Cytokinetics (CYTK) had the highest return in December 2023 by a mid-cap US stock, returning 149%.

ASSET	MONTH	% RETURN
Cytokinetics (CYTK)	December 2023	149%
Bitdeer Technologies Group Class A Ordinary Shares (BTDR)	December 2023	113.42%
Sezzle (SEZL)	December 2023	105.41%
Terawulf (WULF)	December 2023	101.68%
Aurora Innovation (AUR)	December 2023	101.38%
CleanSpark (CLSK)	December 2023	86.63%
Edgewise Therapeutics (EWTX)	December 2023	81.73%
Ocular Therapeutix (OCUL)	December 2023	78.4%
Arcutis Biotherapeutics (ARQT)	December 2023	74.59%
Compass (COMP)	December 2023	71.69%
Liquidia Technologies (LQDA)	December 2023	68.02%
CommScope (COMM)	December 2023	67.86%
Compania de Minas Buenaventura SAA ADR (BVN)	December 2023	60.25%
GeneDx (WGS)	December 2023	59.88%
Upstart Holdings (UPST)	December 2023	54.31%
Sunrun (RUN)	December 2023	54.08%
Century Aluminum (CENX)	December 2023	53.28%
American Bitcoin (ABTC)	December 2023	52.63%
Opendoor Technologies (OPEN)	December 2023	50.84%
Viking Therapeutics (VKTX)	December 2023	50.08%
Scholar Rock (SRRK)	December 2023	49.44%
Cipher Mining (CIFR)	December 2023	47.5%
Applied Opt (AAOI)	December 2023	46.47%
Recursion Pharmaceuticals (RXRX)	December 2023	45.86%
Xometry (XMTR)	December 2023	45.68%

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