Stock-Based Compensation Expense | Note 5. Stock-Based Compensation Expense (a) General Stock-based compensation expense for restricted stock, restricted stock units, stock options and issuances of common stock pursuant to our employee stock purchase plan was classified in the accompanying consolidated statements of operations as follows: Three Months Six Months Ended 2016 2015 2016 2015 (in thousands) Stock-based compensation expense: Cost of revenue $ 142 $ 52 $ 279 $ 101 Research and development 1,524 266 3,017 410 Sales and marketing 1,224 195 4,125 310 General and administrative 751 318 1,739 585 Total stock-based compensation expense $ 3,641 $ 831 $ 9,160 $ 1,406 We recognize compensation cost of all awards on a straight-line basis over the applicable vesting period, which is generally four years. (b) Restricted Stock and Restricted Stock Units Restricted stock and restricted stock unit activity during the six months ended June 30, 2016 was as follows: Restricted Weighted Outstanding as of December 31, 2015 1,149,257 $ 19.34 Granted 697,537 12.94 Vested (359,401 ) 20.42 Forfeited (56,472 ) 14.13 Outstanding as of June 30, 2016 1,430,921 $ 16.15 As of June 30, 2016, the unrecognized compensation expense related to our unvested restricted stock and restricted stock units expected to vest was $16.6 million. This unrecognized compensation expense will be recognized over an estimated weighted-average amortization period of 2.7 years. During the three months ended June 30, 2016, we repurchased 47,003 shares of our common stock in settlement of employee tax withholding obligations due upon the vesting of restricted stock. (c) Stock Options Stock option activity during the six months ended June 30, 2016 was as follows: Shares Weighted Weighted Aggregate Outstanding as of December 31, 2015 4,246,525 $ 5.99 Granted 1,138,576 13.02 Exercised (335,368 ) 4.53 Forfeited/cancelled (283,413 ) 10.10 Outstanding as of June 30, 2016 4,766,320 7.53 7.5 $ 25,351 Vested and exercisable as of June 30, 2016 2,804,883 4.85 6.6 $ 21,785 Vested and expected to vest as of June 30, 2016 4,382,101 7.12 7.4 $ 24,942 As of June 30, 2016, the unrecognized compensation expense related to our unvested stock options expected to vest was $7.7 million. This unrecognized compensation expense will be recognized over an estimated weighted-average amortization period of 2.8 years. The total fair value of stock options vested in the six months ended June 30, 2016 was $1.6 million. The weighted-average grant date fair value of stock options granted in the six months ended June 30, 2016 was $6.19 per share. (d) Employee Stock Purchase Plan Under the 2015 Employee Stock Purchase Plan (ESPP), employees may set aside up to 15% of their gross earnings, on an after-tax basis, to purchase our common shares at a discounted price, which is calculated at 85% of the lesser of: (i) the market value of our common stock at the beginning of each offering period and (ii) the market value of our common stock on the applicable purchase date. On March 15, 2016, we issued 192,676 shares of common stock to employees for aggregate proceeds of $2.1 million. The purchase price of the shares of common stock was $10.88 per share, which was discounted in accordance with the terms of the ESPP from the closing price of our common stock on March 15, 2016 of $12.80. |