Soleno Therapeutics (SLNO) had the highest return in September 2023 by a mid-cap US stock, returning 495%.

ASSET	MONTH	% RETURN
Soleno Therapeutics (SLNO)	September 2023	494.96%
Structure Therapeutics Inc American Depositary Shares (GPCR)	September 2023	76.6%
Tango Therapeutics (TNGX)	September 2023	73.77%
Crinetics Pharmaceuticals (CRNX)	September 2023	69.94%
Immunovant (IMVT)	September 2023	67.42%
Immunome (IMNM)	September 2023	29.06%
Warrior Met Coal (HCC)	September 2023	27%
Alpha Metallurgical Resources (AMR)	September 2023	26.12%
TAL Education (TAL)	September 2023	24.62%
Mirum Pharmaceuticals (MIRM)	September 2023	19.29%
Nextnav Acquisition (NN)	September 2023	18.98%
Peabody Energy (BTU)	September 2023	18.14%
VEON (VEON)	September 2023	17.97%
Alignment Healthcare LLC (ALHC)	September 2023	17.83%
Uranium Energy (UEC)	September 2023	17.58%
Centrus Energy (LEU)	September 2023	17.15%
Mobileye Global Inc Class A Common Stock (MBLY)	September 2023	16.32%
Dianthus Therapeutics (DNTH)	September 2023	15.6%
Denison Mines (DNN)	September 2023	15.38%
CECO Environmental (CECO)	September 2023	14.97%
Liberty Oilfield Services (LBRT)	September 2023	14.22%
AeroVironment (AVAV)	September 2023	14.09%
Energy Fuels (UUUU)	September 2023	13.85%
Scholar Rock (SRRK)	September 2023	13.42%
Alliance Resource Partners (ARLP)	September 2023	12.43%

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