2/24/2018 S-1 Table of Contents The information in this preliminary prospectus is not complete and may be changed. These securities may not be sold until the registration statement filed with the Securities and Exchange Commission is effective. This preliminary prospectus is not an offer to sell nor does it seek an offer to buy these securities in any jurisdiction where the offer or sale is not permitted. Subject To Completion. Dated February 23, 2018. Shares Class A Common Stock This is an initial public offering of shares of Class A common stock of Dropbox, Inc. Dropbox, Inc. is offering to sell shares of Class A common stock in this offering. The selling stockholders identified in this prospectus are offering to sell an additional shares of Class A common stock. We will not receive any of the proceeds from the sale of the shares being sold by the selling stockholders. We have three classes of authorized common stock, Class A common stock, Class B common stock, and Class C common stock. The rights of the holders of Class A common stock, Class B common stock, and Class C common stock are identical, except with respect to voting and conversion. Each share of Class A common stock is entitled to one vote per share. Each share of Class B common stock is entitled to ten votes per share and is convertible at any time into one share of Class A common stock. Shares of Class C common stock have no voting rights, except as otherwise required by law, and will convert automatically into Class A common stock, on a share­for­share basis, upon the conversion of all outstanding shares of Class B common stock into shares of Class A common stock. Following this offering, outstanding shares of Class B common stock will represent approximately % of the voting power of our outstanding capital stock. Prior to this offering, there has been no public market for the Class A common stock. It is currently estimated that the initial public offering price per share will be between $ and $ . We have applied to list the Class A common stock on the Nasdaq Global Select Market under the symbol “DBX”. We will be treated as an “emerging growth company,” as defined in the Jumpstart Our Business Startups Act of 2012, for certain purposes until we complete this offering. As such, in this registration statement we have taken advantage of certain reduced disclosure obligations that apply to emerging growth companies regarding selected financial data and executive compensation arrangements. See “Risk Factors” beginning on page 15 to read about factors you should consider before buying shares of our Class A common stock. Neither the Securities and Exchange Commission nor any other regulatory body has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense. Per share Total Initial public offering price $ $ (1) Underwriting discount $ $ Proceeds, before expenses, to Dropbox, Inc. $ $ Proceeds, before expenses, to Selling Stockholders $ $ (1) See the section titled “Underwriting (Conflicts of Interest)” for a description of the compensation payable to the underwriters. To the extent that the underwriters sell more than shares of Class A common stock, the underwriters have the option to purchase up to an additional shares from Dropbox, Inc. and the selling stockholders at the initial public offering price less the underwriting discount. The underwriters expect to deliver the shares against payment in New York, New York, on or about , 2018. Goldman Sachs & Co. LLC J.P. Morgan Deutsche Bank Securities Allen & Company LLC BofA Merrill Lynch RBC Capital Markets Jefferies Macquarie Capital Canaccord Genuity JMP Securities KeyBanc Capital Markets Piper Jaffray Prospectus dated , 2018 https://www.sec.gov/Archives/edgar/data/1467623/000119312518055809/d451946ds1.htm 2/235