The department’s scrutiny comes after repeated attacks on the industry’s biggest names by Trump, who is more outspoken on antitrust than any president in possibly a century, said New York University law professor Harry First.

The president repeatedly accuses tech platforms of bias against conservative views, which the companies deny, while directing ire toward Amazon founder Jeff Bezos, threatening his company with antitrust enforcement and higher shipping fees.

The antitrust division is already taking steps in its inquiry, hearing out third parties who have complaints about competitive harm, according to the people. Its review will look at concerns raised by consumers, businesses and entrepreneurs about search, social media and online retail, according to the statement.

Amazon, Google, Apple and Facebook Inc. declined to comment on the Justice Department’s announcement.

Tech giants are separately contending with a broad investigation by the House antitrust panel led by David Cicilline, a Rhode Island Democrat. Cicilline on Tuesday accused Facebook, Google and Amazon of “evasive, incomplete, or misleading answers” when their executives testified before his committee last week.

“We should all welcome greater scrutiny of dominant online platforms,” he said after the Justice Department’s announcement. “Unfortunately, I don’t have a lot of confidence that Donald Trump’s Justice Department will put the interests of working people ahead of billionaires for a change.”

Still, the move was cheered by others.

“American consumers and news publishers desperately need high tech markets to be more competitive,” said Dina Srinivasan, a former digital advertising executive who wrote a paper titled “The Antitrust Case Against Facebook.”

“Increased competition will help to solve the systemic privacy problems that consumers face with companies like Google and Facebook,” she said.

While the Justice Department pursues its own review, FTC Chairman Joseph Simons earlier this year formed a task force to investigate conduct in the industry and review past acquisitions to determine whether mergers harmed competition.