$46.96. As of December 31, 2014, total unrecognized compensation cost related to non-vested stock-based
compensation plans was $21.3 million. We will adjust the total unrecognized compensation cost for future
changes in estimated forfeitures. We expect to recognize this cost over a weighted average period of 1.1 years.
Restricted Stock Unit Activity
The following table summarizes the RSU activity for the year ended December 31, 2014 (in thousands,
except per share data):
Number of
Shares
Weighted
Average
Grant Date
Fair Value
Per Share
Non-vested at December 31, 2013. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
425
$13.67
Granted . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
349
$44.94
Vested . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(117)
$13.74
Cancelled/forfeited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(19)
$22.41
Non-vested at December 31, 2014. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
638
$30.52
For the years ended December 31, 2014, 2013 and 2012, the weighted-average grant date fair value of
RSUs granted was $44.94, $17.42 and $8.36 per RSU, respectively. As of December 31, 2014, total
unrecognized compensation cost related to RSUs was $9.8 million. We will adjust the total unrecognized
compensation cost for future changes in estimated forfeitures. We expect to recognize this cost over a weighted
average period of 1.4 years.
Stock-basedValuation and Compensation Expense Information
The following table summarizes stock-based compensation expense for the years ended December 31, 2014,
2013 and 2012 (in thousands), which was allocated as follows:
Year Ended December 31,
2014
2013 2012
Research, development and patents . . . . . . . . . . . . . . . . . . . . . . . . . . $25,843 $ 9,673 $7,246
General and administrative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5,540 1,745 1,325
Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $31,383 $11,418 $8,571
Determining Fair Value
Valuation.
We measure stock-based compensation expense for equity-classified awards, principally related to
stock options, RSUs, and stock purchase rights under the ESPP at the grant date, based on the estimated fair
value of the award and we recognize the expense over the employee’s requisite service period. We value RSUs
based on the market price of our common stock on the date of grant.
We use the Black-Scholes model to estimate the fair value of stock options granted and stock purchase
rights under our ESPP. The expected term of stock options granted represents the period of time that we expect
them to be outstanding. We estimate the expected term of options granted based on actual and projected exercise
patterns. We recognize compensation expense for stock options granted, RSUs, and stock purchase rights under
the ESPP using the accelerated multiple-option approach. Under the accelerated multiple-option approach (also
known as the graded-vesting method), an entity recognizes compensation expense over the requisite service
period for each separately vesting tranche of the award as though the award were in substance multiple awards,
which results in the expense being front-loaded over the vesting period.
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