Quarterly report pursuant to Section 13 or 15(d)

Stock Plans (Tables)

v3.5.0.2
Stock Plans (Tables)
 6 Months Ended
Jun. 30, 2016
Stock Plans [Abstract]  
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]
The following table summarizes the stock-based compensation expense recorded for awards under the stock option plans for the three and six month periods ended June 30, 2016 and 2015:
 
 
 
Three Months Ended
June 30,
 
Six Months Ended
June 30,
 
(in thousands, except per share amounts)
 
2016
 
2015
 
2016
 
2015
 
Research and development
 
$
85
 
$
35
 
$
217
 
$
238
 
General and administrative
 
 
164
 
 
41
 
 
364
 
 
329
 
Total stock-based compensation expenses
 
$
249
 
$
76
 
$
581
 
$
567
 
Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block]
We use the Black-Scholes-Merton option-pricing model with the following assumptions to estimate the stock-based compensation expense for the three and six month periods ended June 30, 2016 and 2015:
 
 
 
Three Months Ended
June 30,
 
Six Months Ended
June 30,
 
 
 
2016
 
2015
 
2016
 
2015
 
Weighted-average risk-free interest rate
 
 
1.5
%
 
1.7
%
 
1.5
%
 
1.8
%
Expected dividend payments
 
 
—
 
 
—
 
 
—
 
 
—
 
Expected holding period (years) 1
 
 
6.5
 
 
4.5
 
 
6.5
 
 
6.4
 
Weighted-average volatility factor 2
 
 
0.92
 
 
1.65
 
 
0.92
 
 
1.61
 
Estimated forfeiture rates 3
 
 
29
%
 
30
%
 
29
%
 
30
%
 
(1)
Expected holding period is based on historical experience of similar awards, giving consideration to the contractual terms of the stock-based awards, vesting schedules and the expectations of future employee behavior.
(2)
Weighted average volatility is based on the historical volatility of our common stock.
(3)
Estimated forfeiture rates are based on historical data.
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]
The following table summarizes option activity for the six month period ended June 30, 2016:
 
(in thousands, except per share amounts)
 
Options
 
Weighted
Average
Exercise
Price
 
Weighted
Average
Remaining
Option
Term
 
Aggregate
Intrinsic
Value
 
Outstanding at January 1, 2016
 
 
1,883
 
$
5.83
 
 
5.14
 
$
388
 
Granted
 
 
168
 
 
5.10
 
 
 
 
 
 
 
Exercised
 
 
(8)
 
 
3.37
 
 
 
 
 
 
 
Expired or cancelled
 
 
(17)
 
 
7.70
 
 
 
 
 
 
 
Forfeited
 
 
—
 
 
—
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Outstanding at June 30, 2016
 
 
2,026
 
$
5.76
 
 
6.12
 
$
1,346
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Exercisable at June 30, 2016
 
 
1,594
 
$
5.94
 
 
5.20
 
$
1,186