There is growing bipartisan concern over the power Silicon Valley’s oligopolies wield over American society. Amazon alone controls 72% of U.S. adult book sales, Airbnb accounts for a fifth of domestic lodging expenditures and Facebook accounts for almost three-quarters of social media visits. Just two companies, Apple and Google, act as gatekeepers to 99% of smartphones, while two others, Uber and Lyft, control 98% of the ride-share market in the U.S. Yet, for government to take robust antitrust action against Silicon Valley requires the kind of data it currently lacks: documenting the harm this market consolidation inflicts on consumers. A new RealClearFoundation report offers a look at how amending Section 230 of the Communications Decency Act to require platform transparency could aid such antitrust efforts.