The NYSE Arca Biotechnology Index (BTK) - Quarterly Rebalancing			
"Changes effective before the open of trading Monday, July 22, 2013"			
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Symbol	Component Name	Previous Share Weight	Rebalanced Share Weight
AFFX	Affymetrix Inc	17983	Deletion
ALXN	Alexion Pharmaceuticals Inc	742	692
AMGN	Amgen Inc	617	709
BIIB	Biogen Idec Inc	338	337
BMRN	BioMarin Pharmaceutical Inc	1050	1198
CELG	Celgene Corp	561	571
CPHD	Cepheid	Addition	2203
DNDN	Dendreon Corp	15032	16975
EXAS	Exact Sciences Corp	Addition	5361
GILD	Gilead Sciences Inc	1291	1291
ILMN	Illumina Inc	1225	1044
IMGN	Immunogen Inc	4580	4105
INCY	Incyte Corp	3166	3357
ITMN	InterMune Inc	7459	6065
LIFE	Life Technologies Corp	934	Deletion
MYGN	Myriad Genetics Inc	2403	2502
NKTR	Nektar Therapeutics	6245	6023
QGEN	Qiagen NV	3336	3753
REGN	Regeneron Pharmaceuticals Inc	323	282
SQNM	Sequenom Inc	17303	16901
UTHR	United Therapeutics Corp	1140	1108
VRTX	Vertex Pharmaceuticals Inc	805	876
			
Additions			
CPHD	Cepheid		
EXAS	Exact Sciences Corp		
			
Deletions			
AFFX	Affymetrix Inc		
LIFE	Life Technologies Corp