Slack Technologies Inc. Chief Executive officer Stewart Butterfield took to Twitter on Wednesday afternoon to share new data about the rapid user growth the company is seeing as a consequence of the coronavirus pandemic.

Butterfield’s tweets came about a week after the Slack disclosed it had added paying 7,000 customers between Feb. 1 and March 17. The same day, Microsoft Corp. said its rival Microsoft Team service had gained 12 million active daily users in seven days.

Butterfield detailed that Slack’s new-customer count has since grown from 7,000 last week to more than 9,000 now. Usage is increasing in lockstep. The average number of messages sent per user is up 20%, according to the CEO, while the amount of time spent in Slack across its  entire installed base is now over a billion minutes per weekday.

“Meanwhile, existing customers are expanding. Enterprise deals are getting done. More new teams are signing up. More upgrading to paid plans,” Butterfield elaborated in a tweet.

But he cautioned investors that Slack likely won’t be capable of providing an accurate projection for how the coronavirus pandemic will affect its business, at least not anytime soon.  “We literally have no idea what is going to happen and neither does anyone else, really.” Butterfield wrote.

He explained that any expected growth in paying users would have to be weighed against a potential loss of existing customers. “In the worst-case scenarios many thousands of those would go out of business.”

Even so, Wall Street is betting that Slack’s user growth will offset the adverse effects. The team chat provider’s stock rose as much as 15% on Butterfield’s tweet thread and is still trading almost 9.8% higher.

The investor confidence around the growth of cloud communications software is lifting other stocks as well. Most notably, shares of video conferencing provider Zoom Video Communications Inc. are up more than 30% since the start of the year. In a related development, the U.S. Securities and Exchange Commission today suspended trading of a firm called Zoom Technologies Inc. that has seen its stock surge in recent weeks in apparent confusion over its name.

For providers such as Slack, the spike in users adopting their platforms could translate into a long-term revenue boost. A company that moves hundreds or thousands of employees’ communications to Slack to meet the need for remote working becomes less likely to switch to a different team chat service further down the road.

That also applies to Microsoft’s Teams. The company’s recent disclosure that Teams had gained 12 million users in a week suggests the service could be growing even faster than Slack, though it’s not clear if the numbers correspond to regular usage.

Photo: Slack