On December 9, the Federal Trade Commission and almost all states filed bipartisan lawsuits accusing Facebook of anticompetitive behavior. Less than a week later, European policymakers introduced a competition law and new requirements for blocking online hate speech. On December 24, Chinese regulators opened an antitrust investigation into Alibaba after rejecting an IPO for Ant.

Antitrust and content moderation have been where technology companies are most vulnerable. Google, Facebook, Apple, Alibaba, Amazon, and other companies clearly dominate the online advertising, search, e-commerce, and app marketplaces, and have wondered whether they have inappropriately used their clout to buy rivals, their own Promote products in front of others and block rivals.

Companies are also scrutinizing how hate speech and other harmful online material can get into the offline world, leading to calls for better content control.

The antitrust push has intensified particularly in the USA, as pioneering lawsuits were filed against Google and Facebook last year. Republican and Democratic lawmakers have said they are drafting new antitrust, privacy and language regulations for Facebook, Google, Apple and Amazon. They have also proposed cutting a law protecting sites like YouTube, which Google owns, from complaining about content posted by their users.

“This is a monopoly moment. Not just for the United States, but for the whole world, “House Subcommittee on Antitrust Law Chairman David Cicilline, Democrat of Rhode Island, said in a statement. “Countries must work together to take over the monopoly power of the largest technology platforms and restore competition and innovation to the digital economy.”

Mr. Biden has also selected technology critics for key administrative roles. Tim Wu, a law professor who supports a breakup of Facebook, joined the White House last month, while Lina Khan, a law professor who had influence on antitrust law, was nominated for a seat on the Federal Trade Commission.