Fair Value Measurements

6 Months Ended

Jun. 30, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

Fair Value Measurements

The following tables set forth the Company’s financial instruments carried at fair value using the lowest level of input that is significant to each financial instrument as of June 30, 2020 and December 31, 2019 (in thousands):

	June 30, 2020
	Quoted Prices in Active Markets for Identical Items (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Money market funds	$	232,582	$	—	$	—	$	232,582
Corporate obligations	—		60,982		—		60,982
U.S. Treasury securities	—		64,054		—		64,054
Certificates of deposit	—		249		—		249
Total assets	$	232,582	$	125,285	$	—	$	357,867
Liabilities:
Warrants to purchase common stock	$	—	$	—	$	3,516	$	3,516
Total liabilities	$	—	$	—	$	3,516	$	3,516

	December 31, 2019
	Quoted Prices in Active Markets for Identical Items (Level 1)		Significant other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Money market funds	$	193,867	$	—	$	—	$	193,867
Corporate obligations	—		138,369		—		138,369
U.S. Treasury securities	—		83,819		—		83,819
Certificates of deposit	—		493		—		493
Mortgage and other asset backed securities	—		12,470		—		12,470
Total assets	$	193,867	$	235,151	$	—	$	429,018
Liabilities:
Warrants to purchase common stock	$	—	$	—	$	1,856	$	1,856
Total liabilities	$	—	$	—	$	1,856	$	1,856

The money market funds noted above are included in cash and cash equivalents in the accompanying condensed consolidated balance sheets. The Company recognizes transfers between levels of the fair value hierarchy as of the end of the

reporting period. There were no transfers within the hierarchy during the six months ended June 30, 2020 or the year ended December 31, 2019.

Items measured at fair value on a recurring basis include short-term and long-term investments (Note 5), and warrants to purchase common stock (Note 12). During the periods presented, the Company has not changed the manner in which it values assets and liabilities that are measured at fair value using Level 3 inputs.

The following table sets forth a summary of changes in the fair value of the Company’s common stock warrant liabilities, which represent a recurring measurement that is classified within Level 3 of the fair value hierarchy, wherein fair value is estimated using significant unobservable inputs (in thousands):

	Six Months Ended June 30,
	2020		2019
Beginning balance	$	1,856	$	1,491
Change in fair value	1,660		(102)
Ending balance	$	3,516	$	1,389

The fair value of the warrants to purchase common stock on the date of issuance and on each re-measurement date for those warrants classified as liabilities was estimated using either the Monte Carlo simulation framework, which incorporates future financing events over the remaining life of the warrants to purchase common stock, or for certain re-measurement dates, due to the warrants being deeply in the money, the Black-Scholes option pricing model. Due to the nature of these inputs, the valuation of the warrants is considered a Level 3 measurement. At each reporting period, the Company evaluates the best valuation methodology. At June 30, 2020, the Black-Scholes option pricing model was used.