Investments

Debt Securities

As of January 31, 2019, debt securities consisted of the following (in thousands):



	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
U.S. treasury securities	$	396,347	$	61	$	(178	)	$	396,230
U.S. agency obligations	241,914		73		(151		)	241,836
Corporate bonds	419,784		336		(352		)	419,768
Commercial paper	254,175		—		(2		)	254,173
	$	1,312,220	$	470	$	(683	)	$	1,312,007
Included in cash and cash equivalents	$	216,270	$	—	$	—		$	216,270
Included in marketable securities	$	1,095,950	$	470	$	(683	)	$	1,095,737

As of January 31, 2018, debt securities consisted of the following (in thousands):



	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
U.S. treasury securities	$	797,977	$	—	$	(1,142	)	$	796,835
U.S. agency obligations	683,551		—		(1,127		)	682,424
Corporate bonds	470,259		16		(1,154		)	469,121
Commercial paper	602,727		—		—			602,727
	$	2,554,514	$	16	$	(3,423	)	$	2,551,107
Included in cash and cash equivalents	$	417,613	$	—	$	(1	)	$	417,612
Included in marketable securities	$	2,136,901	$	16	$	(3,422	)	$	2,133,495

We do not believe the unrealized losses represent other-than-temporary impairments based on our evaluation of available evidence as of January 31, 2019, which includes an assessment of whether it is more likely than not we will be required to sell the investment before recovery of the investment’s amortized cost basis. The unrealized losses on debt securities that have been in a net loss position for 12 months or more were not material as of January 31, 2019. We sold $950 million, $244 million, and $133 million of our debt securities during fiscal 2019, 2018, and 2017, respectively, and the realized gains and losses from the sales were immaterial.

Equity Investments

Money market funds and marketable equity investments are investments with readily determinable fair values. Non-marketable equity investments consist of investments in privately held companies without readily determinable fair values.

Equity investments consisted of the following (in thousands):



		January 31,
	Consolidated Balance Sheets Location	2019		2018
Money market funds	Cash and cash equivalents	$	237,071	$	551,804
Marketable equity investments	Marketable securities	44,127		—
Non-marketable equity investments	Other assets	36,925		28,005
		$	318,123	$	579,809

There were no adjustments made to the carrying value of the non-marketable equity investments as measured under the measurement alternative during fiscal 2019. Realized and unrealized gains and losses associated with our equity investments consisted of the following (in thousands):



	Year Ended January 31,
	2019		2018			2017
Net realized gains (losses) recognized on equity investments sold	$	8,333	$	720		$	65
Net unrealized gains (losses) recognized on equity investments held	32,127		(692		)	(15,000		)
Total net gains (losses) recognized in other income (expense), net	$	40,460	$	28		$	(14,935	)