Genesis Healthcare (GEN) had the lowest return in May 2018 by a US stock in the S&P 500 (GSPC), returning -25.1%.

ASSET	MONTH	% RETURN
Genesis Healthcare (GEN)	May 2018	-25.09%
Cardinal Health (CAH)	May 2018	-18.19%
Campbell Soup Company Common Stock (CPB)	May 2018	-17.22%
Dollar Tree (DLTR)	May 2018	-13.82%
Molson Coors Brewing (TAP)	May 2018	-13.45%
International Flavors & Fragrances (IFF)	May 2018	-13.08%
Match (MTCH)	May 2018	-12.85%
Warner Bros Discovery (WBD)	May 2018	-11.68%
Best Buy (BBY)	May 2018	-10.44%
Hewlett Packard Enterprise (HPE)	May 2018	-10.3%
Dollar General (DG)	May 2018	-9.12%
CoreSite Realty (COR)	May 2018	-8.79%
Henry Schein (HSIC)	May 2018	-8.69%
Huntington Ingalls Industries (HII)	May 2018	-8.61%
McKesson (MCK)	May 2018	-8.57%
CVS Health (CVS)	May 2018	-8.44%
T-Mobile US (TMUS)	May 2018	-8.34%
Cboe Global Markets (CBOE)	May 2018	-8.05%
Fifth Third Bancorp (FITB)	May 2018	-7.84%
Prudential Financial (PRU)	May 2018	-7.83%
Cognizant Technology Solutions Corp Class A (CTSH)	May 2018	-7.62%
Paycom Soft (PAYC)	May 2018	-7.48%
Ball (BALL)	May 2018	-7.33%
Cummins (CMI)	May 2018	-6.82%
Monster Beverage (MNST)	May 2018	-6.78%