Stock-Based Compensation

6 Months Ended

Jun. 30, 2021

Share-based Payment Arrangement [Abstract]

Stock Options

On December 17, 2013, the Company adopted the Long-Term Incentive Plan (“Incentive Plan”). The Incentive Plan provides for the issuance of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock, restricted stock units, bonus stock, dividend equivalents, other stock-based awards, performance awards, annual incentive awards or any combination of the foregoing to employees, officers, directors, and consultants of the Company. The Board of Directors governs the maximum number of shares of common stock that may be issued over the term of the Incentive Plan at the time of grant. Options under the plan are granted at the estimated fair value of the shares on the date of grant. The maximum term of options granted under the plan is ten years from the date of grant. Options normally vest according to a four-year vesting schedule, with 25% of the shares vesting on the one-year anniversary and equal monthly vesting installments

thereafter. As of June 30, 2021, 6.0 million shares of common stock were allocated for issuance under the plan, of which 0.7 million shares remained available for future issuance.

The following table summarizes the stock option activity under the Incentive Plan (in thousands except for per share amounts and years):


	Number of shares	Weighted- average exercise price per share		Weighted- average remaining contractual life (years)	Aggregate intrinsic value
Options outstanding as of December 31, 2020	3,305	$	3.86	7.21	22,952
Granted	537	18.70
Exercised	(419)	2.00
Forfeited and cancelled	(155)	4.73
Options outstanding as of June 30, 2021	3,268	$	6.49	7.22	83,369
Options vested and exercisable at June 30, 2021	1,969	$	2.99	6.22	57,141

Aggregate intrinsic value represents the difference between the Company’s estimated fair value of its common stock and the exercise price of outstanding options. The aggregate intrinsic value of stock options exercised was $8.1 million and $0.1 million during the six months ended June 30, 2021 and 2020, respectively. The Company recognized total stock-based compensation cost related to equity incentive awards of $1.5 million and $1.0 million for the six months ended June 30, 2021 and 2020, respectively.

As of June 30, 2021, unrecognized stock-based compensation cost related to outstanding unvested stock options that are expected to vest was $7.5 million, which is expected to be recognized over a weighted-average period of 2.66 years.

Restricted Stock Awards

The fair value of restricted stock awards (“RSAs”) are determined using the fair value of the Company’s common stock on the date of grant. During the six months ended June 30, 2021, the Company granted 0.2 million RSAs. No RSAs were granted for the six months ended June 30, 2020. During the six months ended June 30, 2021 and 2020, 26,336 and 25,000 RSAs vested and were released from the Company’s right to repurchase, respectively, and no RSAs were cancelled.

The weighted average estimated fair value of RSAs granted for the six months ended June 30, 2021 was $18.70 per share. As of June 30, 2021, the Company had $4.3 million of unrecognized stock-based compensation related to RSAs with a weighted average remaining requisite service period of 3.07 years.

Valuation Assumptions

The Company grants stock options with an exercise price equal to the stock’s fair value at the date of grant. The fair value of a stock option is estimated on the grant date using the Black-Scholes option-pricing model. Stock-based compensation expense is recognized, net of forfeitures, over the requisite service periods of the awards. Stock option awards generally have 10-year terms and vest and become exercisable at a rate of 25% on the first anniversary of the vesting commencement date and 1/48th each month thereafter.

The Black-Scholes assumptions used to value the employee options during the six months ended June 30, 2021 are as follows:

Stock options:

Risk-free interest rate

0.8%

Weighted-average expected term of the options

6.25 years

Expected dividend rate

— %

Expected volatility

53.8%

Fair value of common stock

$18.70

These assumptions and estimates were determined as follows:

•Fair Value of Common Stock. The Company’s board of directors determined the fair value of its common stock using various valuation methodologies, including external valuation analyses.

•Risk-Free Interest Rate. The risk-free interest rate for the expected term of the options was based on the U.S. Treasury yield curve in effect at the time of the grant.

•Weighted-Average Expected Term. The expected term was estimated using the simplified approach, in which the expected term of an award is presumed to be the mid-point between the vesting date and the expiration date of the award, as the Company does not have sufficient historical data relating to stock-option exercises.

•Expected Dividend Yield. The Company has never declared or paid any cash dividends and does not presently plan to pay cash dividends in the foreseeable future. As a result, an expected dividend yield of zero was used.

•Expected Volatility. As there was no public market for the Company’s common stock, the Company has limited information on the volatility of its common stock. Accordingly, the expected volatility for the Company was estimated by taking the average historic price volatility for industry peers, consisting of several public companies in the Company’s industry which are either similar in size, stage of life cycle, or financial leverage, over a period equivalent to the expected term of the awards.