Marketable Securities

At April 30, 2017, marketable securities consisted of the following (in thousands):



	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
U.S. agency obligations	$	1,022,208	$	22	$	(1,067	)	$	1,021,163
U.S. treasury securities	254,523		2		(103		)	254,422
Corporate bonds	320,798		18		(367		)	320,449
Commercial paper	362,364		—		—			362,364
Money market funds	57,308		—		—			57,308
	$	2,017,201	$	42	$	(1,537	)	$	2,015,706
Included in cash and cash equivalents	$	398,936	$	—	$	—		$	398,936
Included in marketable securities	$	1,618,265	$	42	$	(1,537	)	$	1,616,770

At January 31, 2017, marketable securities consisted of the following (in thousands):



	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
U.S. agency obligations	$	908,874	$	179	$	(535	)	$	908,518
U.S. treasury securities	192,028		48		(25		)	192,051
Corporate bonds	290,272		42		(429		)	289,885
Commercial paper	323,106		—		—			323,106
Money market funds	24,425		—		—			24,425
	$	1,738,705	$	269	$	(989	)	$	1,737,985
Included in cash and cash equivalents	$	281,163	$	—	$	—		$	281,163
Included in marketable securities	$	1,457,542	$	269	$	(989	)	$	1,456,822

We do not believe the unrealized losses represent other-than-temporary impairments based on our evaluation of available evidence, which includes our intent to hold these investments to maturity as of April 30, 2017. No marketable securities held as of April 30, 2017 have been in a continuous unrealized loss position for more than 12 months. We classify our marketable securities as available-for-sale at the time of purchase and reevaluate such classification as of each balance sheet date. We consider all marketable securities as available for use in current operations, including those with maturity dates beyond one year, and therefore classify these securities as current assets in the accompanying condensed consolidated balance sheets. Marketable securities on the condensed consolidated balance sheets consist of securities with original maturities at the time of purchase greater than three months and the remainder of the securities are reflected in cash and cash equivalents. During the three months ended April 30, 2017 and 2016, we sold $9 million and $0.2 million, respectively, of our marketable securities and the realized gains from the sales are immaterial.