Slack on Monday announced it had confidentially filed to go public.

The company is backed by venture-capital firms like Kleiner Perkins, Andreessen Horowitz, and Accel, as well as SoftBank.

It was most recently valued at $7 billion in 2018.

Slack, one of the most hotly anticipated IPOs of 2019, announced Monday that it had confidentially filed to go public with the Securities and Exchange Commission.

The company, which sells an enterprise collaboration and chat platform, joins the ranks of Silicon Valley unicorns including Lyft, Uber, and Zoom that could make history as the largest cohort of multibillion-dollar privately funded companies to hit the public markets.

Slack was most recently valued at $7 billion in 2018. It's backed by famed venture-capital firms such as Kleiner Perkins, Google's GV, SoftBank, Accel Partners, and Andreessen Horowitz.

All together, the company raised $1.2 billion in capital, according to PitchBook.

Slack started as a gaming company

Slack was founded in 2013 by Stewart Butterfield and Cal Henderson out of a failed gaming startup called Tiny Speck. Butterfield had recently sold the photo-sharing company Flickr to Yahoo, and while Tiny Speck didn't take off, the pair found success with the chat platform the team used internally to communicate.

The company announced last week that it had 10 million daily active users. The company had about $900 million in cash on its balance sheet as of October, according to The Information.

While Slack's planned initial public offering is no surprise, the company's announcement comes in what some see as a narrow window of opportunity with the SEC. The regulatory body was closed for much of January as the result of the federal government shutdown, which meant companies that filed at the beginning of the year did not get feedback or move forward with the process.

While the SEC is now open, it's unclear whether it will stay open after February 15, since the government reopened with just three weeks of funding on January 25.

Here is the full statement:

Slack Technologies, Inc. today announced that it has confidentially submitted a draft registration statement on Form S-1 with the Securities and Exchange Commission (the "SEC") relating to the proposed public listing of its Class A common stock. The public listing is expected to take place after the SEC completes its review process, subject to market and other conditions.

This press release does not constitute an offer to sell or the solicitation of an offer to buy any securities. Any offers, solicitations or offers to buy, or any sales of securities will be made in accordance with the registration requirements of the Securities Act of 1933, as amended ("Securities Act"). This announcement is being issued in accordance with Rule 135 under the Securities Act.