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Stock-based Compensation
 9 Months Ended
Oct. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]  
Stock-based Compensation

11. Stock-based Compensation

The following table presents the classification of stock-based compensation for the periods indicated:

 

 

 

Three Months Ended October 31,

 

 

Nine Months Ended October 31,

 

 

 

2018

 

 

2017

 

 

2018

 

 

2017

 

 

 

(in thousands)

 

Stock-based compensation:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Cost of revenue

 

$

310

 

 

$

343

 

 

$

942

 

 

$

978

 

Research and development

 

 

9,720

 

 

 

8,906

 

 

 

27,847

 

 

 

25,532

 

Selling, general and administrative

 

 

5,582

 

 

 

5,419

 

 

 

16,148

 

 

 

15,565

 

Total stock-based compensation

 

$

15,612

 

 

$

14,668

 

 

$

44,937

 

 

$

42,075

 

 

As of October 31, 2018, total unrecognized compensation cost related to unvested stock options was $5.1 million and is expected to be recognized over a weighted-average period of 2.66 years. Total unrecognized compensation cost related to unvested restricted stock units was $112.2 million and is expected to be recognized over a weighted-average period of 2.94 years. Total unrecognized compensation cost related to unvested restricted stock awards was $1.4 million and is expected to be recognized over a weighted-average period of 0.60 years.

The following table sets forth the weighted-average assumptions used to estimate the fair value of stock options and employee stock purchase plan awards for the periods indicated:

 

 

 

Three Months Ended October 31,

 

 

Nine Months Ended October 31,

 

 

 

2018

 

 

2017

 

 

2018

 

 

2017

 

Stock Options:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Volatility

 

 

53

%

 

 

53

%

 

 

54

%

 

 

53

%

Risk-free interest rate

 

 

2.78

%

 

 

1.78

%

 

 

2.75

%

 

 

2.02

%

Expected term (years)

 

5.45

 

 

6.08

 

 

 

5.40

 

 

6.07

 

Dividend yield

 

 

0

%

 

 

0

%

 

 

0

%

 

 

0

%

Employee stock purchase plan awards:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Volatility

 

 

44

%

 

 

50

%

 

 

45

%

 

 

45

%

Risk-free interest rate

 

2.35

 

 

 

1.17

%

 

 

2.15

%

 

 

1.03

%

Expected term (years)

 

0.5

 

 

0.5

 

 

 

0.5

 

 

 

0.5

 

Dividend yield

 

 

0

%

 

 

0

%

 

 

0

%

 

 

0

%

 

Starting from fiscal year 2019, the Company calculates expected volatility for stock options based on its own historical stock price for a period commensurate with the expected term. In the prior fiscal year, the Company calculated expected volatility for stock options based on the weighted average of historical volatilities of its own stock price and the stock prices of similar companies that are publicly available for a period commensurate with the expected term. The Company calculates expected volatility for ESPP based on its own historical stock price for a period commensurate with the offering period.

The following table summarizes stock option activities for the period indicated:

 

 

 

Option Outstanding

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Weighted-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Total Intrinsic

 

 

Average

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Weighted-

 

 

Value Of

 

 

Remaining

 

 

Aggregate

 

 

 

 

 

 

 

Weighted-

 

 

Average

 

 

Options

 

 

Contractual

 

 

Intrinsic

 

 

 

 

 

 

 

Average

 

 

Grant-date

 

 

Exercised

 

 

Term

 

 

Value

 

 

 

Shares

 

 

Exercise Price

 

 

Fair Value

 

 

(in thousands)

 

 

(in years)

 

 

(in thousands)

 

Outstanding at January 31, 2018

 

 

1,611,344

 

 

$

24.56

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Granted

 

 

97,600

 

 

 

42.81

 

 

$

21.83

 

 

 

 

 

 

 

 

 

 

 

 

 

Exercised

 

 

(207,770

)

 

 

5.12

 

 

 

 

 

 

$

8,196

 

 

 

 

 

 

 

 

 

Forfeited

 

 

(16,732

)

 

 

54.28

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Expired

 

 

(9,007

)

 

 

47.55

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Outstanding at October 31, 2018

 

 

1,475,435

 

 

 

28.03

 

 

 

 

 

 

 

 

 

 

4.68

 

 

$

20,331

 

Exercisable at October 31, 2018

 

 

1,254,926

 

 

$

24.13

 

 

 

 

 

 

 

 

 

 

 

3.96

 

 

$

20,327

 

 

The intrinsic value of options outstanding and exercisable is calculated based on the difference between the fair market value of the Company’s ordinary shares on the reporting date and the exercise price. The closing price of the Company’s ordinary shares on October 31, 2018 was $34.78, as reported by The NASDAQ Global Market. The intrinsic value of exercised options is calculated by the difference between the fair market value of the Company’s ordinary shares on the exercise date and the exercise price.

The following table summarizes restricted stock and restricted stock units activities for the period indicated:

 

 

 

 

 

 

 

Weighted-

 

 

 

 

 

 

 

Average

 

 

 

 

 

 

 

Grant-Date

 

 

 

Shares

 

 

Fair Value

 

Unvested at January 31, 2018

 

 

2,103,281

 

 

$

56.45

 

Granted

 

 

1,319,200

 

 

 

39.94

 

Vested

 

 

(742,338

)

 

 

53.25

 

Forfeited

 

 

(35,330

)

 

 

51.72

 

Unvested at October 31, 2018

 

 

2,644,813

 

 

$

49.18

 

 

As of October 31, 2018, the aggregate intrinsic value of unvested restricted stock and restricted stock units was $92.0 million.