International Business Machines Corp. plans to move about 110,000 retirees off its company-sponsored health plan and instead give them a payment to buy coverage on a health-insurance exchange, in a sign that even big, well-capitalized employers aren't likely to keep providing the once-common benefits as medical costs continue to rise.

The move, which will affect all IBM retirees once they become eligible for Medicare, will relieve the technology company of the responsibility of managing retirement health-care benefits. IBM...