Common Stock (Tables)
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12 Months Ended |
Dec. 31, 2015 |
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| Equity [Abstract] |
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| Schedule of Common Stock |
Gross proceeds of $24.0 million and underwriting discounts and commissions and offering expenses of $1.6 million were allocated as follows:
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Series B
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Pre-funded
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Series A
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Series B
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Common
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Common
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Common
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Common
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Stock
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Stock
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Stock
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Stock
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Warrants
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Warrants
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Warrants
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Units Issued
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5,559,866
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1,340,538
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2,779,933
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670,269
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Gross Proceeds (in thousands)
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$
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14,084
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$
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3,387
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$
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5,261
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$
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1,268
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Underwriting discount and offering expense (in thousands)
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$
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885
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$
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213
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$
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428
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$
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103
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| Summary of Fair Value of Option Awards |
The estimated fair value of stock options granted in the respective periods was determined using the Black-Scholes option pricing model using the following weighted average assumptions:
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2015
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2014
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2013
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Risk-free interest rates
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1.76
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%
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1.83
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%
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1.25
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%
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Expected dividend yield
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0
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%
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0
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%
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0
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%
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Expected life
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5.8 years
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5.9 years
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5.8 years
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Expected volatility
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63
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%
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82
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%
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86
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%
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| Summary of Share-Based Compensation Expense |
The results for the periods set forth below included stock-based compensation expense in the following expense categories of the consolidated statements of loss (in thousands):
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Years ended
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December 31,
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2015
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2014
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2013
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Research and development
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$
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1,111
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$
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1,893
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$
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1,296
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General and administrative
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1,217
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1,967
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1,538
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Total stock-based compensation
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$
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2,328
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$
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3,860
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$
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2,834
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| Summary of Stock Options Activity |
Stock option transactions and the number of stock options outstanding are summarized below:
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Number of
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Weighted
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Optioned
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Average
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Common
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Exercise
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Shares
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Price
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Balance, January 1, 2013
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805,281
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$
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11.34
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Granted
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239,282
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11.32
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Expired
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(3,061
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)
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4.11
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Exercised
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(3,475
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)
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3.00
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Forfeited
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(30,536
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)
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13.87
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Balance, December 31, 2013
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1,007,491
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$
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11.39
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Granted
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382,097
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8.97
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Expired
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(12,169
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)
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18.93
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Exercised
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(10,000
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)
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3.00
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Forfeited
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(84,000
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)
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12.14
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Balance, December 31, 2014
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1,283,419
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$
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10.55
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Granted
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502,047
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1.91
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Expired
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(247,766
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)
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2.96
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Exercised
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(5,359
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)
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2.69
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Forfeited
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(53,120
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)
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14.37
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Balance, December 31, 2015
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1,479,221
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$
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8.78
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| Summary of Stock Options Outstanding Regarding Number of Common Shares Issuable upon Exercise of Outstanding Options |
(1) Number of common shares issuable upon exercise of outstanding options:
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Weighted-
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Average
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Remaining
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Weighted-
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Contractual
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Average
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Life
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Exercise Prices
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Number of Options
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Exercise Price
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(in years)
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$1.16 - $1.54
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8,750
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$
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1.17
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9.93
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$1.55 - $1.88
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424,797
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1.86
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9.38
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$1.89 - $3.04
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115,500
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2.35
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9.24
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$3.05 - $11.17
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143,879
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5.89
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7.09
