The Supreme Court decision Silicon Valley is reading

The ripples of the Supreme Court ruling in favor of American Express could be felt on the West Coast, with some arguing it would make it harder for antitrust enforcers to take on big online platforms like Google, Facebook and Amazon. Many of tech’s most profitable firms have created two-sided markets: Google and Facebook serve consumers on one side and marketers on another. Uber links up riders and drivers. Amazon serves customers and also the merchants who use its platform. All these situations make defining a monopoly more difficult. Justice Clarence Thomas agreed with a lower court that when making an antitrust call on a company that does transactions across a two-sided marketplace, you have to consider whether the whole enterprise is anticompetitive — not just one side of the market. (The case in question concerned American Express' policy discouraging merchants who tried to push customers to use cards with lower merchant fees.) But, Justice Thomas split up companies that create two sided markets into two categories, and only applied his analysis to one of them.