Microsoft's $13 billion investment in OpenAI is under scrutiny by EU antitrust regulators, who are considering an investigation to determine if the partnership restricts competition within the EU. While not currently investigated under EU merger rules, concerns exist about Microsoft's market power and potential distortion of competition. The European Commission is gathering evidence and has not yet decided to proceed with an investigation. Microsoft holds a non-voting position on OpenAI's board without owning any part of the company.