Product Sales



	Three Months Ended June 30,				Six Months Ended June 30,
Net Product Sales in the United States	2017		2016		2017		2016
EYLEA^®	$	919,466	$	830,936	$	1,773,853	$	1,611,781
ARCALYST^®	4,667		3,283		8,525		6,620
Net Product Sales	$	924,133	$	834,219	$	1,782,378	$	1,618,401

The Company had product sales to certain customers that accounted for more than 10% of total gross product revenue for each of the three and six months ended June 30, 2017 and 2016. Sales to each of these customers as a percentage of the Company's total gross product revenue are as follows:



	Three Months Ended June 30,				Six Months Ended June 30,
	2017		2016		2017		2016
Besse Medical, a subsidiary of AmerisourceBergen Corporation	50	%	56	%	51	%	58	%
McKesson Corporation	29	%	28	%	28	%	28	%
Curascript SD Specialty Distribution, a subsidiary of Express Scripts	20	%	15	%	20	%	13	%

Revenue from product sales is recorded net of applicable provisions for rebates and chargebacks, distribution-related fees, and other sales-related deductions. The following table summarizes the provisions and credits/payments for these sales-related deductions during the six months ended June 30, 2017 and 2016.



	Rebates & Chargebacks			Distribution- Related Fees			Other Sales- Related Deductions			Total
Balance as of December 31, 2016	$	12,712		$	29,465		$	3,674		$	45,851
Provision related to current period sales	78,250			90,077			20,531			188,858
Credits/payments	(67,850		)	(90,519		)	(21,312		)	(179,681		)
Balance as of June 30, 2017	$	23,112		$	29,023		$	2,893		$	55,028

Balance as of December 31, 2015	$	6,419		$	48,313		$	517		$	55,249
Provision related to current period sales	41,326			74,289			12,341			127,956
Credits/payments	(36,110		)	(94,467		)	(11,782		)	(142,359		)
Balance as of June 30, 2016	$	11,635		$	28,135		$	1,076		$	40,846