Summit Therapeutics (SMMT) had the lowest return in June 2020 by a large-cap US stock, returning -26.8%.

ASSET	MONTH	% RETURN
Summit Therapeutics (SMMT)	June 2020	-26.85%
PG&E (PCG)	June 2020	-23%
DraftKings (DKNG)	June 2020	-18.36%
Pilgrims Pride (PPC)	June 2020	-18.29%
Tenet Healthcare (THC)	June 2020	-17.72%
Ulta Beauty (ULTA)	June 2020	-17.47%
Liberty Media Corporation Series A Liberty Formula One Common Stock (FWONA)	June 2020	-17.08%
Teledyne Technologies (TDY)	June 2020	-16.44%
Antero Resources (AR)	June 2020	-15.33%
Encompass Health (EHC)	June 2020	-15.07%
Reinsurance Group of America (RGA)	June 2020	-14.33%
L3Harris Technologies (LHX)	June 2020	-13.99%
CACI International (CACI)	June 2020	-13.26%
Energy Transfer (ET)	June 2020	-13.07%
Uber Technologies (UBER)	June 2020	-12.79%
Cboe Global Markets (CBOE)	June 2020	-12.5%
Biogen (BIIB)	June 2020	-12.49%
Ross Stores (ROST)	June 2020	-12.2%
Valero Energy (VLO)	June 2020	-11.99%
Tradeweb Markets (TW)	June 2020	-11.56%
Universal Health Services (UHS)	June 2020	-11.53%
Curtiss-Wright (CW)	June 2020	-11.5%
Genesis Healthcare (GEN)	June 2020	-11.16%
Contura Energy (CTRA)	June 2020	-10.75%
Leidos (LDOS)	June 2020	-10.65%

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