People familiar with the situation said on Thursday that Microsoft is likely to be the subject of an EU antitrust inquiry as authorities increase their examination of its business practices in a case brought on by Salesforce’s Slack.

Slack filed a complaint with the European Commission last year, alleging that Microsoft had improperly incorporated Teams, a video and chat application for the office, into its Office product.

To capture a portion of the lucrative and quickly expanding workplace communication industry, Microsoft unveiled Teams in 2017.

Microsoft under the microscope

Slack pleaded with the EU competition watchdog to urge the American software behemoth to split Teams from the Office Suites and offer it separately at reasonable market rates.

According to the sources, the Commission sent out another round of questionnaires in October as a follow-up to those given out in October last year, indicating that the EU competition enforcer is laying the groundwork for launching a formal probe.

According to one of the sources, the Commission is looking at Microsoft’s integration and bundling again, but in greater depth this time. They are searching for information that will help them identify solutions. 

A second source said the Commission is laying the groundwork for a probe

Both the Commission and Microsoft, which was fined 2.2 billion euros in prior cases concerning so-called “tying” and other misconduct, declined to comment.

Three weeks ago, Microsoft failed to provide a remedy to the EU over its Activision deal. Nevertheless, the company said it would continue to work with the Commission to address marketplace concerns. Without concessions, other gaming sector giants fear that Microsoft will favor itself.

For instance, Sony fears that the Call of Duty game will be available on Xbox early, severely impacting its PlayStation base.