Laboratory Corporation of America (LH) had the best quarter by a large-cap US stock in Q1 1990, returning 4,952,760%.

ASSET	QUARTER	% RETURN
Laboratory Corporation of America (LH)	Q1 1990	4,952,760%
National Grid PLC ADR (NGG)	Q3 2005	379,214.71%
Ferguson (FERG)	Q1 2010	12,254.96%
Regencell Bioscience (RGC)	Q2 2025	7,281.73%
Suncor Energy (SU)	Q4 1993	3,627.32%
Canadian Pacific Railway (CP)	Q4 2012	2,962.01%
Leidos (LDOS)	Q4 2006	1,317.66%
QXO (QXO)	Q1 2012	1,025.01%
Canadian Pacific Railway (CP)	Q4 1988	961.61%
GameStop (GME)	Q1 2021	899.05%
Canadian Pacific Railway (CP)	Q4 1991	881.64%
Canadian Pacific Railway (CP)	Q4 1997	824.18%
Hubbell (HUBB)	Q4 1994	814.5%
Royal Gold (RGLD)	Q2 1992	697.9%
Circle Internet (CRCL)	Q2 2025	543.84%
Regencell Bioscience (RGC)	Q1 2025	527.92%
eBay (EBAY)	Q4 1998	466.04%
Canadian Pacific Railway (CP)	Q4 2002	440.86%
Canadian Pacific Railway (CP)	Q4 2006	431%
Primo Brands (PRMB)	Q2 2009	427.05%
QXO (QXO)	Q4 2023	416.92%
Canadian Pacific Railway (CP)	Q4 2016	370.89%
IONQ (IONQ)	Q4 2024	369.85%
Canadian Pacific Railway (CP)	Q4 2007	359.87%
Encompass Health (EHC)	Q2 2003	344.46%

Large-cap stocks are treated as having a market cap of $10B+.