The CEOs United States House of Representatives Committee has rescheduled its congressional hearing including CEOs of tech giants Google, Facebook, Amazon and Apple for its ongoing competition probe to Wednesday, July 29.

The hearing which was earlier scheduled for July 27 will now take place on Wednesday, July 29, 12:00pm ET.

The hearing has been rescheduled due to scheduling conflict with a planned memorial service for late Rep. John Lewis who passed away on July 17, Axios reported.

The hearing on “Online Platforms and Market Power, Part 6: Examining the Dominance of Amazon, Facebook, Google, and Apple” will have Jeff Bezos, CEO, Amazon, Tim Cook, CEO, Apple, Sundar Pichai, CEO, Google and Mark Zuckerberg, CEO, Facebook as witnesses. They will testify as part of the Committee’s ongoing probe into competition in the digital marketplace.

“Given the central role these corporations play in the lives of the American people, it is critical that their CEOs are forthcoming. As we have said from the start, their testimony is essential for us to complete this investigation,” the Committee said in a joint statement.

It is likely to be a hectic day for Zuckerberg as Facebook is also set to report its quarterly earnings on the same day as the hearing.

The CEOs will be facing a barrage of questions as part of the antitrust probe, especially Amazon. The Amazon CEO had also been summoned for an investigation into its business practices and its treatment of its online sellers earlier in May following a report of unethical practices related to third-party sellers.

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