Medicare Part D plans provide prescription coverage to millions of American seniors. This industry has seen much consolidation among providers in recent years. In “Heterogeneous Effects of Consolidation on Premiums in Medicare Part D,” Partner Nicholas Hill and Manager Mathis Wagner analyze the effect of the consolidation of standalone Part D plan providers on policy premiums, using variation in concentration induced by the 2011 merger between CVS and Universal American. Drs. Hill and Wagner find that markets that saw a significant increase in concentration also saw significant increases in premiums. See more here.