Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

Equity (Tables)

v3.10.0.1
Equity (Tables)
6 Months Ended
Jun. 30, 2018
Equity [Abstract]  
Summary of Stock Option Activity
A summary of the stock option activity under the Company’s plans for the six months ended June 30, 2018 is as follows:
 
 
 
Number of
shares
 
Weighted average price
Options outstanding at December 31, 2017
 
6,342,526

 
$
6.51

Options granted
 
2,168,602

 
$
8.34

Less:
 
 
 
 
Options exercised
 
1,030,576

 
$
5.53

Options canceled or expired
 
25,498

 
$
8.72

Options outstanding at June 30, 2018
 
7,455,054

 
$
7.18

Exercisable at June 30, 2018
 
2,958,222

 
$
6.14

Summary of Fair Value of Each Stock Option Award Granted
The fair value of each stock option award granted during the six months ended June 30, 2018 was estimated as of the grant date using a trinomial lattice model with the following weighted average assumptions:
 
Six Months Ended
June 30, 2018
Expected term (in years)
2.0 - 4.0
Risk-free interest rate (%)
2.4%
Expected volatility (%)
35.6% - 45.5%
Dividend yield (%)
Weighted average fair value/share at grant date
$2.61
Summary of Restricted Stock Activity
A summary of the restricted stock activity under the Company’s plans for the six months ended June 30, 2018 is as follows:
 
 
 
Number of
shares
 
Weighted average price
Nonvested at December 31, 2017
 
327,211

 
$
7.27

Granted
 
41,382

 
$
11.60

Vested
 
(119,180
)
 
7.27

Nonvested at June 30, 2018
 
249,413

 
$
7.99

Summary of Stock-Based Compensation Expense Recognized for Stock Options and Restricted Stock Included in Consolidated Statements of Operations
Stock based compensation expense recognized for stock options and restricted stock and included in the consolidated statements of operations was allocated as follows (in thousands): 
 
 
Three Months Ended June 30,
 
Six Months Ended June 30,
 
 
2018
 
2017
 
2018
 
2017
Research and development expense
 
$
251

 
$
285

 
$
269

 
$
327

General and administrative expense
 
2,082

 
1,637

 
3,688

 
2,725

Total stock based compensation expense
 
$
2,333

 
$
1,922

 
$
3,957

 
$
3,052