Shares were down as much as 20% in extended trading after it posted its latest results. For the fourth quarter, Slack posted revenue of $181.9 million versus an analyst consensus of $174.2 million. Its non-GAAP loss came in at 4 cents per share, versus a consensus estimate of a loss of 6 cents per share.
Slack's outlook for the current quarter was lighter than expected, however. The company expects revenue of between $185 million and $188 million, compared to an analyst consensus of $188.2 million.
Slack finished 2019 with 110,000 paying customers and 893 customers spending more than $100,000 annually, the company said.
"We continue to see significant momentum in our enterprise business and finished the year with 70 customers spending more than $1 million annually on Slack, up 79% year over year," said CEO Stewart Butterfield in a press release.
Shares of Slack were down almost 10% in regular hours trading amid the day's market rout. The stock has been dogged by questions of how well it can weather competition from major competitors such as Microsoft (MSFT) - Get Report.