Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2021

Summary of Financial Instruments Measured on a Recurring Basis

The following table summarizes the conclusions reached as of December 31, 2021 and 2020 for financial instruments measured at fair value on a recurring basis (in thousands):

			Fair Value Hierarchy Classification
	Balance		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
December 31, 2021
Cash	$	310	$	310		—		—
Restricted cash		218		218		—		—
Money market funds		104,187		104,187		—		—
Total assets	$	104,715	$	104,715		—		—

Warrant liabilities	$	18,062		—		—	$	18,062
Derivative liabilities		1,358		—		—		1,358
Total liabilities	$	19,420		—		—	$	19,420


December 31, 2020
Cash	$	117	$	117		—		—
Restricted cash		273		273		—		—
Money market funds		92,924		92,924		—		—
Total assets	$	93,314	$	93,314		—		—

Warrant liabilities	$	51,156		—		—	$	51,156
Derivative liability		5,954		—		—		5,954
Total liabilities	$	57,110		—		—	$	57,110

Summary of Reconciliation of Beginning and Ending Balances for Liabilities Measured at Fair Value on Recurring Basis

A reconciliation of the beginning and ending balances for liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) is as follows (in thousands):

	Warrant Liabilities
Balance – January 1, 2021	$	51,156
Loan agreement warrants		362
Gain adjustment to fair value		(30,365	)
Settlement for December 2020 Public Offering - Series 1 warrant exercises		(2,841	)
Settlement for December 2019 Public Offering warrant exercises		(250	)
Balance – December 31, 2021	$	18,062

	Derivative Liabilities
Balance – January 1, 2021	$	5,954
Adjustment for conversion of April 2020 Notes		(3,426	)
Gain adjustment to fair value		(1,170	)
Balance – December 31, 2021	$	1,358