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Microsoft facing UK antitrust lawsuit from Slack over Teams ‘bundling’

By Thomson Reuters Apr 27, 2026 | 10:36 AM

LONDON, April 27 (Reuters) – Salesforce and its workspace messaging app Slack are suing Microsoft at London’s ​High Court over alleged ‌anticompetitive practices relating to its Teams app.

Slack Technologies LLC and related companies filed the lawsuit on April 23, which a ‌Slack ​spokesperson said was “because Microsoft’s ⁠practices harmed competition, ⁠using tying and bundling of Teams to limit customer choice”.

Microsoft did not immediately respond to a request ​for comment.

Slack had in 2020 complained to the European Commission, ⁠accusing Microsoft of ⁠bundling Teams with its Office ​product to gain an unfair advantage ​over rivals.

The U.S. software giant avoided ‌a potentially hefty fine by promising reduced prices for Office products excluding Teams in an agreement with ⁠the European Commission last year.

The filing of the lawsuit came in the same ⁠week that ‌London’s Competition Appeal Tribunal ⁠certified a mass lawsuit ​alleging ‌Microsoft overcharged British businesses to ​use Windows ⁠Server software on cloud computing services provided by rivals.

Microsoft disputes the allegations made in that case.

(Reporting by Sam TobinEditing by Tomasz JanowskiEditing by ​Tomasz Janowski)