The CEOs of four of the world's most prominent tech corporations — Amazon, Apple, Facebook and Google — will convene Wednesday on Washington in a congressional hearing focused on various antitrust issues. The hearing was originally scheduled for Monday but the House confirmed Saturday that the hearing would be pushed two days.

The House Judiciary Committee will hear from Amazon's Jeff Bezos, Apple's Tim Cook, Facebook's Mark Zuckerberg and Google's Sundar Pichai. The four companies have a combined market cap of about $4.7 trillion. 

The antitrust subcommittee is investigating Amazon's treatment of third-party sellers, Apple's App Store policies, Facebook’s social media power after the purchase of WhatsApp and Instagram, as well as Google’s ad-market share. Results from the committee's investigation are expected to be released by early fall.

The companies have faced criticism for other reasons aside from possibly stifling competitions. Facebook has come under fire for its handling of misinformation and hate speech, while Amazon was scrutinized for warehouse-worker safety during the pandemic. 

Facebook on Friday agreed to pay a $650 million settlement stemming from a lawsuit surrounding its facial recognition technology and alleged privacy violations.

The CEOs will testify on a four-person panel and it will be the first time Bezos testifies before Congress.

There has been pressure on the federal government to crack down on powerful companies in the digital age. In February, House Judiciary Committee Chairman Jerry Nadler, D-N.Y., and Subcommittee on Antitrust, Commercial and Administrative Law Chairman David Cicilline, D-R.I., publicly denounced the New York District Court approval of the merger of Sprint and T-Mobile.

The tech hearing is scheduled for 12 p.m. ET on Wednesday.