Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2021

Share-based Payment Arrangement [Abstract]

Schedule of stock option activity under our equity plans

A summary of stock option activity under our equity plans for the nine months ended September 30, 2021 follows:

	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Balance, December 31, 2020		11,008,533		$	13.94		8.4	$	105,341,482
Granted		37,500			45.41
Exercised		(363,064	)		3.28				15,744,316
Balance, March 31, 2021		10,682,969			14.41				249,345,242
Granted		-
Exercised		(200,532	)		3.39				5,616,689
Balance, June 30, 2021		10,482,437			14.62				109,293,775
Granted		283,396			11.15
Exercised		(91,523	)		3.28				1,207,973
Forfeited		(32,050	)
Balance, September 30, 2021		10,642,260			14.67				60,733,771
Exercisable		4,511,251			4.79		5.47		52,112,514
Vested and expected to vest		10,642,260		$	14.67		8.12	$	60,733,771

Schedule of share based compensation activity

The following table provides additional information regarding the cash-settleable stock options:

	Accounting Grant Date
	July 23, 2021		July 23, 2021		August 12,2021
Number of stock options		244,073		1,154,616		312,258
Exercise price	$	18.24	$	24.20	$	24.20
Vesting date(s)	July 23, 2022		February 1, 2024		February 1, 2024
			July 23, 2023
	July 23, 2024
September 30, 2021 fair value	$	6.68	$	5.25	$	5.27

Schedule of option award on the date of grant using the Black-Scholes option

We have estimated the fair values of our option awards on the date of grant using the Black-Scholes option pricing model with the following assumptions:

	Three Months Ended September 30,
	2021
Expected annual dividend yield (1)	0.00%
Expected volatility (2)	45.4%
Risk-free rate (3)	0.88% to 0.97%
Expected option term (years) (4)	6

(1) We have not paid and do no currently anticipate paying a cash dividend on our common stock.

(2) We estimated the expected volatility using the mean stock price for selected peer public companies over a historic timeframe similar to the expected return.

(3) We estimated the risk-free rate of return using the U.S. Treasury yield curve in effect as of the valuation date.

(4) We estimated the expected term using the "simplified" method described in SEC Staff Accounting Bulletin 14,