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, 2013	$	966		$	569
Addition (reduction) to allowance	189			(74		)
Amounts written off	(25		)	(3		)
Foreign currency translation	1			(1		)
Balances, March 31, 2014	$	1,131		$	491

Two customers each accounted for 14% of trade accounts receivable and one other customer accounted for 10% of trade accounts receivable, as of March 31, 2014. One customer accounted for 17% of trade accounts receivable as of December 31, 2013.

Two customers each accounted for 17% of consolidated revenue during the quarter ended March 31, 2014. The revenue from one of these customers, which totaled $7.6 million, is reflected in our RealPlayer Group and Games segments. The other customer, which accounted for $7.8 million of consolidated revenue during the quarter ended March 31, 2014, is reflected in our Mobile Entertainment segment. One customer accounted for 14%, or $8.1 million, of consolidated revenue during the quarter ended March 31, 2013. The revenue from this customer is reflected in our RealPlayer Group and Games segments.