v3.8.0.1

Note 12 - Stock-based Compensation | 12 Months Ended
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Dec. 31, 2017
Notes to Financial Statements |
Disclosure of Compensation Related Costs, Share-based Payments [Text Block] | 12. Stock-Based Compensation The Company recorded total stock-based compensation expense for stock options, stock awards and the ESPP as follows (in thousands):
|  | December 31, 201 7 |  |  | December 31, 201 6 |  |  | December 31, 201 5 |
Cost of goods sold |  | $ | 324 |  |  | $ | 302 |  |  | $ | 67 |
Research and development |  |  | 1,901 |  |  |  | 2,308 |  |  |  | 2,587 |
General and administrative |  |  | 2,069 |  |  |  | 1,869 |  |  |  | 2,356 |
Total |  | $ | 4,294 |  |  | $ | 4,479 |  |  | $ | 5,010 |
The following table summarizes option activity under the 2011 Plan and 2006 Plan:
|  | Number of Stock Options Outstanding |  |  | Weighted- Average Exercise Price |  |  | Weighted- Average Remaining Contractual Life (Years) |  |  | Aggregate Intrinsic Value |
|  |  |  |  |  |  |  |  |  |  |  |  |  | (in thousands) |
December 31, 2016 |  |  | 6,307,756 |  |  | $ | 5.00 |  |  |  |  |  |  |  |  |
Granted |  |  | 3,007,155 |  |  |  | 2.99 |  |  |  |  |  |  |  |  |
Forfeited |  |  | (438,519 | ) |  |  | 4.28 |  |  |  |  |  |  |  |  |
Expired |  |  | (351,922 | ) |  |  | 7.31 |  |  |  |  |  |  |  |  |
Exercised |  |  | (69,372 | ) |  |  | 1.52 |  |  |  |  |  |  |  |  |
December 31, 2017 |  |  | 8,455,098 |  |  | $ | 4.25 |  |  |  | 7.1 |  |  | $ | 13 |
Vested and exercisable options —December 31, 2017 |  |  | 4,529,174 |  |  | $ | 5.11 |  |  |  | 5.56 |  |  | $ | 13 |
Vested and expected to vest —December 31, 2017 |  |  | 8,455,098 |  |  | $ | 4.25 |  |  |  | 7.1 |  |  | $ | 13 |
As of December 31, 2017, there were 2,368,992 shares available for future grant under the 2011 Plan. In January 2018, an additional 2,035,966 shares were authorized for issuance under the 2011 Incentive Plan. Additional information regarding the Company ’s stock options outstanding and vested and exercisable as of December 31, 2017 is summarized below:
|  |  |  | Options Outstanding |  |  | Options Vested and Exercisable |
Exercise Prices |  | Number of Stock Options Outstanding |  |  | Weighted-Average Remaining Contractual Life (Years) |  |  | Weighted-Average Exercise Price per Share |  |  | Shares Subject to Stock Options |  |  | Weighted-Average Exercise Price per Share |
$1.20 | - | $2. 30 |  |  | 105,900 |  |  |  | 8.4 |  |  | $ | 2.13 |  |  |  | 38,400 |  |  | $ | 1.84 |
$2. 40 | - | $3.77 |  |  | 5,592,633 |  |  |  | 7.7 |  |  | $ | 3.10 |  |  |  | 1,948,300 |  |  | $ | 3.17 |
$ 3.92 | - | $6.60 |  |  | 2,060,565 |  |  |  | 5.7 |  |  | $ | 5.45 |  |  |  | 1,880,190 |  |  | $ | 5.36 |
$8.18 | - | $10.55 |  |  | 696,000 |  |  |  | 6.2 |  |  | $ | 10.28 |  |  |  | 662,284 |  |  | $ | 10.28 |
|  |  |  |  | 8,455,098 |  |  |  | 7.1 |  |  | $ | 4.25 |  |  |  | 4,529,174 |  |  | $ | 5.11 |
The weighted average grant-date fair value of options granted during the years ended December 31, 2017, 2016 and 2015 was $1.91, $2.24 and $2.69 per share, respectively. As of December 31, 2017, total stock-based compensation expense related to unvested options to be recognized in future periods was $7.1 million which is expected to be recognized over a weighted-average period of 2.6 years. The grant date fair value of shares vested during the years ended December 31, 2017, 2016 and 2015 was $3.5 million, $3.9 million and $5.4 million, respectively. The total intrinsic value of options exercised during the year ended December 31, 2017 was $40 thousand. There were no option exercises during the year ended December 31, 2016, and the total intrinsic value of options exercised during the year ended December 31, 2015 was $1.3 million. The Company used the following assumptions to calculate the fair value of each employee stock option:
|  | Year Ended December 31, |
|  | 201 7 |  |  | 201 6 |  |  | 201 5 |
Expected term (in years) |  | 5.70 |  |  | 5.25 | - | 6.25 |  |  | 5.25 | - | 6.25 |
Risk-free interest rate |  | 1.82% | - | 2.09% |  |  | 1.24% | - | 1.47% |  |  | 1.35% | - | 1.82% |
Expected volatility |  | 73% |  |  | 80% |  |  | 72% |
Expected dividend rate |  | 0% |  |  | 0% |  |  | 0% |

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- Definition The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -URI http://asc.fasb.org/topic&trid=2228938 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 50 -URI http://asc.fasb.org/subtopic&trid=2208855 + Details
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