Stockholders' Equity (Tables)
|
12 Months Ended |
Dec. 31, 2018 |
|---|
| Summary of Stock Option Award Activity |
The following table summarizes the stock option award activity under the Stock Plans during the year ended December 31, 2018:
|
|
|
Class A
Number
of Shares |
|
|
Class B
Number
of Shares |
|
|
Weighted-
Average
Exercise
Price |
|
|
Weighted-
Average
Remaining
Contractual
Term
(in years) |
|
|
Aggregate
Intrinsic
Value(1) |
|
|
|
|
(in thousands, except per share data) |
|
|
Outstanding at December 31, 2017 |
|
|
20,807 |
|
|
|
11,790 |
|
|
$ |
4.10 |
|
|
|
4.99 |
|
|
$ |
343,110 |
|
|
Granted |
|
|
4,987 |
|
|
|
— |
|
|
$ |
13.55 |
|
|
|
— |
|
|
$ |
— |
|
|
Exercised |
|
|
(10,688 |
) |
|
|
(8,582 |
) |
|
$ |
2.49 |
|
|
|
— |
|
|
$ |
— |
|
|
Forfeited |
|
|
(1,784 |
) |
|
|
(239 |
) |
|
$ |
14.57 |
|
|
|
— |
|
|
$ |
— |
|
|
Outstanding at December 31, 2018 |
|
|
13,322 |
|
|
|
2,969 |
|
|
$ |
7.83 |
|
|
|
6.41 |
|
|
$ |
34,567 |
|
|
Exercisable at December 31, 2018 |
|
|
7,853 |
|
|
|
2,969 |
|
|
$ |
6.76 |
|
|
|
5.12 |
|
|
$ |
27,356 |
|
|
Vested and expected to vest at December 31, 2018 |
|
|
12,605 |
|
|
|
2,969 |
|
|
$ |
7.52 |
|
|
|
6.28 |
|
|
$ |
34,560 |
|
|
(1) |
The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying stock option awards and the closing market price of our Class A common stock as of December 31, 2017 and December 31, 2018, respectively. |
|
| Summary of Weighted-Average Assumptions Used To Determine Fair Value of Employee Stock Options Granted |
The weighted-average assumptions used to determine the fair value of stock options granted and assumed during the year ended December 31, 2018 were as follows:
|
Expected term from grant date (in years) |
|
|
5.8 |
|
|
Risk-free interest rate |
|
|
3 |
% |
|
Expected volatility |
|
|
55 |
% |
|
Dividend yield |
|
|
0 |
% |
|
Strike price |
|
$ |
13.55 |
|
|
| Summary of Total Stock-based Compensation Expense |
Total stock-based compensation expense by function was as follows:
|
|
|
Year Ended December 31, |
|
|
|
|
2016 |
|
|
2017 |
|
|
2018 |
|
|
|
|
(in thousands) |
|
|
Cost of revenue |
|
$ |
532 |
|
|
$ |
26,071 |
|
|
$ |
4,393 |
|
|
Research and development |
|
|
21,935 |
|
|
|
1,154,430 |
|
|
|
340,533 |
|
|
Sales and marketing |
|
|
3,956 |
|
|
|
236,474 |
|
|
|
84,059 |
|
|
General and administrative |
|
|
5,419 |
|
|
|
1,222,920 |
|
|
|
109,226 |
|
|
Total |
|
$ |
31,842 |
|
|
$ |
2,639,895 |
|
|
$ |
538,211 |
|
|
| Restricted Stock Units |
|
| Summary of RSU and RSA Award Activity |
The following table summarizes the RSU award activity during the year ended December 31, 2018:
|
|
|
Class A
Outstanding
RSUs |
|
|
Class B
Outstanding
RSUs |
|
|
Weighted-
Average
Grant Date
Fair Value
per RSU |
|
|
|
|
(in thousands, except per share data) |
|
|
Unvested at December 31, 2017 |
|
|
154,728 |
|
|
|
7,791 |
|
|
$ |
15.90 |
|
|
Granted |
|
|
88,174 |
|
|
|
— |
|
|
$ |
11.30 |
|
|
Vested |
|
|
(50,701 |
) |
|
|
(6,331 |
) |
|
$ |
15.50 |
|
|
Forfeited |
|
|
(42,563 |
) |
|
|
(968 |
) |
|
$ |
15.92 |
|
|
Unvested at December 31, 2018 |
|
|
149,638 |
|
|
|
492 |
|
|
|
|
|
|
| Restricted Stock Awards |
|
| Summary of RSU and RSA Award Activity |
The following table summarizes the RSA activity during the year ended December 31, 2018:
|
|
|
|
|
Class A Outstanding
RSAs |
|
|
Weighted-
Average
Grant Date
Fair Value
per RSA |
|
|
|
|
|
|
(in thousands, except per share data) |
|
|
Unvested at December 31, 2017 |
|
|
|
|
1,277 |
|
|
$ |
14.89 |
|
|
Granted |
|
|
|
|
7,317 |
|
|
$ |
6.69 |
|
|
Vested |
|
|
|
|
(421 |
) |
|
$ |
14.89 |
|
|
Forfeited |
|
|
|
|
(39 |
) |
|
$ |
14.94 |
|
|
Unvested at December 31, 2018 |
|
|
|
|
8,134 |
|
|
|
|
|
|