Financial Instruments

The following is a summary of cash equivalents and available-for-sale securities as of the end of the periods presented:



	March 28, 2015									March 29, 2014
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Money market funds	$	235,583	$	—	$	—		$	235,583	$	213,988	$	—	$	—		$	213,988
Financial institution
securities	304,999		—		—			304,999		366,906		—		—			366,906
Non-financial institution
securities	429,005		25		(6		)	429,024		753,888		3,428		(1,244		)	756,072
Auction rate securities	10,500		—		(188		)	10,312		21,500		—		(1,340		)	20,160
Municipal bonds	49,064		744		(152		)	49,656		31,367		604		(205		)	31,766
U.S. government and
agency securities	757,954		91		(129		)	757,916		548,568		1,135		(184		)	549,519
Foreign government and
agency securities	197,932		—		—			197,932		354,935		—		—			354,935
Mortgage-backed securities	1,075,730		8,942		(4,496		)	1,080,176		1,234,237		11,380		(10,528		)	1,235,089
Asset-backed securities	211,487		1,130		(159		)	212,458		—		—		—			—
Debt mutual funds	101,350		—		(6,150		)	95,200		81,350		216		(4,652		)	76,914
Bank loans	98,131		29		(60		)	98,100		—		—		—			—
	$	3,471,735	$	10,961	$	(11,340	)	$	3,471,356	$	3,606,739	$	16,763	$	(18,153	)	$	3,605,349

The following tables show the fair values and gross unrealized losses of the Company’s investments, aggregated by investment category, for individual securities that have been in a continuous unrealized loss position for the length of time specified, as of March 28, 2015 and March 29, 2014:



	March 28, 2015
	Less Than 12 Months					12 Months or Greater					Total
(In thousands)	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Non-financial institution securities	$	7,190	$	(6	)	$	—	$	—		$	7,190	$	(6	)
Auction rate securities	—		—			10,312		(188		)	10,312		(188		)
Municipal bonds	10,014		(94		)	1,931		(58		)	11,945		(152		)
U.S. government and
agency securities	451,296		(129		)	—		—			451,296		(129		)
Mortgage-backed securities	448,770		(3,169		)	49,207		(1,327		)	497,977		(4,496		)
Asset-backed securities	75,009		(159		)	—		—			75,009		(159		)
Debt mutual funds	38,608		(1,392		)	56,592		(4,758		)	95,200		(6,150		)
Bank loans	65,085		(60		)	—		—			65,085		(60		)
	$	1,095,972	$	(5,009	)	$	118,042	$	(6,331	)	$	1,214,014	$	(11,340	)



	March 29, 2014
	Less Than 12 Months					12 Months or Greater					Total
(In thousands)	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Non-financial institution securities	$	112,470	$	(1,167	)	$	4,488	$	(77	)	$	116,958	$	(1,244	)
Auction rate securities	—		—			20,160		(1,340		)	20,160		(1,340		)
Municipal bonds	5,917		(166		)	1,743		(39		)	7,660		(205		)
U.S. government and
agency securities	118,125		(184		)	—		—			118,125		(184		)
Mortgage-backed securities	457,903		(7,225		)	132,376		(3,303		)	590,279		(10,528		)
Debt mutual fund	56,698		(4,652		)	—		—			56,698		(4,652		)
	$	751,113	$	(13,394	)	$	158,767	$	(4,759	)	$	909,880	$	(18,153	)

As of March 28, 2015, the gross unrealized losses that had been outstanding for less than twelve months were primarily related to mortgage-backed securities and debt mutual funds due to the general rising of the interest-rate environment and foreign currency movement, although the percentage of such losses to the total estimated fair value of the mortgage-backed securities and the debt mutual funds was relatively insignificant. The gross unrealized losses that had been outstanding for more than twelve months were primarily related to debt mutual funds and mortgage-backed securities, which were primarily due to the general rising of the interest-rate environment and foreign currency movement.

The Company reviewed the investment portfolio and determined that the gross unrealized losses on these investments as of March 28, 2015 and March 29, 2014 were temporary in nature as evidenced by the fluctuations in the gross unrealized losses within the investment categories. These investments are highly rated by the credit rating agencies and there have been no defaults on any of these securities, and we have received interest payments as they become due. Additionally, in the past several years a portion of the Company's investment in the auction rate securities and the mortgage-backed securities were redeemed or prepaid by the debtors at par. Furthermore, the aggregate of individual unrealized losses that had been outstanding for twelve months or more was not significant as of March 28, 2015 and March 29, 2014. The Company neither intends to sell these investments nor concludes that it is more-likely-than-not that it will have to sell them until recovery of their carrying values. The Company also believes that it will be able to collect both principal and interest amounts due to the Company at maturity, given the high credit quality of these investments and any related underlying collateral.

The amortized cost and estimated fair value of marketable debt securities (financial institution securities, non-financial institution securities, auction rate securities, municipal bonds, U.S. and foreign government and agency securities, mortgage-backed securities, asset-backed securities and bank loans), by contractual maturity, are shown below. Actual maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations without call or prepayment penalties.



	March 28, 2015
(In thousands)	Amortized Cost		Estimated Fair Value
Due in one year or less	$	1,583,478	$	1,583,407
Due after one year through five years	334,112		334,318
Due after five years through ten years	293,754		294,645
Due after ten years	923,459		928,202
	$	3,134,803	$	3,140,572

As of March 28, 2015, $1.39 billion of marketable debt securities with contractual maturities of greater than one year were classified as short-term investments. Additionally, the above table did not include investments in money market and mutual funds because these funds do not have specific contractual maturities.

Certain information related to available-for-sale securities is as follows:



(In thousands)	March 28, 2015			March 29, 2014			March 30, 2013
Gross realized gains on sale of available-for-sale securities	$	15,101		$	2,080		$	3,488
Gross realized losses on sale of available-for-sale securities	(3,223		)	(2,412		)	(673		)
Net realized gains (losses) on sale of available-for-sale securities	$	11,878		$	(332	)	$	2,815
Amortization of premiums on available-for-sale securities	$	23,579		$	27,293		$	25,123

The cost of securities matured or sold is based on the specific identification method.