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$11.18 - $11.84
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218,147
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11.78
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8.14
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$11.85 - $11.99
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154,251
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11.95
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7.14
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$12.00 - $13.06
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136,325
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12.87
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6.26
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$13.07 - $15.74
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37,676
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14.33
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5.35
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$15.75 - $16.40
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110,250
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15.97
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4.96
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$16.41 - $22.28
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129,646
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20.06
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4.23
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Total
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1,479,221
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$
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8.78
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7.56
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| Summary of Stock Options Outstanding Regarding Number of Common Shares Issuable upon Exercise of Vested Options |
(2) Number common shares issuable upon exercise of vested options:
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Weighted-
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Average
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Remaining
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Weighted-
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Contractual
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Average
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Life
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Exercise Prices
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Number of Options
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Exercise Price
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(in years)
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$1.16 - $1.54
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547
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$
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1.17
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9.93
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$1.55 - $1.88
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96,695
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1.86
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9.38
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$1.89 - $3.04
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19,042
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2.44
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9.05
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$3.05 - $11.17
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99,764
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6.58
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6.50
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$11.18 - $11.84
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107,491
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11.78
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8.07
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$11.85 - $11.99
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113,949
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11.95
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7.12
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$12.00 - $13.06
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134,044
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12.87
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6.26
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$13.07 - $15.74
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35,284
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14.39
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5.25
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$15.75 - $16.40
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110,250
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15.97
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4.96
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$16.41 - $22.28
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129,646
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20.06
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4.23
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Total
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846,712
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$
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11.93
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6.53
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| Summary of Restricted Stock Unit Award Activity |
The following table summarizes our restricted stock unit award activity during the years ended December 31, 2015, 2014 and 2013:
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Weighted
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Number
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Average
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of
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Grant Date
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Shares
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Fair Value
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Balance, January 1, 2013
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172,085
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$
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13.01
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Granted
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255,895
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11.64
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Vested
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(50,773
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)
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12.95
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Forfeited or expired
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(20,618
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)
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12.51
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Balance, December 31, 2013
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356,589
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$
|
12.06
|
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Granted
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814,800
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|
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6.48
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Vested
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(199,887
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)
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7.00
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Forfeited or expired
|
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(291,301
|
)
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10.93
|
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Balance, December 31, 2014
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680,201
|
|
|
$
|
7.34
|
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Granted
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249,775
|
|
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|
1.92
|
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Vested
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(269,401
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)
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8.08
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Forfeited or expired
|
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(19,816
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)
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7.27
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|
Balance, December 31, 2015
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|
640,759
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|
$
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4.92
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| Summary of Outstanding Warrants |
The following is a summary of outstanding warrants to purchase common stock at December 31, 2015:
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Total
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Outstanding
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Exercise
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and
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price per
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Exercisable
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Share
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Expiration Date
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(1) Series A Warrants issued in July 2014 financing
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|
2,779,933
|
|
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|
4.00
|
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|
July 2019
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|
(2) Series B Warrants issued in July 2014 financing
|
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|
670,269
|
|
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|
4.00
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July 2019
|
|
(3) Series A-1 Warrants issued in April 2015 financing
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|
239,234
|
|
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|
2.40
|
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|
October 2020
|
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| Summary of Fair Value of Warrants Issued |
The estimated fair value of warrants issued and classified as liabilities is reassessed at each reporting date using the Black-Scholes option pricing model.
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As of
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December 31,
|
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|
Series A and Series B Warrant Valuation Assumptions
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|
2015
|
|
|
2014
|
|
|
Risk-free interest rates
|
|
|
1.42
|
%
|
|
|
1.51
|
%
|
|
Expected dividend yield
|
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|
0
|
%
|
|
|
0
|
%
|
|
Expected life
|
|
3.50 years
|
|
|
4.50 years
|
|
|
Expected volatility
|
|
|
77
|
%
|
|
|
63
|
%
|
|
| Computation of Basic and Diluted Net Loss Attributable to Common Shareholders Per Share |
The following table presents the computation of basic and diluted net loss attributable to common stockholders per share (in thousands, except per share and share amounts):
|
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|
Years ended December 31,
|
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|
2015
|
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|
2014
|
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2013
|
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|
Numerator
|
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Net loss
|
|
$
|
(16,801
|
)
|
|
$
|
(26,240
|
)
|
|
$
|
(31,849
|
)
|
|
Denominator
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|
|
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|
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Weighted average number of common shares outstanding
|
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|
26,147,344
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|
|
|
18,098,799
|
|
|
|
14,683,389
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|
Basic and diluted net loss per common share
|
|
$
|
(0.64
|
)
|
|
$
|
(1.45
|
)
|
|
$
|
(2.17
|
)
|
|