Share-based compensation (Tables)
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12 Months Ended |
Dec. 31, 2018 |
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| Summary of vesting information |
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Options granted in 2009:
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100% on the third anniversary of the grant date
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Options granted in 2011, 2012, 2013 and April 2014:
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25% on the first anniversary of the grant date and 75% in annual installments over the following three years
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Options granted in December 2014:
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25% on the first anniversary of the grant date and 75% in monthly installments over the following three years
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| Summary of share-based compensation expense included in the unaudited consolidated statements of operations |
The following table shows the total share-based compensation expense included in the consolidated statement of operations (thousands):
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Year ended
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December 31,
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2018
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2017
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2016
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Research and development
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$
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8,340
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5,268
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$
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4,185
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General and administrative
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7,862
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5,536
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4,636
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$
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16,202
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10,804
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$
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8,821
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| Summary of all stock option activity |
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Weighted
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Average
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average
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remaining
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Aggregate
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exercise price
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contractual
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intrinsic value
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Options
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per option
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term (years)
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(thousands)
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Outstanding at January 1, 2018
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74,943,667
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£
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0.58
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Changes during the period:
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Granted
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20,771,970
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£
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0.63
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Exercised
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(5,334,936)
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£
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0.42
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Forfeited
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(2,815,982)
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£
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0.80
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Outstanding at December 31, 2018
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87,564,719
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£
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0.60
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7.6
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$
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25,905
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Exercisable at December 31, 2018
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47,678,481
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£
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0.55
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6.7
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$
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15,207
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| Summary of information about stock options outstanding |
The following table summarizes information about stock options outstanding as of December 31, 2018:
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Outstanding
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Exercisable
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Weighted-
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average
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Weighted-
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Weighted-
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Total share
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remaining
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average
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Total share
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average
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Exercise price
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options
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contractual life
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exercise price
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options
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exercise price
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£
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0
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8,099,412
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9.2
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£
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0.00
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—
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£
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—
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0.01 - 0.25
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7,268,412
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4.9
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0.12
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7,268,412
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0.12
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0.26 - 0.50
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16,714,988
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6.1
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0.43
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16,156,497
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0.42
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0.51 - 0.75
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28,617,051
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8.2
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0.61
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13,465,614
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0.61
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0.76 - 1.00
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22,317,845
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8.0
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0.93
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9,323,729
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0.90
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1.01 - 1.50
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2,751,818
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8.5
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1.18
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934,295
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1.04
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1.51 - 2.00
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1,795,243
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8.6
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1.71
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529,934
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1.82
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Total
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87,564,769
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7.6
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£
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0.60
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47,678,481
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£
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0.55
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| Summary of the assumptions used to estimate the fair values of the share options granted using the Black-Scholes option-pricing model |
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Year ended
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Year ended
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Year ended
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December 31,
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December 31,
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December 31,
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2018
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2017
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2016
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Expected term (years)
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5 years
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5 years
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5 years
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Expected volatility
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66 - 69%
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66 - 71%
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68 - 73%
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Risk free rate
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0.90 - 1.15%
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0.40 - 0.76%
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0.17 - 1.07%
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Expected dividend yield
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0%
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0%
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0%
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| Non-executive director |
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| Summary of vesting information |
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Options granted to non-executive directors on May 11, 2015:
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Immediately on grant date
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Options granted to a non-executive director on June 23, 2016:
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25% on the first anniversary of the grant date and 75% in monthly installments over the following two years
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Options granted to non-executive directors on August 11, 2016:
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100% on the first anniversary of the grant date
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Options granted to non-executive directors on November 28, 2016:
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25% on the first anniversary of the grant date and 75% in monthly installments over the following two years
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Options granted to non-executive directors on July 3, 2017
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100% on the first anniversary of the grant date
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Options granted to non-executive directors on June 22, 2018:
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100% on the first anniversary of the grant date
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Options granted to a non-executive director on July 5, 2018:
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25% on the first anniversary of the grant date and 75% in monthly instalments over the following two years
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