Marketable Securities and Equity Investments

Pursuant to the adoption of ASU 2016-01 on January 1, 2018, the Company began recording changes in the fair value of its investments in corporate equity securities (except those accounted for under the equity method of accounting or those that result in consolidation of an investee) to “Other (expense) income, net” in the Company’s consolidated statements of operations. Prior to its adoption of ASU 2016-01, the Company recorded changes in the fair value of its investments in corporate equity securities to “Accumulated other comprehensive income (loss)” on its consolidated balance sheet until the related gains or losses were realized. The Company continues to record unrealized gains (losses) on available-for-sale debt securities as a component of accumulated other comprehensive income (loss) until such gains and losses are realized.

A summary of the Company’s cash equivalents and marketable securities is shown below:



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(in thousands)
As of December 31, 2018
Cash equivalents:
Money market funds	$	1,226,603	$	—	$	—		$	1,226,603
U.S. Treasury securities	5,967		—		(1		)	5,966
Government-sponsored enterprise securities	7,124		—		(1		)	7,123
Commercial paper	58,271		—		(3		)	58,268
Total cash equivalents	1,297,965		—		(5		)	1,297,960
Marketable securities:
U.S Treasury securities (matures within 1 year)	6,026		—		—			6,026
Government-sponsored enterprise securities (matures within 1 year)	10,704		—		—			10,704
Corporate debt securities (matures within 1 year)	232,845		25		(450		)	232,420
Corporate debt securities (matures after 1 year through 5 years)	1,243		2		—			1,245
Commercial paper (matures within 1 year)	100,498		—		(108		)	100,390
Total marketable debt securities	351,316		27		(558		)	350,785
Corporate equity securities	133,157		40,619		(6,453		)	167,323
Total marketable securities	$	484,473	$	40,646	$	(7,011	)	$	518,108

As of December 31, 2017
Cash equivalents:
Money market funds	$	614,951	$	—	$	—		$	614,951
Government-sponsored enterprise securities	12,679		—		(1		)	12,678
Commercial paper	57,371		—		(14		)	57,357
Total cash equivalents	685,001		—		(15		)	684,986
Marketable securities:
Government-sponsored enterprise securities (matures within 1 year)	2,304		—		(1		)	2,303
Corporate debt securities (matures within 1 year)	215,639		—		(363		)	215,276
Corporate debt securities (matures after 1 year through 5 years)	50,697		—		(106		)	50,591
Commercial paper (matures within 1 year)	80,372		—		(109		)	80,263
Total marketable debt securities	349,012		—		(579		)	348,433
Available-for-sale corporate equity securities	43,213		31,608		—			74,821
Total marketable securities	$	392,225	$	31,608	$	(579	)	$	423,254

Available-for-sale debt securities were recorded in the Company's consolidated balance sheets as follows:



	As of December 31,
	2018		2017
	(in thousands)
Cash and cash equivalents	$	1,297,960	$	684,986
Marketable securities	350,785		348,433
Total	$	1,648,745	$	1,033,419

The Company has a limited number of available-for-sale debt securities in insignificant loss positions as of December 31, 2018, which it does not intend to sell and has concluded it will not be required to sell before recovery of the amortized costs for the investments at maturity. The Company did not record any charges for other-than-temporary declines in the fair value of available-for-sale debt securities or gross realized gains or losses in 2018, 2017 or 2016.

The Company maintains strategic investments separately from the investment policy that governs its other cash, cash equivalents and marketable securities. The Company’s investments in the common stock of publicly traded companies have readily determinable fair values and are recorded in “Marketable securities” on its consolidated balance sheets. As of December 31, 2018, the fair value of the Company’s investments in the common stock of CRISPR, a publicly traded company and a related party, and Moderna, which became a publicly traded company in December 2018, were $153.7 million and $13.6 million, respectively. During the year ended December 31, 2018, the Company recorded unrealized gains of $2.6 million related to its investment in corporate equity securities, which included an unrealized gain of $9.0 million related to its investment in CRISPR offset by an unrealized loss of $6.5 million related to its investment in Moderna. In 2018, the Company invested $69.9 million in additional shares of CRISPR’s common stock.

As of December 31, 2018, the carrying value of the Company’s equity investments without readily determinable fair values, which are recorded in “Other assets” on its consolidated balance sheets, was $13.6 million.