FAIR VALUE MEASUREMENTS

Cash Equivalents and Short-term Investments

The financial instruments of the Company measured at fair value on a recurring basis are cash equivalents and short-term investments.

The Company’s fixed income available-for-sale securities consist of high quality, investment grade securities. The Company values these securities based on pricing from pricing vendors, who may use quoted prices in active markets for identical assets (Level 1) or inputs other than quoted prices that are observable either directly or indirectly (Level 2) in determining fair value.

The types of instruments valued based on quoted market prices in active markets include money market accounts. Such instruments are generally classified within Level 1 of the fair value hierarchy.

The types of instruments valued based on quoted prices in markets that are less active, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency are generally classified within Level 2 of the fair value hierarchy and include U.S. treasury securities.

The types of instruments valued based on unobservable inputs which reflect the reporting entity’s own assumptions or data that market participants would use in valuing an instrument are generally classified within Level 3 of the fair value hierarchy. The Company had no Level 3 instruments as of March 31, 2018 and December 31, 2017.

Financial instruments measured at fair value on a recurring basis as of March 31, 2018 and December 31, 2017 are classified based on the valuation technique in the table below:



	March 31, 2018
	Fair value measurements using
(in thousands)	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
U.S. Treasury securities	$	—	$	19,842	$	—	$	19,842
Money market accounts	56,273		—		—		56,273
Total assets at fair value	$	56,273	$	19,842	$	—	$	76,115

The above table excludes $62.9 million of cash held in banks.



	December 31, 2017
	Fair value measurements using
(in thousands)	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
U.S. Treasury securities	$	—	$	21,916	$	—	$	21,916
Money market accounts	1,117		—		—		1,117
Total assets at fair value	$	1,117	$	21,916	$	—	$	23,033

The above table excludes $23.5 million of cash held in banks.

U.S. Treasury securities are classified as short-term investments, and money market accounts are classified as cash equivalents on the Company’s condensed consolidated balance sheets.

Short-term Investments



	March 31, 2018
(in thousands)	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
U.S. Treasury securities	$	19,860	$	—	$	(18	)	$	19,842
Total	$	19,860	$	—	$	(18	)	$	19,842



	December 31, 2017
(in thousands)	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
U.S. Treasury securities	$	21,939	$	—	$	(23	)	$	21,916
Total	$	21,939	$	—	$	(23	)	$	21,916

The contractual maturities of the short-term investments (classified as available-for-sale securities) on March 31, 2018 and December 31, 2017 were all due within one year. There were no transfers of instruments between Level 1 and 2 during the three months ended March 31, 2018 and the year ended December 31, 2017.