//Periscope says users can now add up to three guests as voice call-ins to a stream, “like a talkshow”, and is working on letting the guests share video (Kris Holt/Engadget)

Periscope says users can now add up to three guests as voice call-ins to a stream, “like a talkshow”, and is working on letting the guests share video (Kris Holt/Engadget)

Slack says it has submitted a confidential draft IPO filing with the SEC  —  Slack confidentially filed to go public, according to a press release published Monday.  —  Slack is one of a number of tech IPOs expected in 2019, including Uber, Lyft and Airbnb.  —  Here is the full release from Slack: