The United States Department of Justice has opened an antitrust investigation into UnitedHealth, the Wall Street Journal reports.

One focus of the investigation revolves around the relationship between UnitedHealthcare and Optum, an arm of United Health that owns healthcare provider groups. According to the Wall Street Journal, investigators are looking into the possible effects of the company’s doctor-group acquisitions on rivals and consumers.

Healthcare providers have expressed serious concerns about how UnitedHealth or other insurers could build a large physician network and use that as an unfair competitive advantage for its insurance business.

Glenn Melnick, PhD, a healthcare economist at the University of Southern California, told MedPage Today that the concern is that if an insurer can “get control of a local market’s physician supply, are they going to use that to disadvantage competing health plans?”

“I control all the docs in the county — I give myself a good price and I charge all the other plans 30% more,” he explained. “Within a couple years, their premiums are going to be way above mine, and I’m going to control the insurance market.”

Since Optum was established in 2011, the company has grown to become the largest employer of physicians in the United States. With 90,000 doctors in its network, it controls roughly 10% of the physician workforce.

The antitrust investigation is just one of more than a dozen investigations, audits or reviews that UnitedHealth is facing from U.S. authorities.

Time and time again, it appears United Healthcare is focused on padding the company’s profits — even if it threatens the quality of care that its customers receive.

Florida residents are counting on insurers like United to maintain a robust network pf physicians, including the life-saving services that anesthesiologists bring to the healthcare system. Doing otherwise can have dire consequences.