“One might wonder why consolidation among insurers did not allow them to resist the providers’ demand for increased payments. The simple answer is that there were two concentrated parts of the market and one fragmented part. The insurers had to choose between fighting a full-pitched battle with the providers or exploiting their own market power vis-à-vis the employers. Raising premiums to employers was a lot easier. In theory, employers could have demanded restrictive networks (at lower prices). But since everyone had agreed that employees did not like restrictive networks, and providers (especially hospitals) were not willing to discount much to get into such networks, there were not many available for purchase. Individual employers could not invent such a product; they could only shop around and find the relatively best deal by customizing other contract terms, such as cost sharing.”