IDEXX Laboratories (IDXX) had the lowest return in April 2015 by a US stock in the S&P 500 (GSPC), returning -18.5%.

ASSET	MONTH	% RETURN
IDEXX Laboratories (IDXX)	April 2015	-18.47%
Royal Caribbean Cruises (RCL)	April 2015	-16.8%
Advanced Micro Devices (AMD)	April 2015	-15.04%
Generac (GNRC)	April 2015	-14.13%
PulteGroup (PHM)	April 2015	-13.34%
Super Micro Computer (SMCI)	April 2015	-13.16%
Charles River Laboratories (CRL)	April 2015	-12.62%
Applied Materials (AMAT)	April 2015	-12.16%
Centene (CNC)	April 2015	-12.15%
Molina Healthcare (MOH)	April 2015	-11.95%
Wynn Resorts (WYNN)	April 2015	-11.93%
Lennar (LEN)	April 2015	-11.65%
Biogen (BIIB)	April 2015	-11.64%
CH Robinson Worldwide (CHRW)	April 2015	-11.61%
DR Horton (DHI)	April 2015	-11.19%
Packaging Corp of America (PKG)	April 2015	-11.15%
ResMed (RMD)	April 2015	-11.15%
Valero Energy (VLO)	April 2015	-11.05%
West Pharmaceutical Services (WST)	April 2015	-11.02%
Edwards Lifesciences (EW)	April 2015	-10.85%
Norwegian Cruise Line (NCLH)	April 2015	-10.4%
Motorola Solutions (MSI)	April 2015	-10.37%
Kroger (KR)	April 2015	-10.19%
Amun Bitwise Select 10 Large Cap Crypto ETP (KEYS)	April 2015	-10.01%
Insulet (PODD)	April 2015	-9.98%