Share-based Compensation
9 Months Ended
Sep. 30, 2022
Share-Based Payment Arrangement [Abstract]  
Share-based Compensation Share-Based Compensation
In 2015, the Board of Directors approved and adopted the 2015 Equity Incentive Plan, or 2015 Plan. Pursuant to the 2015 Plan, the Company granted RSAs and stock options to members of the Board of Directors, employees and consultants.
In 2018, the Board of Directors terminated the 2015 Plan and approved the 2018 Equity Incentive Plan, or the 2018 Plan, with an initial reserve of 1,500,000 common shares. Under the 2018 Plan, the Company may grant stock options, equity appreciation rights, RSUs and RSAs. If an award granted under the 2018 Plan expires, terminates, is unexercised, or is forfeited, or if any shares are surrendered in connection with an incentive award, the shares subject to such award and the surrendered shares become available for further awards under the 2018 Plan.
Pursuant to the “evergreen” provision contained in the 2018 Plan, the number of common shares reserved for issuance under the 2018 Plan automatically increases on first day of each fiscal year, commencing on January 1, 2019, in an amount equal to the least of (1) 750,000 shares, (2) 4% of the total number of the Company’s common shares outstanding on the last day of the preceding fiscal year, or (3) a number of common shares as may be determined by the Company’s Board of Directors prior to any such increase date. On each of January 1, 2019 through 2022 the number of common shares authorized for issuance increased automatically by 750,000 shares in accordance with the “evergreen” provision, increasing the number of common shares reserved under the 2018 Plan to 4,500,000 as of September 30, 2022.
During the periods presented, the Company recorded the following share-based compensation expense for stock options and restricted stock awards:
Three Months Ended September 30,Nine Months Ended September 30,
2022202120222021
(in thousands)
Sales, general and administrative $2,309$2,396$8,479$5,473
Research and development6126681,6181,904
Total $2,921$3,064$10,097$7,377
Stock Options
 Number of Options OutstandingWeighted-Average Exercise PriceWeighted-Average Remaining Contractual Term (in years)Aggregate Intrinsic Value (in thousands)
Balances at December 31, 20212,098,087 $37.49 7.67$67,357 
Granted (weighted-average fair value $37.74 per share)
230,750 63.41 
Exercised(244,896)13.84 
Forfeited/canceled(213,272)61.16 
Balances at September 30, 20221,870,669 $41.08 7.13$38,212 
As of September 30, 2022, 1,005,674 options were vested and exercisable with weighted-average exercise price of $28.29 per share and a total aggregate intrinsic value of $30.2 million.
During the nine months ended September 30, 2022, 244,896 options were exercised at a weighted-average price of $13.84 per share. The intrinsic value of the options exercised during the nine months ended September 30, 2022 and 2021 was $11.7 million and $25.4 million, respectively. Upon the exercise of stock options, the Company issued new shares from its authorized shares.
At September 30, 2022, unrecognized compensation expense was $21.4 million related to stock options granted to employees and members of the Board of Directors and $1.0 million related to stock options granted to consultants. The weighted-average period over which such compensation expense will be recognized is 2.4 years.
Stock Options Granted to Employees
Share-based compensation expense for employees is based on the grant date fair value. The Company recognizes compensation expense for all share-based awards ratably on a straight-line basis over the requisite service period of the awards, which is generally the vesting term of four years. During the nine months ended September 30, 2022 and 2021, the Company recognized $7.7 million and $5.5 million, respectively, of share-based compensation expense for stock options granted to employees.
The Company uses the Black-Scholes option valuation model to value options granted to employees and consultants, which requires the use of highly subjective assumptions to determine the fair value of share-based awards. The assumptions used in the Company’s option-pricing model represent management’s best estimates. These estimates are complex, involve a number of variables, uncertainties and assumptions and the application of management’s judgment. If factors change and different assumptions are used, the Company’s share-based compensation expense could be materially different in the future. The assumptions and estimates that the Company uses in the Black-Scholes model are as follows:
Fair Value of Common Shares. The closing price of the Company’s publicly-traded common shares on the date of grant is used as the fair value of the shares. The Board of Directors intended all options granted to be exercisable at a price per share not less than the estimated per share fair value of the shares underlying those options on the date of grant.
