Financial Instruments

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



	September 26, 2015									March 28, 2015
(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	$	203,815	$	—	$	—		$	203,815	$	235,583	$	—	$	—		$	235,583
Financial institution
securities	300,006		—		—			300,006		304,999		—		—			304,999
Non-financial institution
securities	471,681		82		(232		)	471,531		429,005		25		(6		)	429,024
Auction rate securities	10,500		—		(87		)	10,413		10,500		—		(188		)	10,312
Municipal bonds	62,776		584		(246		)	63,114		49,064		744		(152		)	49,656
U.S. government and
agency securities	451,441		144		(7		)	451,578		757,954		91		(129		)	757,916
Foreign government and
agency securities	201,481		—		—			201,481		197,932		—		—			197,932
Mortgage-backed securities	1,116,561		8,489		(4,845		)	1,120,205		1,075,730		8,942		(4,496		)	1,080,176
Asset-backed securities	214,120		1,251		(523		)	214,848		211,487		1,130		(159		)	212,458
Debt mutual funds	101,350		—		(13,029		)	88,321		101,350		—		(6,150		)	95,200
Bank loans	104,101		44		(93		)	104,052		98,131		29		(60		)	98,100
Commercial mortgage-
backed securities	159,227		424		(833		)	158,818		—		—		—			—
	$	3,397,059	$	11,018	$	(19,895	)	$	3,388,182	$	3,471,735	$	10,961	$	(11,340	)	$	3,471,356

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 September 26, 2015 and March 28, 2015:



	September 26, 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	$	65,885	$	(232	)	$	—	$	—		$	65,885	$	(232	)
Auction rate securities	—		—			10,414		(87		)	10,414		(87		)
Municipal bonds	24,204		(107		)	2,407		(139		)	26,611		(246		)
U.S. government and
agency securities	63,640		(7		)	—		—			63,640		(7		)
Mortgage-backed securities	471,040		(3,681		)	52,141		(1,164		)	523,181		(4,845		)
Asset-backed securities	72,972		(479		)	9,631		(44		)	82,603		(523		)
Debt mutual funds	34,650		(5,350		)	53,671		(7,679		)	88,321		(13,029		)
Bank loans	42,444		(61		)	28,253		(32		)	70,697		(93		)
Commercial mortgage-
backed securities	70,654		(819		)	342		(14		)	70,996		(833		)
	$	845,489	$	(10,736	)	$	156,859	$	(9,159	)	$	1,002,348	$	(19,895	)



	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	)

As of September 26, 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. 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 same reasons stated above. The percentages of the losses to the total estimated fair value of the investments were insignificant.

The Company reviewed the investment portfolio and determined that the gross unrealized losses on these investments as of September 26, 2015 and March 28, 2015 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 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 September 26, 2015 and March 28, 2015. 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, bank loans and commercial mortgage-backed securities), 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.



	September 26, 2015
(In thousands)	Amortized Cost		Estimated Fair Value
Due in one year or less	$	1,263,805	$	1,263,844
Due after one year through five years	420,118		419,993
Due after five years through ten years	292,227		292,621
Due after ten years	1,115,744		1,119,588
	$	3,091,894	$	3,096,046

As of September 26, 2015, $1.68 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:



	Three Months Ended						Six Months Ended
(In thousands)	September 26, 2015			September 27, 2014			September 26, 2015			September 27, 2014
Proceeds from sale of available-for-sale securities	$	54,989		$	236,263		$	121,030		$	295,844
Gross realized gains on sale of available-for-sale securities	$	476		$	2,243		$	836		$	3,080
Gross realized losses on sale of available-for-sale securities	(88		)	(501		)	(218		)	(668		)
Net realized gains on sale of available-for-sale securities	$	388		$	1,742		$	618		$	2,412
Amortization of premiums on available-for-sale securities	$	7,043		$	6,413		$	13,511		$	12,646

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