Investments

Available-for-Sale Securities

The amortized cost and fair value of available-for-sale investments as of December 31, 2017 were as follows:



(in thousands)	Cost			Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
U.S. government treasuries and agencies securities	$	72,038		$	1	$	(721	)	$	71,318
Money market funds	60,818			—		—			60,818
Asset-backed securities	15,445			—		(50		)	15,395
Corporate bonds	139,775			56		(761		)	139,070
International government bonds	6,524			6		(20		)	6,510
Corporate commercial paper	10,139			—		—			10,139
Bank deposits	34,133			—		—			34,133
Repurchase agreements	97			—		—			97
Total available-for-sale investments	338,969			63		(1,552		)	337,480
Less amounts classified as cash equivalents	(73,414		)	—		—			(73,414		)
Short-term investments	$	265,555		$	63	$	(1,552	)	$	264,066

The amortized cost and fair value of available-for-sale investments as of April 2, 2017 were as follows:



(in thousands)	Cost			Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
U.S. government treasuries and agencies securities	$	62,048		$	16	$	(508	)	$	61,556
Money market funds	140,425			—		—			140,425
Asset-backed securities	13,865			5		(23		)	13,847
Corporate bonds	96,660			42		(326		)	96,376
International government bonds	5,423			2		(15		)	5,410
Corporate commercial paper	4,898			—		—			4,898
Bank deposits	12,305			—		—			12,305
Repurchase agreements	173			—		—			173
Total available-for-sale investments	335,797			65		(872		)	334,990
Less amounts classified as cash equivalents	(143,498		)	—		—			(143,498		)
Short-term investments	$	192,299		$	65	$	(872	)	$	191,492

The cost and estimated fair value of available-for-sale securities as of December 31, 2017, by contractual maturity, were as follows:



(in thousands)	Amortized Cost		Estimated Fair Value
Due in 1 year or less	$	132,920	$	132,878
Due in 1-2 years	102,654		101,798
Due in 2-5 years	103,395		102,804
Total investments in available-for-sale securities	$	338,969	$	337,480

The following table shows the gross unrealized losses and fair value of the Company’s investments with unrealized losses as of December 31, 2017, aggregated by investment category and length of time that individual securities have been in a continuous loss position.



	Less Than 12 Months					12 Months or Greater					Total
(in thousands)	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss			Fair Value		Unrealized Loss
Corporate bonds	$	98,494	$	(529	)	$	25,038	$	(240	)	$	123,532	$	(769	)
Asset-backed securities	14,503		(42		)	892		(8		)	15,395		(50		)
U.S. government treasuries and agencies securities	24,443		(113		)	37,884		(607		)	62,327		(720		)
International government bonds	—		—			2,636		(13		)	2,636		(13		)
Total	$	137,440	$	(684	)	$	66,450	$	(868	)	$	203,890	$	(1,552	)

The following table shows the gross unrealized losses and fair value of the Company’s investments with unrealized losses, as of April 2, 2017, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position.



	Less Than 12 Months					12 Months or Greater				Total
(in thousands)	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Corporate bonds	$	71,308	$	(326	)	$	—	$	—	$	71,308	$	(326	)
Asset-backed securities	11,294		(23		)	—		—		11,294		(23		)
U.S. government treasuries and agencies securities	55,497		(508		)	—		—		55,497		(508		)
International government bonds	2,634		(15		)	—		—		2,634		(15		)
Total	$	140,733	$	(872	)	$	—	$	—	$	140,733	$	(872	)

Currently, a significant portion of the Company’s available-for-sale investments that it holds are high grade instruments. As of December 31, 2017, the unrealized losses on the Company’s available-for-sale investments represented an insignificant amount in relation to its total available-for-sale portfolio. Substantially all of the Company’s unrealized losses on its available-for-sale marketable debt instruments can be attributed to fair value fluctuations in an unstable credit environment that resulted in a decrease in the market liquidity for debt instruments. Because the Company has the ability to hold these investments until a recovery of fair value, which maybe maturity, the Company did not consider these investments to be other-than-temporarily impaired as of December 31, 2017 and April 2, 2017.

Non-marketable Equity Securities

As of December 31, 2017 and April 2, 2017, the Company holds capital stock of privately-held companies with total amount of $25.7 million and $13.2 million, respectively. During the first, second and third quarters of fiscal 2018, the Company purchased common stock of privately-held companies for $1.2 million, $10.0 million and $1.3 million, respectively. These investments in stocks (included in Other Assets on the Condensed Consolidated Balance Sheet) are accounted for as cost-method investments, as the Company owns less than 20% of the voting securities and does not have the ability to exercise significant influence over operating and financial policies of each entity. The Company did not record any impairment charges for these investments during the three and nine months ended December 31, 2017 and January 1, 2017.