Fair Value Measurements

12 Months Ended

Dec. 31, 2022

FAIR VALUE MEASUREMENTS

The Company’s financial assets and liabilities subject to fair value measurement on a recurring basis and the level of inputs used for such measurements were as follows (in thousands):


	Fair value measurements at reporting date using
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair Value at December 31, 2022
Assets included in:
Cash and cash equivalents
Money market securities	$	129,100	$	—	$	—	$	129,100
Marketable securities
Corporate debt securities	—		45,762		—		45,762
Asset-backed securities	—		2,904		—		2,904
U.S. treasury securities	—		14,675		—		14,675
Total fair value	$	129,100	$	63,341	$	—	$	192,441


	Fair value measurements at reporting date using
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair Value at December 31, 2021
Assets included in:
Cash and cash equivalents
Money market securities	$	121,162	$	—	$	—	$	121,162
Marketable securities
Commercial paper	—		47,939		—		47,939
Corporate debt securities	—		24,694		—		24,694
Asset-backed securities	—		19,143		—		19,143
U.S. treasury securities	—		11,918		—		11,918
Total fair value	$	121,162	$	103,694	$	—	$	224,856

The fair value of the Company’s money market funds is determined using quoted market prices in active markets for identical assets.

The fair value for the available-for-sale marketable securities is determined based on valuation models using inputs that are observable either directly or indirectly (Level 2 inputs), such as quoted prices for similar assets or liabilities, yield curve, volatility factors, credit spreads, default rates, loss severity, current market and contractual prices for the underlying instruments or debt, broker and dealer quotes, as well as other relevant economic measures.

Series B Convertible Preferred Stock Tranche Rights Liability

The fair value for the tranche liability was estimated as a forward contract using a valuation model, calibrated at issuance. The valuation model at issuance estimated the implied value of the Series B stock as of the expected milestone date utilizing the probability of milestone achievement, expected timing of milestone achievement, and risk-free rate. The model was calibrated such that the value of the initial tranche and the forward contract were equal to the initial tranche proceeds at issuance. Subsequently, the fair value of the liability was discounted to the valuation date and adjusted for probability of the achievement of the milestone event. The calibrated valuation model was updated as of the end of each reporting period and in the Stay Private scenario utilized in the hybrid methodology as of June 17, 2021 (the date of the Milestone Closing, as further discussed in Note 7). Significant estimates and assumptions impacting fair value include the discount rate,

expected time to the Milestone Closing, and probability of the Milestone Closing. The discount rate was equal to the risk-free rate commensurate with the estimated timing of the Milestone Closing.

The following assumptions were used in the estimation of the fair value of the tranche liability as a forward contract as of each of the dates indicated:


	June 17, 2021	December 31, 2020
Risk-free interest rate	0.07%	0.12%
Expected time to Milestone Closing (in years)	0.8	1.3
Probability of achievement of Milestone Closing	100%	65%

For the other portion of the hybrid method used as of June 17, 2021, the fair value for the tranche liability was estimated based upon an allocation of the underlying equity value, which was determined using an IPO value as estimated through analysis of IPOs for comparable guideline companies, to arrive at a value per share in the IPO scenario. The estimated fair value of the tranche liability was $81.2 million and $5.0 million as of the Milestone Closing on June 17, 2021 and December 31, 2020, respectively. The significant increase in the June 17, 2021 valuation stemmed from both a shift in methodology from an option pricing method (“OPM”) to a Hybrid Model where the concluded value of the forward tranche was derived by the sum of the probability weighted present value of the forward tranche in the Stay Private and IPO scenarios (with the former including all other potential exit scenarios other than an imminent IPO), as well as the increase in the probability of achievement of the Milestone Closing. The resulting difference in estimated fair value was recognized as a change in fair value within other income in the accompanying statements of operations.

The tranche liability was revalued each reporting period with the change in fair value recorded in the accompanying statements of operations through the issuance of the Milestone Shares on June 17, 2021. Following the Milestone Closing, the remaining tranche liability was reclassified to convertible preferred stock on the balance sheet.

Series A-1 Convertible Preferred Stock Warrant Liability

On October 19, 2018, the Company issued a ten-year warrant (the “Series A-1 Warrant”) to purchase up to an aggregate of 447,426 shares of Series A-1 convertible preferred stock at an exercise price of $2.794 on or before October 18, 2028.

The warrant liability met the definition of a freestanding financial instrument, as it was legally detachable and separately exercisable from the initial closing of the Series A-1 convertible preferred stock. As such, it was revalued each reporting period with the change in fair value recorded in the accompanying statements of operations until the warrant was exercised on June 22, 2021.

The fair value of the warrant liability was estimated using the OPM backsolve method as of December 31, 2020 and using a hybrid method, which included an OPM backsolve in the Stay Private scenario as of June 22, 2021. The following assumptions were used in the estimation of the fair value of the warrant liability using the OPM backsolve method as of each of the dates indicated:


	June 22, 2021	December 31, 2020
Risk-free interest rate	0.25%	0.13%
Expected term (in years)	2.0	2.0
Expected volatility	90%	90%
Expected dividend yield	0%	0%

The hybrid method used to value the warrant liability at June 22, 2021 considered both the underlying equity value determined using the OPM backsolve method in a Stay Private scenario, as well as the underlying equity value that was determined using an expected IPO value as estimated through analysis of IPOs for comparable guideline companies, to arrive at a value per share in the IPO scenario. The underlying equity values from each approach were probability weighted

based upon the expected likelihood of each scenario. The fair value of the warrant liability was estimated to be $12.02 and $0.85 as of June 22, 2021 and December 31, 2020, respectively.

The following table provides a reconciliation of the tranche liability and warrant liability measured at fair value using Level 3 significant unobservable inputs (in thousands):


	Series A-1 Preferred Stock Warrant		Series B Tranche Rights		Total
Balance, January 1, 2021	$	380	$	5,033	$	5,413
Change in fair value	5,000		76,157		81,157
Settlement of tranche liability due to issuance of Milestone Shares	—		(81,190)		(81,190)
Settlement of warrant liability upon exercise of warrant	(5,380)		—		(5,380)
Balance, December 31, 2021	$	—	$	—	$	—

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

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