-2023	720.36%
Dillards (DDS)	2021-2023	633.1%
Tecnoglass (TGLS)	2021-2023	578.5%
Chord Energy (CHRD)	2021-2023	545.53%
SM Energy (SM)	2021-2023	541.59%
PBF Energy (PBF)	2021-2023	526.39%
Alliance Resource Partners (ARLP)	2021-2023	499.83%
Globalstar, Inc Common Stock (GSAT)	2021-2023	482.76%
Scorpio Tankers (STNG)	2021-2023	470.82%
ELF Beauty (ELF)	2021-2023	470.29%
MoonLake Immunotherapeutics (MLTX)	2021-2023	458.13%
Catalyst Pharmaceuticals (CPRX)	2021-2023	404.8%
Avis Budget (CAR)	2021-2023	394.75%
F&G Annuities & Life (FG)	2021-2023	374.45%
Modine Manufacturing (MOD)	2021-2023	373.06%
Matador Resources (MTDR)	2021-2023	371.47%
Sterling Construction (STRL)	2021-2023	370.72%
Lantheus (LNTH)	2021-2023	358.92%
Northern Oil & Gas (NOG)	2021-2023	352.25%

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