8. Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit)

Redeemable Convertible Preferred Stock

        Upon closing of the Company's initial public offering, the 15,293,960 shares of issued and outstanding redeemable convertible preferred stock were converted into common stock. Each share of redeemable convertible preferred stock, shown as issued and outstanding in the table below, was converted into one share of common stock. The carrying value of the redeemable preferred stock at August 7, 2013 of $116.3 million was reclassified to common stock and additional paid-in capital.

        Redeemable convertible preferred stock consisted of the following at December 31, 2012 and August 7, 2013 (in thousands, except share data):

        Prior to their conversion, the Series A, Series B, Series C, Series D, Series E, Series F, Series G, Series G-1 and Series H redeemable convertible preferred stockholders were entitled to receive, when, as and if declared by the Company's Board of Directors, dividends at a rate of $0.21, $0.34, $0.44, $0.85, $0.91, $1.39, $0.74, $0.74, and $0.79 per share per year, respectively. To the extent that additional dividends were declared by the Board of Directors, those amounts would have been distributed equally among the Preferred Stockholders and common stockholders. As of December 31, 2013, no dividends had been declared by the Board of Directors.

Warrants to Purchase Stock and Preferred Stock Warrant Liability

        Warrants to purchase common and preferred stock are summarized in the following table:

        Upon the closing of the Company's initial public offering, warrants to purchase 723,901 shares of the Company's common and preferred stock were net exercised, and the Company issued 293,232 shares of common stock to the holders of the warrants.

        In 2009, the Series G-1 investors received warrants to purchase 182,666 shares of Series G-1 redeemable convertible preferred stock at a price of $9.26 per share. The warrants became immediately exercisable upon the closing of the Series G-1 financing and the fair value of $0.4 million was recorded as a liability with the offsetting charge to expense. Because the holders of the preferred stock were able to elect to redeem the shares for cash, the Company's outstanding preferred stock warrants were classified as liabilities and were revalued at the end of each reporting period using the Black-Scholes option-pricing valuation model. Changes in fair value were reflected in the Company's statements of operations as other income or expense. Upon the effective date of the Company's initial public offering, the Company adjusted the liability based upon the offering price of $16.00 per share. During the years ended December 31, 2012 and 2013, the change in fair value for the redeemable preferred stock warrant liability of $0.3 million and $0.7 million were recorded to other expense.

        As discussed above, upon the closing of the Company's initial public offering, the warrants to purchase shares of the Company's redeemable convertible preferred stock were net exercised. Of the 293,232 shares issued, the Company issued 76,964 shares of common stock to the warrant holder of Series G-1 redeemable convertible preferred stock. The then-current aggregate fair value of the warrant liability of $1.3 million was reclassified from long-term liabilities to additional paid-in capital, a component of stockholders' equity, and the Company ceased to record any further periodic fair value adjustments relating to the warrant liability.

Stock Options

        In 2003, the Board of Directors adopted the 2003 Equity Incentive Plan (the "2003 Plan"), which provided for the granting of nonqualified and incentive stock options, stock appreciation rights, stock awards and restricted stock. Under the 2003 Plan, the Company was able to grant nonqualified and incentive stock options to directors, employees and non-employees providing services to the Company. On June 11, 2013, the Company's Board of Directors adopted the 2013 Stock Option and Incentive Plan (the "2013 Plan"), which was subsequently approved by the Company's stockholders. The 2013 Plan became effective as of the closing of the Company's initial public offering. To the extent that any awards outstanding under the 2003 Plan are forfeited or lapse unexercised subsequent to August 1, 2013, the shares of common stock subject to such awards will become available for issuance under the 2013 Plan. The 2013 Plan provides for annual increases in the number of reserved shares of up to 5% of the outstanding number of shares of the Company's Common Stock.

        A summary of stock option activity for the years ended December 31, 2011, 2012 and 2013 is presented below:

        The following table summarizes information about stock options outstanding and exercisable at December 31, 2013:

        The following table summarizes the aggregate intrinsic-value of options exercised, outstanding and exercisable (in thousands):

        The fair value of each option award is estimated on the date of grant using the Black-Scholes option-pricing model with the following assumptions:

        Total stock-based compensation expense has been classified as follows in the accompanying statements of operations (in thousands):

        At December 31, 2013, there was $7.2 million of total unrecognized compensation cost related to non-vested stock option awards that will be recognized over a weighted-average period of 2.9 years.