INVESTMENTS

Investments in Marketable Securities

The Company’s investments in available-for-sale marketable securities are made pursuant to its investment policy, which has established guidelines relative to the diversification of the Company’s investments and their maturities, with the principal objective of capital preservation and maintaining liquidity that is sufficient to meet cash flow requirements.

The following is a summary of investments in marketable securities, including those that meet the definition of a cash equivalent, as of December 31, 2017 (in thousands):



	December 31, 2017
	Amortized Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value		Cash Equivalent		Investments
Money market funds	$	358,859	$	—	$	—		$	358,859	$	358,859	$	—
Certificate of deposit	10,000		—		—			10,000		10,000		—
Corporate bonds	74,868		—		(220		)	74,648		—		74,648
U.S. treasury securities	189,310		—		(430		)	188,880		—		188,880
	$	633,037	$	—	$	(650	)	$	632,387	$	368,859	$	263,528

The following is a summary of investments in marketable securities, including those that meet the definition of a cash equivalent, as of December 31, 2016 (in thousands):



	December 31, 2016
	Amortized Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value		Cash Equivalent		Investments
Money market funds	$	48,136	$	—	$	—		$	48,136	$	48,136	$	—
Corporate bonds	60,725		1		(50		)	60,676		—		60,676
Agency bonds	28,954		2		(26		)	28,930		—		28,930
U.S. treasury securities	157,829		17		(160		)	157,686		—		157,686
Commercial paper	10,473		—		—			10,473		—		10,473
	$	306,117	$	20	$	(236	)	$	305,901	$	48,136	$	257,765

As of December 31, 2017, the Company’s investment in corporate bonds, agency bonds and U.S. treasury securities had a weighted-average maturity date of approximately nine months. Unrealized gains and losses on investments were not significant, and the Company does not believe the unrealized losses represent other-than-temporary impairments as of December 31, 2017. No marketable securities held have been in a continuous unrealized loss position for more than 12 months as of December 31, 2017.

Strategic Investments

During the year ended December 31, 2017, the Company made $1.5 million in strategic investments. As of December 31, 2017, the Company had aggregate strategic investments of $3.0 million. During the year ended December 31, 2016, the Company made $0.6 million in strategic investments. As of December 31, 2016, the Company had aggregate strategic investments of $2.1 million. The Company accounted for each of these investments using the cost method of accounting, as the Company does not have significant influence or a controlling financial interest over these entities.

These investments are subject to periodic impairment reviews and are considered to be impaired when a decline in fair value is judged to be other-than-temporary. During the year ended December 31, 2017, the Company recognized $0.6 million of impairment losses recorded in Other, net in the accompanying Consolidated Statement of Operations. During the year ended December 31, 2016, the Company did not recognize any impairment losses.