A coalition of some of the largest labor unions in the US have formally petitioned the Federal Trade Commission to investigate Amazon for anticompetitive practices. The petition, filed Thursday, is a 28-page document with nearly 150 footnotes, and it asks the FTC to conduct a study exploring Amazon’s effects on the economy and whether the structure of its sprawling empire gives it unfair advantages in the marketplace.

The collective union members total more than 5.3 million. The groups participating include the International Brotherhood of Teamsters, which includes 1.4 million truck drivers and other transportation-related workers; the Communications Workers of America, a media labor union including millions of telecommunications and customer service workers; the United Food and Commercial Workers, the largest private sector union in the US; and the Service Employees International Union, which covers healthcare and certain private sector employees.

“The company demands urgent inquiry.”

“Amazon is unique, not only in its current size and growth trajectory, but in the breadth of its interests across markets and its expansion into all levels of the supply chain,” the petition reads. “The company demands urgent inquiry, best achieved through the Federal Trade Commission’s unique authority and expertise.”

The areas the union coalition want investigated include the extent of Amazon’s control over prices on its platform, the company’s search engine rankings with regard to the placement of its own products, Amazon’s use of data it obtains from competitors on its Marketplace and AWS cloud computing platforms, and the company’s impact on worker wages.

Amazon, unlike other big tech rivals, is not yet the subject of a specific investigation over antirust or anticompetitive behavior, although investigators last year began questioning Amazon Marketplace sellers over the company’s brand gating deal with Apple, among other potential violations.

Both Facebook and Google are currently under investigation by the US Department of Justice, which is looking into Google alongside all 50 state attorneys general, and the FTC, which is handling privacy and antirust investigations into Facebook. However, Amazon is still broadly in the crosshairs of federal investigators who have in the last couple of years decided to more closely scrutinize Big Tech in general, and Amazon was included in a new 10-year acquisition review the FTC launched earlier this month.