FAIR VALUE MEASUREMENTS

Cash Equivalents and Short-term Investments

The Company's financial instruments 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.

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

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.

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. As of March 31, 2019 and December 31, 2018, the Company did not hold any Level 3 instruments.

Financial instruments measured at fair value on a recurring basis as of March 31, 2019 and December 31, 2018 are classified based on the valuation technique in the table below (in thousands):



	March 31, 2019
	Fair Value Measurements Using
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Money market accounts	$	70,848	—		—		$	70,848
U.S. Treasury securities	—		14,959		$	—	14,959
Total assets at fair value ⁽¹⁾	$	70,848	$	14,959	$	—	$	85,807

(1) The above table excludes $31.8 million of cash held in banks.



	December 31, 2018
	Fair Value Measurements Using
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Money market accounts	$	81,425	—		—		$	81,425
U.S. Treasury securities	—		13,930		$	—	13,930
Total assets at fair value ⁽²⁾	$	81,425	$	13,930	$	—	$	95,355

(2) The above table excludes $29.6 million of cash held in banks.

The contractual maturities of the Company’s available-for-sale securities on March 31, 2019 and December 31, 2018 were all due within one year. There were no transfers of instruments between Level 1 and 2 during the three months ended March 31, 2019 and the year ended December 31, 2018.

Money market accounts are classified as cash equivalents and U.S. Treasury securities (classified as available-for-sale securities), with maturity dates less than one year, are within short-term investments on the Company’s condensed consolidated balance sheets.

Short-term Investments

Short-term investments as of March 31, 2019 and December 31, 2018 consists of the following (in thousands):



	March 31, 2019
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
U.S. Treasury securities	$	14,960	$	—	$	(1	)	$	14,959
Total	$	14,960	$	—	$	(1	)	$	14,959



	December 31, 2018
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
U.S. Treasury securities	$	13,936	$	—	$	(6	)	$	13,930
Total	$	13,936	$	—	$	(6	)	$	13,930