The Federal Trade Commission served civil investigative demands on six of the largest U.S. artificial-intelligence employers late Friday, formalizing a labor-market investigation that had been running on an informal footing since early March and converting it into the most substantial federal antitrust action against the sector since the agency’s 2024 inquiry into cloud computing.

The subpoenas, which were transmitted by the commission’s Bureau of Competition shortly before the close of business and confirmed by four people familiar with their contents, demand internal communications, compensation records, hiring committee minutes and recruiter correspondence going back to January 2024. They were directed at Microsoft, Alphabet, Amazon, Meta Platforms, OpenAI and Anthropic, the people said. A seventh demand, narrower in scope, went to the executive search firm Linden Strand, which has placed several of the senior researchers at the center of the agency’s interest.

The FTC’s general counsel, Rebecca Kelly Slaughter, said in a written statement that the commission was acting “to determine whether arrangements among dominant employers in the artificial-intelligence labor market have suppressed researcher mobility, restrained compensation below competitive levels, or otherwise harmed the workers and downstream consumers of an industry that increasingly shapes the American economy.” Slaughter said the demands were the product of “more than a year of careful staff work” and emphasized that no findings of wrongdoing had been made.

Spokespeople for Microsoft, Alphabet and Amazon declined to comment Friday evening. Meta said in a brief statement that it would “cooperate fully” with the commission and was “confident our hiring practices comply with the law.” OpenAI and Anthropic did not immediately respond to requests for comment. A spokesperson for Linden Strand confirmed receipt of the demand and said the firm intended to comply.

The action lands at a delicate moment for the industry. The collapse of the Sanders-Ocasio-Cortez moratorium in the House Ways and Means Committee on April 22 was widely read on Wall Street as the end of immediate federal regulatory risk for the largest AI firms, sending hyperscaler equity values to fresh highs and reigniting a bidding war for senior researchers that recruiters have described as the most overheated in two decades. Friday’s subpoenas, several lawyers said, complicate that narrative.

“The signal here is that the post-moratorium Washington story is not ‘AI is in the clear,’” said Margaret Hsu, a former deputy director of the FTC’s competition bureau now in private practice at the firm Levant & Roe. “It is ‘the venue moved.’ If you cannot get to these companies through energy and water concerns, you go through their labor market, and the labor-market case has been sitting in a drawer for a year because staff thought it was strong.”

People familiar with the FTC’s work said the agency’s theory has two prongs. The first concerns alleged “gentleman’s agreements” among senior hiring executives at three of the named firms, in which one or more of them are said to have committed informally not to make unsolicited offers to a small set of named researchers at peer companies. Career staff have collected at least nine recruiter affidavits attesting to specific instances in which offers were withdrawn or never extended after such conversations, two of the people said. The agency’s position, one of the people said, is that “an agreement does not need a handshake to be an agreement.”

The second prong involves non-compete and clawback clauses in researcher employment agreements that the staff considers unusually aggressive — in some cases, the people said, requiring repayment of signing bonuses if a researcher takes a position at any of a list of named competitors within 36 months of departure. Several lawyers said Friday’s subpoenas appeared timed in part to test whether existing case law can be used to reach the most egregious examples without a new rulemaking.

“This is a labor case dressed in antitrust clothing, and that is by design,” said Tariq Mansoor, a labor economist at the Roosevelt Institute who has written about concentration in technical labor markets. “The FTC has been clear since the start of the year that it sees AI labor concentration as a wage-suppression story. The post-moratorium environment gives them air cover that they did not have when the bill was live.”

The FTC’s two Republican commissioners, Andrew Ferguson and Melissa Holyoak, both issued separate statements Friday evening signaling skepticism. Ferguson said he had voted to authorize the demands “because the underlying conduct deserves scrutiny” but warned against “treating the artificial-intelligence sector as a special antitrust target on the basis of newspaper coverage and recruiter gossip.”

The political reaction was predictably split. Sen. Elizabeth Warren, who has pressed the agency for more than a year to act in the sector, called the demands “long overdue.” House Speaker Mike Johnson, in remarks to reporters at an event in Bossier City, Louisiana, said the inquiry “smells like the same regulatory overreach we just defeated in committee.”

Industry officials, speaking on condition of anonymity to discuss legal strategy, said the named companies were likely to challenge the breadth of the requests in court, particularly the demand for hiring committee minutes, which they maintain are protected by attorney-client privilege when in-house counsel was present. Two of the people said outside counsel had been engaged in the past 48 hours, suggesting the companies had received informal notice of the demands’ arrival.

The action also has implications for state-level moratorium fights in California, New York and Connecticut, where labor concentration has been a recurring theme in committee testimony. Aides to Gov. Gavin Newsom said Friday’s federal action was “directly relevant” to provisions of the California Senate bill that would require hyperscalers operating in the state to disclose compensation ranges.

Markets had closed before the demands were transmitted, but analysts at Cowen and at Bernstein circulated brief notes to clients calling the action “manageable in the near term” while flagging the possibility that a contested investigation could weigh on share-based compensation costs in 2027 and beyond.

The FTC has set a 60-day window for initial responses, the agency said. Slaughter declined in her statement to estimate how long the underlying investigation would take, saying only that the commission would proceed “as expeditiously as the record permits.”