Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2019

Summary of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis

The following tables summarize the Company’s financial assets and liabilities measured at fair value on a recurring basis by level within the fair value hierarchy:

		December 31, 2019
	Valuation Hierarchy	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Aggregate Fair Value
				(in thousands)
Assets:
Money market funds(1)	Level 1	$	106,127	$	—	$	—		$	106,127
U.S. government treasuries (2)	Level 2		298,256		140		(5	)		298,391
Bank time deposits	Level 2		2,500		—		—			2,500
Total financial assets		$	406,883	$	140	$	(5	)	$	407,018
Liabilities:
Derivative liability	Level 3	$	12,449	$	—	$	—		$	12,449
Contingent consideration	Level 3		17,580		—		—			17,580
Total financial liabilities		$	30,029	$	—	$	—		$	30,029

(1) Includes $13.5 million of restricted cash equivalents.

(2) Includes $24.3 million classified as long-term investments.

		December 31, 2018
	Valuation Hierarchy	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Aggregate Fair Value
		(in thousands)
Assets:
Money market funds(1)	Level 1	$	43,600	$	—	$	—		$	43,600
Structured deposits	Level 2		1,000		—		—			1,000
U.S. government treasuries	Level 2		49,859		—		(14	)		49,845
Total financial assets		$	94,459	$	—	$	(14	)	$	94,445
Liabilities:
Convertible preferred stock warrant liability	Level 3	$	1,024	$	—	$	—		$	1,024
Contingent consideration	Level 3		9,250		—		—			9,250
Total financial liabilities		$	10,274	$	—	$	—		$	10,274

(1) Includes $11.8 million of restricted cash equivalents.

Summary of Changes in Estimated Fair Value of Financial Liabilities

The following table sets forth the changes in the estimated fair value of the Company’s Level 3 financial liabilities (in thousands):

	Contingent Consideration		Derivative Liability			Warrant Liability			Total
Balance at December 31, 2018	$	9,250	$	—		$	1,024		$	10,274
Initial fair value		—		13,599			—			13,599
Changes in fair value		8,330		(1,150	)		2,049			9,229
Reclassification of warrant liability to additional    paid-in capital upon the IPO		—		—			(3,073	)		(3,073	)
Balance at December 31, 2019	$	17,580	$	12,449		$	—		$	30,029

Convertible Preferred Stock Warrant Liability

Assumptions Used to Calculate Convertible Preferred Stock Warrant Liability and Stock Options

As a result, the Company remeasured and reclassified the convertible preferred stock warrant liability to additional paid-in capital. Prior to the IPO, the convertible preferred stock warrant liability was valued using the Black-Scholes option pricing model. The assumptions used to calculate the convertible preferred stock warrant liability as of October 15, 2019, the date immediately before the closing of the IPO, and December 31, 2018 were as follows:

	October 15, 2019			December 31, 2018
Exercise price	$	4.50		$	4.50
Expected term		6.9			7.7
Expected stock price volatility		88.8	%		83.5	%
Risk-free interest rate		1.7	%		2.6	%
Expected dividend yield		—			—