Fair Value of Financial Assets and Liabilities

6 Months Ended

Jun. 30, 2020

Fair Value of Financial Assets and Liabilities

Fair Value of Financial Assets and Liabilities

3.           Fair Value of Financial Assets and Liabilities

Short-term investments as of June 30, 2020 and December 31, 2019 consisted of U.S. Treasury notes which investments were each due within six months of such date. As of June 30, 2020 and December 31, 2019, the fair value of short-term investments was $128,942 and $186,452, respectively. As of June 30, 2020, the amortized cost was $128,933

and gross unrealized gain was $9. As of December 31, 2019, the amortized cost was $186,415 and gross unrealized gain was $37.

The following tables present information about the Company’s financial instruments measured at fair value on a recurring basis and indicate the level of the fair value hierarchy used to determine such fair values:

	Fair Value Measurements
	as of June 30, 2020 Using:
	Level 1		Level 2		Level 3		Total
Assets:
Restricted cash — money market funds	$	210	$	—	$	—	$	210
Cash equivalents — money market funds		44,473		—		—		44,473
Cash equivalents — U.S. Treasury notes		—		32,896		—		32,896
Short-term investments — U.S. Treasury notes		—		128,942		—		128,942
	$	44,683	$	161,838	$	—	$	206,521

	Fair Value Measurements
	as of December 31, 2019 Using:
	Level 1		Level 2		Level 3		Total
Assets:
Restricted cash — money market funds	$	210	$	—	$	—	$	210
Cash equivalents — money market funds		25,207		—		—		25,207
Cash equivalents — U.S. Treasury notes		—		10,192		—		10,192
Short-term investments — U.S. Treasury notes		—		186,452		—		186,452
	$	25,417	$	196,644	$	—	$	222,061

As of June 30, 2020, the Company held seventeen securities that were in an unrealized loss position. The aggregate fair value of securities held by the Company in an unrealized loss position was $113,682 at June 30, 2020. As of December 31, 2019, the Company held seven securities that were in an unrealized loss position. The aggregate fair value of securities held by the Company in an unrealized loss position was $43,107 at December 31, 2019. As of both June 30, 2020 and December 31, 2019, these securities were held by the Company in an unrealized loss position for less than 12 months. The Company determined that there was no material change in the credit risk of these securities. As a result, the Company determined it did not hold any investments with an other-than-temporary impairment as of June 30, 2020 and December 31, 2019.

During the six months ended June 30, 2020 and the year ended December 31, 2019 there were no transfers between Level 1, Level 2 and Level 3. The money market funds were valued using quoted prices in active markets, which represent a Level 1 measurement in the fair value hierarchy. The Company's cash equivalents and short-term investments as of June 30, 2020 and December 31, 2019 included U.S. Treasury notes, which are not traded on a daily basis and, therefore, represent a Level 2 measurement in the fair value hierarchy at each period end.