The Justice Department has opened a broad antitrust inquiry into whether Silicon Valley giants are unlawfully stifling competition.

The announcement under Attorney General William Barr confirms that Facebook, Google and Amazon are all in the crosshairs, significantly ratcheting up the pressure on Big Tech as lawmakers also conduct their own hearings into issues of privacy, hate speech and content moderation.

The review will examine the concerns that consumers, businesses, and entrepreneurs have expressed about "search, social media, and some retail services online," according to a department press release.

“Without the discipline of meaningful market-based competition, digital platforms may act in ways that are not responsive to consumer demands,” Assistant Attorney General Makan Delrahim of the Antitrust Division said in a statement. “The Department’s antitrust review will explore these important issues.”

It's not currently known how long the investigations will take, and it's possible some of the Justice Department's work could overlap with ongoing probes of Big Tech happening at the Federal Trade Commission.

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"There is no defined end-goal yet for the Big Tech review other than to understand whether there are antitrust problems that need addressing, but a range of options are on the table, the officials said. The inquiry could eventually lead to more focused investigations of specific company conduct," sources told The Wall Street Journal.

The Justice Department will also be seeking information from the public and other industry stakeholders who have direct knowledge about competition in online platforms.

The Justice Department is already at work examining these antitrust issues.

"It recently hosted a private presentation where officials heard from critics of Facebook, including academics, who walked through their concerns about the social-media giant and advocated for its breakup, according to people familiar with that meeting," the Journal reports.

As Fox News previously reported, the Justice Department has been examining whether Alphabet, which is the parent company of Google, is engaging in monopolistic practices. The Mountain View, Calif., company has also come under fire from conservatives who accuse it of being biased against them via Google Search and Google News. Google strongly denies any political bias in its products.

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The Federal Trade Commission announced Wednesday a historic settlement with Facebook that will force the company to pay a $5 billion fine and abide by new privacy regulations. Meanwhile, Amazon has been taken to task for its influence over third party sellers and dominance of e-commerce.

“I don’t think big is necessarily bad, but I think a lot of people wonder how such huge behemoths that now exist in Silicon Valley have taken shape under the nose of the antitrust enforcers,” Attorney General Barr told senators back in January. “You can win that place in the marketplace without violating the antitrust laws, but I want to find out more about that dynamic.”

After the announcement, shares of Apple, Amazon, Facebook and Alphabet were all down.

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