Stockholders' Equity (Tables)

The following table presents the amount of stock-based compensation related to stock-based awards to employees on the Company’s consolidated statements of operations during the periods presented (in thousands):



	Year Ended April 30,
	2016		2015		2014
Cost of revenue	$	2,167	$	1,517	$	1,155
Sales and marketing	2,956		3,923		4,496
Research and development	2,671		1,960		2,176
General and administrative	6,967		4,677		5,357
Loss from discontinued operations, net of tax	—		124		643
Stock-based expense	14,761		12,201		13,827
Capitalized stock-based compensation	813		601		641
Total stock-based compensation	15,574		12,802		14,468

Stock option activity was as follows:



	Number of Options (in thousands)		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Balance as of April 30, 2014	7,091		7.74
Options granted	939		7.31
Options exercised	(1,246	)	4.18
Options forfeited	(877	)	8.98
Options expired	(814	)	10.78
Balance as of April 30, 2015	5,093		$	7.83	7.00	$	1,590
Options granted	2,947		4.83
Options exercised	(227	)	3.95
Options forfeited	(484	)	7.42
Options expired	(641	)	8.14
Balance as of April 30, 2016	6,688		$	6.64	6.43	$	591
Options vested and expected to vest at April 30, 2016	6,666		$	6.64	6.43	$	591
Options vested and exercisable as of April 30, 2016	3,004		$	8.04	4.58	$	373

The summary of stock options as of April 30, 2016 is as follows (number of options in thousands):



	Options Outstanding				Options Exercisable
Range of Exercise Prices	Number of Options	Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)	Number of Options	Weighted Average Exercise Price
$0.16 - $3.03	392,937	$	2.35	3.23	332,937	$	2.23
$3.15 - $3.15	990,000	3.15		6.84	—	—
$3.42 - $4.86	734,387	4.36		7.23	254,387	4.69
$4.87 - $6.28	261,911	5.49		8.49	112,327	5.44
$6.42 - $6.42	1,196,400	6.42		8.77	—	—
$6.54 - $7.36	788,373	6.96		7.34	523,263	6.89
$7.39 - $7.53	756,475	7.47		4.27	489,204	7.46
$7.60 - $9.51	892,709	9.18		6.78	635,401	9.21
$9.52 - 15.12	639,808	12.60		2.61	621,392	12.61
$18.67 - $18.67	35,200	18.67		5.93	35,200	18.67
$0.16 - $18.67	6,688,200	$	6.64	6.43	3,004,111	$	8.04

Restricted stock activity was as follows (number of restricted shares in thousands):



	Number of Restricted Shares		Weighted Average Grant Date Fair Value
Unvested balance as of April 30, 2014	2,977		$	8.44
Restricted shares granted	2,305		7.66
Restricted shares vested	(715	)	8.74
Restricted shares forfeited	(1,079	)	8.38
Unvested balance as of April 30, 2015	3,488		$	7.88
Restricted shares granted	3,863		5.93
Restricted shares vested	(964	)	7.70
Restricted shares forfeited	(1,420	)	7.16
Unvested balance as of April 30, 2016	4,967		$	6.60

The fair value of the Company’s options was estimated at the date of grant using a Black-Scholes option pricing model with the following assumptions:



	Year Ended April 30,
	2016	2015	2014
Expected volatility	42% - 42%	43% - 50%	53% - 54%
Risk-free interest rate	1.50% - 1.92%	1.46% - 1.93%	1.30% - 2.09%
Expected term (in years)	6.00	6.00	6.00 - 6.25
Dividend yield	—	—	—

The fair value of the Company’s ESPP was estimated at the date of grant using a Black-Scholes option pricing model with the following assumptions:



	Year Ended April 30,
	2016	2015	2014
Expected volatility	30% - 57%	36% - 57%	36% - 43%
Risk-free interest rate	0.10% - 0.46%	0.05% - 0.11%	0.05% - 0.11%
Expected term (in years)	0.5	0.5	0.5
Dividend yield	—	—	—