The cuts will mean turmoil and confusion for many beneficiaries, as well as the risk of higher premiums, fewer benefits or both.

The massive insurer now expects to lose 550,000 Medicare Advantage members — roughly one-tenth its individual MA footprint — this year as a result of plan cuts.

Humana depends more than other insurers on revenue from Medicare Advantage, private versions of the government’s program for older and disabled people. Investors are concerned about the long-term results from the business as the government has lowered Humana’s quality ratings, called stars, that affect future payments.