Fair Value Measurements

12 Months Ended

Dec. 31, 2021

Fair Value Disclosures [Abstract]

Fair Value Measurements

Note 5. Fair Value Measurements

The following tables show the Company’s financial assets and liabilities measured at fair value on a recurring basis and the level of inputs used in such measurements as of December 31, 2021 and 2020 (in thousands):

	December 31, 2021
	Adjusted Cost		Unrealized Gains		Unrealized Losses			Fair Value		Fair Value Level
Assets
Cash and cash equivalents:
Cash	$	6,094	$	—	$	—		$	6,094
Money market funds		49,488		—		—			49,488	Level 1
Commercial paper		50,005		—		(2	)		50,003	Level 2
Total cash and cash equivalents		105,587		—		(2	)		105,585
Short-term investments:
Commercial paper		18,068		—		(2	)		18,066	Level 2
U.S. government securities		50,040		—		(15	)		50,025	Level 2
Corporate debt securities		18,059		—		(7	)		18,052	Level 2
U.S. agency securities		19,738		—		(35	)		19,703	Level 2
Asset-backed securities		75,787		—		(154	)		75,633	Level 2
Total short-term investments		181,692		—		(213	)		181,479
Total assets measured at fair value	$	287,279	$	—	$	(215	)	$	287,064

	December 31, 2020
	Adjusted Cost		Unrealized Gains		Unrealized Losses			Fair Value		Fair Value Level
Assets
Cash and cash equivalents:
Cash	$	4,767	$	—	$	—		$	4,767
Money market funds		22,614		—		—			22,614	Level 1
Commercial paper		41,145		—		(1	)		41,144	Level 2
Total cash and cash equivalents		68,526		—		(1	)		68,525
Short-term investments:
Commercial paper		25,470		—		—			25,470	Level 2
U.S. government securities		18,260		1		—			18,261	Level 2
Corporate debt securities		29,576		—		(8	)		29,568	Level 2
U.S. agency securities		61,436		31		(1	)		61,466	Level 2
Total short-term investments		134,742		32		(9	)		134,765
Total assets measured at fair value	$	203,268	$	32	$	(10	)	$	203,290

Realized gains or losses on marketable debt securities are immaterial for the periods presented. No security has been in an unrealized loss position for 12 months or greater. The Company determined that it did have the ability and intent to hold all marketable securities that have been in a continuous loss position until maturity or recovery. As of December 31, 2021, the Company does not consider any of its marketable debt securities to be other-than-temporarily impaired.

The Company’s marketable debt securities at December 31, 2021 have maturities due in one year or less, except for debt securities with an aggregate cost basis of $40.5 million and fair value of $40.3 million that have maturities ranging from 13 months to 21 months.

The Black-Scholes option-pricing model was used to estimate the fair value of the convertible preferred stock warrants at the date of issuance and at each subsequent consolidated balance sheet date. The fair value of the convertible preferred stock warrants was also estimated at the time of conversion to common stock warrants (see Note 10). Under this option-pricing model, convertible preferred stock warrants were valued by creating a series of call options with exercise prices based on the liquidation preferences and conversion terms of each equity class. The values of the redeemable convertible preferred stock and common stock are inferred by analyzing these options.

The fair value of each convertible preferred stock warrant was estimated using the Black-Scholes option-pricing model with the assumptions described below. Upon conversion to common stock warrants in the second quarter of 2019 (see Note 10), no further fair value measurements were made. Therefore, there is no activity with respect to periods after the second quarter of 2019. For the periods indicated, the Company has limited historical volatility information available, and the expected volatility was based on actual volatility for comparable public companies projected over the expected terms of the warrants. The Company did not apply a forfeiture rate to the warrants as there is not enough historical information available to estimate such a rate. The risk-free interest rate was based on the U.S. Treasury yield curve over the expected term of the warrants.

	Period Ended
	June 24, 2019
Expected term (in years)	5.01 - 5.26
Volatility	57.20% - 57.24%
Risk-free interest rate	1.75%
Dividend yield	–%

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

	Warrant Liability
Balance — December 31, 2018	$	683
Change in fair value		1,403
Reclassification of warrant liability to additional paid-in capital on conversion		(2,086	)
Balance — December 31, 2019	$	—