While it’s well known that some U.S. hospitals are more expensive than others, the rates health insurers actually negotiate with them have been shrouded in secrecy. Indeed, the prices that insurers have negotiated for the very same procedure (such as an MRI) at the same hospital vary dramatically. To save money, self-insured employers that are on the hook for these prices should find an insurer that has negotiated lower procedure prices. It’s not easy, but if they do their research carefully, the savings can be substantial.