14. Stock incentive plans

In March 2011, our board of directors approved the 2011 Plan. The 2011 Plan provides for the grant of incentive and nonstatutory stock options, stock appreciation rights, restricted shares of our common stock, stock units, and performance cash awards. As of January 1^st 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, 2013, 7,108,013 shares of common stock are reserved for issuance. As of December 31, 2013, options to purchase 5,026,486 shares of common stock and 799,289 RSUs have been granted under the 2011 Plan.

No further awards will be made under our 2001 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, 2013, options to purchase 1,858,543 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 2013, 2012 and 2011:

	Years ended December 31,

	2013		2012		2011
Network operations	$	888	$	352	$	463
Development and technology		380		352		577
Selling and marketing		1,045		571		650
General and administrative		2,193		1,460		1,733


Total stock-based compensation expense	$	4,506	$	2,735	$	3,423

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 2013, 2012 and 2011 is presented below:

			Weighted Average Exercise Price			Aggregate Intrinsic Value

Outstanding at December 31, 2010	5,288		$	1.25	6.3	$	38,279
Granted	2,381		$	13.02
Exercised	(1,015	)	$	1.01
Canceled/forfeited	(53	)	$	6.58


Outstanding at December 31, 2011	6,601		$	5.50	7.0	$	30,996
Granted	1,391		$	8.29
Exercised	(1,899	)	$	1.36
Canceled/forfeited	(1,048	)	$	11.85


Outstanding at December 31, 2012	5,045		$	6.50	6.4	$	14,742
Granted	1,351		$	6.73
Exercised	(461	)	$	1.33
Canceled/forfeited	(980	)	$	10.20


Outstanding at December 31, 2013	4,955		$	6.31	6.6	$	9,535




Vested, exercisable and expected to vest at December 31, 2013	4,788		$	6.25	6.5	$	9,520
Exercisable at December 31, 2013	2,739		$	4.52	4.8	$	9,329

The aggregate intrinsic value in the table above represents the difference between the estimated fair value of our common stock at December 31, 2013 and the option exercise price, multiplied by the number of in-the-money options at December 31, 2013. The intrinsic value changes are based on the estimated fair value of our common stock.

Stock options to purchase 461,000, 1,899,000 and 1,015,000 shares of our common stock were exercised during the years ended December 31, 2013, 2012 and 2011 for cash proceeds of $614, $2,573 and $1,028, respectively. The total intrinsic value of stock options exercised for the years ended December 31, 2013, 2012 and 2011 was $2,662, $14,901 and $9,754, respectively. We realized $55, $2,190 and $246 of tax benefits for the deductions from stock option exercises during 2013, 2012 and 2011, respectively.

The weighted average grant date fair value of options granted for the years ended December 31, 2013, 2012 and 2011 was $6.60, $8.10 and $6.68, respectively.

At December 31, 2013, the total remaining stock-based compensation expense for unvested stock option awards is $7,345, which is expected to be recognized over a weighted average period of 2.95 years.

Restricted stock unit awards

During the year ended December 31, 2013, we issued RSUs to executive and non-executive personnel and members of our board of directors. The executive and non-executive RSUs generally vest over a two year period with 50% of the RSUs vesting when the individual completes 12 months of continuous service and the remaining 50% vesting on a quarterly basis thereafter. The board of directors RSUs generally vests over a one year period for existing members and 25% per year over a four year period for new members. A summary of the RSU activity in 2013 is as follows:

			Weighted Average Grant Date Fair Value

Nonvested at December 31, 2012	—		$	—
Granted	799		$	6.21
Vested	(6	)	$	6.39
Canceled/forfeited	(40	)	$	6.05


Nonvested at December 31, 2013	753		$	6.22

The RSUs that vested during the year ended December 31, 2013 resulted from the accelerated vesting for an employee that retired during 2013. At December 31, 2013, the total remaining stock-based compensation expense for unvested RSU awards is $2,750, which is expected to be recognized over a weighted average period of 1.4 years.