Equity (Tables)

12 Months Ended

Dec. 31, 2021

Summary of Common Stock Warrant Activity

The following is a summary of the common stock warrant activity during the years ended December 31, 2021 and 2020:

	Number of Common Stock Warrants			Weighted- Average Exercise Price			Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2019		57,420		$	7.95			4.83	$	—
Granted		—		$	—
Exercised		—		$	—
Expired		(208	)	$	(96.00	)
Outstanding and exercisable at December 31, 2020		57,212		$	7.62			3.64	$	98
Granted		—		$	—
Exercised		—		$	—
Expired		(208	)	$	(192.00	)
Outstanding and exercisable at December 31, 2021		57,004		$	6.94			2.91	$	2.26

Equity and Debt Fundraising Events | Warrant

Summary of Common Stock Warrant Activity

The following is a summary of the common stock warrant activity related to common stock warrants issued in conjunction with equity and debt fundraising events for the years ended December 31, 2021 and 2020:

	Number of Common Stock Warrants			Weighted- Average Exercise Price			Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2019		26,823		$	102.74			9.17	$	—
Granted		1,099,536		$	1.40
Exercised		(710,211	)	$	0.01
Expired		(3,886	)	$	64.32
Outstanding at December 31, 2020		412,262		$	9.60			6.71	$	1,380
Granted		1,648,707		$	0.01
Exercised		(1,648,707	)	$	(0.01	)
Expired		—		$	—
Outstanding at December 31, 2021		412,262		$	9.81			5.71	$	723