6. Redeemable Convertible Preferred Stock

Prior to the completion of its IPO in September 2014 (Note 7), the Company had outstanding Series A, Series B-1, Series B-2, Series C, Series D-1, Series D-2, Series D-3 and Series E redeemable convertible preferred stock (collectively, the “Redeemable Preferred Stock”). The Company classified the Redeemable Preferred Stock outside of stockholders’ equity (deficit) because the shares contained redemption features that were not solely within the Company’s control. In connection with the closing of the Company’s IPO, all of the Company’s outstanding Redeemable Preferred Stock automatically converted into common stock on a 10.47-for-1 basis. No Redeemable Preferred Stock was outstanding as of December 31, 2014 or 2015.

In May and October 2013, the Company issued an aggregate of 56,892,391 shares of Series E redeemable convertible preferred stock to existing and new investors at $0.62398475 per share for gross proceeds of $35,500. The Company incurred issuance costs of $94 in connection with the sale and issuance of these shares of Series E redeemable convertible preferred stock which were immediately accreted to the carrying value of the Series E redeemable convertible preferred stock.