The Company’s product revenues recorded in the United States, net of sales discounts, allowances and reserves, for the three months ended March 31, 2025 and 2024 were $149.9 million and $163.1 million, respectively. The Company’s product revenues consist of sales of EMPAVELI and SYFOVRE to specialty pharmacies and specialty distributors.

The table reflects product revenue by major source for the following periods (in thousands):


	Three Months Ended March 31,
	2025		2024
Products:
EMPAVELI	$	19,726	$	25,610
SYFOVRE		130,174		137,465
Total Product revenue, net	$	149,900	$	163,075

The Company’s accounts receivable balance of $235.2 million as of March 31, 2025 and $264.9 million as of December 31, 2024, consisted of EMPAVELI and SYFOVRE product sales receivable and licensing and other revenue receivables from our collaboration

with Sobi. The Company does not have a reserve related to expected credit losses against its accounts receivable balance and expects to collect its accounts receivable in the ordinary course of business.

The Company’s product sales reserves totaled $38.9 million and $45.1 million as of March 31, 2025 and December 31, 2024, respectively. These amounts are included in accrued expenses on the Company’s unaudited condensed consolidated balance sheets.

The following table summarizes activity in each of the product revenue allowance and reserve categories for the three months ended March 31, 2025 and 2024 (in thousands):


	Fees and patient assistance			Government and other rebates			Returns			Total
Ending balance at December 31, 2024	$	11,589		$	31,533		$	2,023		$	45,145
Provision related to sales in the current year		10,277			24,139			976			35,392
Adjustments related to prior period sales		439			(13	)		(382	)		44
Credits and payments made		(13,084	)		(28,467	)		(126	)		(41,677	)
Ending balance at March 31, 2025	$	9,221		$	27,192		$	2,491		$	38,904


	Fees and patient assistance			Government and other rebates			Returns			Total
Ending balance at December 31, 2023	$	5,674		$	8,898		$	2,053		$	16,625
Provision related to sales in the current year		9,575			13,125			1,355			24,055
Adjustments related to prior period sales		146			(19	)		(96	)		31
Credits and payments made		(9,724	)		(9,906	)		(1,859	)		(21,489	)
Ending balance at March 31, 2024	$	5,671		$	12,098		$	1,453		$	19,222

Significant customers - Gross product revenues and product sales receivable from the Company's customers who individually accounted for 10% of more of total gross product revenues and/or 10% or more of total product sales receivable consisted of the following:


	Percent of Total Gross Product Revenues
	Three Months Ended March 31,
	2025	2024
Customer A	11%	15%
Customer C	18%	19%
Customer D	58%	59%


	Percent of Product Sales Receivable
	As of March 31,
	2025	2024
Customer A	4%	3%
Customer C	31%	21%
Customer D	49%	67%

Factoring of accounts receivable and associated fees for the period ended March 31, 2025 and 2024 were as follows (in thousands):


	For the Three Months Ended March 31,
	2025			2024
Accounts receivable sold	$	99,735		$	—
Less: factoring fees		(1,212	)		—
Net cash proceeds	$	98,523		$	—

The accounts receivable sold that remained outstanding as of March 31, 2025 and December 31, 2024 was $99.7 million and $86.1 million, respectively.