Risk-Free Interest Rate. The Company bases the risk-free interest rate used in the Black-Scholes valuation model on the implied yield available on U.S. Treasury zero-coupon issues with a term equivalent to that of the term of the options for each option group on the measurement date.
Term. For employee stock options, the expected term represents the period that the Company’s share-based awards are expected to be outstanding. Because of the limitations on the sale or transfer of the Company’s shares during the period the Company was a privately held company, the Company does not believe its historical exercise pattern is indicative of the pattern it experiences as a publicly traded company. The Company consequently uses the Staff Accounting Bulletin 110, or SAB 110, simplified
method to calculate the expected term of employee stock options, which is the average of the contractual term and vesting period. The Company plans to continue to use the SAB 110 simplified method until it has sufficient trading history as a publicly traded company. For consultant stock options, the term used is equal to the remaining contractual term on the measurement date.
Volatility. The Company determines the price volatility based on the historical volatilities of industry peers as it does not have sufficient trading history for its shares. Industry peers consist of several public companies in the medical device industry with comparable characteristics, including revenue growth, operating model and working capital requirements. The Company intends to continue to consistently apply this process using the same or a similar peer group of public companies until a sufficient amount of historical information regarding the volatility of its own shares becomes available, or unless circumstances change such that the identified peer companies are no longer similar, in which case other suitable peer companies whose common share prices are publicly available would be utilized in the calculation. The volatility is calculated based on the term on the measurement date.
Dividend Yield. The expected dividend assumption is based on the Company’s current expectations about its anticipated dividend policy. The Company has no expectation that it will declare dividends on its common shares, and therefore has used an expected dividend yield of zero.
The fair value of stock options granted to employees was estimated using the following assumptions:
Nine Months Ended September 30,
20222021
Volatility
56% - 59%
60%
Risk-free interest rate
1.6% - 3.2%
0.7% - 1.1%
Term (in years)6.256.25
Dividend yield
Stock Options Granted to Non-Employees
Share-based compensation expense related to stock options granted to non-employees is recognized as the stock options are earned using an accelerated attribution method. The Company believes that the estimated fair value of the stock options is more readily measurable than the fair value of the services rendered. For the nine months ended September 30, 2022 and 2021, the Company recognized expense of $0.3 million and $1.5 million, respectively, for stock options granted to consultants.
The fair value of stock options granted to consultants was estimated using the following assumptions during the following periods presented:
Nine Months Ended September 30,
20222021
Volatility
56% - 58%
60%
Risk-free interest rate
2.4% - 2.9%
1.6%
Term (in years)1010
Dividend yield
Restricted Stock
Each vested RSU entitles the holder to be issued one common share. These awards vest according to a vesting schedule determined by the Compensation Committee of the Company’s Board of Directors, generally over a one to four year period.
The following table represents RSU activity for fiscal 2022:
 Restricted Stock Units Weighted-
Average
Grant Date
Fair Value
Outstanding unvested at December 31, 20213,982 $69.05 
Granted171,897 61.94 
Vested(12,542)50.39 
Forfeited/canceled(17,205)65.97 
Outstanding unvested at September 30, 2022146,132 $62.65 
The fair value of RSUs is the grant date market value of common shares. The Company recognizes share-based compensation expense related to RSUs using a straight-line method over the vesting term of the awards. The share-based compensation expense for RSUs that vested during the nine months ended September 30, 2022 and 2021, was $2.1 million and $0.4 million, respectively, which was calculated based on the market value of the Company’s common shares on the applicable grant date.
As of September 30, 2022, the Company had unrecognized share-based compensation cost of approximately $7.7 million associated with unvested awards of RSUs. This cost is expected to be recognized over a weighted-average period of approximately 3.0 years.