|
Equity Incentive Plans and Stock Based Compensation (Tables)
|
12 Months Ended |
|
Dec. 31, 2014
|
| Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |
|
| Stock Option Activity Under Equity Incentive Plan |
Activity under the 2004 and 2014 Plans is set forth below:
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Weighted |
|
|
|
|
Shares |
|
|
Outstanding Options |
|
|
Average |
|
|
|
|
Available |
|
|
Number of |
|
|
Exercise |
|
|
Exercise |
|
|
|
|
for Grant |
|
|
Shares |
|
|
Price |
|
|
Price |
|
|
Balances, December 31, 2011 |
|
|
1,077,784 |
|
|
|
3,672,179 |
|
|
$ |
0.42–3.18 |
|
|
$ |
1.45 |
|
|
Additional shares reserved |
|
|
1,250,000 |
|
|
|
— |
|
|
|
|
|
|
|
|
|
|
Options granted |
|
|
(1,844,000 |
) |
|
|
1,844,000 |
|
|
1.38–7.75 |
|
|
|
6.24 |
|
|
Options exercised |
|
|
— |
|
|
|
(402,580 |
) |
|
0.79–3.08 |
|
|
|
1.39 |
|
|
Options canceled |
|
|
14,627 |
|
|
|
(14,627 |
) |
|
0.79–6.18 |
|
|
|
4.25 |
|
|
Balances, December 31, 2012 |
|
|
498,411 |
|
|
|
5,098,972 |
|
|
$ |
0.42–7.75 |
|
|
$ |
3.18 |
|
|
Additional shares reserved |
|
|
1,250,000 |
|
|
|
— |
|
|
|
|
|
|
|
|
|
|
Options granted |
|
|
(1,663,500 |
) |
|
|
1,663,500 |
|
|
4.45–5.58 |
|
|
|
5.10 |
|
|
Options exercised |
|
|
— |
|
|
|
(145,641 |
) |
|
0.79–3.46 |
|
|
|
1.56 |
|
|
Options canceled |
|
|
90,325 |
|
|
|
(90,325 |
) |
|
1.44–7.75 |
|
|
|
6.49 |
|
|
Balances, December 31, 2013 |
|
|
175,236 |
|
|
|
6,526,506 |
|
|
$ |
0.42–7.75 |
|
|
$ |
3.66 |
|
|
Additional shares reserved |
|
|
7,250,000 |
|
|
|
— |
|
|
|
|
|
|
|
|
|
|
Shares expired |
|
|
(1,286,025 |
) |
|
|
— |
|
|
|
|
|
|
|
|
|
|
Options granted |
|
|
(1,895,250 |
) |
|
|
1,895,250 |
|
|
2.91–4.99 |
|
|
|
3.78 |
|
|
Options exercised |
|
|
— |
|
|
|
(73,282 |
) |
|
0.64–4.90 |
|
|
|
1.43 |
|
|
Options canceled |
|
|
179,532 |
|
|
|
(179,532 |
) |
|
1.64–6.18 |
|
|
|
4.63 |
|
|
Balances, December 31, 2014 |
|
|
4,423,493 |
|
|
|
8,168,942 |
|
|
$ |
0.42–7.75 |
|
|
$ |
3.69 |
|
|
| Stock Options Outstanding and Exercisable by Exercise Price |
At December 31, 2014, stock options outstanding and exercisable by exercise price were as follows:
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|
Options Outstanding |
|
|
Options Exercisable |
|
|
Range of
Exercise
Prices |
|
Number
Outstanding |
|
|
Weighted
Average
Remaining
Contractual
Life (Years) |
|
|
Weighted
Average
Exercise
Price |
|
|
Number
Exercisable |
|
|
Weighted
Average
Exercise
Price |
|
|
$0.42-$1.38 |
|
|
544,315 |
|
|
|
3.25 |
|
|
$ |
1.11 |
|
|
|
533,481 |
|
|
$ |
1.11 |
|
|
$1.44-$1.44 |
|
|
1,351,681 |
|
|
|
5.38 |
|
|
$ |
1.44 |
|
|
|
1,351,681 |
|
|
$ |
1.44 |
|
|
$1.49-$3.46 |
|
|
1,509,094 |
|
|
|
6.57 |
|
|
$ |
1.98 |
|
|
|
1,234,515 |
|
|
$ |
1.88 |
|
|
$3.62-$3.62 |
|
|
1,449,916 |
|
|
|
9.36 |
|
|
$ |
3.62 |
|
|
|
265,344 |
|
|
$ |
3.62 |
|
|
