The chief executives of Apple, Amazon, Facebook and Google testified about antitrust issues in front of a House Judiciary subcommittee on Wednesday. It was the highest-profile showdown to date in the increasingly fraught relationship between Washington and Silicon Valley, which could culminate in efforts to break up one, or more, of the companies. Dan was joined by subcommittee chair Rep. David Cicilline (D-R.I.) after the hearing ended to discuss what the committee learned, why he wanted the four CEOs to testify together, and which companies he thinks should be broken up.