CNN: Slack files antitrust complaint against Microsoft in Europe. “Slack is ratcheting up its battle with Microsoft, filing an antitrust complaint in the European Union against its rival. The company claims Microsoft (MSFT) is engaging in ‘illegal and anti-competitive practice of abusing its market dominance to extinguish competition’ by tying in its own communications platform, called Teams, to its popular Microsoft Office suite. Slack (WORK) says in its complaint Microsoft force-installs Teams for millions of people and blocks its removal.”