Note 5. Cash, Money Market Funds and Marketable Securities

As of September 30, 2017, the Company held $64.1 million in cash and cash equivalents and $362.5 million of available-for-sale securities which are reported at fair value on the Company’s Consolidated Balance Sheets. Unrealized holding gains and losses are reported within accumulated other comprehensive income/ (loss) in the statements of comprehensive loss. If a decline in the fair value of a marketable security below the Company’s cost basis is determined to be other than temporary, such marketable security is written down to its estimated fair value as a new cost basis and the amount of the write-down is included in earnings as an impairment charge. To date, only temporary impairment adjustments have been recorded.

The Company regularly invests excess operating cash in deposits with major financial institutions, money market funds, notes issued by the U.S. government, as well as fixed income investments and U.S. bond funds both of which can be readily purchased and sold using established markets. The Company believes that the market risk arising from its holdings of these financial instruments is mitigated as many of these securities are either government backed or of the highest credit rating. Investments that have original maturities greater than 3 months but less than 1 year are classified as short-term, while investments that have maturities greater than 1 year are classified as long-term.

For the nine months ended September 30, 2017, the Company recognized a loss of $0.2 million, related to derivative instruments not designated as hedging instruments in other expense in the Consolidated Statements of Operations. As the forward contract expired in June 2017, there was no liability in the Consolidated Balance Sheets as of September 30, 2017.

Cash and available-for-sale securities are all current unless mentioned otherwise and consisted of the following as of September 30, 2017 and December 31, 2016 (in thousands):

	As of September 30, 2017
	Cost		Gross unrealized Gain		Gross unrealized Loss			Fair Value
Cash balances	$	64,133	$	—	$	—		$	64,133
Corporate debt securities, current portion	192,851		5		(75		)	192,781
Corporate debt securities, non-current portion	15,121		—		(12		)	15,109
Commercial paper	123,880		11		(10		)	123,881
Asset backed securities	30,346		—		(20		)	30,326
Money market	350		—		—			350
Certificate of deposit	50		—		—			50

	$	426,731	$	16	$	(117	)	$	426,630

Included in cash and cash equivalents	$	64,133	$	—	$	—		$	64,133
Included in marketable securities	362,598		16		(117		)	362,497

Total cash and marketable securities	$	426,731	16		$	(117	)	$	426,630

	As of December 31, 2016
	Cost		Unrealized Gain		Unrealized Loss			Fair Value
Cash balances	$	187,026	$	—	$	—		$	187,026
Corporate debt securities, current portion	74,564		2		(31		)	74,535
Commercial paper	68,258		132		—			68,390
Money market	350		—		—			350
Certificate of deposit	50		—		—			50

	$	330,248	$	134	$	(31	)	$	330,351

Included in cash and cash equivalents	$	187,026	$	—	$	—		$	187,026
Included in marketable securities	143,222		134		(31		)	143,325

Total cash and marketable securities	$	330,248	134		$	(31	)	$	330,351

For the nine months ended September 30, 2017 and the year ended December 31, 2016, there were no realized gains or losses. The cost of securities sold is based on the specific identification method.

Unrealized loss positions in the available for sale securities as of September 30, 2017 and December 31, 2016 reflect temporary impairments that have been in a loss position for less than twelve months and as such are recognized in other comprehensive gain/ (loss). The fair value of these available for sale securities in unrealized loss positions was $241.5 million and $58.7 million as of September 30, 2017 and December 31, 2016, respectively.

The Company holds available-for-sale investment securities which are reported at fair value on the Company’s balance sheet. Unrealized holding gains and losses are reported within accumulated other comprehensive income (“AOCI”) in the statements of comprehensive loss.