Allowance for Doubtful Accounts Receivable and Sales Returns

Activity in the allowance for doubtful accounts receivable and sales returns (in thousands):



	Allowance For
	Doubtful Accounts Receivable			Sales Returns
Balances, December 31, 2012	$	1,010		$	653
Addition (reduction) to allowance	210			(47		)
Amounts written off	(61		)	(21		)
Foreign currency translation	20			—
Balances, September 30, 2013	$	1,179		$	585

One customer accounted for 13% of trade accounts receivable and one other customer accounted for 12% of trade accounts receivable, as of September 30, 2013. No one customer accounted for more than 10% of trade accounts receivable as of December 31, 2012.

One customer accounted for approximately 12%, or $6.0 million, and 14% or $21.1 million, of consolidated revenue during the quarter and nine months ended September 30, 2013, respectively. The revenue from this customer is reflected in our RealPlayer Group and Games segments. One other customer accounted for approximately 14%, or $6.8 million, and 11% or $17.3 million, of consolidated revenue during the quarter and nine months ended September 30, 2013, respectively, in our Mobile Entertainment segment. One customer accounted for 11%, or $6.4 million, of revenue during the quarter ended September 30, 2012. No one customer accounted for more than 10% of consolidated revenue during the nine months ended September 30, 2012.