(Adds detail on direct listing, context with Uber)
NEW YORK, May 13 (Reuters) - Slack Technologies, the owner of a popular workplace instant messaging app, plans to go public on June 20, the company said on Monday, a test of investor appetite for loss-making technology stocks in the wake of Uber Technologies Inc's underwhelming market debut.
The date could still be subject to change, Jesse Hulsing, Slack vice president of investor relations, told an investor event, which was streamed via webcast.
Uber shares fell as much as 10% on Monday, more than doubling their losses since the ride-hailing giant's poorly received Wall Street debut last week and raising more questions about investors' faith in its ability to make profits.
Slack reported losses from operations of $143.85 million for 2018, a fraction of the $3 billion lost from operations by Uber in 2018.
San Francisco-based Slack is seeking to go public via a direct listing instead of an initial public offering (IPO), which has been the traditional route to the public markets for companies like Google parent Alphabet, Facebook Inc and Uber.
Music streaming app Spotify Technology SA last year went public via a direct listing. Unlike a traditional IPO in which companies sell shares to raise proceeds, a direct listing is purely a way for existing shareholders to sell stock.
Slack expects to trade on the New York Stock Exchange under the symbol "SK".
(Reporting by Joshua Franklin in New York Editing by Nick Zieminski)