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

ASSET	MONTH	% RETURN
Soleno Therapeutics (SLNO)	September 2023	494.96%
Sezzle Inc Common Stock (SEZL)	August 2023	257.97%
VinFast Auto Ltd Ordinary Shares (VFS)	August 2023	212.7%
Applied Digital (APLD)	May 2023	167.41%
Telephone and Data Systems (TDS)	August 2023	166.96%
Array Digital Infrastructure (AD)	August 2023	160.48%
United States Cellular (USM)	August 2023	160.48%
D-Wave Quantum (QBTS)	May 2023	149.01%
Cytokinetics (CYTK)	December 2023	149%
TMC the metals (TMC)	June 2023	143.28%
Bitdeer Technologies Group Class A Ordinary Shares (BTDR)	June 2023	126.72%
Hut 8 Corp Common Stock (HUT)	January 2023	126.21%
Arlington Asset Investment (AI)	May 2023	125.54%
Kingsoft Cloud Holdings (KC)	March 2023	120.6%
Bitdeer Technologies Group Class A Ordinary Shares (BTDR)	December 2023	113.42%
Trump Media & Technology (DJTWW)	July 2023	111.15%
Cipher Mining (CIFR)	January 2023	107.61%
WM Technology (MAPSW)	July 2023	105.67%
Sezzle Inc Common Stock (SEZL)	December 2023	105.41%
Sotera Health (SHC)	January 2023	104.27%
TransMedics (TMDX)	November 2023	103.5%
Rigetti Computing (RGTI)	July 2023	102.44%
Terawulf (WULF)	December 2023	101.68%
BridgeBio Pharma (BBIO)	July 2023	100.86%
Upstart Holdings (UPST)	May 2023	96.82%

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