Slack generated more than $400 million in revenue in fiscal 2019, up 82 percent year over year, according to a regulatory filing Friday. It also posted more than $138 million in losses. (Noah Berger/AFP/Getty Images)

Office messaging platform Slack is on the verge of becoming a publicly traded company, the latest in a series of highly anticipated IPOs from multibillion-dollar start-ups.

Slack generated more than $400 million in revenue in fiscal 2019, up 82 percent from the year prior, according to a Friday filing with the U.S. Securities and Exchange Commission. The company still is not profitable, posting more than $138 million in losses. The company said investments to expand its operations are driving the losses.

In an unusual move, Slack will bypass many of the steps in a traditional Wall Street public offering. It will conduct what’s known as a direct listing, in which early investors and employees can sell existing shares to the public. Slack won’t be launching a typical “roadshow” with underwriters trying to persuade big institutional investors to buy in. Instead, the company said it will host an investor day with a digital presentation that will be publicly available.

The alternative route to the public market can save companies money by minimizing the role investment banks play in an IPO. It also frees employees to sell their stock immediately; many workers with equity in a company are typically barred from selling their shares for at least 180 days after an IPO. In addition, a company that is already well capitalized may not need to raise money through a traditional IPO, which involves issuing new shares to investors.

A direct listing does come with risks, however. It’s unclear how many of Slack’s early investors will sell their shares, or what the demand is for buying them. Slack said that a lack of trading information and investor awareness could lower the value of the stock or lead to volatility in what people are willing to pay for the shares.

The music streaming service Spotify went public last year through a direct listing, in what was widely seen as a successful debut.

Slack, expected to go public in the coming months, will follow the ride-hailing giant Uber, which is slated to go public in May.

More than 600,000 organizations use Slack, adding up to more than 10 million daily active users. More than half of the people on Slack are located outside the United States.

The company describes its messaging service in simple terms, highlighting its potential as a next-generation communication tool with broad appeal.

“The most helpful explanation of Slack is often that it replaces the use of email inside the organization. Like email (or the Internet or electricity), Slack has very general and broad applicability. It is not aimed at any one specific purpose, but nearly anything that people do together at work.”

Slack counts more than 88,000 paying customers, including 65 companies in the Fortune 100, according to the filing. But the bulk of its customers — 500,000 organizations, or more than 80 percent of its customer base — are on the company’s free subscription plan.

Subscriptions are Slack’s primary source of revenue. Companies pay based on the number of people who use the software, on a monthly or annual basis, the filing said. In broad terms Slack described the organizations that use it as accountants, customer support reps, journalists and salespeople, among many others. Collectively, users are on Slack more than 50 million hours in a given week.

The messaging company touts the platform’s ease of use and contends it’s better than email as a selling point. “People love using Slack and many become advocates for wider use inside of their organizations,” the filing said. “They also tend to recommend Slack when they switch jobs or join organizations that are not yet using Slack.”

These recommendations across organizations are driving its growth, Slack said, and the type of customer evangelism associated with the service is unusual for software that people use at work.

On the private markets, Slack is valued at just under $17 billion, according to CNBC. Last summer, during its latest funding round, the company had a $7.1 billion valuation.

Slack stock will be divided into two classes, A and B. The Class B shares, currently held by 435 stockholders, will have a super-voting power of 10 votes per share. Class A stock will have one vote per share.

The Slack filing lists Accel as its largest shareholder at 24 percent, holding nearly 120 million shares in the company. Andreessen Horowitz owns 66.5 million shares, about 13.3 percent. Social Capital’s share is 10.2 percent, followed by SoftBank at 7.3 percent. Slack co-founder and chief executive Stewart Butterfield owns 8.6 percent of the company. Slack director Andrew Braccia of Accel is listed as a 24 percent owner.

Slack is expected to trade on the New York Stock Exchange under the symbol SK.

Staff writer Thomas Heath contributed to this report.