Eldorado Gold (EGO) had the best quarter by a mid-cap US stock in Q1 2003, returning 1,565,000%.

ASSET	QUARTER	% RETURN
Eldorado Gold (EGO)	Q1 2003	1,565,000%
Star Bulk Carriers (SBLK)	Q4 2007	505,406.68%
Danaos (DAC)	Q4 2006	310,671.28%
Weatherford International (WFRD)	Q4 2019	100,097.43%
Chord Energy (CHRD)	Q4 2020	15,341.3%
QMMM Holdings Limited Ordinary Shares (QMMM)	Q3 2025	8,428.57%
Argan (AGX)	Q4 1995	6,996.95%
Rigetti Computing (RGTI)	Q4 2024	1,834.09%
Teekay Tankers (TNK)	Q4 2019	1,743.88%
Par Pacific (PARR)	Q3 2012	1,650%
Travere Therapeutics (TVTX)	Q1 2007	1,566.67%
AutoNation (AN)	Q1 1987	1,521.05%
Talos Energy (TALO)	Q2 2016	1,507.49%
Opendoor Technologies (OPEN)	Q3 2025	1,389.72%
InterDigital (IDCC)	Q4 1999	1,279.32%
Paramount Skydance Corporation Class B Common Stock (PSKY)	Q4 2005	1,134.44%
Abivax SA American Depositary Shares (ABVX)	Q3 2025	984.29%
Aura Minerals Inc Common Shares (AUGO)	Q1 2019	954.93%
DXP Enterprises (DXPE)	Q4 1996	833.33%
CleanSpark (CLSK)	Q2 2015	791.08%
Applied Digital (APLD)	Q2 2021	767%
D-Wave Quantum (QBTS)	Q4 2024	757.14%
Applied Digital (APLD)	Q3 2009	712.5%
Celldex Therapeutics (CLDX)	Q2 2020	702.47%
Sonic Automotive (SAH)	Q2 2009	681.51%

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