NATIONAL BUREAU OF ECONOMIC RESEARCH
NATIONAL BUREAU OF ECONOMIC RESEARCH

Paying a Premium on Your Premium? Consolidation in the U.S. Health Insurance Industry

Leemore Dafny, Mark Duggan, Subramaniam Ramanarayanan

NBER Working Paper No. 15434
Issued in October 2009
NBER Program(s):   HC   IO   PE

We examine whether and to what extent consolidation in the U.S. health insurance industry is leading to higher employer-sponsored insurance premiums. We make use of a proprietary, panel dataset of employer-sponsored healthplans enrolling over 10 million Americans annually between 1998 and 2006 to explore the relationship between premium growth and changes in market concentration. We exploit the differential impact of a large national merger of two insurance firms across local markets to estimate the causal effect of concentration on market-level premiums. We estimate real premiums increased by approximately 7 percentage points (in a typical market) due to the rise in concentration during our study period. We also find evidence that consolidation facilitates the exercise of monopsonistic power vis a vis physicians, whose absolute employment and relative earnings decline in its wake.

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This paper was revised on December 5, 2011

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Document Object Identifier (DOI): 10.3386/w15434

Published: Leemore Dafny & Mark Duggan & Subramaniam Ramanarayanan, 2012. "Paying a Premium on Your Premium? Consolidation in the US Health Insurance Industry," American Economic Review, American Economic Association, vol. 102(2), pages 1161-85, April. citation courtesy of

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