Stock-Based Compensation
 9 Months Ended
Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]  
Stock-Based Compensation
Stock-Based Compensation
The Company’s stock option awards activity and related information for the nine months ended September 30, 2016 were as follows (in thousands, except share and per share data):
 
 
 
 
 
 
 
Weighted-avg.
 
 
 
 Shares
 
 
 
 Weighted-avg.
 
Remaining
 
Aggregate
 
 Available
 
 Stock Options
 
 Exercise Price
 
Contractual
 
Intrinsic
 
 for Grant
 
 Outstanding
 
 Per Share
 
Life (in Years)
 
Value
 
 
 
 
 
 
 
 
 
 
 Balance at December 31, 2015
1,299,301

 
2,429,511

 
$
7.00

 
8.01
 
$
287

 Additional shares authorized
1,400,000

 
—

 
 
 
 
 
 
 Stock options granted
(1,537,000
)
 
1,537,000

 
$
2.94

 
 
 
 
 Stock options canceled
354,951

 
(354,951
)
 
$
7.00

 
 
 
 
 Stock options exercised
—

 
(23,938
)
 
$
1.09

 
 
 
 
 Balance at September 30, 2016
1,517,252

 
3,587,622

 
$
5.30

 
7.88
 
$
230

 
 
 
 
 
 
 
 
 
 
At September 30, 2016:
 
 
 
 
 
 
 
 
 
    Vested and expected to vest
 
 
3,474,777

 
$
5.36

 
7.84
 
$
228

    Exercisable
 
 
1,532,114

 
$
7.16

 
6.48
 
$
187


The aggregate intrinsic value of options exercised under all option plans was $42,000 for the nine months ended September 30, 2016 determined as of the date of option exercise. No options were exercised during the nine months ended September 30, 2015.
The Company recognized stock-based compensation expense within the condensed consolidated statements of operations and comprehensive loss as follows (in thousands):
 
Three Months Ended
September 30,
 
Nine Months Ended
September 30,
 
2016
 
2015
 
2016
 
2015
Research and development
$
139

 
$
192

 
$
516

 
$
456

General and administrative
864

 
766

 
2,652

 
2,404

Total
$
1,003

 
$
958

 
$
3,168

 
$
2,860

At September 30, 2016, there were 111,000 unvested options outstanding with performance conditions related to the achievement of certain clinical milestones. During the three and nine months ended September 30, 2016, stock-based compensation expense recorded for theses performance-based options was insignificant to the interim condensed consolidated financial statements.
In April 2016, the Company’s board of directors approved an amendment and restatement of the Company’s Fourth Amended and Restated 2011 Stock Option and Incentive Plan (the “2011 Plan”) to, among other things, increase the maximum number of shares that may be issued under the 2011 Plan from 3,602,328 to 5,002,328 shares. The amendment and restatement of the 2011 Plan was approved by the Company’s stockholders on June 14, 2016.
As of September 30, 2016, there was unrecognized stock-based compensation expense of $6.2 million related to stock options. The Company expects to recognize those costs over a weighted average period of 2.16 years.
Stock-based compensation expense for stock options is estimated at the grant date based on the fair value using the Black-Scholes option pricing model. The fair value of employee stock options is being amortized on a straight-line basis over the requisite service period of the awards. The fair value of all stock options granted was estimated using the following ranges of weighted-average assumptions:


Three Months Ended
September 30,

Nine Months Ended
September 30,


2016

2015

2016

2015
Expected dividend yield

—

—

—

—
Risk-free interest rates

0.59% - 1.39%

1.59% - 1.64%

0.59% - 1.97%

1.52% - 2.08%
Expected term in years

0.95 - 4.43

5.52 - 6.08

0.95 - 8.14

5.49 - 8.06
Expected volatility

73% - 87%

78% - 80%

73% - 94%

78% - 92%

On January 6, 2016, the Company granted certain of its executive officers non-qualified stock options to purchase 206,625 shares of the Company’s common stock that vest on a monthly basis in equal installments over 48 months following the grant date if the Company's stock price equals or exceeds $6.00 for 20 consecutive trading days on or before June 30, 2017. The options expire ten years from the date of the grant.
The fair values of these options were determined using a Monte Carlo simulation model incorporating the following ranges of weighted-average assumptions:
 
 
Nine Months Ended
September 30, 2016
Expected dividend yield

—
Risk-free interest rates

1.82% - 2.05%
Expected term in years

6.02 - 8.00
Expected volatility

77% - 89%
Weighted-average fair value per share

1.33 - 1.42

The estimated expense for these awards is being recognized on an accelerated basis over the estimated requisite service period, with no adjustments in the future periods based upon the Company's actual common stock price. The Company recorded $0.1 million in stock-based compensation expense during the nine months ended September 30, 2016 in connection with such awards. Stock-based compensation expense related to these awards was insignificant during the three months ended September 30, 2016.