Prairie State Energy Campus

A view of the outside of the Peabody Energy building in St. Louis.
St. Louis Public Radio

One of the nation's biggest coal producers says federal security regulators are investigating the company's role in development of a southwestern Illinois power plant.

St. Louis-based Peabody Energy Corp. says in its annual report that the Securities and Exchange Commission served the company with a subpoena last month requesting information and documents related to the Prairie State project.