Cash, cash equivalents, and investments consisted of the following (in thousands):



	March 30, 2014		December 31, 2013
Cash	$	36,740	$	40,124
Money market instruments	5,723		520
Cash and cash equivalents	42,463		40,644
Corporate bonds	33,585		109,040
Municipal bonds	4,766		9,276
Sovereign bonds	3,016		11,448
Asset-backed securities	410		53,559
Agency bonds	—		1,499
Short-term investments	41,777		184,822
Corporate bonds	190,767		109,909
Treasury bills	86,804		73,666
Asset-backed securities	74,475		21,820
Sovereign bonds	17,401		16,385
Municipal bonds	7,013		5,919
Agency bonds	1,500		—
Limited partnership interest	1,956		1,956
Long-term investments	379,916		229,655
	$	464,156	$	455,121

The Company’s investment portfolio includes corporate bonds, municipal bonds, sovereign bonds, asset-backed securities, treasury bills, and agency bonds. Corporate bonds consist of debt securities issued by both domestic and foreign companies; municipal bonds consist of debt securities issued by state and local government entities; sovereign bonds consist of direct debt issued by foreign governments; asset-backed securities consist of debt securities collateralized by pools of receivables or loans with credit enhancement; treasury bills consist of debt securities issued by both the U.S. and foreign governments; and agency bonds consist of domestic or foreign obligations of government agencies and government sponsored enterprises that have government backing.

The following table summarizes the Company’s available-for-sale investments as of March 30, 2014 (in thousands):



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Short-term:
Corporate bonds	$	33,480	$	105	$	—		$	33,585
Municipal bonds	4,758		8		—			4,766
Sovereign bonds	2,996		20		—			3,016
Asset-backed securities	410		—		—			410
Long-term:
Corporate bonds	190,185		680		(98		)	190,767
Treasury bills	86,941		2		(139		)	86,804
Asset-backed securities	74,471		69		(65		)	74,475
Sovereign bonds	17,367		52		(18		)	17,401
Municipal bonds	6,968		45		—			7,013
Agency bonds	1,500		—		—			1,500
	$	419,076	$	981	$	(320	)	$	419,737

The following table summarizes the Company’s gross unrealized losses and fair values for available-for-sale investments in an unrealized loss position as of March 30, 2014 (in thousands):



	Unrealized Loss Position For:
	Less than 12 Months					12 Months or Greater					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Corporate bonds	$	55,024	$	(98	)	$	—	$	—		$	55,024	$	(98	)
Asset-backed securities	23,535		(38		)	8,456		(27		)	31,991		(65		)
Sovereign bonds	3,347		(18		)	—		—			3,347		(18		)
Treasury bills	82,753		(139		)	—		—			82,753		(139		)
	$	164,659	$	(293	)	$	8,456	$	(27	)	$	173,115	$	(320	)

As of March 30, 2014, the Company did not recognize an other-than-temporary impairment of these investments. In its evaluation, management considered the type of security, the credit rating of the security, the length of time the security has been in a loss position, the size of the loss position, our intent and ability to hold the security to expected recovery of value, and other meaningful information. The Company does not intend to sell, and is unlikely to be required to sell, any of these available-for-sale investments before its effective maturity or market price recovery.

The Company recorded gross realized gains and gross realized losses on the sale of investments totaling $512,000 and $11,000, respectively, during the three-month period ended March 30, 2014 and $50,000 and $19,000, respectively, during the three-month period ended March 31, 2013. These gains and losses are included in "Investment income" on the Consolidated Statements of Operations.

The following table presents the effective maturity dates of the Company’s available-for-sale investments as of March 30, 2014 (in thousands):



	1 Year or Less		1-2 Years		2-3 Years		3-4 Years		4-5 Years		5-8 Years		Total
Corporate bonds	$	33,585	$	64,435	$	94,424	$	2,428	$	29,480	$	—	$	224,352
Treasury bills	—		32,317		54,487		—		—		—		86,804
Asset-backed securities	410		5,287		14,663		29,396		21,243		3,886		74,885
Sovereign bonds	3,016		12,502		4,899		—		—		—		20,417
Municipal bonds	4,766		3,981		1,475		1,557		—		—		11,779
Agency bonds	—		—		1,500		—		—		—		1,500
	$	41,777	$	118,522	$	171,448	$	33,381	$	50,723	$	3,886	$	419,737

The Company is a Limited Partner in Venrock Associates III, L.P. (Venrock), a venture capital fund. The Company has committed to a total investment in the limited partnership of up to $20,500,000, with an expiration date of December 31, 2015. As of March 30, 2014, the Company contributed $19,886,000 to the partnership. The remaining commitment of $614,000 can be called by Venrock at any time before December 31, 2015. Distributions and contributions are at the discretion of Venrock’s management. No contributions were made and no distributions were received during the three-month period ended March 30, 2014.