S-I/A subordinate to the preferred stock with respect to dividend rights and rights upon liquidation, winding up and dissolution of the Company. As of December 31, 2013 and 2014, there were 370.000,000 and 445,000,000 shares of common stock authorized for each period presented and 138.017.900 and 154.603,683 shares issued and outstanding, respectively. As of September 30, 2015 there were 445,000,000 shares of common stock authorized and 156.742,206 shares issued and outstanding. Common Stock Subject to Repurchase In 2011. the Company gave service providers the option of amending their existing stock option agreements to allow them to exercise stock options prior to vesting. This amendment was not considered to be a modification of a stock option F-36 Table of Contents( for accounting purposes. After the amendment was made, the Company offered this option to all new service providers that received stock option grants. The Company has the right to repurchase at the original purchase price any unvested (but outstanding) common shares upon termination of service of a service provider. The consideration received for an early exercise of a stock option is considered to be a deposit of the exercise price and the related amount is recorded as a liability. The liability is reclassified into equity on a ratable basis as the stock options vest. The Company has recorded a liability, in other current and other non-current liabilities, of $9.2 million as of December 31, 2014 for the 16,455,816 shares that were early exercised by service providers in 2011 through 2014 and initially subject to repurchase by the Company. Unvested shares of 2,465,866 at December 31, 2014 were subject to a repurchase right held by the Company at the original issuance price in the event the optionees' employment is terminated either voluntarily or involuntarily. The Company has recorded a liability, in other current and other non- current liabilities, of $3.5 million as of September 3