The Federal Trade Commission (FTC) reportedly launched an investigation to determine whether Amazon controls an inappropriately large share of the retail market.

Bloomberg News reported Wednesday that at least three merchants that sell products on Amazon’s platform have been contacted by FTC investigators who are reportedly seeking to determine how much of their business relies on Amazon’s services.

Representatives for Amazon and the FTC declined a request for comment from The Hill. The probe follows a similar investigation launched by regulators in the European Union in July.

Members of both parties in Washington have raised alarms about the growing dominance of tech companies in retail and other markets in recent months.

Treasury Secretary Steven Mnuchin called specifically for an antitrust probe of Amazon and other companies earlier this year.

“If you look at Amazon, although there’s certain benefits to it, they’ve destroyed the retail industry across the United States, so there’s no question they’ve limited competition,” Mnuchin said in July.

“There’s areas where they’ve hurt small businesses, so I don’t think this is a one-size-fits-all and I don’t have an opinion going other than I think it’s absolutely right that the attorney general is looking into these issues,” he added at the time.

A spokesperson for the Free & Fair Markets Initiative, a consumer watchdog focused on Amazon’s business practices, applauded news of the probe in a statement on Twitter.

“It is welcome news to see that regulators are finally getting serious about taking on the unfair advantage Amazon has staked out on its platform,” said Robert Engel, the group’s spokesman.