Slack plans to go public. The company behind the popular workplace chat app filed with the Securities and Exchange Commission today, revealing plans to list on the New York Stock Exchange under the symbol “SK.” In an unusual move, the public offering won’t raise money for Slack; it’ll just allow existing shareholders to begin selling their stock.

In its filing, Slack reported rapidly growing revenue, to $400.6 million from $105.2 million over the past three fiscal years. The company has been losing money all this time, but its losses are shrinking, albeit at a much slower rate, falling to $138.9 million in the most recent fiscal year from $146.9 million two years earlier.

Slack has 10 million daily users who are split across more than 600,000 organizations that use its app. Of those, the vast majority — more than 500,000 — are using Slack’s free tier, an offering the company says is designed to convince organizations to eventually start paying. There are around 88,000 paying organizations as of January 31st, up from 59,000 a year earlier.

The filing also lists the potential risks Slack faces, with one noting the particular threat posed by hackers. Because Slack’s software holds an immense deal of sensitive communications, any sort of breach could reflect poorly on Slack. “Despite significant efforts to create security barriers to such threats, it is virtually impossible for us to entirely mitigate these risks,” the company writes. The company mentions having suffered a security breach that exposed private information in 2015.