UnitedHealth (UNH) had the lowest return last month by a large-cap US stock, returning -26.6%.

ASSET	MONTH	% RETURN
UnitedHealth (UNH)	May 2025	-26.6%
Summit Therapeutics (SMMT)	May 2025	-25.29%
Cooper Companies (COO)	May 2025	-17.65%
Regeneron Pharmaceuticals (REGN)	May 2025	-16.75%
Copart (CPRT)	May 2025	-15.27%
Entegris (ENTG)	May 2025	-14.06%
Fidelity National Financial (FNF)	May 2025	-13.88%
Fair Isaac (FICO)	May 2025	-13.67%
Atlassian (TEAM)	May 2025	-13.37%
Warner Music (WMG)	May 2025	-13.05%
Texas Pacific Land Trust (TPL)	May 2025	-12.83%
Vertex Pharmaceuticals (VRTX)	May 2025	-12.81%
Eli Lilly and (LLY)	May 2025	-12.42%
Humana (HUM)	May 2025	-11.76%
CVS Health (CVS)	May 2025	-11.67%
Frank's International (FI)	May 2025	-11.47%
Alcon (ALC)	May 2025	-11.47%
Booz Allen Hamilton (BAH)	May 2025	-11.19%
Lineage, Inc Common Stock (LINE)	May 2025	-11.17%
argenx NV ADR (ARGX)	May 2025	-10.89%
Reddit (RDDT)	May 2025	-10.57%
Zimmer Biomet (ZBH)	May 2025	-10.22%
Joint Stock Company Kaspikz American Depository Shares (KSPI)	May 2025	-9.89%
Doximity (DOCS)	May 2025	-9.74%
Ke Holdings (BEKE)	May 2025	-9.69%

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