Both IBM and Time Warner are transitioning their retirees into private health insurance exchanges, moves announced against the backdrop of the upcoming operation of the Health Insurance Marketplaces created by the Affordable Care Act (ACA).

Specifically, the two companies are planning to give retirees subsidies and/or options to purchase Medicare supplements on their own.

IBM has signed up with Extend Health, the country's largest private Medicare Exchange, to service its retirees' needs. Time Warner says it will make allocations to a Health Reimbursement Arrangement account so retirees can purchase what they need on an exchange, but does not specify any exchange by name.

If the moves are cost related, the companies are mum about it.

"IBM didn't make this change to save money — it does not reduce our costs," a spokesman said.

The shift "will ultimately be beneficial for all retirees by providing more choice of coverage … for, in many cases, a lower cost," reads a Time Warner announcement that was written by James Cummings, the company's senior vice president of global compensation and benefits.

Both changes take effect at the beginning of next year.