15. Stock incentive plans

In March 2011, our board of directors approved the 2011 Plan. The 2011 Plan provides for the grant of incentive and non-statutory stock options, stock appreciation rights, restricted shares of our common stock, stock units, and performance cash awards. As of January 1st of each year, the number of shares of common stock reserved for issuance under the 2011 Plan shall automatically be increased by a number equal to the lesser of (a) 4.5% of the total number of shares of common stock then outstanding, (b) 3,000,000 shares of common stock or (c) as determined by our board of directors. As of December 31, 2015, 10,324,899 shares of common stock were reserved for issuance. As of December 31, 2015, options to purchase 5,229,486 shares of common stock and 3,896,251 RSUs have been granted under the 2011 Plan.

At the 2015 Annual Meeting of Stockholders held on June 12, 2015, our stockholders approved the following amendments to our 2011 Equity Incentive Plan: (a) termination of the automatic "evergreen" share reserve increase feature after January 2018, so that no additional automatic annual share increases will occur thereafter; (b) remove the discretion to re-price any stock award; (c) implement more conservative "share counting" provisions, so that the following shares will no longer be available for subsequent issuance: (i) shares applied to pay the exercise price of an option, (ii) shares not otherwise issued in connection with the stock settlement of stock appreciation rights, (iii) shares used to satisfy tax withholding obligations relating to any stock award, and (iv) shares reacquired by us using cash proceeds from the exercise of options; and (d) ensure that certain awards are intended to qualify as performance-based compensation under Section 162(m) of the Internal Revenue Code.

No further awards will be made under our Amended and Restated 2001 Stock Incentive Plan and it will be terminated. Options outstanding under the 2001 Plan will continue to be governed by their existing terms. As of December 31, 2015, options to purchase 1,220,562 shares of common stock were outstanding under the 2001 Plan.

The following table summarizes our stock-based compensation expense included in the consolidated statements of operations for 2015, 2014 and 2013:

	Years ended December 31,
	2015		2014		2013
Network operations	$	1,504	$	1,356	$	888
Development and technology		731		600		380
Selling and marketing		3,411		2,017		1,045
General and administrative		3,752		3,191		2,193

Total stock-based compensation expense	$	9,398	$	7,164	$	4,506

For the year ended December 31, 2015 and 2014, we capitalized $778 and $398, respectively, of stock-based compensation expense.

Stock option awards

We grant stock option awards to both employees and non-employee directors. The grant date for these awards is the same as the measurement date. The stock option awards generally vest over a four year service period with 25% vesting when the individual completes 12 months of continuous service and the remaining 75% vesting monthly thereafter. These awards are valued as of the measurement date and the stock-based compensation expense, net of estimated and actual forfeitures, is recognized on a straight-line basis over the requisite service period. A summary of the activity for stock option awards for 2015 is presented below:

	Number of Options (000's)			Weighted Average Exercise Price		Weighted- Average Remaining Contract Life (years)		Aggregate Intrinsic Value
Outstanding at December 31, 2014		4,341		$	6.60		5.8	$	11,017
Exercised		(440	)	$	3.12
Canceled/forfeited		(153	)	$	9.51

Outstanding at December 31, 2015		3,748		$	6.89		5.0	$	6,611


Vested, exercisable and expected to vest at December 31, 2015		3,728		$	6.89		5.0	$	6,605
Exercisable at December 31, 2015		3,175		$	6.73		4.6	$	6,475

The aggregate intrinsic value in the table above represents the difference between the estimated fair value of our common stock at December 31, 2015 and the option exercise price, multiplied by the number of in-the-money options at December 31, 2015. The intrinsic value changes are based on the estimated fair value of our common stock.

Stock options to purchase approximately 440,000, 458,000 and 461,000 shares of our common stock were exercised during the years ended December 31, 2015, 2014 and 2013 for cash proceeds of $1,373, $1,158 and $614, respectively. The total intrinsic value of stock options exercised for the years ended December 31, 2015, 2014 and 2013 was $2,214, $2,027 and $2,662, respectively. We realized $55 of tax benefits for the deductions from stock option exercises during 2013.

The weighted average grant date fair value of options granted for the years ended December 31, 2014 and 2013 was $2.92 and $3.03, respectively.

At December 31, 2015, the total remaining stock-based compensation expense for unvested stock option awards is $1,564, which is expected to be recognized over a weighted average period of 1.2 years.

Restricted stock unit awards

We grant time-based restricted stock units ("RSU") to executive and non-executive personnel and non-employee directors. The time-based RSUs granted to executive and non-executive personnel generally vest over a two to three year period subject to continuous service on each vesting date. The time-based RSUs for our non-employee directors generally vest over a one year period for existing members and 25% per year over a four-year period for new members subject to continuous service on each vesting date.

We grant performance-based RSUs to executive personnel. These awards vest subject to certain performance objectives based on the Company's annual revenue growth achieved during the specified performance period and certain long-term service conditions. The maximum number of RSUs that may vest is determined based on actual Company achievement with one-third of the performance-based RSUs vesting when the individual completes 12 months of continuous service and the balance vesting over a series of eight successive equal quarterly installments thereafter subject to continuous service on each vesting date. We recognize stock-based compensation expense for performance-based RSUs when we believe that it is probable that the performance objectives will be met. As of December 31, 2015, the performance condition for these performance-based RSUs has been met.

A summary of the RSU activity in 2015 is as follows:

	Number of Shares (000's)			Weighted Average Grant Date Fair Value
Non-vested at December 31, 2014		1,385		$	6.09
Granted		1,472		$	7.55
Vested		(949	)	$	7.69
Canceled/forfeited		(89	)	$	7.14

Non-vested at December 31, 2015		1,819		$	6.39

During the year ended December 31, 2015, 949,254 shares of time-based RSUs vested. The Company issued 618,238 shares and the remaining shares were withheld to pay minimum statutory federal, state, and local employment payroll taxes on those vested awards.

At December 31, 2015, the total remaining stock-based compensation expense for unvested RSU awards is $9,510, which is expected to be recognized over a weighted average period of 1.95 years.