The chief executives of Google parent Alphabet Inc. /zigman2/quotes/202490156/composite GOOGL +0.80% /zigman2/quotes/205453964/composite GOOG +0.54% , Amazon.com Inc. /zigman2/quotes/210331248/composite AMZN +2.17% , Apple Inc. /zigman2/quotes/202934861/composite AAPL +1.26% , and Facebook Inc. /zigman2/quotes/205064656/composite FB +1.64% have agreed to testify before Congress on antitrust issues in late July, Rep. David Cicilline, D-R.I., chairman of the House Judiciary Antitrust Subcommittee, told tech journalist Kara Swisher late Wednesday. The office of Rep. Jerry Nadler, D-N.Y., confirmed the hearing with NBC News. Cicilline's office was not immediately available for comment. Amazon has previously said it would make CEO Jeff Bezos available to testify this summer. Facebook declined comment. Alphabet and Apple were not immediately available for comment. The four companies are the subject of investigations by the Department of Justice and Federal Trade Commission into their business practices and the substantial clout they wield over the tech industry and the economy.