4.	Financial Instruments Measured at Fair Value

Our cash, cash equivalents, and short-term investments consisted primarily of cash and other investment grade securities. We do not hold investment securities for trading purposes. All short-term investments are classified as available-for-sale and recorded at fair value. Investment securities are exposed to market risk due to changes in interest rates and credit risk and we monitor credit risk and attempt to mitigate exposure by making high-quality investments and through investment diversification.

Gains and losses on investments are calculated using the specific-identification method and are recognized during the period in which the investment is sold or when an investment experiences an other-than-temporary decline in value. Factors that could indicate an impairment exists include, but are not limited to: earnings performance, changes in credit rating or adverse changes in the regulatory or economic environment of the asset. Gross realized gains and losses on sales of short-term investments are included in interest income. Realized gains and losses for the periods presented were not significant.

Investments that we have classified as short-term, by security type, are as follows

(

in thousands

)

	September 26, 2015
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Foreign government security	$	465	$	-	$	-	$	465
Bank certificates of deposit		1,002		-		-		1,002
	$	1,467	$	-	$	-	$	1,467

	December 27, 2014
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Municipal securities	$	155	$	-	$	-	$	155
Bank certificates of deposit		1,000		-		-		1,000
	$	1,155	$	-	$	-	$	1,155

Effective maturities of short-term investments are as follows

(in thousands)

	September 26, 2015				December 27, 2014
	Amortized		Estimated		Amortized		Estimated
	Cost		Fair Value		Cost		Fair Value
Due in one year or less	$	1,467	$	1,467	$	1,155	$	1,155

Accounting standards pertaining to fair value measurements establish a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value. These tiers include: Level 1, defined as observable inputs such as quoted prices in active markets; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. When available, we use quoted market prices to determine the fair value of our investments, and they are included in Level 1. When quoted market prices are unobservable, we use quotes from independent pricing vendors based on recent trading activity and other relevant information, and they are included in Level 2.

The following table summarizes, by major security type, our financial instruments that are measured at fair value on a recurring basis and are categorized using the fair value hierarchy

(in thousands)

	Fair value measurements at September 26, 2015 using:
							Total estimated
	Level 1		Level 2		Level 3		fair value
Cash	$	84,642	$	-	$	-	$	84,642
Money market funds		-		4,618		-		4,618
Bank certificates of deposit		-		1,002		-		1,002
Foreign government security		-		465		-		465
	$	84,642	$	6,085	$	-	$	90,727

	Fair value measurements at December 27, 2014 using:
							Total estimated
	Level 1		Level 2		Level 3		fair value
Cash	$	66,467	$	-	$	-	$	66,467
Municipal securities		-		155		-		155
Money market funds		-		4,418		-		4,418
Bank certificates of deposit		-		1,000		-		1,000
	$	66,467	$	5,573	$	-	$	72,040