The mechanism is blunt: force AAPL to allow third-party app stores and direct sideloading on iOS, and you immediately impair the 15–30% commission the company extracts from every in-app purchase, subscription, and digital download on its platform. The EU's Digital Markets Act already compelled Apple to open iOS 17 to alternative distribution in Europe. Congressional bills — including the American Innovation and Choice Online Act and the Open App Markets Act — are pushing the same lever domestically. If a U.S. mandate lands, it does not just trim a revenue line. It attacks Apple's highest-margin business segment. Services, which includes the App Store, ran at gross margins estimated above 70% in recent filings — roughly double the margin of the iPhone hardware that made Apple famous. Every percentage point of commission Apple concedes, or every developer that routes around the App Store entirely, is a hit to the margin profile that Wall Street has spent years re-rating the stock around.