In 2020, Slack accused Microsoft of abusing its dominance by forcing users to install Teams alongside its Microsoft and Office 365 software packages, limiting users' ability to uninstall it. This practice allegedly disadvantaged Slack, which offers a modular communication platform that integrates with various third-party applications, unlike Microsoft's bundled approach.

The European Commission has now initiated an investigation into these claims, which could lead to significant implications for Microsoft's business practices. The case hinges on defining the relevant markets for productivity software and communication tools, which is crucial for establishing whether Microsoft has engaged in abusive tying practices.

Concerns have been raised about potential foreclosure in the communication tools market and the deterrence of new entrants in both the tying and tied product markets. The investigation will require a thorough analysis of the competitive effects of Microsoft's practices, particularly in light of the complexities involved in the current market dynamics.

Microsoft has announced changes to its distribution strategy, including offering unbundled versions of its software at reduced prices and enhancing interoperability with third-party solutions. However, these changes may not adequately address the competitive harm alleged by Slack, and the Commission must carefully scrutinize them before deciding whether to continue the investigation.

The outcome of this case could set important precedents for future tying and bundling practices in the tech industry, depending on the evidence of anti-competitive effects and the nature of Microsoft's software offerings.