Feb 28 (Reuters) - UnitedHealth Group shares fell more than 5% on Wednesday following a report that the U.S. Department of Justice has launched an antitrust investigation into the healthcare conglomerate.

At $485.98, more than $25 billion was set to be wiped out in market value, a day after about $11 billion was erased following the report from the Wall Street Journal just ahead of market close.

The report said investigators have in recent weeks been interviewing healthcare industry representatives in sectors where UnitedHealth competes, including doctor groups.

UnitedHealth is also grappling with the fallout from an outage since last week at its technology unit, Change Healthcare, due to a cybersecurity attack.

The company's shares were the biggest drag on the blue-chip Dow Jones Industrial Average on Wednesday. (Reporting by Christy Santhosh; Editing by Sriraj Kalluvila)