2/24/2018 S-1 Table of Contents Stock­based compensation The Company has granted RSUs to its employees and members of the Board of Directors under the 2008 Equity Incentive Plan (“2008 Plan”) and the 2017 Equity Incentive Plan (“2017 Plan”). The Company had two types of RSUs outstanding as of December 31, 2017: • One­tier RSUs, which have a service­based vesting condition over a four year period. These awards typically have a cliff vesting period of one year and continue to vest quarterly thereafter. The Company began granting one­tier RSUs under its 2008 Plan in August 2015 and it continues to grant one­tier RSUs under its 2017 Plan. The Company recognizes compensation expense associated with one­tier RSUs ratably on a straight­line basis over the requisite service period. • Two­tier RSUs, which have both a service­based vesting condition and the Performance Vesting Condition. The service­based vesting period for these awards is typically four years with a cliff vesting period of one year and continue to vest monthly thereafter. Upon satisfaction of the Performance Vesting Condition, these awards will vest quarterly. The Performance Vesting Condition is satisfied on the earlier of (i) an acquisition or change in control of the Company or (ii) the earlier of (a) six months after the Company’s initial public offering or (b) March 15 of the year following the Company’s initial public offering. Prior to August 2015, the Company granted two­tier RSUs under the 2008 Plan. The Company’s Board of Directors has approved the acceleration of the Performance Vesting Condition for two­tier RSUs, for which the service condition was satisfied as of December 31, 2017, to occur upon the effectiveness of its registration statement related to this offering. The last grant date for two­tier RSUs was in May 2015. As of December 31, 2017, all compensation expense related to two­tier RSUs remained unrecognized because the Performance Vesting Condition was not satisfied. At the time the Performance Vesting Condition becomes probable, the Company will recognize the cumulative stock­based compensation expense for the two­tier RSUs that have met their service­based vesting condition using the accelerated attribution method. If the Performance Vesting Condition had occurred on December 31, 2017, the Company would have recorded $415.6 million of stock­based compensation expense using the accelerated attribution method. As of December 31, 2017, 42.2 million two­tier RSUs were outstanding, of which 39.1 million had met their service condition. If the Performance Vesting Condition had been satisfied on these two­tier RSUs as of December 31, 2017, unamortized stock­based compensation expense of $5.6 million would be recognized over a weighted­average period of approximately one year if the requisite service is provided. See Note 11, “Stockholders’ Equity” for further discussion. Since August 2015, the Company has granted RSUs as the only stock­based payment awards to its employees, excluding to its co­founders, and has not granted any stock options since then. The fair values of the common stock underlying the RSUs were determined by the Board of Directors, with input from management and contemporaneous third­party valuations, which were performed at least quarterly. In December 2017, the Board of Directors approved a grant to the Company’s co­founders of restricted stock awards (“RSAs”) with respect to 22.1 million shares of Class A Common Stock in the aggregate (collectively, the “Co­Founder Grants”), of which 15.5 million RSAs were granted to Mr. Houston, the Company’s co­founder and Chief Executive Officer, and 6.6 million RSAs were granted to Mr. Ferdowsi, the Company’s co­founder and Director. These Co­Founder Grants have service­based, market­based, and performance­based vesting conditions. The Co­Founder Grants comprise nine tranches that are eligible to vest based on the achievement of stock price goals, or, each, a Stock Price Target. The Company estimated the grant date fair value of the Co­Founder Grants using a model based on multiple stock price paths developed through the use of a Monte Carlo simulation that incorporates into the valuation the possibility that the Stock Price Targets may not be satisfied. The average grant date fair value of each Co­Founder Grant was estimated to be $7.07 per share, and the Company will recognize aggregate stock­based compensation expense of $156.2 million over the requisite service period of F­11 https://www.sec.gov/Archives/edgar/data/1467623/000119312518055809/d451946ds1.htm 201/235

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