Fair Value Measurements

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Fair Value Measurements

4. Fair Value Measurements

The following tables set forth the fair value of financial assets and liabilities as of December 31, 2019 and 2018 that were measured at fair value on a recurring basis (in thousands):

	December 31, 2019
	Level 1		Level 2		Level 3		Total
Financial assets
Money market funds	$	88,683	$	—	$	—	$	88,683
Commercial paper		—		121,867		—		121,867
U.S. government debt and agency securities		—		377,243		—		377,243
Corporate bonds		—		86,615		—		86,615
Total financial assets	$	88,683	$	585,725	$	—	$	674,408

	December 31, 2018
	Level 1		Level 2		Level 3		Total
Financial assets
Money market funds	$	45,998	$	—	$	—	$	45,998
Commercial paper		—		16,887		—		16,887
U.S. government debt and agency securities		—		85,623		—		85,623
Corporate bonds		—		7,478		—		7,478
Total financial assets	$	45,998	$	109,988	$	—	$	155,986
Financial liabilities
Convertible preferred stock warrant liability	$	—	$	—	$	336	$	336
Total financial liabilities	$	—	$	—	$	336	$	336

Level 1 securities include highly liquid money market funds, which we measure the fair value based on quoted prices in active markets for identical assets or liabilities. Level 2 securities consist of U.S. government debt securities, U.S. government agency securities, commercial paper and corporate bonds, and are valued based on recent trades of securities in inactive markets or based on quoted market prices of similar instruments and other significant inputs derived from or corroborated by observable market data. Level 3 liabilities that were measured at fair value on a recurring basis consisted of a convertible preferred stock warrant liability.

The fair value of the convertible preferred stock warrant liability was last calculated as of June 30, 2019, prior to reclassification to shareholders’ equity in connection with the completion of our initial public offering on July 1, 2019. The fair value was estimated using the Black-Scholes option-pricing model with the following inputs: (1) a fair value estimate of $48.30, (2) an expected term of 1.8 years, (3) a risk-free interest rate of 1.8%, (4) an expected volatility of 61.1% and (5) an expected dividend yield of zero. As of December 31, 2018, the fair value of the convertible preferred stock warrant liability was estimated using the Black-Scholes option-pricing model with the following inputs:

	December 31, 2018
Fair value estimate	$	8.27
Expected term (in years)		2.31
Risk-free interest rate		2.5	%
Expected volatility		55.3	%
Expected dividend yield		—