$4.14-$5.09 |
|
|
1,752,625 |
|
|
|
8.39 |
|
|
$ |
4.97 |
|
|
|
690,927 |
|
|
$ |
5.04 |
|
|
$5.25-$7.75 |
|
|
1,561,311 |
|
|
|
7.38 |
|
|
$ |
6.80 |
|
|
|
1,095,923 |
|
|
$ |
6.75 |
|
|
$0.42-$7.75 |
|
|
8,168,942 |
|
|
|
7.19 |
|
|
$ |
3.69 |
|
|
|
5,171,871 |
|
|
$ |
3.23 |
|
|
| Stock-Based Compensation Expense |
Stock-based compensation expense, which consists of the compensation cost for employee stock options and ESPP, and the value of options issued to non-employees for services rendered, was allocated to research and development and general and administrative in the consolidated statements of operations as follows (in thousands):
|
|
|
Years Ended December 31, |
|
|
|
|
2014 |
|
|
2013 |
|
|
2012 |
|
|
Stock-based compensation expense: |
|
|
|
|
|
|
|
|
|
|
|
|
|
Research and development |
|
$ |
3,123 |
|
|
$ |
2,562 |
|
|
$ |
1,521 |
|
|
General and administrative |
|
|
2,365 |
|
|
|
2,360 |
|
|
|
1,489 |
|
|
|
|
$ |
5,488 |
|
|
$ |
4,922 |
|
|
$ |
3,010 |
|
|
| Weighted-Average Fair Value Valuation Assumptions |
The fair value of employee stock options and employee purchase rights under the Company’s ESPP was estimated using the following weighted-average assumptions for the years ended December 31, 2014, 2013 and 2012:
|
|
|
Years Ended December 31, |
|
|
|
|
2014 |
|
|
2013 |
|
|
2012 |
|
|
Employee Stock Options |
|
|
|
|
|
|
|
|
|
|
|
|
|
Risk-free interest rate |
|
|
1.83 |
% |
|
|
1.14 |
% |
|
|
1.12 |
% |
|
Expected life (in years) |
|
|
5.98 |
|
|
|
5.97 |
|
|
|
5.99 |
|
|
Dividend yield |
|
|
— |
|
|
|
— |
|
|
|
— |
|
|
Volatility |
|
|
94 |
% |
|
|
101 |
% |
|
|
105 |
% |
|
Weighted-average fair value of stock options granted |
|
$ |
2.89 |
|
|
$ |
4.04 |
|
|
$ |
5.09 |
|
|
Employee Stock Purchase Plan |
|
|
|
|
|
|
|
|
|
|
|
|
|
Risk-free interest rate |
|
|
0.20 |
% |
|
|
0.19 |
% |
|
|
0.21 |
% |
|
Expected life (in years) |
|
|
1.24 |
|
|
|
1.25 |
|
|
|
1.25 |
|
|
Dividend yield |
|
|
— |
|
|
|
— |
|
|
|
— |
|
|
Volatility |
|
|
49 |
% |
|
|
77 |
% |
|
|
111 |
% |
|
Weighted-average fair value of ESPP purchase rights |
|
$ |
1.60 |
|
|
$ |
2.27 |
|
|
$ |
3.46 |
|
|
| Non-employee Stock-based Compensation Expense |
|
| Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |
|
| Weighted-Average Fair Value Valuation Assumptions |
The fair value of the stock options granted were revalued at each reporting date using the Black-Scholes valuation model as prescribed by ASC 505-50 Equity-Based Payments to Non-Employees using the following assumptions:
|
|
|
Years Ended December 31, |
|
|
|
|
2014 |
|
|
2013 |
|
|
2012 |
|
|
Risk-free interest rate |
|
|
2.52 |
% |
|
|
2.51 |
% |
|
|
1.93 |
% |
|
Expected life (in years) |
|
|
10 |
|
|
|
10 |
|
|
|
10 |
|
|
Dividend yield |
|
|
— |
|
|
|
— |
|
|
|
— |
|
|
Expected volatility |
|
|
97 |
% |
|
|
100 |
% |
|
|
101 |
% |
|