Such a company simply wouldn't offer a group plan. Leaving aside the mandate to do so under health care reform, this would essentially transition away from employer-sponsored plans to individual plans, which strict regulation determining pricing of plans. Yes, there'd also have to be redistribution between insurance companies, or they'll just compete for the healthiest people, which is inefficient.And then comes the breakdown of that whole theory, as all the healthy single people opt out of the group plan, and the cost of the plan rises.