Stock Awards

We have a 2005 Stock Option Plan, or 2005 Plan, which provides for grants of stock awards, including options to purchase shares of common stock, stock purchase rights and RSUs to certain employees, officers, directors and consultants. As of December 31, 2013, there were 53,731,033 total shares of common stock authorized for issuance under the 2005 Plan, which includes shares already issued under such plan and shares reserved for issuance pursuant to outstanding options and RSUs.

On April 27, 2012, the board of directors approved the 2012 Equity Incentive Plan, or 2012 Plan and the 2012 Employee Stock Purchase Plan, or the 2012 ESPP, which became effective on June 27, 2012 and June 28, 2012, respectively.

Our 2012 Plan provides for the grant of incentive stock options, nonqualified stock options, stock appreciation rights, RSUs, performance-based stock awards and other forms of equity compensation, or collectively, stock awards. In addition, the 2012 Plan provides for the grant of performance cash awards. Incentive stock options may be granted only to employees. All other awards may be granted to employees, including officers, as well as directors and consultants. The share reserve may increase to the extent that outstanding stock options under the 2005 Plan expire or terminate unexercised. The share reserve also automatically increases on January 1 of each year until January 1, 2022, by up to 5% of the total number of shares of the common stock outstanding on December 31 of the preceding year as determined by the board of directors. As of December 31, 2013, there were 21,767,792 total shares of common stock authorized for issuance under the 2012 Plan, excluding 7,017,730 shares of common stock automatically added to the 2012 Plan on January 1, 2014 pursuant to the provision described in the preceding sentence.

Our 2012 ESPP authorizes the issuance of shares of common stock pursuant to purchase rights granted to our employees. The number of shares of common stock reserved for issuance automatically increases on January 1 of each year, from January 1, 2013 through January 1, 2022, by up to 1% of the total number of shares of the common stock outstanding on December 31 of the preceding year. The price at which common stock is purchased under the 2012 ESPP is equal to 85% of the fair market value of the common stock on the first or last day of the offering period, whichever is lower. Offering periods are six months long and begin on February 1 and August 1 of each year. As of December 31, 2013, we had 6,263,677 total shares of common stock reserved for issuance under the 2012 ESPP, excluding 1,403,546 shares of common stock automatically added to the 2012 Plan on January 1, 2014.

Stock Options

The stock options are exercisable at a price equal to the market value of the underlying shares of common stock on the date of the grant as determined by our board of directors or, for those stock options issued subsequent to our IPO, the closing price of our common stock as reported on the New York Stock Exchange on the date of grant. Stock options granted under our 2005 Plan and the 2012 Plan to new employees generally vest 25% one year from the date the requisite service period begins and continue to vest monthly for each month of continued employment over the remaining three years. Options granted generally are exercisable for a period of up to 10 years. Option holders under the 2005 Plan can exercise unvested options to acquire restricted stock. Upon termination of service, we have the right to repurchase at the original purchase price any unvested (but issued) shares of common stock.

A summary of the stock option activity for the year ended December 31, 2013 is as follows:



	Number of Shares		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2011	39,601,640		$	2.20
Granted	7,695,730		15.03
Exercised	(6,654,558	)	0.76			$	84,215
Canceled/forfeited	(4,527,352	)	3.35
Outstanding at December 31, 2012	36,115,460		5.05
Granted	2,339,523		38.07
Exercised	(12,951,123	)	3.34			$	446,054
Canceled/forfeited	(2,104,486	)	7.66
Outstanding at December 31, 2013	23,399,374		$	9.07	7.70	$	1,097,746
Vested and expected to vest as of December 31, 2013	22,304,397		$	8.71	7.73	$	1,054,997
Vested and exercisable as of December 31, 2013	9,333,628		$	4.43	7.30	$	481,448

Aggregate intrinsic value represents the difference between the estimated fair value of our common stock and the exercise price of outstanding, in-the-money options. The total intrinsic value of the options exercised was $2.4 million and $7.5 million for the six months ended December 31, 2011 and fiscal 2011, respectively. The weighted-average grant date per share fair value of options granted was $18.70, $7.68, $2.52 and $1.16 for the years ended December 31, 2013 and 2012, the six months ended December 31, 2011 and fiscal 2011, respectively. The total fair value of shares vested was $33.1 million, $19.2 million, $2.6 million and $2.0 million for the years ended December 31, 2013 and 2012, the six months ended December 31, 2011 and fiscal 2011, respectively.

As of December 31, 2013, total unrecognized compensation cost, adjusted for estimated forfeitures, related to unvested stock options was approximately $75.3 million. The weighted-average remaining vesting period of unvested stock options at December 31, 2013 was 2.62 years.

RSUs

Activity with respect to outstanding RSUs in the year ended December 31, 2013 was as follows:



	Number of Shares		Weighted Average Grant Date Fair Value (Per Share)		Aggregate Fair Value (in thousands)
Outstanding at December 31, 2011	—		$	—
Granted	1,470,072		17.02
Vested	—		—		$	—
Forfeited	(12,202	)	31.97
Outstanding at December 31, 2012	1,457,870		16.89
Granted	4,558,929		38.15
Vested	(322,623	)	15.15		$	13,510
Forfeited	(266,667	)	30.65
Outstanding at December 31, 2013	5,427,509		$	34.02	$	303,995
Expected to vest as of December 31, 2013	5,018,553				$	281,089

RSUs granted under the 2005 Plan and the 2012 Plan to employees generally vest annually over a four-year period. As of December 31, 2013, total unrecognized compensation cost, adjusted for estimated forfeitures, related to unvested RSUs was approximately $145.7 million and the weighted-average remaining vesting period was 3.51 years.