Excerpt: This study makes use of a privately-gathered national database of insurance contracts agreed upon by a sample of large, multisite employers between 1998 and 2005. To gauge the competitiveness of the group health insurance industry, I investigate whether health insurers charge higher premiums, ceteris paribus, to more profitable firms. I find they do, and this result is not driven by cross-sectional differences across firms or plans: firms with positive profit shocks subsequently face higher premium growth, even for the same healthplans. Moreover, this relationship is strongest in geographic markets served by a small number of insurance carriers.

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