Balance Sheet Components

12 Months Ended

Dec. 25, 2021

Marketable Securities

Marketable securities consisted of the following (in thousands):


December 25, 2021	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. treasuries	$	39,128	$	—	$	(143)	$	38,985
Commercial paper	32,174		—		(13)		32,161
Corporate bonds	52,832		29		(151)		52,710
Certificate of deposit	1,200		1		(2)		1,199

	$	125,334	$	30	$	(309)	$	125,055


December 26, 2020	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. treasuries	$	40,602	$	124	$	—	$	40,726

Corporate bond	24,156		176		(2)		24,330
Certificate of deposit	2,160		19		—		2,179
U.S. agency securities	575		—		—		575
	$	67,493	$	319	$	(2)	$	67,810

We typically invest in highly-rated securities with low probabilities of default. Our investment policy requires investments to be rated single A or better, limits the types of acceptable investments, concentration as to security holder and duration of the investment. The gross unrealized gains and losses in fiscal 2021 and 2020 were caused primarily by changes in interest rates.

The longer the duration of marketable securities, the more susceptible they are to changes in market interest rates and bond yields. As yields increase, those securities with a lower yield-at-cost show a mark-to-market unrealized loss. We anticipate recovering the full cost of the securities either as market conditions improve, or as the securities mature. Accordingly, we believe that the unrealized losses are not as a result of a credit loss. As of December 25, 2021 and December 26, 2020, gross unrealized losses related to our marketable securities portfolio were not material.

The contractual maturities of marketable securities were as follows (in thousands):


	December 25, 2021				December 26, 2020
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Due in one year or less	$	75,804	$	75,778	$	50,500	$	50,679
Due after one year to five years	49,530		49,277		16,993		17,131
	$	125,334	$	125,055	$	67,493	$	67,810

See also Note 9, Fair Value.

Inventories, net

Inventories consisted of the following (in thousands):


	December 25, 2021		December 26, 2020
Raw materials	$	57,673	$	48,122
Work-in-progress	35,935		30,806
Finished goods	17,940		20,301
	$	111,548	$	99,229

Property, Plant and Equipment, net

Property, plant and equipment, net consisted of the following (in thousands):


	December 25, 2021		December 26, 2020
Land	$	4,751	$	4,751
Building and building improvements	41,722		—
Machinery and equipment	252,632		226,185
Computer equipment and software	44,667		36,361
Furniture and fixtures	7,293		6,894
Leasehold improvements	82,266		79,144
Sub-total	433,331		353,335
Less: Accumulated depreciation and amortization	(312,700)		(294,468)
Net property, plant and equipment	120,631		58,867
Construction-in-progress	25,924		45,236
Total	$	146,555	$	104,103

Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):


	December 25, 2021		December 26, 2020
Accrued compensation and benefits	$	29,706	$	33,110
Accrued employee stock purchase plan contributions withheld	4,693		4,240
Accrued warranty	2,805		3,918
Accrued income and other taxes	8,086		6,976
Accrued restructuring charges	2,478		—
Accrued contingent consideration	—		4,012
Other accrued expenses	3,068		3,086
	$	50,836	$	55,342