Dropbox said to have filed confidentially for U.S. IPO Dropbox. Photo: Company portal Alex Barinka January 11, 2018 PremiumDropbox Inc., the file-sharing private company valued at $10 billion, has filed confidentially for a U.S. initial public offering, people familiar with the matter said. Continue reading this story with a subscription to DealStreetAsia. Subscribe Already a subscriber? Log in Should your colleagues be reading this article too? Contact us for corporate subscriptions at firstname.lastname@example.org.