Stock-Based Compensation | 1 0 . Stock-Based Compensation A summary of the Company’s stock option activity and related information is as follows: Options Outstanding Shares Available for Grant Number of Stock Options Outstanding Weighted- Average Exercise Price Weighted- Average Remaining Contractual Life (Years) Aggregate Intrinsic Value (In thousands) Balance at December 31, 2018 1,908,626 11,603,708 $ 6.64 7.6 $ 10,151 Additional options authorized 3,853,280 Options granted (2,493,505 ) 2,493,505 8.35 Options exercised - (1,701,627 ) 4.82 Options canceled 410,410 (410,410 ) 6.67 RSUs granted (679,325 ) RSUs canceled 48,413 Balance at June 30, 2019 3,047,899 11,985,176 $ 7.20 8.2 $ 21,838 Vested and exercisable at June 30, 2019 3,467,682 $ 4.50 6.5 $ 14,977 Vested and expected to vest at June 30, 2019 11,351,730 $ 7.16 8.1 $ 21,454 The weighted-average grant date fair value of options granted to employees were $4.79 and $4.18 per share during the six months ended June 30, 2019 and 2018, respectively. The grant date fair values of options vested were $3.3 million and $2.5 million during the six months ended June 30, 2019 and 2018, respectively. Aggregate intrinsic value represents the difference between the estimated fair value of the underlying common stock and the exercise price of outstanding, in-the-money options. The aggregate intrinsic values of options exercised were $6.5 million and $2.2 million during the six months ended June 30, 2019 and 2018, respectively. At June 30, 2019, total unrecognized compensation cost related to stock options granted to employees, net of estimated forfeitures, was $32.6 million which is expected to be recognized over a weighted-average period of 3.1 years. Determination of Fair Value The determination of the fair value of stock options on the date of grant using an option-pricing model is affected by the estimated fair value of the Company’s common stock, as well as assumptions regarding a number of complex and subjective variables. The variables used to calculate the fair value of stock options using the Black-Scholes option-pricing model include actual and projected employee stock option exercise behaviors, expected price volatility of the Company’s common stock, the risk-free interest rate and expected dividends. Each of these inputs is subjective and generally requires significant judgment to determine. The fair value of employee stock options is estimated at the date of grant using a Black-Scholes option-pricing model with the following weighted-average assumptions: Six Months Ended June 30, 2019 2018 Expected term (in years) 6.0 6.0 Expected volatility% 60.1% 61.2% Risk-free interest rate% 2.5% 2.8% Expected dividend yield% 0.0% 0.0% Restricted Stock Units From time to time, the Company grants Restricted Stock Units, or RSUs, to its Board of Directors and certain employees for their services. The RSUs granted to board members are either fully vested upon issuance or vest over a period of time from the grant date and will be released and settled upon termination of the board member’s services or the occurrence of a change in control event. In January 2019, the Company granted RSUs to its Board of Directors as part of the director compensation program. In March 2019, the Company began granting RSUs to certain employees. These RSUs vest in equal annual installments over either two or three years from the grant date and are subject to the participants continuing service to the Company over that period. The fair value of RSUs is based on the closing market price of the Company’s common stock on the grant date. RSUs Number of Shares Weighted Average Grant Date Fair Value Unvested at December 31, 2018 1,736,234 $ 9.65 RSUs granted 679,325 7.75 RSUs vested (36,981 ) 6.26 Unvested at June 30, 2019 2,378,578 $ 9.22 Vested and unreleased 104,019 Outstanding at June 30, 2019 2,482,597 The total grant date fair value of RSUs awarded was $5.3 million for the six months ended June 30, 2019. The total fair value of RSUs vested was $0.2 million for the six months ended June 30, 2019. There were no RSUs awarded or vested in the six months ended June 30, 2018. As of June 30, 2019, total unrecognized stock-based compensation cost related to RSUs was $14.3 million, which is expected to be recognized over a weighted-average period of 2.1 years. As of June 30, 2019, 2,111,168 RSUs are expected to vest. Stock-Based Compensation Expense Total stock-based compensation expense recognized in the Company’s condensed consolidated statements of operations and comprehensive loss is classified as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Research and development $ 453 $ 347 $ 844 $ 550 Selling and marketing 347 194 612 321 General and administrative 4,107 1,142 8,003 2,002 Total stock-based compensation expense $ 4,907 $ 1,683 $ 9,459 $ 2,873 During the three and six months ended June 30, 2019 and 2018, there was no stock-based compensation expense capitalized as a component of inventory or recognized in cost of revenue. Stock-based compensation relating to stock-based awards granted to consultants was insignificant during the three and six months ended June 30, 2019 and 2018. |