Basis of Presentation and Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2021

Basis of Presentation and Significant Accounting Policies

Contract assets and contract liabilities

The following tables present changes in the Company’s contract assets and contract liabilities during the nine months ended September 30, 2021 and 2020 (in thousands):

	Balance at								Balance at
Nine months ended September 30, 2021	December 31, 2020		Additions		Deductions		Impact of Netting		September 30, 2021
Contract asset	$	—	$	2,500	$	—	$	—	$	2,500
Contract liabilities (deferred revenue)	$	110,109	$	25	$	(4,129)	$	—	$	106,005

	Balance at								Balance at
Nine months ended September 30, 2020	December 31, 2019		Additions		Deductions		Impact of Netting		September 30, 2020
Contract asset	$	3,631	$	—	$	(8,000)	$	4,369	$	—
Contract liabilities (deferred revenue)	$	127,432	$	50	$	(1,325)	$	4,369	$	130,526

The Company recognized the following revenues as a result of changes in contract asset and contract liability balances in the respective periods (in thousands):

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2021		2020		2021		2020
Revenue recognized in the period from:
Amounts included in contract liabilities at the beginning of the period	$	3,292	$	72	$	4,129	$	1,300

Schedule of common stock equivalents, as calculated in accordance with the treasury-stock method

The Company’s common stock equivalents, as calculated in accordance with the treasury-stock method for options and unvested restricted stock and the if-converted method for the convertible notes, are shown in the following table (in thousands):

	Three Months Ended		Nine Months Ended
	September 30,		September 30,
	2021	2020	2021	2020
Options outstanding to purchase common stock, shares issuable under the employee stock purchase plan, and unvested restricted stock/units at end of period	20,862	19,181	20,862	19,181
Common stock equivalents under treasury stock method for options, shares issuable under the employee stock purchase plan, and unvested restricted stock/units	2,116	929	2,743	1,112
Common stock equivalents under if-converted method for convertible notes	-	501	-	501

Schedule of risk-free rate of the stock options based on US Treasury rate

	Three Months Ended September 30,		Nine Months Ended September 30,
	2021	2020	2021	2020
Dividend	None	None	None	None
Volatility	82.7%	88.3%	85.2%	85.0%
Risk-free interest rate	0.95%	0.36%	0.68%	1.23%
Expected life (years)	6.0	6.0	6.0	6.0

Summary of stock option activity

A summary of option activity under the Company’s equity plans for the nine months ended September 30, 2021 is presented below (in thousands, except weighted-average data):

		Weighted-
	Number	Average
	of Stock	Exercise
	Options	Price
Outstanding at December 31, 2020	18,398	$	6.10
Granted	4,380		7.53
Exercised	(503)		3.34
Forfeited/Canceled	(1,415)		8.06
Outstanding at September 30, 2021	20,860		6.34

Summary of restricted stock activity

A summary of restricted stock and restricted stock unit activity under the Company’s equity plans for the nine months ended September 30, 2021 is presented below (in thousands, except weighted-average data):

	Number of	Weighted-
	Restricted	Average Grant
	Stock Shares	Date Fair Value
Unvested at December 31, 2020	61	$	2.47
Vested	(2)		2.53
Forfeited	(57)		2.47
Unvested at September 30, 2021	2	$	2.53