Shares of Humana and other health insurers fell Thursday after the Centers for Medicare & Medicaid Services said it plans to take a more "aggressive" approach to auditing Medicare Advantage plans.

The Trump administration plans to expand government audits of private Medicare health plans, adding more scrutiny to an industry that’s been a profit driver for insurers.

The Centers for Medicare & Medicaid Services May 21 announced it will immediately begin annual audits of all Medicare Advantage plans and work to clear a backlog of audits from 2018 through 2024.