Financial Instruments

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



	July 1, 2017									April 1, 2017
(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	$	379,788	$	—	$	—		$	379,788	$	298,307	$	—	$	—		$	298,307
Financial institution
securities	424,586		—		—			424,586		348,797		—		—			348,797
Non-financial institution
securities	433,609		700		(335		)	433,974		409,109		647		(496		)	409,260
U.S. government and
agency securities	157,433		4		(182		)	157,255		130,749		8		(223		)	130,534
Foreign government and
agency securities	394,121		3		—			394,124		322,172		—		(51		)	322,121
Mortgage-backed securities	1,194,714		5,407		(10,549		)	1,189,572		1,186,732		3,527		(14,757		)	1,175,502
Asset-backed securities	222,552		589		(441		)	222,700		220,033		404		(686		)	219,751
Debt mutual funds	101,350		—		(11,453		)	89,897		101,350		—		(12,674		)	88,676
Bank loans	164,300		604		(160		)	164,744		153,281		839		(106		)	154,014
Commercial mortgage-
backed securities	233,242		246		(3,293		)	230,195		221,504		146		(3,679		)	217,971
	$	3,705,695	$	7,553	$	(26,413	)	$	3,686,835	$	3,392,034	$	5,571	$	(32,672	)	$	3,364,933

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 July 1, 2017 and April 1, 2017:



	July 1, 2017
	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	$	73,844	$	(334	)	$	1,018	$	(1	)	$	74,862	$	(335	)
U.S. government and
agency securities	53,539		(178		)	4,596		(4		)	58,135		(182		)
Mortgage-backed securities	809,678		(9,098		)	95,890		(1,451		)	905,568		(10,549		)
Asset-backed securities	125,635		(418		)	5,858		(23		)	131,493		(441		)
Debt mutual fund	—		—			89,897		(11,453		)	89,897		(11,453		)
Bank loans	35,556		(160		)	—		—			35,556		(160		)
Commercial mortgage-
backed securities	150,751		(1,216		)	24,435		(2,077		)	175,186		(3,293		)
	$	1,249,003	$	(11,404	)	$	221,694	$	(15,009	)	$	1,470,697	$	(26,413	)



	April 1, 2017
	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	$	68,850	$	(492	)	$	1,022	$	(4	)	$	69,872	$	(496	)
U.S. government and
agency securities	64,895		(223		)	—		—			64,895		(223		)
Mortgage-backed securities	811,058		(11,872		)	139,931		(2,885		)	950,989		(14,757		)
Asset-backed securities	119,845		(651		)	4,689		(35		)	124,534		(686		)
Debt mutual funds	—		—			88,676		(12,674		)	88,676		(12,674		)
Bank loans	15,139		(106		)	—		—			15,139		(106		)
Foreign government and
agency securities	64,857		(51		)	—		—			64,857		(51		)
Commercial mortgage-
backed securities	165,393		(1,706		)	24,362		(1,973		)	189,755		(3,679		)
	$	1,310,037	$	(15,101	)	$	258,680	$	(17,571	)	$	1,568,717	$	(32,672	)

As of July 1, 2017, the gross unrealized losses that had been outstanding for less than twelve months were primarily related to mortgage-backed securities due to the general rising of the interest-rate environment, although the percentage of such losses to the total estimated fair value of the mortgage-backed securities was relatively insignificant. The gross unrealized losses that had been outstanding for more than twelve months were primarily related to debt mutual funds, commercial mortgage-backed securities 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 July 1, 2017 and April 1, 2017 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, there have been no defaults on any of these securities and we have received interest payments as they become due. Therefore, the Company believes that it will be able to collect both principal and interest amount due to the Company. 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 July 1, 2017 and April 1, 2017, the majority of which were related to debt mutual funds due to foreign currency and interest rate fluctuations. 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 amortized cost and estimated fair value of marketable debt securities (financial institution securities, non-financial institution securities, U.S. and foreign government and agency securities, asset-backed securities, bank loans, mortgage-backed securities and commercial mortgage-backed securities), by contractual maturity, are shown in the table below. Actual maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations without call or prepayment penalties.



	July 1, 2017
(In thousands)	Amortized Cost		Estimated Fair Value
Due in one year or less	$	1,224,751	$	1,224,739
Due after one year through five years	477,162		475,193
Due after five years through ten years	319,892		319,444
Due after ten years	1,202,752		1,197,774
	$	3,224,557	$	3,217,150

As of July 1, 2017, $1.98 billion of marketable debt securities with contractual maturities of greater than one year were classified as short-term investments. Additionally, the above table does not include investments in money market and debt 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
(In thousands)	July 1, 2017			July 2, 2016
Proceeds from sale of available-for-sale securities	$	119,922		$	99,474
Gross realized gains on sale of available-for-sale securities	$	832		$	721
Gross realized losses on sale of available-for-sale securities	(386		)	(512		)
Net realized gains on sale of available-for-sale securities	$	446		$	209
Amortization of premiums on available-for-sale securities	$	5,522		$	6,762

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