we had a net unrealized gain of $4.8 million, which was comprised of gross unrealized gains of $7.2 million, offset by $2.4 million of gross unrealized losses. 



Our accounts receivable are highly concentrated. Two customers accounted for 30% of our accounts receivable balance at January 25, 2015. We maintain an allowance for doubtful accounts for estimated losses resulting from the inability of our customers to make required payments. This allowance consists of an amount identified for specific customers and an amount based on overall estimated exposure.



Our cash balances are held in numerous locations throughout the world, including substantial amounts held outside of the United States. As of January 25, 2015, we had cash, cash equivalents and marketable securities of $1.72 billion held within the United States and $2.90 billion held outside of the United States.  Most of the amounts held outside the United States may be repatriated to the United States but, under current law, would be subject to U.S. federal income taxes, less applicable foreign tax credits.  Further, repatriation of some foreign balances may be restricted by local laws. As of January 25, 2015, we have not provided for U.S. federal and state income taxes on approximately $2.27 billion of undistributed earnings of non-United States subsidiaries, as such earnings are considered indefinitely reinvested outside the United States.  Although we have no current need to do so, if we repatriate foreign earnings for cash requirements in the United States, we would incur U.S. federal and state income tax, less applicable foreign tax credits, and reduced by the current amount of our U.S. federal and state net operating loss and tax credit carryforwards.  Further, in addition to the $1.72 billion of cash, cash equivalents and marketable securities held within the United States and available to fund our U.S. operations and any other U.S. cash needs, we have access to external sources of financing if cash is needed in the United States other than by repatriation of foreign earnings where U.S. income tax may otherwise be due.  Accordingly, we do not reasonably expect any material effect on our business, as a whole, or to our financial flexibility with respect to our current cash balances held outside of the United States.



Dividend payments and any share repurchases must be made from cash held in the United States. For fiscal year 2015, we made total cash dividend payments of $186.5 million and repurchased $813.6 million of our common stock, utilizing a significant amount of our U.S. cash balance previously taxed as of January 25, 2015.

Convertible Notes



On December 2, 2013, we issued $1.50 billion of 1.00% Convertible Senior Notes, or the Notes, due in 2018 and concurrently entered into separate note hedge and warrant transactions and used $14.3 million to repurchase shares of our common stock from purchasers of the Notes in privately negotiated transactions. The Notes will mature on December 1, 2018 unless earlier repurchased or converted in accordance with their terms prior to such date. As of January 25, 2015, none of the conditions allowing holders of the Notes to convert