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

  • Leemore Dafny
  • Mark Duggan
  • Subramaniam Ramanarayanan

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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Paper provided by National Bureau of Economic Research, Inc in its series NBER Working Papers with number 15434.

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Date of creation: Oct 2009
Date of revision:
Publication status: published as 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.
Handle: RePEc:nbr:nberwo:15434
Note: HC IO PE
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  1. Steven T. Berry & Joel Waldfogel, 2001. "Do Mergers Increase Product Variety? Evidence From Radio Broadcasting," The Quarterly Journal of Economics, MIT Press, vol. 116(3), pages 1009-1025, August.
  2. Cotterill, Ronald W, 1986. "Market Power in the Retail Food Industry: Evidence from Vermont," The Review of Economics and Statistics, MIT Press, vol. 68(3), pages 379-86, August.
  3. Town, Robert, 2001. "The welfare impact of HMO mergers," Journal of Health Economics, Elsevier, vol. 20(6), pages 967-990, November.
  4. Alan T. Sorensen, 2003. "Insurer-hospital bargaining: negotiated discounts in post-deregulation connecticut," Journal of Industrial Economics, Wiley Blackwell, vol. 51(4), pages 469-490, December.
  5. Wholey, Douglas & Feldman, Roger & Christianson, Jon B., 1995. "The effect of market structure on HMO premiums," Journal of Health Economics, Elsevier, vol. 14(1), pages 81-105, May.
  6. Borenstein, Severin & Rose, Nancy L, 1994. "Competition and Price Dispersion in the U.S. Airline Industry," Journal of Political Economy, University of Chicago Press, vol. 102(4), pages 653-83, August.
  7. Capps, Cory & Dranove, David & Satterthwaite, Mark, 2003. " Competition and Market Power in Option Demand Markets," RAND Journal of Economics, The RAND Corporation, vol. 34(4), pages 737-63, Winter.
  8. McClellan, Mark & Cutler, David & Newhous, Joseph P., 2000. "How Does Managed Care Do It?," Scholarly Articles 2643884, Harvard University Department of Economics.
  9. Moriya, Asako S. & Vogt, William B. & Gaynor, Martin, 2010. "Hospital prices and market structure in the hospital and insurance industries," Health Economics, Policy and Law, Cambridge University Press, vol. 5(04), pages 459-479, October.
  10. Evans, William N & Froeb, Luke M & Werden, Gregory J, 1993. "Endogeneity in the Concentration-Price Relationship: Causes, Consequences, and Cures," Journal of Industrial Economics, Wiley Blackwell, vol. 41(4), pages 431-38, December.
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