The European Union has warned X that it may calculate fines against the social-media platform by including revenue from Elon Musk’s other businesses, including Space Exploration Technologies Corp. and Neuralink Corp., an approach that would significantly increase the potential penalties for violating content moderation rules. Under the EU’s Digital Services Act, the bloc can slap online platforms with fines of as much as 6% of their yearly global revenue for failing to tackle illegal content and disinformation or follow transparency rules. Regulators are considering whether sales from SpaceX, Neuralink, xAI and the Boring Company, in addition to revenue generated from...