Slack’s (WORK) stock is open for trading.

Shares of the workplace messaging company opened at $38.50 Thursday on the New York Stock Exchange (NYSE). The stock ended the session at $38.62 by market close.

Wednesday evening, the NYSE set a reference price for Slack at $26.00 per share. The reference price was not an offering price from investors, as would be the case in a traditional initial public offering. Instead, it served as a starting point as broker-traders initiated buy-sell orders Thursday morning.

Slack is going public by way of a direct listing, meaning the company did not issue new equity, and employees and other private investors instead converted their stock into publicly tradeable shares. This also meant no fresh capital was raised ahead of Slack’s public listing.

The unusual go-public method – which is less costly for a company and less dilutive to existing shareholders – was also embraced by music-streaming platform Spotify (SPOT) last year.

Slack's opening share price gave it a market capitalization of $19.4 billion, based on Class A and Class B shares outstanding as listed by the company in a Securities and Exchange Commission filing Wednesday.

Last year, Slack was valued privately at $7.1 billion, and had raised more than $1 billion in total private funding since its founding in 2009.

Shares of Slack had traded in a range of between $21.00 per share and $31.50 per share in private transactions during the period of February 1 through May 30, the company said in its prospectus.

Slack is a cloud-based messaging platform that allows users to share files, create channels and chat instantaneously with team members around the world. It has marketed itself as a replacement for email.

The company boasted 10 million daily active users worldwide in its most recent fiscal year. More than half of its users are outside the U.S.

The vast majority of the 600,000 organizations on Slack’s platform are on a free version of the platform. The company generates a large portion of its revenue from a relatively small pool of companies paying high annual fees for use of the software.

As of January, 575 companies paid more than $100,000 per year to Slack, the company said in its prospectus. This was more than double the number from the year prior. These big-ticket customers comprised 40% of Slack’s $400.6 million in annual revenue for the year ending January 31.

Like many of its newly public peers, Slack is not yet profitable. Its losses, however, have remained relatively stable on an annual basis. Its net loss in its most recent fiscal year totaled $139 million, or slightly lower than the two fiscal years prior.