Stock-based Compensation (Tables)
|
6 Months Ended |
Jun. 30, 2015 |
|---|
| Stock-based Compensation [Abstract] |
|
| Weighted average assumptions |
The fair value of the stock options granted during the three and six months ended June 30, 2015 and 2014, was estimated based on the following weighted average assumptions:
| |
|
Three Months Ended June 30, |
|
|
Six Months Ended June 30, |
|
| |
|
2015 |
|
|
2014 |
|
|
2015 |
|
|
2014 |
|
Dividend yield |
|
|
0 |
% |
|
|
0 |
% |
|
|
0 |
% |
|
|
0 |
% |
Expected volatility |
|
|
81 |
% |
|
|
91 |
% |
|
|
82 |
% |
|
|
93 |
% |
Risk-free interest rate |
|
|
1.65 |
% |
|
|
1.68 |
% |
|
|
1.40 |
% |
|
|
1.71 |
% |
Expected term |
|
5.6 years |
|
|
5.6 years |
|
|
5.6 years |
|
|
5.6 years |
|
|
| Stock option activity |
Stock option activity for the six months ended June 30, 2015, was as follows:
| |
|
Options |
|
|
Weighted Average Exercise Price Per Share |
|
|
Weighted Average Remaining Contractual Life
(in years) |
|
|
Aggregate
Intrinsic
Value
(in thousands)
|
|
Outstanding at January 1, 2015 |
|
|
7,702,309 |
|
|
$ |
8.15 |
|
|
|
|
|
|
|
Granted |
|
|
1,636,639 |
|
|
|
3.74 |
|
|
|
|
|
|
|
Exercised |
|
|
(104,438 |
) |
|
|
1.54 |
|
|
|
|
|
|
|
Forfeited, expired or cancelled |
|
|
(771,854 |
) |
|
|
21.84 |
|
|
|
|
|
|
|
Outstanding at June 30, 2015 |
|
|
8,462,656 |
|
|
$ |
6.13 |
|
|
|
7.24 |
|
|
$ |
4,107 |
|
Vested and expected to vest at June 30, 2015 |
|
|
8,118,591 |
|
|
$ |
6.20 |
|
|
|
7.16 |
|
|
$ |
4,054 |
|
Exercisable at June 30, 2015 |
|
|
5,172,965 |
|
|
$ |
7.15 |
|
|
|
6.20 |
|
|
$ |
3,179 |
|
|
| Unvested RSU activity |
Unvested RSU activity for the six months ended June 30, 2015, is summarized below:
| |
|
Number of
Shares
|
|
|
Weighted-
Average Grant-
Date Fair Value
|
|
Unvested balance at January 1, 2015 |
|
|
1,953,879 |
|
|
$ |
5.46 |
|
Granted |
|
|
1,586,017 |
|
|
|
3.78 |
|
Vested |
|
|
(881,832 |
) |
|
|
4.86 |
|
Forfeited |
|
|
139,308 |
|
|
|
4.54 |
|
Unvested balance at June 30, 2015 |
|
|
2,797,372 |
|
|
$ |
4.65 |
|
|
| Stock-based compensation expense |
The following table shows total stock-based compensation expense included in the condensed consolidated statements of comprehensive loss for the three and six months ended June 30, 2015 and 2014 (in thousands):
| |
|
Three Months Ended June 30 |
|
|
Six Months Ended June 30, |
|
| |
|
2015 |
|
|
2014 |
|
|
2015 |
|
|
2014 |
|
Research and development |
|
$ |
1,399 |
|
|
$ |
953 |
|
|
$ |
3,595 |
|
|
$ |
3,359 |
|
Selling, general and administrative |
|
|
1,290 |
|
|
|
1,471 |
|
|
|
2,759 |
|
|
|
2,989 |
|
Total stock-based compensation expense |
|
$ |
2,689 |
|
|
$ |
2,424 |
|
|
$ |
6,354 |
|
|
$ |
6,348 |
|
|