5. Stock-Based Compensation

The Company accounts for stock-based compensation at fair value. The fair value of stock options is determined at the grant date using the Black-Scholes option pricing model. The fair value of restricted stock units (“RSUs”) is equal to the closing price of the underlying common stock on the grant date. The fair value of an award that is ultimately expected to vest is recognized on a straight-line basis over the requisite service or performance period and is classified in the accompanying condensed consolidated statements of operations and comprehensive income in a manner consistent with the classification of the recipient’s compensation. Stock-based awards to non-employee consultants are expensed at their fair value as services are provided according to the terms of their agreements and are classified in selling, general and administrative expenses in the accompanying condensed consolidated statements of operations and comprehensive income.

During 2012, the Company’s stockholders approved a stock incentive plan (the “2012 Stock Incentive Plan”) to provide stock-based awards, including nonqualified stock options, incentive stock options, restricted stock and other equity securities, as incentives and rewards for employees, consultants and non-employee directors. As of June 30, 2014, 13,416,019 shares of common stock were authorized for issuance as awards under the 2012 Stock Incentive Plan.

Members of the Company’s board of directors elected to receive a portion of their 2014 annual compensation in the form of equity awards, in an aggregate amount of approximately 112,000 stock options and 108,000 RSUs. These stock options and RSUs were granted in January 2014 and vest through the end of 2014, with 25% vesting on the last day of each calendar quarter. The estimated aggregate grant-date fair value of the stock options was $0.3 million. The estimated aggregate grant-date fair value of the RSUs was $0.7 million.

During the six months ended June 30, 2014, the Company granted approximately 878,000 stock options and 786,000 service-based RSUs to its employees. Employee stock options and service-based RSUs generally vest over a four-year service period with 25% vesting on the first anniversary of the grant date and the remainder vesting ratably on a quarterly basis thereafter. In March 2014, the Company awarded approximately 207,000 performance-based RSUs to the Company’s executives (the “March 2014 RSUs”). Vesting of these March 2014 RSUs is dependent upon the Company’s achievement of defined performance goals over a two-year measurement period. The number of March 2014 RSUs that will ultimately vest may range from 0% to 150% of the original grant based on the level of achievement of the performance goals. If the Company achieves the performance goals, 50% of the March 2014 RSUs will vest at the end of two years and the remaining 50% will vest at the end of the third year, subject to continued service. In June 2014, the Company awarded approximately 323,000 performance-based RSUs to its executives and employees (the “June 2014 RSUs”). Vesting of the June 2014 RSUs is dependent upon the Company’s achievement of defined performance goals for the 2014 fiscal year. The level of achievement, if any, of performance goals will be determined by the compensation committee. The Company expects this determination to occur in the first quarter of 2015. The Company records stock-based compensation expense related to performance-based RSUs when it is considered probable that the performance conditions will be met. The estimated aggregate grant-date fair values of the stock options, service-based RSUs, March 2014 RSUs, and June 2014 RSUs granted during the six months ended June 30, 2014 were $2.5 million, $5.1 million, $1.3 million, and $2.6 million, respectively.

In June 2014, the Company granted 45,000 stock options to non-employee consultants. The stock options granted to consultants are generally subject to service vesting and vest quarterly over a two-year service period. The fair value of the consultant options is the then-current fair value attributable to the vesting portions of the awards, calculated using the Black-Scholes option pricing model. The estimated aggregate grant-date fair value of the stock options granted to non-employee consultants during the three months ended June 30, 2014 was $0.2 million.