4. Cash, Cash Equivalents and Marketable Securities

The following tables summarize the Company's cash, cash equivalents and marketable securities as of December 31, 2015 and December 31, 2014 (in thousands):

As of December 31, 2015	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Cash, money market funds and overnight repurchase agreements	$	61,461	$	—	$	—		$	61,461
U.S. government-sponsored enterprise securities due in one year or less		24,285		5		—			24,290
Corporate debt securities due in one year or less		73,735		1		(84	)		73,652
Commercial paper obligations due in one year or less		125,693		120		(8	)		125,805
Asset-backed securities due in one year or less		64,866		—		(30	)		64,836

Total	$	350,040	$	126	$	(122	)	$	350,044


Reported as:
Cash and cash equivalents	$	61,461	$	—	$	—		$	61,461
Marketable securities		288,579		126		(122	)		288,583

Total	$	350,040	$	126	$	(122	)	$	350,044

As of December 31, 2014	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Cash and money market funds	$	60,369	$	—	$	—		$	60,369
Corporate debt securities due in one year or less		71,669		3		(24	)		71,648
Commercial paper obligations due in one year or less		15,237		13		—			15,250
Foreign government bonds due in one year or less		18,519		2		(1	)		18,520
Asset-backed securities due in one year or less		25,751		—		(9	)		25,742

Total	$	191,545	$	18	$	(34	)	$	191,529


Reported as:
Cash and cash equivalents	$	61,349	$	—	$	—		$	61,349
Marketable securities		130,196		18		(34	)		130,180

Total	$	191,545	$	18	$	(34	)	$	191,529

At December 31, 2015 and December 31, 2014, the Company held 66 and 44 marketable securities, respectively, which were in a continuous unrealized loss position for less than one year. At December 31, 2015, there were no marketable securities in a continuous unrealized loss position for greater than one year. At December 31, 2014, there was one marketable security in a continuous unrealized loss position for greater than one year. The unrealized losses were caused by fluctuations in interest rates.

The following table summarizes the aggregate fair value of these securities at December 31, 2015 and December 31, 2014 (in thousands):

	As of December 31, 2015					As of December 31, 2014
	Aggregate Fair Value		Unrealized Losses			Aggregate Fair Value		Unrealized Losses
Corporate debt securities due in one year or less	$	70,657	$	(84	)	$	63,221	$	(24	)
Commercial paper obligations due in one year or less	$	33,734	$	(8	)	$	—	$	—
Asset-backed securities due in one year or less	$	61,337	$	(30	)	$	25,742	$	(9	)
Foreign government bonds due in one year or less	$	—	$	—		$	12,773	$	(1	)