Former UnitedHealth Group chief executive officer Stephen Hemsley to replace Andrew Witty. Here's what we know.

The Wall Street Journal on Wednesday cited people familiar with the matter as saying that the probe has been ongoing since last year.

Key Takeaways Shares of health insurance providers tumbled on a report UnitedHealth Group is being investigated by U.S. officials over possible fraud.The Wall Street Journal said the Department of Justice was looking into the company's Medicare Advantage business.

Stephen Hemsley ran UnitedHealth Group for more than a decade. It's a different company after four years with Andrew Witty in charge.

Andrew Witty has resigned as chief executive of US health conglomerate UnitedHealth Group, as the company pulled its financial forecasts for 2025, adding to a sense of crisis after a turbulent period.