A court-appointed special master says the Justice Department hasn’t developed “any evidence” for key claims. Her recommendation now goes to a federal judge.

The case began with a whistleblower who said UnitedHealth bilked billions of dollars through the Medicare Advantage program.

The probe is analyzing the company’s practice of frequently logging diagnoses that trigger larger payments to its Medicare Advantage plans, according to a report.

The Wall Street Journal says the U.S. Justice Department in recent months has launched an investigation into UnitedHealth Group’s billing practices to see if the company fraudulently used diagnosis data to trigger extra Medicare Advantage payments.

U.S. Senator Chuck Grassley had demanded detailed information on UnitedHealth's Medicare billing practices, according to a letter sent to CEO Andrew Witty on Monday. Shares of the company fell 1.7% to $453.

UnitedHealth Group shares tumbled early Friday on a report that the U.S. Department of Justice has started an investigation into the health care giant’s Medicare billing practices.

The Department of Justice has reportedly launched an investigation into UnitedHealth Group's Medicare billing practices, adding to the scrutiny the company is facing.

The Iowa Republican’s letter to the company cites findings from a series of Wall Street Journal articles.