Shares of UnitedHealth Group (UNH) slumped 16% in intraday trading Thursday, leading S&P 500 decliners, on a report that the U.S. Department of Justice is investigating the embattled health insurance provider for possible criminal Medicare fraud.

Citing people familiar with the matter, The Wall Street Journal reported that the healthcare-fraud unit of the DOJ's criminal division is overseeing the probe, which is focused on the company's Medicare Advantage business.

The investigation has been active "since at least last summer," the Journal said, adding that the DOJ's "criminal healthcare fraud unit focuses on crimes such as kickbacks that trigger higher Medicare or Medicaid payments."

The news comes two days after UnitedHealth Group shares 澳洲幸运5官方开奖结果体彩网:plummeted 18% after CEO Andrew Witty stepped down and▨ the෴ firm suspended its 2025 outlook. Shares are down nearly 40% this year entering Thursday.

UnitedHealth Group denied the report. "We have not been notified by the Department of Justice of the supposed criminal investigation reported, without official attribution, in the Wall Street Journal today," it said in a statement.

"We stand by the integrity of our Medicare Advantage program," the company added.

The DOJ didn't immediately respond to a request for comment.

UPDATE—May 15, 2025: This article has been updated to include the UnitedHealth Group denial and refreshed share prices.