Dropbox Files for I.P.O., and Other ‘Unicorns’ Are Watching

Dropbox, an online file storage company that has ranked among Silicon Valley’s highest-valued privately held start-ups, filed paperwork to sell its shares to the public, heralding a potential wave of other such initial public offerings.

In a filing with the Securities and Exchange Commission on Friday, Dropbox said it planned to raise up to $500 million in the offering, and intended to use the money for a variety of purposes, including potential acquisitions. Dropbox was last valued by private-market investors at about $10 billion.

Drew Houston, chief executive of Dropbox, helped found the company in 2007, initially naming it Evenflow after the song “Even Flow” by the rock band Pearl Jam. His goal was to make it easier for people to gain access to all their digital information, including documents and photos, on any device, and to automatically keep all those files updated as they were modified.

Since then, Dropbox, which is based in San Francisco, has grown into one of the leading file-syncing services, though it faces stiff competition from Google, Microsoft and others. In its filing, Dropbox said it had more than 500 million registered users, more than 11 million of whom paid for the service.

While Dropbox still loses money, those deficits are narrowing. Last year, it lost $112 million, compared with $210 million the previous year. The company’s revenue rose to $1.11 billion last year from $845 million the year before.

Other unicorns — a term for start-ups that have been valued at more than $1 billion in the past by private investors — that may sell shares to the public in the future include Airbnb, Lyft and Uber.