Dropbox has raised $325 million with the option to go for $450 million, according to a new SEC filing (hat tip to Fortune’s Erin Griffith for spotting it). Those figures are sort of in line with January estimates that the company had raised about $250 million, with an upside limit of $400 million for an overall valuation of $10 billion.
Update: Fortune updated the story to say Dropbox has, in fact, raised $350 million in this round, for a $10 billion valuation, figures Dropbox confirmed for re-Code. It’s unclear if Dropbox will pursue the full $450 million.
San Francisco-based Dropbox is a huge hit with consumers who want to share and sync their files across devices and store them in the cloud. Last fall the company said it had more than 200 million users, although it always declines to say how many of them use the paid version of the service as opposed to the free version.
Dropbox also claims that 4 million businesses use its service, but again hasn’t broken out how many of those are using the fee-based Dropbox for Business, which competes with Box and a raft of other business-focused cloud storage and file-sharing companies.
To draw more paying business customers, the company will likely have to fill in some security and compliance check boxes. As easy to use as Dropbox is, the perception — and Dropbox execs would argue that it’s purely perception — that the service is not suited for use in security conscious companies could hurt adoption.
This story was updated at 12:50 p.m. PDT to reflect the total $350 million funding number.