Mutual of Omaha has a history of closing a block of business and starting a new company at lower rates. Their history shows they do this about every 3-4 years, at least in many states.
Obviously a company makes more money when there are fewer claims. So for the first few years the people in a plan typically are young and/or healthy. As the plan "matures" there would be more claims since people tend to be sicker as they get older. So they close that company and start a new, fresh company and start over. They can then raise the rates to cover the claims knowing that many people are either too lazy, ignorant, or use lazy or ignorant agents to even check rates. This goes on and on.
I haven't used Mutual of Omaha in at least 10 years because of this. Unfortunately, other companies have learned from them and some are doing the same thing. You need a good agent to help you and review your plans annually so you can remain with as low a price as you can.
You can believe me or not. But this is what I've seen as an agent specializing in Medicare plans.
Rick